How to Get Even Degree Per Side Using SVM-45?

[Thy Will Be Done]

I have several knives that come to me which are too thick to use the new KJ jigs with and need to reprofile them and get even bevel widths and geometry.  I understand this is the drawback of this jig but it would seem just doing one side of the edge bevel and then remeasuring and adjusting the degrees before working the other side would allow for the correct geometry.  Am I missing something here?  It doesn't seem to be a big problem but I do often go back and forth taking a few passes on one side before flipping to the other side to keep things even.  I'm thinking just a few notches one way or the other using the micro adjust should be enough to get the degrees back right and it should be repeatable going back the other way to work the other side of the blade.

[Sir Amwell]

Others will correct me if I'm wrong but I think you should use the new KJ self centring jig for thick knives. Up to 10mm stock thickness I believe. The old svm jigs will not centre on a thick knife and you will get uneven bevels as a result. Only way to correct this would be to mill some of the jaws away ( Knifegrinders has a video on that).
Mucking about lowering and raising the usb with the micro adjust is time consuming and hit and miss.
The self centring of the KJ jig should alleviate that problem ( self explanatory).
Surely that's the whole point of the new KJ jig?

[Ken S]

Here is the Tormek website description of the KJ-45:

https://tormek.com/en/products/grinding-jigs/kj-45-centering-knife-jig

The specs say it will handle non tapered knives up to 10mm and tapered knives up to 6mm thick. Most of my knife sharpening is garden variety kitchen knives. I have never seen a knife thicker than 10mm. Are these knives custom made?

I am sure that Tormek designed the KJ-45 for "typical" knives, including thin knives which also need self centering help.

Please keep us posted.

Ken

[Thy Will Be Done]

This is actually a knife that I get requests for often enough and don't want to turn down the work but I also don't want clean work going out so am concernced how it will turn out.  This knife is 8mm thick with a full flat grind, which I take to mean as Tormek describes 'tapered' because there are no flats to clamp onto.  That said there is no distal taper until the swedge/clip point starts and it's full thickness at the spine until that point.  See link below for pictures of the blade if needed.

https://www.bladeforums.com/threads/introducing-the-sykco-alpha-regulator-9-5-specs-and-pricing-for-wednesday-july-10-2019.1672234/

[Thy Will Be Done]

Will this jig work with these types of thick 'tapered' knife blades over 6mm?

https://schleifjunkies.de/en/product/clamp-closing-on-both-sides-centered-clamping-the-knife/

[Sir Amwell]

Ah. I see your problem now. Don't know about Schleiffjunkies jig. Maybe contact Hanssie directly to find out?

[Sir Amwell]

The other option is to use the new KJ jig and make a portion of the knife spine ' non tapered' by using layers of tape just down from the spine where the jig bites. This will work but maybe a bit inaccurate so to speak so there may still be a discrepancy on the bevel angles. Maybe try it on a similar knife first that you don't mind experimenting with before committing to a customer knife?

[cbwx34]

The other option is to use the new KJ jig and make a portion of the knife spine ' non tapered' by using layers of tape just down from the spine where the jig bites.
...

This was my thought... just shim the knife a bit so it's not as tapered.

Just about any solution will need some adjustment.  I've tried what was in the original post, (adjusting every time you switch sides) it can be done, but it's a pain, easy to lose track, and I like to do alternating passes at the end, so it's not the best option for me.

Someone in the forum made a sleeve that was thicker on one side, that slid onto the SVM jig, so that when you flipped the knife over, it stayed the same.  (Can't find the thread...)  Found a couple...

• https://forum.tormek.com/index.php?topic=3918.0
• https://forum.tormek.com/index.php/topic,4868

Schleifjunkies clamp may work (never tried one), but the sides don't taper, so you'll probably have to adjust for that.

A Lansky clamp works pretty well...

• https://forum.tormek.com/index.php?topic=3792.0
• https://forum.tormek.com/index.php?topic=3834

You could also try a Platform Jig...  https://forum.tormek.com/index.php/topic,3818

[Thy Will Be Done]

The other option is to use the new KJ jig and make a portion of the knife spine ' non tapered' by using layers of tape just down from the spine where the jig bites.
...

This was my thought... just shim the knife a bit so it's not as tapered.

Just about any solution will need some adjustment.  I've tried what was in the original post, (adjusting every time you switch sides) it can be done, but it's a pain, easy to lose track, and I like to do alternating passes at the end, so it's not the best option for me.

Someone in the forum made a sleeve that was thicker on one side, that slid onto the SVM jig, so that when you flipped the knife over, it stayed the same.  (Can't find the thread...)  Found a couple...

• https://forum.tormek.com/index.php?topic=3918.0
• https://forum.tormek.com/index.php/topic,4868

Schleifjunkies clamp may work (never tried one), but the sides don't taper, so you'll probably have to adjust for that.

A Lansky clamp works pretty well...

• https://forum.tormek.com/index.php?topic=3792.0
• https://forum.tormek.com/index.php?topic=3834

You could also try a Platform Jig...  https://forum.tormek.com/index.php/topic,3818

So is my idea correct in that what is ultimately causing the assymetric bevels mainly is a function of slight changes in degree setting of the knife as you go from side to side?  If that is the case I just got the SVM-45 and will give it a go and see how it works on one of my chunky chopper blades and hopefully proof that concept works.

[Sir Amwell]

I think your issue is that the knife is not centered. And so flipping the knife grinds different angles and different bevel widths. If the knife is not symmetrically ground then centring it will not help.
But let us assume it is then centring the knive in the jig will result in even bevels of the same angle. KJ jig is the answer as it will handle thicker blade stock   However your knife is out side the parameters of what it can handle. The jig is only biting on the very edge (as it's a tapered grind) and wobble will occur resulting in off centring. Even a very slight wobble will produce uneven grinds. Only way to correct this is to flatten the taper where the jig bites so that it's clamping on a flat surface not the thickest part on the very edge of the spine. Hence the tape suggestion.
The KJ jig will only handle a taper up to 8mm apparently but that measurement goes up to 10mm if the blade stock or the portion of it where you clamp is flat.
Hope this makes sense?
The old style SVM jig will only be useable for such a thick knife if you mill off some material from the jaws. Even then you would still have the same problem on a fully tapered blade ( I know it sounds confusing but on a 'full flat grind').
Ie you would still have to centre the knife.

[Sir Amwell]

Correction to my last reply. New KJ jig will handle tapered knives up to 6mm.

[cbwx34]

So is my idea correct in that what is ultimately causing the assymetric bevels mainly is a function of slight changes in degree setting of the knife as you go from side to side?  If that is the case I just got the SVM-45 and will give it a go and see how it works on one of my chunky chopper blades and hopefully proof that concept works.

If I understand your question, yes, ultimately it's a degree change.

It might be worth emailing Tormek support and finding out what exactly is the limiting factor in their specs.  There's gotta be more to it than just 6mm thick with taper... for example the taper would be different on a knife that is of different widths from spine to edge...   

[Thy Will Be Done]

One thought I have to get around this with the KJ jig would be to clamp near the tip at around 45 degree angle to match the steep curvature of the belly.  I would have to measure but the swedge/clip may take the thickness down below 6mm there. Any reason you can see not to clamp that far forward on this knife?

[Ken S]

I did an online search and found this. It answered some of my questions:

https://www.ebay.com/itm/124826937345

I see now why this knife would not fit in the KJ-45. Eight mm thick flat (tapered) ground. While this certainly is a very macho knife, I wonder how practical it is. It is too large to be legal to carry in many areas. It is too thick to be useful for bushcraft.

Tormek must design its jigs and accessories to function with the majority of edged tools and knives.

On a positive note, if being able to sharpen these knives with equal bevels is important enough to you to be willing to invest in the project, I believe the KJ-45 could be adapted to properlt center these knives. If I was doing it, I would consult with a local machinist. The jaws of the KJ-45 would need to be milled at a taper matching the taper of the knife's flat grind.

As this slightly thins the jaws of the jig, I would recommend using lighter grinding pressure.

The question of using the KJ-45 with your knife is one of type of questions which pop up from time to time. We must determine two things: First, is it possible? In this case, in my opinion, it does seem possible. Second, is it practical?
This would depend on things like the volume of knives involved and the value, either monetary or sentimental, to the sharpener. You must decide this yourself.

Please keep us posted.

Ken