What am i doing wrong?
1) I set my 10" Wenger chef's knife at about 17 deg which is about what i found as the factory edge using the sharpie.
- Using my left arm it grinds the edge almost right on the original bevel, but when i reverse the jig to flip the knife and use my right arm the edge appears to be grinded about half a mm more than the factory bevel and it is noticeable when you compare the two sides under the light
- The tip is more evident the edge angle is off as one side looks more grinded than the other and looks off center
3) On a few knives i noticed the edge closer to the handle of the knife (ricasso) is deeper into the blade or rounded into the blade of the knife than the rest of the edge
Help!
The knife jigs don't center the blade exactly on the center axis of the jig, and the thicker the blade, the more off-center the blade will be. This is the only true flaw I can see with the current knife jigs.
KSMike is right. The fact that the blade is not perfectly centered shows up in extremely thick blades, and also in extremely thin blades.
In cases where it is critical that the bevels be exactly the same, take the knife out of the jig and turn it over, when switching from one side to the other. It will be necessary to reset the angle, but the adjustment should be minimal.
Also note that not all knives are ground symmetrically, or designed to be. Following the factory bevels on each side is a good start. putting a 50/50 edge on a 70/30 ground knife can lead to steering issues, but these types of edges tend to appear on japanese double bevel knives
Folks,
As much as I hated to admit this to myself: In my opinion, Tormek does not truly have a Knife Jig. A jig is a type of custom-made tool used to control the location and or motion of another tool. A jig's primary purpose is to provide repeatability, accuracy, and interchangeability. A jig is often confused with a fixture; a fixture holds the work in a fixed location. A device that does both functions (holding the work and guiding a tool) is called a jig. An example of a jig is when a key is duplicated, the original is used as a jig so the new key can have the same path as the old one. There are many types of jigs, and each one is custom-tailored to do a specific job. Some are made to increase productivity through consistency, to do repetitive activities or to do a job more precisely.
I am sure that there are many of you who will disagree with the above definition.
For the most part I enjoy the Tormek. Having said that, I can assure everyone that if you take the craftsmanship out of knife sharpening using the Tormek you will have a mess.
To everyone, Please have a blessed New Year!
I agree and wondered what I was doing wrong all this time. Come on Tormek! For this kind of money we should get more. Like a real jig.
By RJM's definition, you would need a different "jig" for every knife you own or sharpen for someone else. Does that really sound practical to anyone? In my opinion, the Tormek jigs, including the knife jig, do exactly what RJM defines as the purpose of a jig, that is to control the motion of the workpiece (knife) and its relationship to the cutting material (grindstone). Does the knife jig control the knives absolutely, in a manner where the user is just a replacement for a servo motor? No. Does it provide the means to sharpen every blade ever designed from the tiniest pen knives to samurai swords? No. But, it does give you the means to control a huge range of sizes in a manner where most errant motion is minimized if you use the jig as it is designed.
There's still some craftsmanship involved in sharpening a knife on a Tormek. You have to pay attention to what you are doing, you have to follow directions, and you have to practice a few times before you can do it perfectly.
Going back to Ric's original issue, Although Mike brought up the issue of centering, I don't think that is Ric's issue. A Wenger chef's knife should be of a thickness that would be very, very close to centered in the jig. From what Ric has written I think he is not rocking the jig on its axis, but is shifting it laterally. That is what I most commonly see when someone says "the angle gets wider at the tip".
Quote from: Jeff Farris on January 04, 2013, 02:36:14 PM
There's still some craftsmanship involved in sharpening a knife on a Tormek. You have to pay attention to what you are doing, you have to follow directions, and you have to practice a few times before you can do it perfectly.
I agree that the knife jig does actually perform as a jig, but it's certainly not the best solution for the problem. The problem with a knife edge is that can be seen as a "dynamic edge", in so much that almost all knives curve and to differing degrees. The answer to the problem is if the knife edge is always at the correct angle whenever presented to the stone. At the moment i am leaning toward the idea of the tool rest or the base of the scissor jig being the basis for a much more reliable jig. IMO!!
Quote from: justin on January 04, 2013, 02:56:22 PM
At the moment i am leaning toward the idea of the tool rest or the base of the scissor jig being the basis for a much more reliable jig. IMO!!
For some exotic profiles you might be right (although I don't see how a platform is a better solution). But, for the vast majority of knife profiles, the knife jig is the correct tool to keep a consistent bevel along a curved edge.
Quote from: Jeff Farris on January 04, 2013, 04:01:05 PM
For some exotic profiles you might be right (although I don't see how a platform is a better solution). But, for the vast majority of knife profiles, the knife jig is the correct tool to keep a consistent bevel along a curved edge.
The reason i like the tool-rest idea is because ALL focus is at the point of contact with the stone. As long as the blade is flat on the rest it can only cut at the set angle. This removes all problems with the angle drifting near the tip of the blade. The problem i see with the knife jig is that the angle is only governed by centre point leaving the extreme ends open to error.
When I think of jigs I think of the devices I use with my table saw to make precise repeatable cuts at the right place and at the right angle. No matter how well the jig is designed, the operator's role is crucial.
And no matter how well a jig is designed the work I do with it can almost always be beat with a production-quality machine designed to do the same thing faster and better.
Things are always a trade-off between faster, better, and cheaper. You can have any two of those, but only at the expense of the third.
Quote from: justin on January 04, 2013, 06:22:49 PM
The reason i like the tool-rest idea is because ALL focus is at the point of contact with the stone. As long as the blade is flat on the rest it can only cut at the set angle. This removes all problems with the angle drifting near the tip of the blade. The problem i see with the knife jig is that the angle is only governed by centre point leaving the extreme ends open to error.
Your concept only works if the blade is flat. With a blade that tapers (as most do), your pressure points and points of contact with the plate will alter the angle.
I'm also guessing that you haven't actually set a table on the machine with an angle appropriate for a knife blade and tried this yet. Unless the table is very, very narrow (like the width of the stone) interference with the case or handle is a constant problem. Also, at the thin angles desired on knives, the table has to be very thin at the edge or the gap between the table and the grindstone is significant.
Quote from: Jeff Farris on January 04, 2013, 09:09:19 PM
Your concept only works if the blade is flat. With a blade that tapers (as most do), your pressure points and points of contact with the plate will alter the angle.
I'm also guessing that you haven't actually set a table on the machine with an angle appropriate for a knife blade and tried this yet. Unless the table is very, very narrow (like the width of the stone) interference with the case or handle is a constant problem. Also, at the thin angles desired on knives, the table has to be very thin at the edge or the gap between the table and the grindstone is significant.
Yes blades with funky bevel/profiles could cause a problem, it does on the Edge pro but is do-able.
Not sure what you mean "table" is that the tool rest? True i haven't set it up as i'm still unsure what is the best piece of kit to purchase without wasting money. I have used the knife jig but unfortunately really didn't like it, hence looking to manufacture an alternative.
What technique would you suggest then, where
"the angle gets wider at the tip".
rocking the jig on its axis, but is shifting it laterally
I lift my elbows straight up causing the tip to lift. If i glide the knife laterally the tip widens without sharpening
Quote from: Ric Albano on January 15, 2013, 04:33:57 PM
What technique would you suggest then, where
"the angle gets wider at the tip".
rocking the jig on its axis, but is shifting it laterally
I lift my elbows straight up causing the tip to lift. If i glide the knife laterally the tip widens without sharpening
Here's Jeff demonstrating/instructing use of the knife jigs. Move to 4m:40s point, does this answer your question?
http://www.youtube.com/watch?v=fYURcwkKGPs
Here's Jeff demonstrating/instructing use of the knife jigs. Move to 4m:40s point, does this answer your question?
http://www.youtube.com/watch?v=fYURcwkKGPs
[/quote]
This knife jig topic comes up quite frequently. My experience when I hit the same roadblock was to review Jeff's video demo very carefully and then practice a lot. Frankly, it worked. I can save everyone a lot of time and energy on this topic.......do EXACTLY as Jeff suggests in both his videos and also following his comments. Don't " think" you have a better way etc, just blindly follow the instructions and stop thinking. Practice this, then practice again, then do it some more....and again. You'll know when to stop because your knives will have easily good enough bevel consistency and they will be dam sharp. What I'm trying to say is just have faith in Jeff's method instead of trying to reinvent all the time. There's nothing wrong with exploring new ways of course, I'm simply advocating learning and mastering Jeff's method FIRST. Then move into possible innovation and improvement of your own design. This is what I did.....and it truly works
As a footnote, I now sharpen all but my expensive knives freehand....guess what....they're easily good enough and a billion miles better than all my friends and neighbours. When it comes to my Japanese jobs, I get the jig out ( don't care how its defined, I care if it works), I practice on two or so cheapies to "re-load" the muscle memory and......grind away....guess what.....it works.
Quote from: Byoomholay on January 16, 2013, 09:28:52 AM
I can save everyone a lot of time and energy on this topic.......do EXACTLY as Jeff suggests in both his videos and also following his comments. Don't " think" you have a better way etc, just blindly follow the instructions and stop thinking.
Although i don't actually really agree with this rather narrow approach, this case renders it a bit pointless seeing as the original poster is having trouble caused by a known flaw in the jig.
Quote from: Justin on January 16, 2013, 08:02:44 PM
Quote from: Byoomholay on January 16, 2013, 09:28:52 AM
I can save everyone a lot of time and energy on this topic.......do EXACTLY as Jeff suggests in both his videos and also following his comments. Don't " think" you have a better way etc, just blindly follow the instructions and stop thinking.
Although i don't actually really agree with this rather narrow approach, this case renders it a bit pointless seeing as the original poster is having trouble caused by a known flaw in the jig.
I refer specifically to the issue of how to raise the curved end bit of the blade....this is where Jeff's techniques score dividends. My point didn't address the non centred jig issue and wasn't intended to. I guess the proper solution to that is an improvement request to the Tormek R&D folks. I was simply stressing that whilst maybe not technically perfect, despite the jig flaw, Jeff's methods when practiced properly are good enough for practical purposes
Quote from: Jeff Farris on January 04, 2013, 02:36:14 PM
From what Ric has written I think he is not rocking the jig on its axis, but is shifting it laterally. That is what I most commonly see when someone says "the angle gets wider at the tip".
To be specific, this was the point my comment was reinforcing. IMO folks will improve their results by recognising one fundamental truth which is that the jigs don't replace skill and craftsmanship. Technique and practice are every bit as important. Even a jig with a lets face it teensy weensy flaw will still perform perfectly adequately in capable hands.
Quote from: Byoomholay on January 16, 2013, 08:52:11 PM
"perfectly adequately" " good enough for practical purposes"
Is that good enough for a professional piece of kit...?
I would not want to show off the sharp edge of anything that cost very much or was a prized possession if the two grinds did not match perfectly. Especially if I was trying to sell a service. Not good enough for a professional kit unless you reclamp the knife to obtain a perfect grind.
I'm going to jump in here and say that I think a few of you are making more out of this than really exists. In my experience, which includes thousands of knives from customers specifically trying to stump me, it is only on the thickest of hunting/combat knives that I feel it is necessary to re-jig the knife to obtain equal bevels. I have never found it necessary on any standard kitchen cutlery or on the vast majority of folding knives.
Yes, in theory, the jig will only produce a "perfectly" centered bevel on a knife of the thickness the jig is designed for. In practice, the variance on most knives is so small as to be indistinguishable.
EDITED TO ADD:
I'm going out on a limb here and guessing that Ric's problem is one of technique, rather than jig design. "...the bevel widening out at the point..." leads me to believe he is rocking the jig laterally rather than axially.
Jeff, this is something I've wondered about since I first started using the knife jig. Does the position of the jig on the knife (closer or further from the knife tip) have an effect on this bevel widening out at the point"?
And as far as this thread is concerned, I agree that we're making too much of the OP's comment. What if the OP is simpling spending more time on one side of the knife than the other? That will make one bevel wider than the other and place the edge off center. Jigs can only take you so far with any piece of equipment. Knowledge, skill, and experience are necessary to get good results.
I agree with Herman that jigs can only take you so far. Then you need some skills. To get the skill you need practice. It is hard to practice on expensive tools because you will end up grinding them all away. But if you don't practice you can't be good. So in the end some knives are going to have to be sacrificed to learn the skills - I don't think there is a solution. This winter I am going to get some cheap knives and learn to hand sharpen on the Tormek.
The OP's knife is a factory ground, and without any offense intended, isn't a top class knife. go into any kitchen knife shop and look at the bevels on the knives. if you find one with a perfectly centred evenly ground edge you'll be lucky.
From the sound of the post this is the first time he's sharpened it and the tormek bevels aren't matching the factory bevel.
The jig being at fault is the last thing i would presume. My order of probability would be wonky factory grind, operator error, then jig.
Quote from: Herman Trivilino on January 18, 2013, 03:56:46 AM
Jeff, this is something I've wondered about since I first started using the knife jig. Does the position of the jig on the knife (closer or further from the knife tip) have an effect on this bevel widening out at the point"? ...
Yes it does, BUT, very, very marginal. If the knife profile is a normal sweeping curve, keep the jig toward the center of the blade.
Quote from: Jeff Farris on January 18, 2013, 07:35:05 PM
Yes it does, BUT, very, very marginal. If the knife profile is a normal sweeping curve, keep the jig toward the center of the blade.
What if it's a butcher knife? Towards the tip the curve no longer sweeps, but has a smaller radius. Would you then recommend that the jig be positioned closer to the tip?
Herman brought out a great question about clamping that I have been wondering about. Jeff answered it very well.
I ran into that problem on a Gerber survival knife that a young fellow brought me to sharpen. I clamped it right before the serrations began, set the angle, and started to sharpen. Made 2 or 3 passes then realized that I didn't like what I was seeing. The point of contact between the knife and the wheel moved drastically from the straight portion of the knife blade to the point of the knife. The point was contacting the wheel 1 inch or better, further up the wheel which would have made the bevel several degrees more blunt. That was using Jeff's method of lifting the handle.
I shut the Tormek off and analyzed the situation. Knowing Jeff says never, I still tried pivoting the knife instead of lifting it (with the Tormek off). That didn't help the problem. I took the knife out of the jig and parked the Tormek. I then clamped it in my DMT Aligner and proceeded to do as before the Tormek. By the way, the DMT is a great tool and will put just a good edge (or better as double bevels are easily obtained) if the proper stones are used. However there is one problem, it is a slow process.
Since then I have wondered if it should have been clamped on down the blade above the serrations. Thanks Jeff for the answer! Next time I get that kind of knife, hopefully I won't be parking the Tormek.
As a side note, the DMT Aligner comes with a tapered diamond rod for doing serrations that works well for touching them up. It accommodates different sizes of serrations because of the taper. I also have one made by Buck that does not have the guide that Aligner has.
Elden
Quote from: Herman Trivilino on January 19, 2013, 01:43:16 AM
What if it's a butcher knife? Towards the tip the curve no longer sweeps, but has a smaller radius. Would you then recommend that the jig be positioned closer to the tip?
Here's how I "eyeball" the jig into position for unusual radii. Position the knife in the jig so that an imaginary line from the center of the curve intersects with the shaft of the jig where it meets the stop.
Jeff, can you clarify that any further? If the shaft of the jig is centered with the curve of the blade (that's how I - maybe incorrectly - interpret your post), would the knife be fully grasped by the jig? It seems like the jig would be hanging off the end of the blade, and much of the blade would be unsupported.
This question of where to "jig" the blade is one I've often wondered about too.
Let's see if this drawing accurately reflects what Jeff was saying.
(http://s1291.beta.photobucket.com/user/htrivilino/media/KnifeJig_zps1de07491.png.html?sort=3&o=0)
http://s1291.beta.photobucket.com/user/htrivilino/media/KnifeJig_zps1de07491.png.html?sort=3&o=0
The curved portion of the blade, near the tip, is an arc of a circle. The "imaginary line" passes through the center of that circle. In other words, the imaginary line is a radial line.
Thank you Herman, that does help. I misunderstood where on the jig Jeff was referring to.
Herman's fine artwork is exactly what I was trying to say.