Asymmetrical bevel result on knives

[Aikijay]

I have been using the knife sharpening jig for a couple of fixed blade knives and a couple of pocket knives, and have been getting a bevel which appears wider on one side of the blade than the other, despite what feels like even pressure and equal number of strokes across the wheel. The jig should be holding the blade centered, and it seems physically impossible that this should be occurring, yet it is. I would appreciate any advice as to what you think the causes of this could be, and what I would need to do to eliminate it thank you very much

[Sir Amwell]

Are you using the self centring jig (kj45)?
If you are then I can only assume that the problem lies with your knife or knives. Unfortunately it is quite common for folding or fixed blade bushcraft/edc knives to have asymmetric grinds before the apex.
If you are using the old style jig (can't think off hand the model number) then it will only centre knives within a tolerance of 2-3mm spine thickness I think. Anything thinner you should increase the thickness with tape to aid centering and avoid wobble. Anything thicker requires altering (thinning) the jaws of the jig to accommodate the extra thickness and centre the knife. Knife Grinders has an informative video about this on the YouTube channel.
For those thicker knives you would probably best get the newer KJ45 self centring jig.
I tried sharpening my brother's custom made bushcraft knife and ran into the same problem. I was literally pulling my hair out trying to get even bevels but got nowhere until I realised the knife had been ground asymmetrically in the first place. Had to keep flipping and adjusting over and over til I got it right. Very frustrating!

[Aikijay]

Thanks for your reply. The jig I'm using actually does not have a model number inscribed on it and I threw away the box a long time ago. It's probably about eight years old now. I would think that if there was an asymmetrical grind put on the blade initially then by re-sharpening it on the Tormek repeatedly, the apex of the grind would re-center itself, assuming the jig is symmetrical. I would attach a photo of it but I'm not sure this forum allows that at least I don't see how to do it. Thank you very much.

[Aikijay]

Thanks for your reply. The jig I'm using actually does not have a model number inscribed on it and I threw away the box a long time ago. It's probably about eight years old now. I would think that if there was an asymmetrical grind put on the blade initially then by re-sharpening it on the Tormek repeatedly, the apex of the grind would re-center itself, assuming the jig is symmetrical. Attached is photo of jig.  Thank you very much.

[Ken S]

Your jig is the SVM-45, Tormek's standard knife jig for many years (decades). while not strictly "symmetrical" or self centering, it was designed to provide reasonably symmetrical bevels for knives in the thickness range of commonly used kitchen knives. This provided quite satisfactory bevels for the majority of knives generally sharpened. Hunting knives thicker than 3mm could be problematic with equal bevels.

I suggest you acquire some practice knives and regrind the bevels. with properly cut bevels, you should find your knives satisfactory.

Ken

[tgbto]

What is the thickness of your knife measured at the spine of the blade ?

[Aikijay]

1/8 inch thick at the spine, so within the range mentioned above. So there's no adjustment or compensation I can/should apply? I was thinking of using a piece of wood veneer on one side of the blade to offset it in the jig to attempt to raise the blade a hair on the side with the shorter bevel which might widen it and equalize the sides

[Ken S]

Wolfgang discusses in this video, starting at 5:50 using the drawing why adding a shim will not correct for a knife being too thick for the OK range of the older jig.

https://www.youtube.com/live/JFHqQg5wZEg?si=GV8RVVi_nE3jMXBM

The inset in the fixed side of the clamp is too shallow. While this can be machined deeper, just adding the KJ-45 is a more practical, cost efficient way to solve the problem. 1/8" is approximately 3mm. the outer thickness range before the difference starts to show is closer to 2.5mm. Knives which are too thin can be shimmed somewhat with tape.

Ken

[cbwx34]

1/8 inch thick at the spine, so within the range mentioned above. So there's no adjustment or compensation I can/should apply? I was thinking of using a piece of wood veneer on one side of the blade to offset it in the jig to attempt to raise the blade a hair on the side with the shorter bevel which might widen it and equalize the sides

As Ken said, you can't shim a thicker blade.  One thing you can try is to clamp the blade in the opposite direction you normally do... this will help tell you whether or not the clamp is the issue.

Also, a forum member posted their method for clamping blades in the older jig to help center it... might try it:  My Way of Mounting Knife in SVM-45 Jig

Also, be careful counting strokes... as Sir Amwell said blades can be uneven/offset to begin with, and counting strokes can actually make it worse.  (Easiest thing to try in this case is sharpen the narrow side first, and a bit more.)