Hypothetical assumption voiced on this forum was that sharpening towards the tip should use a combination of lifting and forward pivoting to maintain the contact with the stone at the same line.
It seemed logical because the belly upward curvature positions the knife tip closer to the support as compared to the heel, and shorter distance to the support increases the grinding angle and narrows the bevel; pivoting forward was assumed to compensate for that.
Practical trials showed this assumption was wrong, moreover, thicker long knives with little belly curvature require pivoting the tip towards yourself/support, i.e. opposite to the hypothetical assumption.
I used 3 knives:
Thin & long knife - 19cm Global chef knife 1.8mm thick at the heel and tapered to 0.6mm at the tip.
Thick & short knife - 9cm Linder knife 4mm thick at the heel and tapered to 1mm at the tip.
Thick & long knife - 18cm custom camping knife 4mm thick at the heel and tapered to 1mm at the tip.
(http://home.exetel.com.au/dropbox/1.JPG)
(http://home.exetel.com.au/dropbox/2.JPG)
Knives were mounted in the jig as shown by Jan in
http://forum.tormek.com/index.php?topic=2562.15
(http://home.exetel.com.au/dropbox/3.jpg)
This is a clever approach to avoid jig position effect on the bevel described in the Tormek Handbook p.53.
All knives were sharpened to included angle of 30 degrees by pulling across the stone WITHOUT pivoting, only lifting the handle of the knife as taper tells to maintain contact with the stone.
To help myself maintain the same blade position as the knife is pulled across the stone, I used Ken's idea of a laser to mark the initial line of contact, "LOC" in Elden's (kb0rvo) terms, as they discussed in http://forum.tormek.com/index.php?topic=2562.15
The same steps for all 3 knives:
- mark the bevel;
- set the 15 degree angle at the heel by manually rotating the wheel and checking the marking;
- sharpen from heel to the tip WITHOUT pivoting.
(http://home.exetel.com.au/dropbox/4.JPG)
(http://home.exetel.com.au/dropbox/5.JPG)
(http://home.exetel.com.au/dropbox/6.JPG)
(http://home.exetel.com.au/dropbox/7.JPG)
RESULTS
Thin & long chef knife - uniform bevel along the edge of 1.3mm.
Thick & short knife - uniform bevel along the edge of 2mm.
Thick & long camping knife - widening bevel, from 1.5mm at the heel to 1.8mm at the tip.
(http://home.exetel.com.au/dropbox/8.JPG)
(http://home.exetel.com.au/dropbox/9.JPG)
(http://home.exetel.com.au/dropbox/10.JPG)
For these knives no pivoting was needed, even for the last knife the difference was practically negligible.
The only explanation I can think of is contrary effect of taper and upward curvature:
Because of the taper contact with the stone extends and bevel widens.
However, the belly upward curvature brings the tip towards the support, increasing the grinding angle and thus compensating for the taper.
Note that curvature of the thin & long chef, and thick & long camping knife used in the trial is comparable.
And note the bevel widening towards the tip of the thick long knife, though slightly (by 0.3mm).
Following the same logic, a thick and long knife with little upward curvature, sharpened without pivoting, will have even wider bevel to the tip. Sashimi knives and pig stickers are good examples of such knives.
And true, look at the bevel widening to the tip in the next picture, also sharpened without pivoting; now there is almost 1mm difference between the heel and the tip.
(http://home.exetel.com.au/dropbox/11.JPG)
To produce a uniform bevel along the edge of this sashimi knife, I had to pivot the tip over 1 cm towards the support/myself.
CONCLUSION
Regular kitchen knives, as well as thicker but short knives do not require pivoting; lifting on the handle as taper tells is all you have to do.
Thick, long & narrow knives that are tapered towards the tip > 2mm, and have little upward curvature, require combination of lifting on the handle, and pivoting the tip towards yourself.
As a rough guide, you move the tip towards yourself about the same distance as the knife lifts over the edge of the stone, sort of translating the vertical movement into horizontal shift.
Knives with false edge require extra backward pivoting to increase grinding angle towards the tip (otherwise you'll grind it off).
With double edged knives and daggers, where you have to make two edges meet at the middle of the tip, as your grinding nears the tip, pivot the blade tip towards yourself , and stop grinding as the water flow reaches the very tip.
Quote from: wootz on September 03, 2015, 08:14:05 AM
Hypothetical assumption voiced on this forum was that sharpening towards the tip should use a combination of lifting and forward pivoting to maintain the contact with the stone at the same line.
It seemed logical because the belly upward curvature positions the knife tip closer to the support as compared to the heel, and shorter distance to the support increases the grinding angle and narrows the bevel; pivoting forward was assumed to compensate for that.
All knives were sharpened to included angle of 30 degrees by pulling across the stone WITHOUT pivoting, only lifting the handle of the knife as taper tells to maintain contact with the stone.
To help myself maintain the same blade position as the knife is pulled across the stone, I used Ken's idea of a laser to mark the initial line of contact, "LOC" in Elden's (kb0rvo) terms, as they discussed in http://forum.tormek.com/index.php?topic=2562.15
The only explanation I can think of is contrary effect of taper and upward curvature:
Because of the taper contact with the stone extends and bevel widens.
However, the belly upward curvature brings the tip towards the support, increasing the grinding angle and thus compensating for the taper.
Regular kitchen knives, as well as thicker but short knives do not require pivoting; lifting on the handle as taper tells is all you have to do.
Let me start with saying, excellent work and stating of your findings, Vadim.
After thinking about this for sometime, I want to express my opinion. I state it as opinion because I have not verified it with measurements. In order for the bevel "angle" to remain the same, contact between the grinding wheel and the knife edge will have to be maintained at the LOC (line of contact). Any deviation from the LOC will result in a change of bevel "angle". If one is to keep the "width" of one bevel face grind consistent as Vadim is striving to do, contact with the LOC will not be the proper approach for the entire blade, as he points out. To maintain the sameness of "width", one will have to vary sharpening procedures according to the knife.
The bevel angle can vary even if the same LOC is maintained. However, if you keep the knife edge the same distance from the universal support (US) then you are assured that maintaining the same LOC will maintain the same bevel angle. This is what Steve has taught us. The Tormek knife jig doesn't always keep the knife edge the same distance from the US. This is the case when the knife edge curves at the tip. Wootz has shown us this in some detail and explained that the compensation mechanisms don't always work the way you might think they would. I get around all these difficulties by not using the knife jig. I instead use a platform. Easier to set up and the same bevel angle is maintained regardless of blade tip curvature.
And even if you vary the LOC it is possible, although seemingly very difficult, to keep the same bevel angle.
Note that when using a platform you keep the LOC the same and you also keep the distance from the US to the knife edge the same. At all times. Regardless of how the blade is shaped.
Wootz, a nice piece of work. Thanks.
Thank you for your replies, guys.
Yes, this trial was all about handling Tormek standard setup with their knife jig.
In adapting my bench stone skills to recently acquired Tormek, I had to clear up the jig behavior for myself.
My past experience, and Steve's decades of sharpening, and everyone else's who sharpens freehand tells to keep the edge at the LOC.
However, when I clamped a Muela pig sticker into the jig, and sharpened at the LOC, the bevel I got was less than satisfactory; frankly, I ruined the knife tip.
It's in the first picture.
The pig sticker is 4.5mm thick at the heel.
I just had to resort to experimenting to sort this out, to save the pig sticker and my reputation.
The above trial helped me to understand that with thick & long knives taper comes into play, partly due to lever effect, and partly due to knife jig design discussed in http://forum.tormek.com/index.php?topic=2577.0
For these knives, pivoting the tip away from the LOC appeared to be the right technique when you use knife jig in Tormek standard setup.
It's the second picture, and I am happy with the result, and the Tormek.
(http://home.exetel.com.au/dropbox/at_LOC.JPG)
Sharpened at LOC
(http://home.exetel.com.au/dropbox/away_from_LOC.JPG)
Sharpened pivoting away from LOC
In that latter photo, Wootz, you can really see that the bevel doesn't have the same mirror finish as the rest of the knife surface. I wonder if the Japanese Waterstone (SJ) would produce something better.
As I've said before, when I grind with the standard SG grindstone carefully prepared fine and then polish on the honing wheel I see a surface with my 40X scope that has a mirror finish on the flat spots between the scratches. Without the scratches there would be a mirror finish, it seems, and I wonder if the SJ would remove these scratches.
Herman, the latter edge is after Japanese SJ.
The SJ definitely gives better result than going from a finely graded standard SG straight to the honing wheel.
I understand what you mean, and yes it is possible, but for the Japanese stone to hone out all SG scratches, I should have spent twice the time.
And the Japanese stone is most expensive, and soft and has to be declogged and trued frequently, wearing off quicker than any other stone.
So I limit knife processing on the SJ to acceptable minimum.
All my experience tells me that jump from finely graded standard SG stone to the 4000 grit SJ is way too much.
I have a dedicated SG stone which I grade only finely, and yet I wouldn't rate it at 1000 grit as the Handbook reads - I'd rate it at 600-800 grit.
And when you move the blade from that to the 4000 grit SJ, it's hard to level out all that bad scratches with this superfine stone.
Yet the Japanese stone definitely delivers more than the honing wheel, and for high end knives I cannot skip it.
I wish Tormek offered a dedicated waterstone of true 1000-1200 grit; using it after 220 grit, and then going from it to the 4000 SJ would be just perfect.
Ahhh. I see that now. There are some places where you've got all the scratches out. Like near the tip.
And getting that mirror finish may not be desirable for many or most applications. A knife cuts a lot of things better when it has a tooth. Those scratches make the knife behave like a saw, albeit on a microscopic scale.
Removing the burr is more important, and that is what the honing wheel does well.
Vadim, congratulations to your great contribution! :)
I just returned from my vacation in the Mediterranean and I was pleasantly surprised by your new thread.
I need some time to digest your contribution, because until now I never grinded a knife pivoting the tip towards myself.
Referring to your image below, I would like to ask you, how do you use the laser LOC to sharpen the tip without pivoting the knife?
Quote from: wootz on September 03, 2015, 08:14:05 AM
(http://home.exetel.com.au/dropbox/7.JPG)
I hope, I will come with some comments and geometrical considerations soon.
Jan
Nice looking sharpening job on the pig sticker dagger, Vadim. I agree that your method for that knife definitely looks nice. Have you measured the degrees of the bevel angle along the entire length of the blade after sharpening? Also, what is the width of the bevel face grind at the heel and the tip?
The thickness of the blade at the tip of the knife is quite thick because of the spine of the knife coming so close to the point of the knife. This would cause the width of the face bevel to become quite wide as your first picture of the knife shows.
Great job, Vadim!
Quote from: kb0rvo on September 15, 2015, 04:08:03 AM
Have you measured the degrees of the bevel angle along the entire length of the blade after sharpening?
Edge angle in the above 3 knives sharpened without pivoting is about the same +/- 2 degrees along the straight part and into the belly, then increasing by 6-13 degrees near the tip (included angle).
So, set at the heel to the included angle of 30 degrees, and sharpened without pivoting, it resulted in 34-42 degrees near the tip.
Bevel face width practically doesn't change from heel to the tip, while the bevel base thickness does increase at the tip.
Quote from: Jan on September 14, 2015, 05:46:00 PM
Referring to your image below, I would like to ask you, how do you use the laser LOC to sharpen the tip without pivoting the knife?
Hi Jan, just by eyeballing along the LOC and further to the staight part of the blade, kept them in line.
Quote from: wootz on September 03, 2015, 08:14:05 AM
Hypothetical assumption voiced on this forum was that sharpening towards the tip should use a combination of lifting and forward pivoting to maintain the contact with the stone at the same line.
It seemed logical because the belly upward curvature positions the knife tip closer to the support as compared to the heel, and shorter distance to the support increases the grinding angle and narrows the bevel; pivoting forward was assumed to compensate for that.
Practical trials showed this assumption was wrong, moreover, thicker long knives with little belly curvature require pivoting the tip towards yourself/support, i.e. opposite to the hypothetical assumption.
.
.
.
CONCLUSION
Regular kitchen knives, as well as thicker but short knives do not require pivoting; lifting on the handle as taper tells is all you have to do.
.
.
.
You can of course sharpen the tip by lifting the handle without pivoting the knife, but you will grind a smaller bevel angle, than at the straight part of the blade. This can be compensated by grinding the tip near to the support, which on the contrary will increase the bevel angle.
I made some geometrical estimations for the above described procedure. I assumed that the edge angle is 30 degrees, i.e. the bevel angle is 15 degrees and the stone diameter is 250 mm = 10 ".
1) When we omit to pivot the knife by some 45 degrees when grinding the tip, we will decrease the edge angle by more than 8 degrees.
2) When we grind the tip at a distance by some 9 mm = 0.35 " shorter to the support than the straight part of the blade, we will increase the edge angle by some 8 degrees.
So, the edge angle decrease caused by replacing pivoting by handle lifting, can be fully compensated by shifting the spot where we grind the tip near to the support.
In my thinking, to maintain constant bevel angle along the belly and the tip, it is more appropriate to pivot the knife so, that the edge meets the stone at the line of contact.
However, I can easily imagine that this concept may not work, when we need to maintain constant "width" of the bevel face along the whole blade, especially for atypical knifes.
Thanks again Vadim, for shearing your well documented practical trials!
As Goethe said, theory is grey, but the golden tree of life is green.
Jan
Hope you don't mind an "old thread" revival... (remember, I asked).... :) but there's a lot of good info in it.
First, a picture to refer to (you can click on it for a larger view)...
(https://thumb.ibb.co/gbqfga/IMG_0083.jpg) (https://ibb.co/gbqfga)
First thing I wanted to point out, that when pivoting the blade (1 & 2 in the picture),,, on smaller blades it won't necessarily allow the belly/tip area to reach the LOC... but will drop below it. So, length of the blade matters.
Second, depending on the setup, when you pivot the blade, you can actually "ride up" on part of the clamp (picture 3). Can be avoided, but something to watch for.
The main reason I brought this thread up though, is honestly, even after reading thru this and the other related thread referenced... I've never been totally convinced that the original intent of the knife jig was to pivot the blade... but to merely lift the handle to follow the belly to tip area. In part, based on Jeff Farris' video saying, lift don't rotate, (in fact he makes a point that pivoting is incorrect) and in part, it just doesn't seem a natural movement on many knives. I understand the purpose... pivoting makes an attempt to maintain the same LOC... so the angle will stay the same... but am not really convinced that the curve of the stop on the jig was designed for this. (I would swear that it wasn't even mentioned in the old manual... but maybe it's just Jeff's voice stuck in my head). :)
Lifting on the other hand, will also allow you to keep the same angle, depending on how you set up the clamp, (as seen in Jan's picture in this thread, although the pivot point would change), and to me, seems to be a more natural way to follow the shape of the knife when using the standard jig. I try to illustrate in pictures 4 & 5... that when you lift the handle, you also change the orientation of the bevel in relation to the wheel... so that the angle is no longer totally dependent on where it is on the wheel, but also includes the "side angle" of the bevel in relation to the wheel. Think of the extreme... if I stood to the side of the Tormek and sharpened a knife on top of and parallel to the wheel (doesn't have to be on top, but easier to visualize)... the angle would totally depend on the angle of the knife. So, when setting the knife in the jig, by adjusting the belly/tip area closer or farther from the pivot point of the jig, this angle can be altered so that, even by merely lifting the handle... the same (or at least similar) angle can be maintained throughout. So, if you clamp the blade where the handle is lifted higher to reach the tip, you increase the angle... and the opposite if you clamp farther away from the tip.
It seemed in reading thru this thread, that the main focus was keeping the angle the same based on the LOC... and not what I'm describing. And, obviously, I'm not saying pivoting doesn't work, (and it of course is the answer for freehanding where the blade is held level, or for Herman Trivilino's setup, etc.)... but I'm of the mind that with the standard jig setup, lifting the handle in many cases, may be the better option.
So, what say y'all? :)
Wootz,
I'm having trouble following your work. I think it would be good to create some language to describe what you are saying relative to movement.
Airplanes use the language of roll & yaw (http://visual.merriam-webster.com/transport-machinery/air-transport/movements-an-airplane.php ). That would work if you used them in terms of movement of the SVM-xxx knife jig, but that's just one option.
Your testing is very worthwhile & I want to understand it better so I can replicate you good learnings. I may not be the brightest crayon in the box, but I am smart enough to learn from my betters & elders.
Kind regards,
Rich
Cbwx, in my thinking grinding the edge of a blade is a trade-off between pivoting and handle lifting. In some situations raising the handle is enough in other situations pure pivoting is sufficient. In every day practice, I think, it is a combination of both.
Handbook picture shows pivoted blade and the text mentions rising the knife handle near the tip. ;)
Jan
To avoid pitching, you do not yaw, you roll.
See this video of Jeff Farris using the SVM-45 to sharpen a knife:
www.youtube.com/watch?v=fYURcwkKGPs
If the link doesn't work go to YouTube and search for "Jeff Farris Tormek knife".
He discusses this issue starting at about 5:45.
Now, I have found that if there's large curvature at the knife tip, like on a butcher knife, this technique doesn't work as well. You have to pay attention to where on the knife you attach the jig. The closer you get to the tip the more blunt the bevel angle. But as I said in my previous post I get around all these issues by using a platform jig. To me it makes all three of the Tormek knife jigs obsolete, and it's sure a heck of a lot cheaper, And it's faster, too. Faster, better, and cheaper; you get all three!
Herman,
You and I shar a common frustration: I honestly believe the kenjig and its variations are the most efficient, accurate and repeatable method of setting up the Tormek knife jigs (other jigs, too). I have long believed, just as fervently, that your small platform jig is one of the most useful and versatile jigs for the Tormek. Neither of us has made the slightest effort to conceal the secret sauce of these ideas, yet, neither idea has been generally accepted. (I might think that some of the sharpening community still believe the earth is flat, but that would not be polite to post)
Ken
ps. It has always been a mystery to me that, if following Jeff Farris' technique of lifting the knife rather than pivoting, why does the adjustable stop on the knife kig have a large radius? I hope one of the first videos produced in the new Tormek studio will be an in depth knife video addressing this issue and several other knife sharpening issues.
I do concede that the jigs radius may have been so that the knife could be pivoted (yaw) (although I feel in use it's more of an afterthought). :o
Setting that aside though, I think lifting (roll) can achieve the same result... and, to me anyway, fits the design/setup of the knife jig. (The Jeff Farris video is what I was referring to earlier). The change in angle by changing the point of contact on the stone, can be offset by the "side" angle you create by jig placement.
Herman, I have not overlooked your setup.... I think it's a good one, and will probably be my next venture. I do have a couple of questions... do you ever have an issue scratching/scuffing the side of the knife? With other platform based sharpeners, that's often the case, but it's also because the 'swarf' can get on the platform, which may not be an issue with the Tormek (since it's for the most part washed away). Also, when you set the angle, do you compensate for the angle of the blade itself? (Not the bevel, but the actual angle of the blade grind).
All in all, I think Wootz was onto something in his original post.. that pivoting the knife introduces more factors than merely maintaining the same point of contact on the stone... when using the jigs.
Here is a link to a video by Ken Schwartz. Ken is the guru who has concocted many of our best modern honing compounds. This video covers tipping a knife when the knife is not held level.
https://m.youtube.com/watch?v=JFhUXgYS0Os
I think the idea presented is very sound. I should note that essentially the same idea is presented by Steve Bottorff in his Sharpening Made Easy book.
I believe there are gains to be made in technique for sharpening knives with the Tormek, both with jigs and without.
Ken
Quote from: Ken S on August 11, 2017, 01:52:04 PM
It has always been a mystery to me that, if following Jeff Farris' technique of lifting the knife rather than pivoting, why does the adjustable stop on the knife kig have a large radius? I hope one of the first videos produced in the new Tormek studio will be an in depth knife video addressing this issue and several other knife sharpening issues.
Quote from: cbwx34 on August 11, 2017, 02:35:16 PM
I do concede that the jigs radius may have been so that the knife could be pivoted (yaw) (although I feel in use it's more of an afterthought). :o
Wootz has been striving to keep the width of the bevel face constant. He achieved this goal by lifting the handle without pivoting at the expense of maintaining constant edge angle. He admits that the edge angle set at the heel to 30° has increased to 34-42° near the tip!
I am convinced that using suitable trade-of between handle lifting and blade pivoting would not increase the edge angle so much.
The water flow over the edge is for me another reason to pivot the blade. When the blade is pivoted so that the outer normal of the blade in the belly area is perpendicular to the stone shaft, then the water flows symmetrically over the edge. This is good to achieve. My hands do it unconsciously.
Jan
Quote from: Jan on August 11, 2017, 04:07:11 PM
Wootz has been striving to keep the width of the bevel face constant. He achieved this goal by lifting the handle without pivoting at the expense of maintaining constant edge angle. He admits that the edge angle set at the heel to 30° has increased to 34-42° near the tip!
I am convinced that using suitable trade-of between handle lifting and blade pivoting would not increase the edge angle so much.
The water flow over the edge is for me another reason to pivot the blade. When the blade is pivoted so that the outer normal of the blade in the belly area is perpendicular to the stone shaft, then the water flows symmetrically over the edge. This is good to achieve. My hands do it unconsciously.
Jan
How so?.... If bevel width is the goal... I'm not sure either method would result in a better angle result... seems to me it would have to be the constant to keep the bevel width the same. (It's the same result you see on production knives... nice looking bevel, but steep angle, and most of those are freehand sharpened).
Although I primarily sharpen with the wheel turning away... I do use the water as an indicator of where the wheel & blade are contacting... I can do it with either method. Like you indicated, it's not the primary way though... you can usually feel it. But I can see the water 'travel' along the edge, especially as I lift the handle to the tip... good indicator of when it's reached.
Quote from: cbwx34 on August 11, 2017, 02:35:16 PMI do have a couple of questions... do you ever have an issue scratching/scuffing the side of the knife? With other platform based sharpeners, that's often the case, but it's also because the 'swarf' can get on the platform, which may not be an issue with the Tormek (since it's for the most part washed away).
Yes, although there was a forum member who claimed he didn't get scratches. I believe he must have used a much lighter touch, perhaps touching the platform but applying no force to, using it only as a guide to keep the angle constant. I found that the cheapest adhesive-backed felt, found in those fabric stores that sell sewing supplies, applied to the top of the platform works great.
QuoteAlso, when you set the angle, do you compensate for the angle of the blade itself? (Not the bevel, but the actual angle of the blade grind).
Yes. When the sides of the blade are not parallel, and you want to measure the angle using the WM-200 or the like, you do need to account for this. There is a post somewhere where I describe this. After setting the platform at the angle I want, I lay the knife blade on top of the platform again and measure the angle of the upper surface of the blade's side. For example, say the platform is set at 20° and the upper surface is at 24°. Half the difference is 2°, so if I want the bevel angle to be 20° I reduce the platform angle by 2°, setting it at 18°. Usually, though, I don't care about a 2° error.
Quote from: cbwx34 on August 11, 2017, 04:30:41 PM
How so?.... If bevel width is the goal... I'm not sure either method would result in a better angle result... seems to me it would have to be the constant to keep the bevel width the same. (It's the same result you see on production knives... nice looking bevel, but steep angle, and most of those are freehand sharpened).
Yes, the bevel width consistency is important, but the change of the edge angle from 30° at the heel to 42° at the tip is too large for me.
My point was, that the handle lifting accompanied by small pivoting may result in very small bevel widening (e.g. 0.25 mm = 0.01") while reducing the edge angle increase towards the tip substantially.
Jan
Herman, thanks for the additional info.
Jan, still don't see it, but I'll ponder your posts.
Ken, that video you linked to actually claims you can't just lift the handle without also pivoting the knife (around 3:42)... not a position I support.
Thanks to all. :)
On topic: I sharpened my first knife on the tormek this past week. Just a cheap paring knife with a thick blade that I use as a utility knife for small tasks, so i didn't mind grinding it different ways and multiple times as practice.
The way that ended up working the best for me (to get an even bevel width and look good) was both pivoting and lifting, but the key thing that made this work was the diagram found in the manual describing how far from the tip to place the jig (as seen in the attachment on this post (https://forum.tormek.com/index.php?topic=2562.msg13392#msg13392) from another thread)
Only in that position did the lift and pivot feel like one smooth motion and give good results from a visual standpoint.
A little less on topic, my 2 cents on the "issue" behind the original topic:
(grab a coffee and get comfy, or feel free to skip to the Cliffnotes at the bottom)
I've always been confused as to why anyone is concerned over even bevel width in the first place.
Does it look nicer? Sure. I guess this makes it good for your collectables/drawer queens/wall hangers.
Does it make for an optimal cutting tool? In some cases it may (either by pure luck, or by very careful design of a skilled knife maker), but I think in the majority of cases it won't.
That pig sticker, for example: the OP said the primary cutting surface measures around 30°, while the tip is up to 42°. In my opinion that could actually work too this particular knife's advantage. A double edged blade that is intended to stab/thrust/puncture should have a sturdier tip. The last thing you want is for the tip to be thinner, wedge in mid - penetration and snap off.
As long as the edges are good and sharp i don't think the bevel angle at the tip is all that important in that case. The rest of the knife that may be used for slicing tasks can focus more on ideal angles.
Compared to that "sashimi" knife (yanagiba), the idea of keeping an even bevel width wouldn't even cross my mind for a second. No way of knowing just from the picture if that was an even bevel angle all the way to the tip in this particular instance, but i've seen knives like this with even bevel angles that varied more than that in bevel widths. (now, on a single/chisel grind knife like that... whether that difference should be dealt with at the edge on a secondary bevel, as seen above, or on the shinogi during thinning.... Or even if a secondary bevel should exist in the first place.... Those are much more in depth discussions of their own)
In this case i feel that keeping a proper bevel angle is much more important, as it's intended for very delicate work and should perform equally from heel to tip.
Likewise, for a chef's knife/gyuto/kiritsuke/santoku, and in many cases paring/petty knives for general purpose kitchen use; I would focus on the bevel angle rather than bevel width on these as well.
In general I would be looking for an even bevel angle throughout. If not kept even, then I would be leaning towards more acute at the tips for more flexibility in delicate work. With most cutting it's rare for the actual tip to be hitting the cutting board anyway, so a more delicate tip shouldn't be an issue. That said, the user needs to be aware and keep it in mind during use.
On the opposite end of the spectrum: a Deba, which is designed for breaking down fish, actually is thicker at the heel by design. This is intentional to be sharpened at a more obtuse angle as you approach the heel. This gives you a heel that can chop bone, while the rest of the blade is better at slicing.
Now, at the risk of making this longer than anyone wants to read (if we're not there already ;D), everything above also assumes we're only dealing with perfectly straight knives that, if wider at heel or tip, have a consistent taper along the whole length.
Know where we see that most often? In mid-range production knives, the kind that are stamped then machine ground. And who usually owns those knives? People who don't care how perfect they look, who aren't likely to spend much on getting them sharpened, and probably own a cheap pull through sharpener, and maybe a honing rod.
But get into higher end knives, that are forged rather than stamped, quenched for heat treatment after shaping rather than heat treated then milled to spec in sheets, ground to final profile by hand.. Then you start seeing inconsistent thicknesses, spines that aren't dead straight, and over/under-grinding issues respectively.
And who most often owns these knives? People who care about function over form, who are willing to shell out this kind of money for a sharpening system, or who will spend $$$ on professional sharpening.....and these are also the kinds of people who will be picky about your results and the kinds of knives that will be expensive to replace if you screw them up...
That's not to say you won't see any or all of those issues in production knives, or that equal care shouldn't be put into sharpening the "cheapies".
I grabbed a handful of low-mid range knives and took some measurements the other day, measuring 1mm behind the blade (2mm on the thick knives where the bevel was longer than 1mm) to do some math. Even the production models showed varying thickness along the edge. Funny enough, the one with the most consistent thickness was the only handmade blade in the bunch.
It I were to focus on maintaining an even bevel width:
-A Kershaw Blur ranged from 0.58-0.51mm wide. If the bevel angle were set to 30° at the widest point then the narrowest point would taper down to 26.3°. If the angle were set at the narrowest point then the widest part of the blade would hit 34.23°.
Not too terrible, but I'd rather keep the same angle and let the bevel width change by 0.14mm
-A Cold Steel SRK ranged from 1.37-1.17mm wide. If the bevel angle were set to 40° at the widest point then the narrowest point would taper down to 33.97°. If the angle were set at the narrowest point then the widest part of the blade would hit 47.22°.
Here a consistent angle could have been held with the bevel width tapering from 1.71-2.0mm.
-An old EdgeMark hunter ranged from 0.62-0.37mm wide. If the bevel angle were set to 30° at the widest point then the narrowest point would taper down to 17.77°. If the angle were set at the narrowest point then the widest part of the blade would hit 51.4°.
Pretty nasty range on this one. Keeping a consistent angle here would still only mean a .54-.91mm bevel width, not a big deal IMO
-A CRKT SnapLock ranged from 1.74-1.36mm wide. If the bevel angle were set to 30° at the widest point then the narrowest point would taper down to 23.0°. If the angle were set at the narrowest point then the widest part of the blade would hit 39.77°.
This one was perhaps the most surprising, as the cutting area is only like an inch and a half long, and the edge itself is practically a straight line. And with this one, to keep a consistent angle, the bevel width would vary from 1.36-1.74mm. Not insignificant over that short length, but not terrible.
There were others, both better and worse, but that should give enough of an idea.
To summarize, my point is that there is no one right answer for how we can treat every type of knife. If the ideal end result can't be expected to be consistent between different styles of knives (not to mention the manufacturing or conditional inconsistencies), then there's no way a single jig setup could ever be achieved.
Either way, in my personal opinion they should all be sharpened for performance, not for looks.
Thanks for the info. (I survived the whole thing). :) Couple of thoughts/questions...
You said lifting + pivoting gave the best result... what differences did you see in that vs the other ways? You are right, regardless of method... the placement of the knife in the jig is key.
As for bevel width... I agree with what you said, about looks vs. performance, but in a commercial sharpening setup... looks probably take precedent in most cases. You're not going to convince most people (or even have the time to if you do a lot of knives) that the knife "looks funny, but will work better... honest". So, to some degree (pun intended), things need to look good.
I'll have to digest the numbers. Good documentation though... thanks.
Lol congrats. Even I had a hard time getting all the way through when proof reading back through it (to be honest, it was written over a few sessions)
If memory serves (forgive me, it was just the one session, with just one knife, and it was a few days ago), but i believe it was that just lifting the handle resulted in a more obtuse angle at the tip, as it rode down the stone. And just pivoting sideways would end up with a wide bevel earlier on, as I'd have to grind through the area in front of the tip before the tip would make contact
Yeah, i can see where a clean edge and an even bevel would be preferred on a fast paced setting for random customers, that's why i stressed it being my personal opinion.
I've had knives that could pass every sharpness test thrown at them, but couldn't cut a raw carrot without snapping it. But thin the blade profile down a bit on the whetstones, really ugly up the whole surface in the process, then resharpen and it cuts like a whole new knife :D
Others that could cut fine, but always "steered" into whatever you were cutting...change the bevel angle just a hair on one side of the blade and voila, even slices every time.
It's funny how much of a difference just a fraction of a mm can make in the way a knife performs, whether the adjustment is in the face or in the bevel angle (especially so on the single bevel knives)
Hello Ken, Jan, Herman, Rich and the new sharp guys.
Apologies for being offline for so long, was too busy establishing my knife grinding business.
Appreciate reviving my topic I wrote when was new to Tormek.
The main conclusion drawn from that little study is the contrary effect of the blade taper towards the tip and upward curvature:
Because of blade thinning towards the tip grinding angle drops and contact with the stone extends and bevel should widen. However, the belly upward curvature brings the tip towards the support, increasing the grinding angle and compensating for the taper, and therefore the bevel height doesn't noticeably change.
Thanks to that for knives with a normal sweeping curve, no need to pivot/yaw.
Both the Tormek manual section on knife grinding and Jeff Farris video are (...how to say) ...if you think they are right you are still about a dozen fucked up edges far from the right technique.
Hello Wootz, glad to have you back in the conversation :)
I don't know if you read my whole big long book there, but the main point/question of it was: which is the "f'ed up" edge? The one with the uneven bevel width, or the one with the uneven bevel angle?
Angle may not be so critical on a pocket/utilityknife, but in kitchen knives it can make a big differing in the way it cuts, that angle is far more important on some knives than the width is.
Particularly that single bevel yanagiba again. I know it's been ages since you sharpened that knife, but i would've loved to have known what the final bevel angles were after you "fixed" it by making the bevel width even.
(also curious if you did any work on the shinogi or if you only ground the cutting edge? Ideally you would want that to move up the side equally with the sharpening, to keep the geometry correct.....something that I doubt can be done on the tormek, I'm afraid)
My guess is that if the main body of the blade allowed for nice, even cuts....I bet it steers into the food once it gets to the tip area with the more obtuse angle.
In case the wording is unfamiliar, by steering i mean; imagine slicing a large potato, as if you were going to make chips. With a properly 'tuned' knife (be it a a well performing single bevel (100/0) or asymmetric (90/10), or a symmetric ground (50/50) edge) you will get straight cuts of even thickness all the way through the cut. Half way through the potato switch to a right hand single bevel knife like that one...if it's prone to 'steering' your cut will start the same as the rest, but once enough of the blade is in it it will start cutting at an angle. If it "steers into the food" then you would have a slice that's thicker at the bottom on this last cut. Steering away /out would be thinner at the bottom.
The only cure for that would be to sharpen at a lower angle and probably thin the knife at the shinogi. Trying to force a knife like that to cut a straight line will just end up splitting the potato ahead of the blade as the knife wedges into it, more akin to the way an axe splits wood as opposed to cutting it.
I know the level of detail in debating this point is a bit outside of the scope of your original point, but i think it's a fundamental point that has to be considered before one can claim that theirs is the "right" way... Especially when speaking so adamantly against what was determined to be correct by the manufacturer. Would be interesting to hear from their development team to know if their goal was consistent widths or angles.... I'd be willing to bet its the latter.
Thoughts/comments? Would love to hear more from your side if you have the time to discuss :)
Yes, Kavik, I've read all you wrote with interest, just to confirm my opinion that this Tormek forum has the most intelligent posters of all forums i know.
Tormek is designed with woodworkers in mind.
As to knife sharpening, Tormek has a potential for precision, but requires inventive approach to materialise this potential.
If you read section on knife sharpening in their first handboook, it is utter absurd.
The only useful bit coming in the following handbooks is about where to clamp the jig.
The rest a knife grinder must invent himself, and learn through pain and frustration.
I am grateful to this forum for shortening my learning curve, but still the only way is through contemplating over the first hundred of f'cked up edges.
But the same can be said all rotary grinders.
In the end you know that Tormek is still the best slow rotary grinder of all available.
Welcome back, Wootz.
Kavik, I am glad that I am not the only one posting large tomes! Sometimes a thought requires a longer post to be properly explained. I do like your "Cliff Notes" brief summary idea. I will start using it in my future long posts; thanks for the idea.
This discussion reminds me of dovetail saws. Mine is a century old Disston. I would call it the garden variety. The teeth are all the same and the edge is parallel with the back. It cuts well. Everything is symmetrical and pleasingly uniform.
In more recent times, a few sawmakers have drifted from this hallowed balance and began filing finer teeth in the first inch of the sawblade for easier starting. Non parallel edges are making a quiet start. This helps overcome the tendency to lower the angle of the saw and cut more deeply (past the line) on the unseen side if the board. Saw design is becoming more subtle. Most customers would not pay the extra for a custom hand filed sawblade. A few would.
This conversation and similar threads are helping knife sharpening to become more subtle. This is not primarily aimed at the weekend farmers market sharpener who must sharpen a hundred knives in a morning. I do believe the more dedicated of these sharpeners are always wanting to learn more. Some of these tweaks will filter into higher volume sharpening.
If we want our high end customers to appreciate and request this higher level of sharpening, we must not only be able to do this level; we must be able to explain it. Good salesmanship is educating the customer.
I find the versatility of the Tormek fascinating. The Tormek can serve the Mom and Pop occasional sharpeners who sharpen their own kitchen knives, and, perhaps the knives of their local churches twice a year. The Tormek can also handle the busy farmers market trade. It can also cater to the very particular few who demand the very best edges.
I trust these ground breaking topics will continue.
Ken
Quote from: wootz on August 15, 2017, 04:34:10 AM
Hello Ken, Jan, Herman, Rich and the new sharp guys.
Apologies for being offline for so long, was too busy establishing my knife grinding business.
Appreciate reviving my topic I wrote when was new to Tormek.
The main conclusion drawn from that little study is the contrary effect of the blade taper towards the tip and upward curvature:
Because of blade thinning towards the tip grinding angle drops and contact with the stone extends and bevel should widen. However, the belly upward curvature brings the tip towards the support, increasing the grinding angle and compensating for the taper, and therefore the bevel height doesn't noticeably change.
Thanks to that for knives with a normal sweeping curve, no need to pivot/yaw.
Both the Tormek manual section on knife grinding and Jeff Farris video are (...how to say) ...if you think they are right you are still about a dozen fucked up edges far from the right technique.
Hey wootz... thanks for responding (glad you didn't mind your thread getting resurrected). :)
Doesn't Jeff's video basically support your "no need to pivot" position (for most knives at least)?
I also think that, in addition to where the knife is on the stone in relation to the support affecting the angle... the relationship of the belly/tip becoming more of a "side angle" (what I described earlier) also affects it. This is another reason why the placement of the knife in the jig is so important. (There has been a lot of discussion on other guided sharpeners... on how the angle can change in the "belly to tip" area... based on how the knife is clamped in relation to the pivot point... and can change quite dramatically once the blade starts to curve).
Basically, I think that, if you're going to pivot the knife... setting the knife in the jig so it maintains the same line (or point) on the stone is important... if you lift the handle, you set the knife in the jig to maintain the angle as the relationship of the knife to the stone changes... not only in relation to the line on the stone... but as the angle "rotates" to the side. And, as you stated in your original post... different shapes/types of knives require a combination of these, or even a modification to achieve the desired result. (Sharpie is your friend). :)
Wootz' last post came in while I was typing. He makes some interesting points.
I believe the Tormek is evolving. Rich has called me the Tormek Historian, with some justification. I find the development of the Tormek fascinating. I agree with Wootz that woodworking tools have been a primary focus. I consider the new 186 gouge jig and the TTS-100 setting tool the present pinnacle combination. For accuracy, repeatability and versatility, this duo leaves most off the other jigs, including all the knife jigs in the dust at the present time. The 90° registration fence of the SE-76 and controlled camber of the SE-77 are certainly giant steps forward. The DBS-22 drill bit jig is a marvel. The TT-50 truing tool and microadjust are advances.
I believe we will see similar advances in knife jigs. A knife jig should be self centering for thickness variations. I think we should have interchangeable stops, with and without the radius. We should remember that we are among the more picky of the Tormek customers. In recent years, I have developed the belief that Sweden is actually reading our posts and giving us some attention. This seems win-win, both for us and for Tormek.
I believe the Tormek is capable of more than is usually expected with our present jigs. We keep evolving.
Ken
Hello Wootz, I like to hear from you again!
Kavik, I have enjoyed your content-rich posts! Very good food for thought. In some cases I need some time to digest it.
CBWX, thanks for starting the useful site: Knife Sharpening on the Tormek.
Ken, you have compiled an interesting list of potential jig's improvements.
Jan
Quote from: Jan on August 15, 2017, 04:13:11 PM
CBWX, thanks for starting the useful site: Knife Sharpening on the Tormek.
Jan
Thanks. It's definitely a "Work In Progress" :)
Quote from: Ken S on August 15, 2017, 03:42:07 PM
I believe we will see similar advances in knife jigs. A knife jig should be self centering for thickness variations. I think we should have interchangeable stops, with and without the radius. We should remember that we are among the more picky of the Tormek customers. In recent years, I have developed the belief that Sweden is actually reading our posts and giving us some attention. This seems win-win, both for us and for Tormek.
...
Ken
Well, if they are listening... self-centering is at the top of the list for me. :P Like you, I agree that the Tormek's strong point is primarily woodworking related tools... but also think it's a great knife sharpener... it's just often overlooked, and it's advantages (for example water cooling), is not properly utilized (if that makes sense).
Thanks all for the interest and the kind words. It's always a risky proposition to be a new guy on a forum questioning existing posts lol glad to find a place that's open to discussion like this
Quote from: wootz on August 15, 2017, 02:31:55 PM
In the end you know that Tormek is still the best slow rotary grinder of all available.
I won't argue that it seems to be an incredibly well built machine. And what it does, it does quite well! As Ken said, a lot of the newer jigs seem to be leaps and bounds above their older counterparts.
But I'd agree that it is better suited for tools than knives.
In a perfect world I'd have a horizontal water wheel for those. A flat surface that leaves flat bevels as opposed to concave ones.
But let's face it, as expensive as the tormek is, those horizontal setups can be 2-3x the cost, are just about impossible to contain the mess in, and would be best suited to having a permanent work area set up for them... Not great for going out and sharpening for others. If I were making knives, or had a business where I had to often reprofile knives and could justify the cost, that's what i would own. And the tormek would stay for the woodworking tools
Everything in life is a trade off though. For many that means going with the speed and ease of the tormek, which is fine in many cases... But in my case, my Japanese kitchen knives will continue to be used with the water stones, not the water wheel.
They're just too finicky for this sort of a system, the entire blade needs to be considered as a whole, not just the actual cutting edge.
If anyone is interested in learning more about it, a great place to start would be "Japanese Knife Imports" youtube channel. Jon, the owner there, is a great guy. Very knowledgeable and extremely helpful. I've dealt with him many times for both questions and purchases and have always been satisfied.
Again, not trying to take away from the tormek here, but every system has it's limitations. If i were doing this as a business I would be studying as much as i can about the different style knives, and how they are traditionally done by hand, to determine if a grinding wheel is an acceptable alternative so i would know what to say when a customer brought one to me
It seems there are two conflating issues about knife blade geometry being discussed here. For a knife with symmetric bevel angles there are two factors to consider.
1. If the cutting edge is not centered the bevel width on one side of the knife will not match the bevel width on the other side.
2. If the knife is thinner at the tip, then either the bevel width or the bevel angle, or both, will be different at the tip than elsewhere along the edge.
The only way to center a cutting edge is to grind more steel away from one side of the knife.
I agree that knife sharpening seems to be secondary to tool sharpening for the Tormek design.
Quote from: Herman Trivilino on August 15, 2017, 07:46:32 PM
It seems there are two conflating issues about knife blade geometry being discussed here. For a knife with symmetric bevel angles there are two factors to consider.
1. If the cutting edge is not centered the bevel width on one side of the knife will not match the bevel width on the other side.
2. If the knife is thinner at the tip, then either the bevel width or the bevel angle, or both, will be different at the tip than elsewhere along the edge.
The only way to center a cutting edge is to grind more steel away from one side of the knife.
I agree that knife sharpening seems to be secondary to tool sharpening for the Tormek design.
I would add "thinner or thicker at the tip". Many knives appear thinner, but the belly/tip area actually moves into a thicker part of the blade... depending on how it is ground. (The width and/or angle will still change... but in the opposite direction).
While sharpening knives may be secondary... if you look at the "stats" of the forum, and eliminate the "General Tormek Questions" section... the "Knife Sharpening" section is only 88 posts (now 87) shy of equaling all the other sections combined. So, the interest certainly appears to be there. :)
Quote from: cbwx34 on August 15, 2017, 03:20:18 PM
Hey wootz... thanks for responding (glad you didn't mind your thread getting resurrected). :)
Doesn't Jeff's video basically support your "no need to pivot" position (for most knives at least)?
....
OMG, with knife that long and where he clamped it in the video, the tip SHOULD be pivoted towards yourself, or you will grind off the tip; other solution is to clamp closer to the tip, not at the centre.
I have all my respect to Jeff, he is a talented presenter - don't take this video as educational, it is 'advertorial' (not sure is this is a right word), but was never meant to be instructional.
I haven't had time yet to watch DVD that Ken mentioned, coming with T8, maybe some hints are there.
Quote from: wootz on August 15, 2017, 10:34:08 PM
OMG, with knife that long and where he clamped it in the video, the tip SHOULD be pivoted towards yourself, or you will grind off the tip; other solution is to clamp closer to the tip, not at the centre.
I have all my respect to Jeff, he is a talented presenter - don't take this video as educational, it is 'advertorial' (not sure is this is a right word), but was never meant to be instructional.
I haven't had time yet to watch DVD that Ken mentioned, coming with T8, maybe some hints are there.
May not be ideal where the clamp was placed... but moving the clamp closer to the tip will increase the angle, resulting in a greater chance of grinding the tip off... not the other way around. For the knife in the video... shouldn't be much of an issue where the clamp is placed... it's not a lot of change.
I think Jeff's video is designed to be an instructional video more than just an advertisement... there's too much detail. My .02 anyway.
Some blades can be sharpen from heel to the tip with no need to pivot while other blades with no need to lift the handle.
Based on my limited experience, the compromise between lifting and pivoting is the suitable approach.
Because it is crucial how the blade is clamped in the jig, some two years ago, I have prepared simple "Knife Tip Settig Template" for kenjig projection length of 139 mm. https://forum.tormek.com/index.php?topic=2654.0
This clamping guarantees that you will get the same bevel angle at the heel and at the tip, more or less with no need to lift the handle. The template is not a universal tool, it works fine only for limited set of blade shape's.
Wootz has shown several examples for which this approach does not provide consistent bevel width. ;)
Jan
P.S.: The template design was extracted by back engineering the radius of the adjustable stop of the knife jig.
Jan,
Just to clarify, the above template setup is intended to work in conjunction with the idea that you should maintain the same line of contact, correct?
Yes Kavik, you are correct. If it is possible that the edge meets the stone along the same line of contact, than the bevel angle should be the same along the entire edge.
When some part of the belly is above the red circular line of my template (goes beyond the line of contact), than it is necessary to lift the handle here to achieve the same bevel angle along the belly also.
Jan
My friend from local knife.cz forum prepared wooden version of my template. I like it. The knife jig is guided and your hands are free to clamp the knife properly. ;)
Jan
Quote from: Jan on August 16, 2017, 10:59:39 AM
Some blades can be sharpen from heel to the tip with no need to pivot while other blades with no need to lift the handle.
Based on my limited experience, the compromise between lifting and pivoting is the suitable approach.
Because it is crucial how the blade is clamped in the jig, some two years ago, I have prepared simple "Knife Tip Settig Template" for kenjig projection length of 139 mm. https://forum.tormek.com/index.php?topic=2654.0
This clamping guarantees that you will get the same bevel angle at the heel and at the tip, more or less with no need to lift the handle. The template is not a universal tool, it works fine only for limited set of blade shape's.
Wootz has shown several examples for which this approach does not provide consistent bevel width. ;)
Jan
P.S.: The template design was extracted by back engineering the radius of the adjustable stop of the knife jig.
Thanks for posting this. Very helpful.
I think your template also illustrated why I feel the jig radius doesn't 'feel' quite right, and why Wootz found it didn't work for the knives he was sharpening, (and as you stated only for certain blade shapes). If you look at the attached picture, you see the clamped knife doesn't fit the radius unless the knife is moved, which equals the the projection length being shortened if I'm 'reading' it right. (So perhaps Wootz could have got it to worked if he had altered the projection length?)
(One thing I've learned in dealing with other guided sharpeners with a pivot... it's a little more complicated than it first appears). ???
Your template is a good reference though... definitely helps define the process of what is going on.
CBWX, thank you for your kind words, highly appreciated. :)
Jan
Thanks for the verification Jan
Soooo... Based on that example from cbwx:
In theory, it seems the only thing that could make for a truly universal setup/technique would be to have collars with different profiles to match different blade types?
I mean, you're obviously not going to have one to match every knife... But say you had even just 2 collars, so that you have the stock pivot angle, a more extreme pivot angle like the one needed for cbwx's example, and then a very gradual curve for something like that pig sticker scenario
Would that allow for a consistent method, using line of contact as a guide, while maintaining proper bevel angle?
(i almost feel like there should be two threads here. One that can discuss technique for maintaining bevel angle... And one to discuss how to keep a knife looking pretty, ie: maintaining bevel width at any cost :P)
Quote from: Kavik on August 16, 2017, 03:33:32 PM
Thanks for the verification Jan
Soooo... Based on that example from cbwx:
In theory, it seems the only thing that could make for a truly universal setup/technique would be to have collars with different profiles to match different blade types?
I mean, you're obviously not going to have one to match every knife... But say you had even just 2 collars, so that you have the stock pivot angle, a more extreme pivot angle like the one needed for cbwx's example, and then a very gradual curve for something like that pig sticker scenario
Would that allow for a consistent method, using line of contact as a guide, while maintaining proper bevel angle?
(i almost feel like there should be two threads here. One that can discuss technique for maintaining bevel angle... And one to discuss how to keep a knife looking pretty, ie: maintaining bevel width at any cost :P)
I think, if I read my picture right... you could use just one collar, and adjust the projection length to get everything to fit. (Of course that eliminates the Kenjig... since you'd have to adjust the USB distance....). Guess it comes down to what your needs are, for example the Kenjig speeds up the process for volume sharpening. If you start introducing multiple collars, it might defeat the purpose, to some extent anyway. (Plus, I'm not sure a lot of people have the means to make collars?)
I don't think "maintaining bevel angle" vs. "bevel width" as separate issues... they are definitely tied together. And, to me, it doesn't have to be one or the other... as Jan has stated, a combination of "lift" and "pivot" may give a compromise to both issues.
Again, I'm just spitballing here based on my very limited experience with the current jig, and observing some of the comments here.
But it just seems to me that with a fixed radius on the stock collar, if trying to maintain line of contact while pivoting, won't you always be compromising between the belly or the tip either extending past or falling below the LOC?
It seems to me that that's where the lifting becomes necessary to counteract that... At which point it becomes guesswork in how much to lift.
Whereas, again in theory, if the radius of the jig were an exact match to the profile of the knife, maintaining LOC should keep the bevel angle exact with NO lift required. Similar to laying it on a tool rest and pivoting to follow the curve of the edge.
I'm in the office today, and don't have one in hand to look at at the moment, but my theory for keeping it simple, fast, and more flexible would be as follows:
- create 3 collars, all of equal thickness (yes, i increased from 2 to 3, so the length of the jig doesn't need to change to match the kenjig system).
- collar 1) a shallow, gentle sweep
- collar 2) match the stock collar profile
- collar 3) a more intense curve
- redraw the kenjig alignment template with 3 arcs drawn and labeled to match the 3 collars
- setup the knife in the jig using the template the same as always (with whichever collar you have on, as they're all the same thickness
- compare the curve of the blade to the 3 lines and match it up to the one that's the closest match
- swap out for the collar that corresponds with that line
- start grinding
My idea for the collar would be something simple, turned on the lathe, then cut in half, using pins and magnets to reconnect around the shaft.
Should add all of 10 seconds to the setup time for any knife that doesn't match the collar you had on the jig from the last knife you did
Quote from: cbwx34 on August 16, 2017, 03:50:27 PM
I don't think "maintaining bevel angle" vs. "bevel width" as separate issues... they are definitely tied together. And, to me, it doesn't have to be one or the other... as Jan has stated, a combination of "lift" and "pivot" may give a compromise to both issues.
In my understanding the handle lifting approach is more aggressive in changing the bevel angle and also allows to sharpen long thick blades. From this point of view, lifting is more universal than the pivoting approach, which is smarter, but in pure form applicable only for thinner blades with "Tormekian" belly.
The compromise to both issues give us some freedom to find suitable trade-off between bevel angle and bevel width consistency along the edge.
Jan
Quote from: Kavik on August 16, 2017, 04:35:04 PM
...
- create 3 collars, all of equal thickness (yes, i increased from 2 to 3, so the length of the jig doesn't need to change to match the kenjig system).
- collar 1) a shallow, gentle sweep
- collar 2) match the stock collar profile
- collar 3) a more intense curve
- redraw the kenjig alignment template with 3 arcs drawn and labeled to match the 3 collars
- setup the knife in the jig using the template the same as always (with whichever collar you have on, as they're all the same thickness
- compare the curve of the blade to the 3 lines and match it up to the one that's the closest match
- swap out for the collar that corresponds with that line
- start grinding
My idea for the collar would be something simple, turned on the lathe, then cut in half, using pins and magnets to reconnect around the shaft.
Should add all of 10 seconds to the setup time for any knife that doesn't match the collar you had on the jig from the last knife you did
My .02.... I think the effort would be better spent making and using one of Herman Trivilino's jigs (https://forum.tormek.com/index.php?topic=1592.msg6634).
Quote from: Jan on August 16, 2017, 04:57:37 PM
Quote from: cbwx34 on August 16, 2017, 03:50:27 PM
I don't think "maintaining bevel angle" vs. "bevel width" as separate issues... they are definitely tied together. And, to me, it doesn't have to be one or the other... as Jan has stated, a combination of "lift" and "pivot" may give a compromise to both issues.
In my understanding the handle lifting approach is more aggressive in changing the bevel angle and also allows to sharpen long thick blades. From this point of view, lifting is more universal than the pivoting approach, which is smarter, but in pure form applicable only for thinner blades with "Tormekian" belly.
The compromise to both issues give us some freedom to find suitable trade-off between bevel angle and bevel width consistency along the edge.
Jan
I don't disagree that doing both may be a good compromise... but lifting the handle, for the most part, gives the same result. I don't think it's more aggressive... because it goes back to placing it in the proper position relative to the pivot (just a change in pivot point).
Edit to add: Jan, you might find this of interest... Geometry and Kinematics of Guided Rod sharpeners by Anthony Yan (https://www.bladeforums.com/threads/geometry-and-kinematics-of-guided-rod-sharpeners.1131476/) While the Tormek isn't really a "Guided Rod" sharpener... it has a lot of info about sharpening in relation to a pivot point.
Quote from: cbwx34 on August 16, 2017, 05:05:47 PM
My .02.... I think the effort would be better spent making and using one of Herman Trivilino's jigs (https://forum.tormek.com/index.php?topic=1592.msg6634).
Would love to see what that is, but... Photobucket >:(
I'll have to look through it later when I have time to read and follow all the links
Honestly, I was wondering why people wouldn't opt for a tool rest type system in the first place, for "volume sharpening"...or heck, even for personal sharpening.
I just assumed since people still use and discuss how to do it with the jigs, they must want to find a better way to make the original jigs work for them *shrugs*
And for what it's worth, I wouldn't expect making the collars would really be all that much effort
Quote from: Kavik on August 16, 2017, 05:38:17 PM
Would love to see what that is,...
https://youtu.be/AcWAkQmoU8c
I have horizontal platform for sharpening in both directions, but for precise sharpening I use the guided knife jig despite all the issues discussed here.
Jan
Cheers for the YouTube link :D
Yeah, something like that seems so simple, practical, versatile, and easy to setup and adjust....really does make the idea of modifying the regular knife jigs seem kinda pointless
(as opposed to some of the other platforms people here have built that, as awesome as they are, would be cumbersome for me to store and would be a more complex build)
Now that my brain has shifted gears from just focusing on improving the use of the SVM45/100/140, to considering just the overall better approach.... I'm left wondering why mess with the SVM jigs at all? What benefit is there over a platform style? (if this is too far off topic let me a know, I can always create a new thread for it)
Seems to me there is one issue that can present itself with either setup, and that's grinding more than is needed if you get careless.
With the platform this could be caused by staying in one spot too long.
With the SVM this could be caused by staying in one spot too long OR by applying more pressure at a certain point, which I would think is fairly easy to do on a fulcrum held against a spinning wheel.
The difference though is that with a platform, removing too much steel is certainly unfortunate, but at least your angle remains constant.
With an overgrind on the SVM you will not only waste steel, but you'll also move the LOC below the original point, resulting in a more obtuse angle.
Now, I haven't done the math to see how far you can drop below the original LOC before the change in bevel angle is significant enough to become an issue, but i imagine it won't take much... And most of us don't have a laser line setup to keep track of that while we're grinding
Jan,
Your last post came in while I was typing this. Can you elaborate at all on why you feel the guided knife jig is more precise for you? As you can see from my thoughts above I'm not trying to be argumentative, just having a hard time wrapping my head around this.
Also, since yours was the comment that got me curious about different profiled collars for the SVM jigs, any thoughts on if you think that would improve some of the need for guesswork and lifting?
Edit: just saw your attachment after I submitted this post. That was the other platform jig I was thinking of when I said awesome looking, but more complex to build
Kavik, the explanation why I do not use my horizontal platform for precise sharpening is simple.
When grinding away from the edge you have to resist quite strong tendency pulling the blade in the direction of rotation. When grinding towards the edge there is some tendency to push away or lift the blade above the wheel.
Struggle with those issues results in less consistent bevel compared with bevel obtained using knife jig which rests on the USB and is secured by the thumb.
Jan
Thanks, I'll keep the in mind when I eventually get around to trying the platform idea
No thoughts on the differently profiled collars?
With the platform jig I grind towards the knife and find that it doesn't tend to lift if you do it correctly. It just takes some practice. On the other hand, more experienced sharpeners prefer other methods. Some don't use a jig at all. It's a matter of preference.
There's a discussion in the Tormek manual about platform jigs, and their philosophy is that it's a useful technique only when the edge angle is blunt such as on a scraper. Note that when using the Tormek Tool Rest jig, which is a platform jig, the edge angle must be blunt because the platform is too far from the Universal Support rod. The idea is that for shallow angles the operator has to apply more force to a platform than to the grindstone. I don't agree. The platform can be used as a guide where very little force is applied to the platform. After all, you can freehand with a Tormek, in which case there's no force at all applied to a platform and the edge angle can be rather shallow.
Using the scissors jig base to mount a platform lets you get the platform much closer to the grindstone so you can grind shallower angles.
That was kinda my thought based on work I've done on other grinders with tool rests....grind into the wheel, with just enough pressure on the spine to keep it flat on the rest, and it shouldn't be an issue....that all comes down to practice and user control i would imagine.... .. But i didn't want to say that out loud before actually trying it myself on this one lol
Was going to work on it tonight, but instead I got stuck at work late, then started working on laying out the platform for my other grinder and the BGM-100 that just arrived, then got distracted from that with a new guitar I just picked up from a friend..... Cuz I needed one more new thing to get into right now :o lol
Quote from: Herman Trivilino on August 17, 2017, 12:50:42 AM
With the platform jig I grind towards the knife and find that it doesn't tend to lift if you do it correctly. It just takes some practice. On the other hand, more experienced sharpeners prefer other methods. Some don't use a jig at all. It's a matter of preference.
Herman, you are correct, practice is sure important, but I hope to understand why you do not experience the lift tendency when grinding towards the edge.
In my thinking the explanation is following: on your steeply inclined platform your hand keeping the knife is sliding down towards the grindstone like a movement on an inclined plane.
In my case it is different, I have to be proactive in pressing the knife against the grindstone. I have found that my "contact" force is not the same during the pass/passes which to some degree influences the bevel grind.
I still use my horizontal platform, but it has not replaced the knife jig especially when sharpening expensive knives. I am not sharpening for money and so I have enough time to mount the knife in the knife jig and to check that it was clamped symmetrically. For batch sharpening and small blades I of course use the platform.
My motivation to build the horizontal platform was twofold:
1) similarity to the way how freehand sharpeners work,
2) very simple bevel angle setting.
Jan
Quote from: Jan on August 16, 2017, 06:38:39 PM
I have horizontal platform for sharpening in both directions...
Jan
Was gonna mention this before... if you ever sold your setup as a kit.... I'd be first in line. Nice setup.
Thank you, CWBX. I am pleased about your interest in my set up! I tried to build it as solid as the Tormek machine. :)
Jan
Quote from: Herman Trivilino on August 17, 2017, 12:50:42 AM
With the platform jig I grind towards the knife and find that it doesn't tend to lift if you do it correctly. It just takes some practice. On the other hand, more experienced sharpeners prefer other methods. Some don't use a jig at all. It's a matter of preference.
There's a discussion in the Tormek manual about platform jigs, and their philosophy is that it's a useful technique only when the edge angle is blunt such as on a scraper. Note that when using the Tormek Tool Rest jig, which is a platform jig, the edge angle must be blunt because the platform is too far from the Universal Support rod. The idea is that for shallow angles the operator has to apply more force to a platform than to the grindstone. I don't agree. The platform can be used as a guide where very little force is applied to the platform. After all, you can freehand with a Tormek, in which case there's no force at all applied to a platform and the edge angle can be rather shallow.
Using the scissors jig base to mount a platform lets you get the platform much closer to the grindstone so you can grind shallower angles.
I find it fascinating that people whose Tormek expertise I respect often have different approaches. Steve Bottorff, my knife sharpening guru, regrinds bevels freehand with the grinding direction trailing with his Tormek. For uniform bevels, Steve's first choice is the Tormek knife jigs. Incidentally, US Tormekers can thank Steve for convincing Jeff Farris to import the 140mm long knife jig. Originally, it was only available in Europe.
I value Herman's thoughts on his small knife jig with the same high regard. Herman designed the jig and probably has more hands on shop time with it than anyone else on the planet. If he states that something can be done with his jig, I believe him.
Herman's jig is designed for a different function than any of the Tormek jigs. His jig was originally designed to sharpen small knives, such as pen knives. It is not limited to this work, but was originally designed for it. Tormek has never made a jig for this purpose. The classic handbook technique for sharpening small knives is freehand. Tormek's platform jig works very well for its intended purpose, sharpening large turning scrapers. Tormek's knife jigs work very well for sharpening their intended purpose, sharpening larger knives. Tormek's small blade tool works very well for its intended purpose, sharpening small carving knives with substantial wooden handles. (Look at the photos). It is clumsy with small pocket knives. Herman's jig is not.
The function of the smaller width, matching the thickness of the grinding wheel, is to allow both bevels to be ground full length without needing to readjust the jig. The thinner leading edge of Herman's jig allows the jig to be placed closer to the grinding wheel.
Incidentally, Herman got it right by using the scissors jig platform. I made two (one each for the T4 and T7, by cutting a platform jig in half. With a higher center of gravity, these do not work as well as Herman's design.
I will restate my belief that a well equipped Tormek knife sharpener should have one of Herman's jigs. This should be in addition to the Tormek jigs, not instead of them.
Ken
Quote from: Kavik on August 16, 2017, 11:15:49 PM
No thoughts on the differently profiled collars?
I have a thought on it this a.m.... it might be better to reduce the size of the collar (considerably).
I've been working with the clamp from the KME sharpener... this morning I just used a small washer so that I could pivot the blade with as little interference from the collar as possible (basically keeping the pivot point near center, and held it against the USB with my thumb)....
(https://image.ibb.co/bR1twk/IMG_0118.jpg)
... as you can see in the sample picture... keeping the pivot point small, and properly positioning the clamp (still necessary of course), allows the blade to pivot with little position change as a result of the collar. (Feels more comfortable too... across a variety of knives).
Might be the route to take.
Very interesting, though it would require creating an entire collar from scratch, threads and all. Quite a bit more complex than my original thought of having different pieces to slap on abov the existing collar, hmmm.....
I wonder if the width on the original had anything to do with helping inexperienced users keep the jig from pivoting unintentionally when working along the flat of the blade?
One of the several ideas in my thought stage is to order several more adjustable stops as spare parts. I would glue a flat piece of round plastic to the front (no radius). This would assist lifting the blade without pivoting.
Ken
Quote from: Kavik on August 18, 2017, 10:05:47 PM
Very interesting, though it would require creating an entire collar from scratch, threads and all. Quite a bit more complex than my original thought of having different pieces to slap on abov the existing collar, hmmm.....
I wonder if the width on the original had anything to do with helping inexperienced users keep the jig from pivoting unintentionally when working along the flat of the blade?
Maybe substitute the collar for something smaller in diameter... just to see if you notice the difference? I'm not sure the radius of a substitute would be that critical... especially if the collar wasn't much bigger than the jig part it would be screwed onto.
(I'll see if I can find something and test the actual Tormek jig).
Honestly, I still don't have enough experience to make a good test subject myself yet
Can you test that theory by just threading your stock collar on backwards?
Quote from: Jan on August 17, 2017, 12:45:09 PM
In my thinking the explanation is following: on your steeply inclined platform your hand keeping the knife is sliding down towards the grindstone like a movement on an inclined plane.
Good point, Jan. I hadn't thought of that. My arms are at about the same angle as the platform, so applying force along the direction of the platform is a natural and productive direction.
Quote from: Ken S on August 17, 2017, 05:39:32 PMTormek's small blade tool works very well for its intended purpose, sharpening small carving knives with substantial wooden handles. (Look at the photos). It is clumsy with small pocket knives. Herman's jig is not.
I've never used the SVM-00, but looking at the picture I see what you mean.
Thanks for your exhaustive list of the benefits of my platform jig. It is also good for machetes. Tormek doesn't have a jig for that, so your only option is freehand.
You are most welcome, Herman. Your small knife jig is a well designed and useful tool. You have also stuck with it long enough to really master. As I have said before, I think it should be part of every knife (and machete) sharpener's kit.
It is easy to be complimentary about a good tool.
Ken
ps Any chance you could delete the annoying photobucket images and replace them using the forum attachment program?
Quote from: Kavik on August 19, 2017, 07:03:07 PM
Honestly, I still don't have enough experience to make a good test subject myself yet
Can you test that theory by just threading your stock collar on backwards?
Actually, you might make a better test subject... no preconceived ideas. :)
Can't really thread it backwards... the internal stop is at the other end of the collar.
I did make a comparison both with and without the collar... using a reference line on the stone as a guide...
(https://image.ibb.co/c5OAu5/IMG_0041.jpg)
... in the top row, you can see the '0' on the knife jig stays pretty much on top of the USB. But with the stop collar, it pulls it well below the line. So if the width of the collar was reduced... this factor would be nearly eliminated.
Without the collar, you actually can still use the jig to maintain the angle... as long as you keep the blade at the same reference point/line. (Sort of a "guided freehand").
Obviously, some of this depends on the knife length. Longer kitchen knives, knives without much 'belly' etc. won't be influenced as much. But I tend to sharpen more EDC/pocket knives, small hunting/camping knives, etc. where this is seen more.
Cbwx, your last post was rather interesting and got me thinking about a few things. So I cut the top off one of my 3 knife jig collars and started experimenting as you did, with the machine off and focusing on the LOC drawn on the wheel.
I'm writing this up while giving my back a little break from standing over the machine, but I'll provide some detail a little later this evening.
So far is looking QUITE promising on 7 very different knives all using one specific combination of sliding, lifting, and pivoting to keep the LOC.
One thing to note: so far the only advantage I see to the stock jig collar is that the wide base stops the lock screw knob from contacting the USB while pivoting. A smaller knob, or a collar from scratch with the lock screw located closer to the base, would be the most likely solutions to this
Edit: it does also help keep straight along the main length of the blade, assuming you set it up properly parallel to the edge... But that's something that probably means a lot less after some practice
Your last sentence brings up a situation. I am as guilty of this as anyone. I think we have a tendency to want to improve our tools before we have had enough experience with them to master them.
My own experience with the Anglemaster illustrates this. I was most of the way through redesigning it before I realized the difficulty I was having was due to poor light. I stumbled upon this realization one day after I set up my Tormek outside. With my personal technique, I rarely use the Anglemaster, however, I now hold it in much higher regard.
Ken
(accidentally hit submit early....pls hold)
Quote from: Ken S on August 20, 2017, 07:03:36 AM
Any chance you could delete the annoying photobucket images and replace them using the forum attachment program?
I'm having trouble finding the originals, but haven't given up yet. I'm also trying to download them from photobucket but haven't yet figured out a way to do that.
You're absolutely right Ken, and if it weren't for this topic I'd still be trying to learn the "right" way with the stock components.....that said, here's what I've come up with that seems to work pretty damn well so far:
First, the drawbacks of a cut down collar: you need to focus a little more on a) keeping the knife flat to the stone when working on the straight edge of the blade and b) keeping the jig on the USB without slipping off
Second, the perk: the pivot point becomes practically stationary, as opposed to moving drastically, as shown in the second row of the pic cbwx posted above
So here's what I did...I cut the wide end off one of my jigs, created a modified template (based on Ken's 139mm length, with cues from Jan's tip projection template, with a couple of twists) then tested the setup with 7 different blades and multiple distances on the USB in both the horizontal and vertical position.
Attachment 1 shows the blades tested, ranging from 3.75" to just over 8" in varying profiles
(the jig has the stock collar on it, obviously...the cut down collar is sitting above it)
Attachment 2 shows one of the knives set up in the jig to set the blade protrusion and to eyeball the horizontal protrusion of the tip
The idea here was that if the tip is going to have the same bevel angle as the flat of the blade, then the tip has to stay on the LOC, therefore the distance has to be the same 139mm from the pivot point to the tip. With the stock jig collar this is impossible to do as that thing is 55mm wide and moves the pivot point by a very large amount.
So to explain my template look at attachment 3: I drew the same box to line up the clamp and set the blade projection like we see in Ken's jig template. I then drew a 45 degree angled line at the same 139mm length. Important to note that the 45 degree angle lines up with the SIDE of the center post of the jig, not in the center of it. I then set the blade projection and by eye I follow the curve of the blade, extending an imaginary line to the end of the 45 degree line on the paper (as illustrated by the green curve)
Attachment 4 shows the most extremely curved tip set up the same way
Once this was set I was able to keep on the LOC from the heel to the tip. I'll explain how shortly, but first I want to go over the second part of the test.
Leaving the knife in the jig I swapped back to a stock collar and tested how the blade rode on the wheel. The chart below shows the distance from the LOC at the highest point I was able to get the tip to with the stock collar (I think I was set up at a 20 degree angle at that point, and this is on a 230mm wheel)
(same order as the picture)
Knife | distance below LOC |
Cold Steel SRK | -7mm |
Gerber (BG) | -9mm |
Old Hickory Butcher's knife | -12mm |
Old Hickory Slicer | -10mm |
Maxim Chef's | -6mm |
EdgeMark Hunter | -7mm |
Gil Hibben's Throwing knife | -7mm |
I'm going to have to finish this in a second post, as I'm out of room for attachments
Part 2:
Attachment 1 shows the cleaned up version of the template (if anyone wants to print it out and test this theory, just make sure to scale it so that the black rectangle is 45x139mm)
Black box is placement of the jig
Red line marks the blade protrusion to 139mm
Blue lines indicate the width of the jig's center post
Orange line is the target for eyeballing the tip projection
Light grey and purple lines are reference points only at this time, for checking the arc of travel
Attachments 2 and 3 show an overlay of the 2 knives in the jigs and how they line up to the 45 degree 139mm line and continue their travel along the purple arc.
Note that these arcs intersect at the tip of the orange line and are NOT intended to overlay each other. The arcs in attachment 3 are close by coincidence only, due to the slope of the tip on that particular knife.
Once this was all set up as described above, here's the method for the motion to use:
- start just as always, I will be describing starting with the tip of the knife pointing to the LEFT
- while grinding the straight length of the knife slide the jig to the right, with no pivoting or lifting until you reach the curve
- once the knife begins curving down to the tip pivot the knife (keep level, pull the handle towards you) until you reach the apex of the curve
at the same time begin sliding the base of the jig slowly back to the left, to keep the pivot point on the USB and the LOC along the width of the stone in line with each other - This step will vary based on the severity of the curve to the tip
- If continuing to pivot does not cause the tip to rise above the LOC then you are all set
- If continuing to pivot will cause the tip to rise above the LOC then you would now lift the handle in addition to pivoting
Sounds more complicated then it is. After a couple of tries it just felt "right", if that makes any sense? It's a very fluid and natural motion. If you focus on the shape of the blade in your mind, it's like your hands are tracing the contours.
I plan to test it soon with actually grinding, but I'm afraid I just ran out of time today. I think the theory is sound though, distance stays the same, LOC stays the same, pivoting keeps the wheel perpendicular to the face of the blade even as you round the curves. If there's anything glaringly obvious that I've overlooked please let me know!
Kavik... thanks for doing all this. Here's my inital thoughts...
It's funny... I was going to suggest cutting the collar off a jig... but didn't want to do it myself, (and don't like suggesting something I won't do). Glad you did it. I think just eliminating the sides of the collar (so that the jig could still "ride" on the USB, yet still pivot without significantly altering the pivot point), might get rid of some of the 'drawbacks'. (BTW: from your earlier post about the lock screw getting in the way... the newer knife jig eliminated the lock screw completely).
Your comment that "after a couple of tries it just felt 'right'"... is what I referred to earlier... that pivoting a knife with the current jig, doesn't feel like a natural motion (and hinders the ability to maintain the LOC).
I think the template is a good reference... but want to point out that it's not really a part of the setup. It does combine it with Ken's Kenjig setup and purpose though. In reality, the only real 'guide' needed is to properly set the knife in the jig, so that the belly/tip area is approximately the same distance as the flat portion from the pivot points. But the template is a good way to do that, and gives a "standard" to work from. (Hope that makes sense).
All in all, I think your testing was well thought out... and seems to validate what I'm thinking. Hopefully your actual testing will further validate it. Interested to hear what others have to say. Thanks again!
I was planning to cut one down anyway, for the idea I had earlier about trying different profiled curved "caps" for it.... Which I think could be a moot point now, we'll see
I know I skipped a lot of the thought process and the steps that got me to that final plan, but:
Quote from: cbwx34 on August 21, 2017, 03:15:18 PM
In reality, the only real 'guide' needed is to properly set the knife in the jig, so that the belly/tip area is approximately the same distance as the flat portion from the pivot points.
Yes, this is exactly what that orange 45 degree line does. I don't know about you, but I can't "eyeball" that long of a distance at 2 angles :-[
Tormek suggests setting this by matching the length of tip protrusion to the height from the shoulder of the jig (I'm not explaining that well, but a picture can be found in the manual)
What I found was that this worked perfectly fine on a couple of my knives, but it seems it was the profile of the tip that determined if setting up like that would result in the tip finishing at, above, or below the LOC, even with the cut down jig collar. (to really prove this i would have to set up each knife with the stock collar again, using the recommended method for tip protrusion and measure them out again and add those measurements to my previous table, but I'm not home at the moment to do that)
That's the part that lead me to the conclusion that a 139mm line at a 45° angle would get me there every time (and looking back now, perhaps the purple arc is all that is needed there. Again, similar to Jan's tip setting jig, just altered to use the small pivot point instead of the wide collar profile)
If you look back to the attachments in my first post, 3.jpg is the Cold Steel SRK. This one was, in fact, close to the Tormek suggested settings: equidistant horizontally and vertically from the shoulder of the square part of the jig.
But if you look at the butcher style knife in 4.jpg, you'll see that a tip with that extreme of a curve ended up needing the jig set much further away from the tip in order for it to reach the LOC.
Again, just thoughts for now, I know. The proof will be in the pudding, so to speak, when i do some actual sharpening like this. Gonna try to find some time in the next couple of days
Quote from: Kavik on August 21, 2017, 04:42:47 PM
Quote from: cbwx34 on August 21, 2017, 03:15:18 PM
In reality, the only real 'guide' needed is to properly set the knife in the jig, so that the belly/tip area is approximately the same distance as the flat portion from the pivot points.
Yes, this is exactly what that orange 45 degree line does. I don't know about you, but I can't "eyeball" that long of a distance at 2 angles :-[
I agree... and perhaps didn't say it right. You can accomplish the same thing just by measuring the distance, (like in the attached picture). The 139mm is more what I was thinking isn't really a part of the process... it's just a convenient measurement... especially, since, as Ken pointed out... a lot of knives fall close to that. But you can accomplish the same thing at any length. (Probably still clear as mud haha).
I think the pudding will come out fine. :)
Oh, yeah. I gotcha. Yup, the 139 was just an easy enough starting point for me, but you're right, it's the equal distance that matters, not the actual length.
But it is sure nice having it there on paper to just lay the knife/jig against, instead of measuring each one with a ruler like that ;)
Okay, so.....the experiment kind of worked. Not quite as spectacularly or as groundbreaking as i might have hoped for, but there did seem to be benefits.
I need to continue practicing more, but the cut down collar and using the arc to align the tip with the 45° line as measured from the left side of the jig shaft DID result in me being able to keep the entire length of the blade at (or very near) the LOC. Whereas setting the tip protrusion per Tormek's instructions and/or using the stock jig collar often left me unable to even come close.
Like I said, I need more practice to get it down consistently, but I managed to almost get an even bevel angle all along the length of that 7" butcher knife with the most extreme belly to tip transition (third one down in my first pic of all the knives). This was the one that fell the furthest below the LOC using the stock jig. So I remain optimistic, if still inexperienced lol
Bevel width changed a bit at the transition to the tip, but not as drastically as I've had with other methods, only what one would expect for the change in blade thickness as the tip approaches the spine.
I'll need to visit a thrift shop and find some more junk knives to keep practicing on,
And i think maybe round off the shoulder on my cut down collar just a bit
Quote from: Kavik on August 23, 2017, 05:01:36 PM
Okay, so.....the experiment kind of worked. Not quite as spectacularly or as groundbreaking as i might have hoped for, but there did seem to be benefits.
I need to continue practicing more, but the cut down collar and using the arc to align the tip with the 45° line as measured from the left side of the jig shaft DID result in me being able to keep the entire length of the blade at (or very near) the LOC. Whereas setting the tip protrusion per Tormek's instructions and/or using the stock jig collar often left me unable to even come close.
Like I said, I need more practice to get it down consistently, but I managed to almost get an even bevel angle all along the length of that 7" butcher knife with the most extreme belly to tip transition (third one down in my first pic of all the knives). This was the one that fell the furthest below the LOC using the stock jig. So I remain optimistic, if still inexperienced lol
Bevel width changed a bit at the transition to the tip, but not as drastically as I've had with other methods, only what one would expect for the change in blade thickness as the tip approaches the spine.
I'll need to visit a thrift shop and find some more junk knives to keep practicing on,
And i think maybe round off the shoulder on my cut down collar just a bit
Thanks again for doing this.
(You and I may be the only ones interested...). :-\
I learned, dealing with another guided sharpener, that most knives can be set based on the belly/tip area... and that the setting actually falls within a pretty similar distance between knives. (Not surprising, since basically, all you want is the belly/tip area approximately the same distance as the "flat" portion from the pivot point(s)). But, as you indicated... hard to find a "perfect" fit. Still, this appears to me to be a better more consistent approach, than the difference the current collar creates in how it keeps the knife near the LOC.
Even the experiment where I didn't use the stop collar at all, and kept the knife at a laser line... I could tell as I tried a few knives that some knives needed a slightly different approach toward the tip... a slight lift, etc.... so doubt if any jig would be "perfect". But hopefully, we're getting closer.
The experiment continues.... :)
My pleasure :) And that's okay, I think it's obvious I don't mind rambling, even if it only helps one person lol
I dunno, I still think a platform and a bit of practice might be more ideal than any pivoting jig... I just haven't gotten around to trying that method yet (I kinda get stuck on one thing once i get an idea in my head, and have to play it out till the end before I try the next approach)
But, yeah, if you're going to pivot a jig, i don't think you can ever really hope for consistency unless the pivot point itself is consistent. (In an ideal world, with unlimited tools and resources at my disposal, the solution i would create for a perfect pivot point is way more involved than anything I'm actually going to go into for this :-X)
I do need to set up one of those laser lines though. I think the inconsistencies I had in my bevel angles were due to losing track of the LOC while just trying to eyeball it to a point on the body of the grinder
Quote from: Kavik on August 23, 2017, 06:10:34 PM
My pleasure :) And that's okay, I think it's obvious I don't mind rambling, even if it only helps one person lol
I dunno, I still think a platform and a bit of practice might be more ideal than any pivoting jig... I just haven't gotten around to trying that method yet (I kinda get stuck on one thing once i get an idea in my head, and have to play it out till the end before I try the next approach)
But, yeah, if you're going to pivot a jig, i don't think you can ever really hope for consistency unless the pivot point itself is consistent. (In an ideal world, with unlimited tools and resources at my disposal, the solution i would create for a perfect pivot point is way more involved than anything I'm actually going to go into for this :-X)
I do need to set up one of those laser lines though. I think the inconsistencies I had in my bevel angles were due to losing track of the LOC while just trying to eyeball it to a point on the body of the grinder
I agree... Herman's platform setup is probably the ideal route... sharpening on a platform is probably the closest thing to freehand sharpening, with the advantage of a guide. Eventually, I might give it a spin.
I'm always torn between the "science" of sharpening... guides, precise angles, etc. vs. the "freedom" of freehand. Adding the laser guide is a definite plus... at least there's some degree of accuracy (pun intended), although certainly not the same as an actual guide. I'll still pursue an ideal jig setup... but most of my actual sharpening... I'll concentrate on improving my freehand results.
You know what's the worst part of this? All the thought I'm giving this issue, and i really don't intend to use this for much knife sharpening anyway lol
Bought it for the tool sharpening, i enjoy my bench stones for my knives too much to give that up, even if I did come up with a perfect jig.
Something to be said about the routine there, setting up and soaking the stones, then just putting on some music and relaxing while working up through the progression.
To me the tormek is functional, efficient, an apt tool when you want to get through the job.
Whereas freehand sharpening on the bench stones is something I'll do for the sake of doing it sometimes. It's as much about enjoying the process as it is about the end result
(not the same for chisels, planes, or turning tools. Those are always a chore in my mind, so the quicker and more accurate the better)
Quote from: Kavik on August 23, 2017, 09:01:15 PM
You know what's the worst part of this? All the thought I'm giving this issue, and i really don't intend to use this for much knife sharpening anyway lol
Bought it for the tool sharpening, i enjoy my bench stones for my knives too much to give that up, even if I did come up with a perfect jig.
Something to be said about the routine there, setting up and soaking the stones, then just putting on some music and relaxing while working up through the progression.
To me the tormek is functional, efficient, an apt tool when you want to get through the job.
Whereas freehand sharpening on the bench stones is something I'll do for the sake of doing it sometimes. It's as much about enjoying the process as it is about the end result
(not the same for chisels, planes, or turning tools. Those are always a chore in my mind, so the quicker and more accurate the better)
I do enjoy some "stone" time... but have found that using the Tormek can be just as enjoyable. One of the reasons I returned to using it more. ;)
Well, finally got some time to finish this small collar idea tonight...... And gotta say it's much nicer than just the straight cut off version.
Turned a little nub on the end of some acrylic blank I had laying around here...but if i were too do it all over again, this could all be done with the stock collar piece chucked up in the lathe...I just felt I cut the first one a bit short anyway
Still no laser line, but i think i did better keeping to the LOC
Operation feels very very smooth. Setup was the same as mentioned previously with my template. Pivot point seems to remain on the side of the shaft (on the side towards the tip), not in the center of the jig shaft
As I hope you can see in the attached pic, the bevel width looks pretty good.
Bevel angle isn't perfect, but it's close all along the length (sorry, i don't have any fancy accurate measuring tools for that).
With the exception of a couple extremes (user error), the bevel width is 1 to 1.4mm. Again, without any serious measuring tools, i think this seems about right for the difference in blade thickness at the heel, belly, and tip
At this point I think i can do pretty well with this collar and setting up something to mark the LOC, with just a bit of practice.
Definitely finding it MUCH easier to keep smooth/even transitions and bevels than the wide stock collar was, so for this part I think I'm now satisfied :)
(apologies for the crap pictures, don't have any good options for resizing here in my phone too meet the attachment size limits while still keeping good detail)
P.S.
Also don't be thrown off by the crazy wide marker on the blade. I wanted to be sure to cover all the old grind experiments, so I just went with a really fat marker right up over the bevels and onto the face
Quote from: Kavik on September 01, 2017, 06:13:59 AM
Well, finally got some time to finish this small collar idea tonight...... And gotta say it's much nicer than just the straight cut off version.
Turned a little nub on the end of some acrylic blank I had laying around here...but if i were too do it all over again, this could all be done with the stock collar piece chucked up in the lathe...I just felt I cut the first one a bit short anyway
Still no laser line, but i think i did better keeping to the LOC
Operation feels very very smooth. Setup was the same as mentioned previously with my template. Pivot point seems to remain on the side of the shaft (on the side towards the tip), not in the center of the jig shaft
As I hope you can see in the attached pic, the bevel width looks pretty good.
Bevel angle isn't perfect, but it's close all along the length (sorry, i don't have any fancy accurate measuring tools for that).
With the exception of a couple extremes (user error), the bevel width is 1 to 1.4mm. Again, without any serious measuring tools, i think this seems about right for the difference in blade thickness at the heel, belly, and tip
At this point I think i can do pretty well with this collar and setting up something to mark the LOC, with just a bit of practice.
Definitely finding it MUCH easier to keep smooth/even transitions and bevels than the wide stock collar was, so for this part I think I'm now satisfied :)
(apologies for the crap pictures, don't have any good options for resizing here in my phone too meet the attachment size limits while still keeping good detail)
P.S.
Also don't be thrown off by the crazy wide marker on the blade. I wanted to be sure to cover all the old grind experiments, so I just went with a really fat marker right up over the bevels and onto the face
Looks good! (Stylish too.) ;)
With a stop collar, a "laser LOC" isn't as necessary. You can setup the knife in the jig, then set your sharpening angle with the AngleMaster (or however you do it), then just draw a line on the stone (or a reference point next to it), and with the power off, just check and see how the knife moves in relationship to the line, and adjust it in the jig, if needed. Experience tells me that after a few knives, you'll be able to set the knife in the jig, pretty much where it needs to be... especially now that your two pivot points are much closer together. The laser becomes more important when there's really nothing else to keep the same point on the stone (freehand or collar free).
I like it. Bevel looks good too. :)
Thanks man 8)
I know the laser line isn't THAT important, but thought it might help still during the training and building muscle memory stage.
Depending on the profile of the curve to the tip, even with the collar it's still possible to end up well above or below the line
If i don't end up working all weekend, maybe I'll just pull one of the laser diodes off my drill press.... I never use it on there anyway, and can always reinstall it when I'm done needing "training wheels" here
Out of curiosity: I know someone said the newer knife jigs don't use the stop screw anymore...I'm guessing a new collar would have no way of working on an old jig, with no o-ring to hold it in place, but would an old collar still thread onto a newer jig?
Quote from: Kavik on September 01, 2017, 04:12:37 PM
Thanks man 8)
I know the laser line isn't THAT important, but thought it might help still during the training and building muscle memory stage.
Depending on the profile of the curve to the tip, even with the collar it's still possible to end up well above or below the line
If i don't end up working all weekend, maybe I'll just pull one of the laser diodes off my drill press.... I never use it on there anyway, and can always reinstall it when I'm done needing "training wheels" here
Out of curiosity: I know someone said the newer knife jigs don't use the stop screw anymore...I'm guessing a new collar would have no way of working on an old jig, with no o-ring to hold it in place, but would an old collar still thread onto a newer jig?
With a stop collar, I don't think you'll see a real benefit to the laser, (but no harm trying... well, unless you stare at it... 8)).
Yes an old collar will work on a newer jig. (A bit of a sidebar, I've found that on the new collar, the stop can turn if you're not careful. Definitely not as secure as the old version, but a bit easier to work with). The collars actually look the same, (there's even an indicator on the new collar of the "spot" for the locking screw), but interestingly enough, the interior diameter of the new collar must be slightly bigger... I had to remove the O-ring to get the old collar on. Once on though, it works no problem.
Interesting............thanks ;D
(check your pm 8))
You guys are liable to end up like me..........with a box of spare Tormek jigs and parts in various stages of repair. :)
Ken
Lol there are worse things to waste money on
But I think I'm happy with just this one mod for the time being, I suggest giving it a try ;)
(still planning to eventually make a platform, but no desire to modify any of the other actual jigs at the moment)
If you've got a lathe and a spare collar, it only takes a few minutes to do
I cut down a second one last night that I'm sending out to cbwx to get a second opinion on it.
I mention this only to show, in the attachment, how easily it can be cut out of the original collar without needing to add an additional piece like i did in the first attempt.
Quote from: Ken S on September 03, 2017, 05:48:25 PM
You guys are liable to end up like me..........with a box of spare Tormek jigs and parts in various stages of repair. :)
Ken
I'm sure I'll give you a run for your money... :)
For me, modifying a sharpener, is 1/2 the fun. I don't expect Tormek, (or anyone else for that matter), to duplicate the setup I made in the other thread (adding a 2nd USB, sharpening parallel, etc).... just a modification I've enjoyed playing around with, to see what comes out. If something develops that benefits someone else... so much the better. No different than modifying a car for one's individual taste... (although cheaper I'm sure). ;)
Quote from: Kavik on September 03, 2017, 06:40:17 PM
I cut down a second one last night that I'm sending out to cbwx to get a second opinion on it.
I mention this only to show, in the attachment, how easily it can be cut out of the original collar without needing to add an additional piece like i did in the first attempt.
Thanks! Looks good... looking forward to giving it a go. :)
I gave up a couple of years ago trying to sharpen our kitchen knives on the Tormek as I was unhappy with the results. I was wrestling with my thoughts on Lift and Pivot, coupled with trying to work out the effects due to the width of the knife jig collar. (We have since used a proprietary knife sharpener in the kitchen and it is more than sufficient for our needs.) I subsequently threw out all the spare knifes on which I had been practising.
Today my son asked me if I could rescue one of his Global knives - the edge is best described as torn to shreds! He doesn't know how, and his propriety sharpener isn't improving matters, and it is only the one knife which has a problem.
So I have just ploughed through all of this Topic, its associated links, printed off the diagrams, got my head round all the various trials and outcomes, and will in the near future have another go at knife sharpening.
With regard to the above comments that it may be of no interest to others (only the two, three main protagonists), if you asked me a week ago I would agree, but now I have a situation to resolve, it is all suddenly very interesting! Some good work has been undertaken and posted. Thank you.
Quote from: RobinW on September 10, 2017, 03:39:08 PM
I gave up a couple of years ago trying to sharpen our kitchen knives on the Tormek as I was unhappy with the results. I was wrestling with my thoughts on Lift and Pivot, coupled with trying to work out the effects due to the width of the knife jig collar. (We have since used a proprietary knife sharpener in the kitchen and it is more than sufficient for our needs.) I subsequently threw out all the spare knifes on which I had been practising.
Today my son asked me if I could rescue one of his Global knives - the edge is best described as torn to shreds! He doesn't know how, and his propriety sharpener isn't improving matters, and it is only the one knife which has a problem.
So I have just ploughed through all of this Topic, its associated links, printed off the diagrams, got my head round all the various trials and outcomes, and will in the near future have another go at knife sharpening.
With regard to the above comments that it may be of no interest to others (only the two, three main protagonists), if you asked me a week ago I would agree, but now I have a situation to resolve, it is all suddenly very interesting! Some good work has been undertaken and posted. Thank you.
Glad to hear... hope it works out. Be interested to know what, if any problems you might encounter... would probably help lead to even a better solution.
If nothing else, you can always fix the damage on the Tormek, then switch to your regular "proprietary" sharpener. (Be curious to know what that is... probably best shared in a private message, if you care to).
Thanks... glad to see there's an interest... hope it helps! :)
As I'm due to be away for a while, I managed to have a couple of hours this afternoon sharpening knives.
First was a 4" paring knife. This brought back to mind another reason why I stopped sharpening knives on the Tormek. A couple of times, whilst grinding towards the edge, it caught and managed to lift the jig off the usb, spun the jig and knife under the usb, whereupon it tried to give me a major Tormek tattoo in the midriff!
So tried sharpening away, and managed to get bevelled surfaces which were pretty rough despite having pre-graded the stone surface with to fine. The edge was not particularly sharp as barely catching my thumbnail and not readily cutting paper. Persevering with free hand honing I managed to polish a lot of the striations out and get a sharp edge.
I then tried an 8" chef's knife. This brought back to mind a previous issue - large knives get obstructed by the honing wheel when sharpening away. However the 8" was accommodated without too many issues. Again the bevelled surfaces were pretty rough, but the situation was again rescued by free hand honing. I always find that free hand honing is liable to round over the edge. I would prefer a jig in the expectation of achieving better results.
So I took the bull by the horns and had a go at the Global knife. Despite getting equal sized bevels on both sides, again with poor surface quality. The edge looked and felt as though there was a burr, but it was not sharp. It didn't want to 'saw' through a piece of paper. After several attempts between honing and re-grinding I eventually got a satisfactory result. I did find when grinding this knife, it did not feel as comfortable on the stone as the previous 8" knife; it was susceptible to wander off line.
Having absorbed the information in the previous posts by others above, I tried to keep the section of the blade being ground, in line with my LOC on the wheel, lifting and pivoting as necessary to maintain this, without being concerned whether it was lift or pivot but what felt comfortable. I did find that towards the heel end of the Global blade it swung above the LOC, whereas the other 8" knife didn't. Overall the bevel thickness was pretty even along the length of the blade, so quite satisfied.
Anyway, for the short time I had, without practice, I have got three sharp knives. More through beginner's luck rather than being in full control of the situation. Certainly not as confident for repeat purposes as I would be when doing chisels and plane blades. Mind you, it took me many attempts (months!) to master the SE76 square edge jig.
Quote from: RobinW on September 10, 2017, 09:02:06 PM
As I'm due to be away for a while, I managed to have a couple of hours this afternoon sharpening knives.
First was a 4" paring knife. This brought back to mind another reason why I stopped sharpening knives on the Tormek. A couple of times, whilst grinding towards the edge, it caught and managed to lift the jig off the usb, spun the jig and knife under the usb, whereupon it tried to give me a major Tormek tattoo in the midriff!
So tried sharpening away, and managed to get bevelled surfaces which were pretty rough despite having pre-graded the stone surface with to fine. The edge was not particularly sharp as barely catching my thumbnail and not readily cutting paper. Persevering with free hand honing I managed to polish a lot of the striations out and get a sharp edge.
I then tried an 8" chef's knife. This brought back to mind a previous issue - large knives get obstructed by the honing wheel when sharpening away. However the 8" was accommodated without too many issues. Again the bevelled surfaces were pretty rough, but the situation was again rescued by free hand honing. I always find that free hand honing is liable to round over the edge. I would prefer a jig in the expectation of achieving better results.
So I took the bull by the horns and had a go at the Global knife. Despite getting equal sized bevels on both sides, again with poor surface quality. The edge looked and felt as though there was a burr, but it was not sharp. It didn't want to 'saw' through a piece of paper. After several attempts between honing and re-grinding I eventually got a satisfactory result. I did find when grinding this knife, it did not feel as comfortable on the stone as the previous 8" knife; it was susceptible to wander off line.
Having absorbed the information in the previous posts by others above, I tried to keep the section of the blade being ground, in line with my LOC on the wheel, lifting and pivoting as necessary to maintain this, without being concerned whether it was lift or pivot but what felt comfortable. I did find that towards the heel end of the Global blade it swung above the LOC, whereas the other 8" knife didn't. Overall the bevel thickness was pretty even along the length of the blade, so quite satisfied.
Anyway, for the short time I had, without practice, I have got three sharp knives. More through beginner's luck rather than being in full control of the situation. Certainly not as confident for repeat purposes as I would be when doing chisels and plane blades. Mind you, it took me many attempts (months!) to master the SE76 square edge jig.
Glad you were able to make a go of it... bummer it didn't come out quite right. It looks like you've been a Tormek user for a while, so you're familiar with the system. The only thing I can think of, in reading your post, is maybe a bit too much pressure? Knives benefit from a light touch... especially the last few passes, I have found. That and marking the edge with a Sharpie or marker, and make sure your hitting the very edge... sometimes when knives are sharpened with another type of sharpener, "matching" another method can take a bit more than expected... especially right at the very edge and if the other sharpener sharpened or honed at a higher angle... it will look like you're there, but there might be a very small section that still needs to be reached, so the knife won't cut well. As for the finish being "rough"... not sure why. Are you basing that on how it looked, or how it cut? I know others have commented that it takes a bit to grade the stone "fine"... that, and once again sharpening pressure can affect the result.
Any other thoughts on the pivoting? Think a smaller collar would make a difference (good or bad)?
But at least you got 'em sharp! :)
Robin,
This must be particularly frustrating for you with your trained and experienced engineer's mind. Looking at what you wrote, what struck me was what you did not write. Did you begin by using the TT-50 truing tool? (Please note that I did not write "a truing tool". Of all the redesigned Tormek jigs and accessories, I consider the TT-50 to be the most essential, "must have" tool, along with a microadjust support bar.)
An untrue grinding wheel, and its accompanying gremlins can sneak up on you. It has happened to me several times, including, embarrassingly, while I was demonstrating the Tormek at a woodworking show. Now, whenever my sharpening is off, I use the truing tool. I prefer to make several light passes. Often my first removes only air. I usually advance by half numbers. The second pass will only touch the highest spots. This is the pass that tells the tale. I make my passes slowly, following the recommended handbook time of ninety seconds. Each succeeding pass is advanced half a number, paying attention to the sound and cutting pattern. When I reach a pass when the entire surface, both circumference and width, is lightly cut, I am done.
I am a devout believer in frequent, light truing. In special cases, I have made quicker passes to give a coarser grit. I have also made deep (half a turn) passes when frustrated with a glazed blackstone. My preference is light, slow passes. When I am on my best behavior (not always), I will true my wheel at the end of my sharpening session. This should be a habit, like checking fuel and oil levels in your car.
I don't mean to sound pious or preachy. I have come to this belief through multiple missteps.
I usually sharpen in the trailing grind direction (away from the knife). My eight inch chef's knife and slicer are my two longest knives. A high production sharpening session may consist of three or four knives. I like to be "plumb with the universe" when I sharpen and not rushed. A freshly trued wheel helps keep my head clear. I prefer light grinding passes. I think rounding with the honing wheel is often caused by not being focused on the work. I am as guilty of that as anyone. Jan proposed having the kenjig double ended, to allow setting Distance with the leather honing wheel. I like that idea for those with agile minds. My preference would be a clearly marked kenjig set for the nonchanging leather honing wheel diameter.
I started the trick and tips (not my title choice) topic. I still believe in learning with a chisel,regardless of what you normally sharpen. That topic needs a follow up knife topic. Ideally, Tormek needs to produce an indepth knife sharpening video in its new video production facility.
I suspect most of us have not really mastered the SE-76 Square Edge Jig, and certainly the newer SE-77 jig. We are penny wise and pound foolish. We will willingly purchase a blackstone or Japanese wheel, but not want to spend the small amount of money for several Irwin 3/4" Blue Chip chisels and spend a very few quiet hours really mastering the Tormek. Like most of us, I procrastinated in using the TT-50 Truing Tool, foolishly not wanting to wear out my precious grinding wheel, and doing mediocre sharpening. I made the same foolish mistake with the stone grader.
Redouble your efforts with a quiet, organized mind, and do not become discouraged.
Ken
ps I think good thoughts about you whenever I make metric measurements.
This is how we do a curved tip:
- Mark the tip radius perpendicular to the edge.
- Clamp in the middle of the straight segment.
- Start at the bolster end, and grind the straight segment as usual, sliding across the stone with the knife jig perpendicular to the Universal Support till you reach the marked radius line.
- At this point fix the jig position at the US, not sliding laterally further.
Do the tip radius by pivoting the jig and raising the handle, till the radius line comes perpendicular to the US (i.e parallel to the wheel margin) - not any farther.
Step 1 - straight segment
(http://knifegrinders.com.au/photos/curved_tip_1.JPG)
Step 2 - curved tip
(http://knifegrinders.com.au/photos/curved_tip_2.JPG)
It would be interesting to do slow motion videos of a dozen expert Tormek knife sharpeners.
Ken
Wootz, thanks for sharing your procedure, appreciated! :)
I applaud your emphasis to maintain the normal to the edge perpendicular to the USB.
Jan
Quote from: wootz on September 13, 2017, 11:36:02 AM
This is how we do a curved tip:
- Mark the tip radius perpendicular to the edge.
- Clamp in the middle of the straight segment.
- Start at the bolster end, and grind the straight segment as usual, sliding across the stone with the knife jig perpendicular to the Universal Support till you reach the marked radius line.
- At this point fix the jig position at the US, not sliding laterally further.
Do the tip radius by pivoting the jig and raising the handle, till the radius line comes perpendicular to the US (i.e parallel to the wheel margin) - not any farther.
Thanks for the example.
I'm not sure "clamp in the middle of the straight segment" can be a guideline. On longer knives, like in your example, it'll work, but the relationship of the clamp distance to the tip, as has been talked about before, plays a large part in the angle at the belly to tip area. On a shorter knife... where you clamp can change the angle more.
I do think, one point worth mentioning is, pivoting to keep the grind line more perpendicular is an advantage to pivoting over just lifting to follow the curve.
Kavik was kind enough to send me a modified collar to try. Haven't had a chance to yet, but just noting in the attached picture how much closer it stays to the LOC, seems to me an improvement.
(I'm jealous of your stone rack in the background). ;)
Glad to see it arrived, usps tracking never updated for me to even say the shipment existed lol
That's a great comparison shot you took, thanks for that!
One thing to keep in mind when you do get a chance to test it. I was setting my tip projection to match the blade protection like we talked about, but using the side of the shaft as the base reference, not the center of the shaft. Play around with different projections (I'm sure you will anyway), but my idea was for knives whose shapes don't allow the tip to stay on the LOC, it should end up slightly above rather than below, allowing you the option to lift to compensate
Feel free to shoot me a pm or follow up here if you run into any issues. But based on your pic, it looks like you're already pretty close to on target with it 8)
I've had a chance to try Kavik's modified collar... and have already told him... he's not getting it back. 8)
With the "sides" of the collar removed, I get a nice fluid movement from straight portion -> belly -> tip.
I'm not much on videos, but tried to make a couple of short ones... just to give an idea. Note how close the knife stays to the (imaginary) LOC on the stone...
https://vimeo.com/234061935
https://vimeo.com/234061995
... in the 2nd video,,, even a blade that is basically curved the entire length, is a nice smooth movement. As a bonus, where the knife is set in the jig appears to be less of an issue... having the pivot basically in the same location gives a nice consistent bevel. (I tried to keep my hands out of the way a bit more in the 2nd video, so maybe you could see the pivot area better.. and showed the shape of the knife at the start).
I thought there might be a problem, since the "stop" is so smooth, it might "ride over" the USB... but maintaining the same pressure needed to keep the jig on the USB... this didn't occur. Also, not an issue keeping the straight portion of the blade parallel to the stone.
Works great... I like it. ;D (I'm not much on making videos... but hoped this would at least give some idea of how well it performed). :-[
As a double bonus... wootz allowed me to beta test his new Android version of the app for setting the USB height to set the angle. Honestly, when I first read it on his website, I thought it would be no easier than the AngleMaster... man, was I wrong. It's great too... makes setup easy and very accurate. Highly recommended. ;D
So glad it's working for you man! ;D
Sounds like you had the same experience as me, it makes the whole motion just feel much more fluid and natural, in addition to keeping closer to the LOC
Not saying it's the be-all-end-all solution to everything or anything like that, but i know which jig I'll be using from this point on 8)
Only other think I might try some day is putting a concave curve on the end of one, rather than convex. See if i can pull the pivot point directly on center instead of just closer, but it's probably not necessary (unfortunately didn't think about this until just this minute)
Quote from: cbwx34 on September 13, 2017, 03:45:38 PM
...
I'm not sure "clamp in the middle of the straight segment" can be a guideline. On longer knives, like in your example, it'll work, but the relationship of the clamp distance to the tip, as has been talked about before, plays a large part in the angle at the belly to tip area. On a shorter knife... where you clamp can change the angle more.
...
To remind of the context, we are talking of a special case of a steep curved tip.
To estimate effect of the clamping position, we ground an identical SWIBO knife from our rental pool the same way and at the same edge angle, but clamped closer to the tip, at 1/3 of the blade length from the tip.
- Start at the bolster end, and grind the straight segment as usual, sliding across the stone with the knife jig perpendicular to the US till you reach the marked radius line.
- At this point fix the jig position at the US, not sliding laterally further. Do the tip radius by pivoting the jig and raising the handle, till the radius line comes perpendicular to the US (i.e parallel to the wheel margin).
Then compared both knives, looking at the bevel height and measuring edge angle with a laser protractor in the straight segment, and at the tip radius.
RUN 1 - clamped at the middle of the straight partNaked-eye increase in bevel height to the tip; the edge angle is almost the same in the middle of the blade and at the tip radius... maybe by less than 0.5 degree larger at the tip, hardly detectable by the portable CATRA laser protractor.
(http://knifegrinders.com.au/photos/curved_tip_2.JPG)
(http://knifegrinders.com.au/photos/clamped_middle1.JPG)
RUN 2 - clamped at the tip 1/3The bevel is of pleasantly even height all along the edge; the edge angle at the tip radius is larger by +4 degrees (per side) compared to the angle in the blade middle.
(http://knifegrinders.com.au/photos/clamped_tip_position.JPG)
Before you ask, I measured the manufacturer's edge angle - SWIBO are very well made knives, probably the best in their class, of 56-58 HRC and 120-130 BESS score out of the box; the bevel is of even height all along the edge, and edge angle at the tip is by only 1 degree larger than in the middle of the blade.
Wootz,
I like your idea of using protective paper on your knife in jif photo. I am starting a new topic with a question for you.
Ken
Quote from: wootz on September 17, 2017, 06:49:37 AM
To remind of the context, we are talking of a special case of a steep curved tip.
....
We might have gotten our wires crossed a bit... I was more stating as a "general rule" don't use "clamp in the middle"... not your specific example.
Thanks for the post though... good information as always, and good info on what to look for in setting the knife in the jig. (Also, a good example of what I'm now calling... the "Collar Effect"). 8) (Your setup effectively deals with that too).
A thought once uttered becomes untrue without the context
Good thought, Wootz.
Ken
Quote from: cbwx34 on September 15, 2017, 11:45:35 PM
I've had a chance to try Kavik's modified collar... and have already told him... he's not getting it back. 8)
With the "sides" of the collar removed, I get a nice fluid movement from straight portion -> belly -> tip.
I'm not much on videos, but tried to make a couple of short ones... just to give an idea. Note how close the knife stays to the (imaginary) LOC on the stone...
https://vimeo.com/234061935
https://vimeo.com/234061995
... in the 2nd video,,, even a blade that is basically curved the entire length, is a nice smooth movement. As a bonus, where the knife is set in the jig appears to be less of an issue... having the pivot basically in the same location gives a nice consistent bevel. (I tried to keep my hands out of the way a bit more in the 2nd video, so maybe you could see the pivot area better.. and showed the shape of the knife at the start).
I thought there might be a problem, since the "stop" is so smooth, it might "ride over" the USB... but maintaining the same pressure needed to keep the jig on the USB... this didn't occur. Also, not an issue keeping the straight portion of the blade parallel to the stone.
Works great... I like it. ;D (I'm not much on making videos... but hoped this would at least give some idea of how well it performed). :-[
As a double bonus... wootz allowed me to beta test his new Android version of the app for setting the USB height to set the angle. Honestly, when I first read it on his website, I thought it would be no easier than the AngleMaster... man, was I wrong. It's great too... makes setup easy and very accurate. Highly recommended. ;D
Is it possible to put these videos on Youtube?
Quote from: troflog on August 10, 2018, 09:28:54 AM
Quote from: cbwx34 on September 15, 2017, 11:45:35 PM
https://vimeo.com/234061935
https://vimeo.com/234061995
Is it possible to put these videos on Youtube?
The above links should work now... (I somehow had set them to private).
BTW, Rick's "Pin Pivot Collar" (https://forum.tormek.com/index.php?topic=3541.0) is a bit better solution, if he has any left to sell.
If not, and if you have a spare collar, you can just cut the collar down to size... I did it here (https://forum.tormek.com/index.php?topic=3522.msg22468#msg22468). (It wasn't the prettiest job, which is why I "censored" it), but it worked. :)
We are fortunate to have a good source for spare parts. Extra parts, plus the courage to risk needing them, help drive our innovative spirit.
Ken
Quote from: cbwx34 on August 10, 2018, 02:43:22 PM
Quote from: troflog on August 10, 2018, 09:28:54 AM
Quote from: cbwx34 on September 15, 2017, 11:45:35 PM
https://vimeo.com/234061935
https://vimeo.com/234061995
Is it possible to put these videos on Youtube?
The above links should work now... (I somehow had set them to private).
BTW, Rick's "Pin Pivot Collar" (https://forum.tormek.com/index.php?topic=3541.0) is a bit better solution, if he has any left to sell.
If not, and if you have a spare collar, you can just cut the collar down to size... I did it here (https://forum.tormek.com/index.php?topic=3522.msg22468#msg22468). (It wasn't the prettiest job, which is why I "censored" it), but it worked. :)
Thank you very much. This is a great forum. I think I will try to make one myself by grinding down the standard collar. But I will try only to grind the sides if it is possible:)
In fairness to the Tormek engineering team, we should acknowledge that we forum members do not have many of the constraints that they have. We do not have the ever presence of various safety commissions examining our work. We do not have the accounting and marketing departments pressing us for a single "one size fits all" cost effective solution. We do not have the experts bemoaning that our designs require the end users to raise their level of skill by 3.17%, thus limiting the market.
The standard issue Tormek knife jigs do a commendable job for most knives at a very reasonable cost for most users. However, I am proud to be one of those in pursuit of a more commendable jig.
Keep on innovating!
Ken
I have one of Rick's pivot pins and along with the information here in this post it has completely changed how much I enjoy my Tormek. Thanks to Rick and all of you for making my Tormek better than it ever was.
Quote from: troflog on August 11, 2018, 09:08:25 AM
Thank you very much. This is a great forum. I think I will try to make one myself by grinding down the standard collar. But I will try only to grind the sides if it is possible:)
troflog,
If you do grind down the standard collar, I would recommend NOT putting a curve/bevel on the front. I did and found it was too easy to have the collar ride up on the USB and slip forward. CB came up with the "shaft collar" innovation, but even that slips up. That was the reason I developed the the "pin pivot" addition. To me it makes all the difference.
If by trying to "only grind the sides", not beveling it is what you mean, I believe you are on the right track.
Rick
Quote from: Kavik on August 21, 2017, 06:14:26 AM
First, the drawbacks of a cut down collar: you need to focus a little more on a) keeping the knife flat to the stone when working on the straight edge of the blade and b) keeping the jig on the USB without slipping off
Second, the perk: the pivot point becomes practically stationary, as opposed to moving drastically, as shown in the second row of the pic cbwx posted above
Hi everybody. I am new in this forum, and this is my very first post. I hope you understand me even as I am not a native english speaker since I am a Danish viking.
But I have read all this about making the collar rig smaller to get a better tilting movement with great enjoyment, and can see a lot of improvements in the ideas from Kavik and cbwx34.
But maybe it can be done even better.
I have an - maybe great - idea to make it even more precisely.
Instead of using the collar at all - what if you drill a hole through the svm-45 upside/down through the handle of the jig itself just behind the zero-center-mark on it. And then you put a piece of a round steelrod or alike through the hole and glue it there so it is protruding equally up and down from the drilled hole. Then you can hold the upper part of the steelrod between your thumb and indexfinger when grinding so it stays on the USB because the lower part of the rod is against the USB itself, and since it is longer than an almost grinded away collar then it wont slip easy. And when you tilt it, it will tilt around the exact center of the jig not moving downward at all, but giving the 100% optimal curve.
Of course you will lose the possibility to adjust the length by using the collar - but on the other hand you also get rid of the feeling of the collar turning on the jig which I find annoying - but it can be height adjusted with the USB up or down instead. And not so hard steering on the straight parts of the blade as else....but what does this intelligent forum think regarding this idea?
Jørgen,
Rick Krug's adapter for the SVM knife jigs does basically that. Nice add-on!
Kind regards,
Rich
@Plekter,have you a Photo or a Drawing for your Idee?
@RichColvin
I had not seen the Rick Krug´s adapter until now. It is basically the same idea as mine, but needs a lot more work to prepare the adapter I think. It must also feel a little more clumsy in the hands since you have all the rings which bear it on the shaft. My idea would be more slick since its only a thinner rod going directly through the rig without all the holding-on-it-stuff. And then you could wrap something around the end of the rig to avoid be irritated by the grooves in the end of the handle.
@Hunter
I have not made it in the real yet - so no photos or drawings.
But since the thickness of the handle itself is around 12 mm or 15/32", then I think the metalrod going through should be no more than 4 mm or 5/32" to not weaken the shaft itself too much and a total length of 5 cm/ 2" should be suitable. So if you can imagine a 2" metalrod going through the shaft of the rig up/down and nothing else so you else have the "clean" shaft to hold to - then you have it. It should be an easy fix - just a drill and some metalworking glue or epoxy to hold it in place. Did you understand my explanation now?
Quote from: Plekter on October 03, 2018, 10:51:19 PM
...
Instead of using the collar at all - what if you drill a hole through the svm-45 upside/down through the handle of the jig itself just behind the zero-center-mark on it. And then you put a piece of a round steelrod or alike through the hole and glue it there so it is protruding equally up and down from the drilled hole. Then you can hold the upper part of the steelrod between your thumb and indexfinger when grinding so it stays on the USB because the lower part of the rod is against the USB itself, and since it is longer than an almost grinded away collar then it wont slip easy. And when you tilt it, it will tilt around the exact center of the jig not moving downward at all, but giving the 100% optimal curve.
Of course you will lose the possibility to adjust the length by using the collar - but on the other hand you also get rid of the feeling of the collar turning on the jig which I find annoying - but it can be height adjusted with the USB up or down instead. And not so hard steering on the straight parts of the blade as else....but what does this intelligent forum think regarding this idea?
Quote from: Plekter on October 04, 2018, 01:33:38 PM
@RichColvin
I had not seen the Rick Krug´s adapter until now. It is basically the same idea as mine, but needs a lot more work to prepare the adapter I think. It must also feel a little more clumsy in the hands since you have all the rings which bear it on the shaft. My idea would be more slick since its only a thinner rod going directly through the rig without all the holding-on-it-stuff. And then you could wrap something around the end of the rig to avoid be irritated by the grooves in the end of the handle.
@Hunter
I have not made it in the real yet - so no photos or drawings.
But since the thickness of the handle itself is around 12 mm or 15/32", then I think the metalrod going through should be no more than 4 mm or 5/32" to not weaken the shaft itself too much and a total length of 5 cm/ 2" should be suitable. So if you can imagine a 2" metalrod going through the shaft of the rig up/down and nothing else so you else have the "clean" shaft to hold to - then you have it. It should be an easy fix - just a drill and some metalworking glue or epoxy to hold it in place. Did you understand my explanation now?
Don't see why it wouldn't work, although I'm not sure gluing it in would be the best solution. Rick's has the advantage of being removable as well as adjustable (and there is nothing "clumsy" about it).
But, bearing in mind you'll probably have to dedicate/sacrifice a jig, I say give it a try... should work similar to what the other methods do... and might be a simpler, more accessible route to take.