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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 

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:

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

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!

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

(accidentally hit submit early....pls hold)

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

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?

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?

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 lol

Thanks, I'll keep the in mind when I eventually get around to trying the platform idea

No thoughts on the differently profiled collars?

Cheers for the YouTube link 

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

My .02.... I think the effort would be better spent making and using one of Herman Trivilino's jigs.

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

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

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  )

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?