KJ-45 video

[Ken S]

This morning I found an interesting video by woodsmans finest (Maximilian Neukäufler). I believe he is Austrian, although he does the video in fluent English. I was impressed both with the depth of his video and the fair and balanced way he compared the KJ-45 and the SVM-45. His technique is close to, but not identical with, the Tormek technique. I have watched this twice, and will include it with the videos I rewatch from time to time. Here is a link:

https://youtu.be/_Gas70kW3mM

Ken

[cbwx34]

Around 7:00 made my day.   

Edit to add:  That entire video was great.  Good find!

[GKC]

I follow Max on YouTube (he is a bushcrafter / spooncarver / toolmaker) and when I saw this video I thought of posting it here, but I thought "Oh God, here we go again with pivot vs lift". At 6:45-8:00 he actually describes the rounded front stop on the KJ-45 as a Tormek feature designed to allow pivoting for broadly-curved knives. That is not how I heard the front stop described in the Tormek video. I would be surprised if Tormek designed the front stop with its narrow/rounded face for that purpose, or would suggest it be used that way (though I might do so). And yet, as you say Ken, when he sharpens his Mora, he does follow the Tormek method pretty closely, because it is a relatively straight blade. He has a nice slow-and-steady technique and gets good results.

[cbwx34]

I follow Max on YouTube (he is a bushcrafter / spooncarver / toolmaker) and when I saw this video I thought of posting it here, but I thought "Oh God, here we go again with pivot vs lift". At 6:45-8:00 he actually describes the rounded front stop on the KJ-45 as a Tormek feature designed to allow pivoting for broadly-curved knives. That is not how I heard the front stop described in the Tormek video. I would be surprised if Tormek designed the front stop with its narrow/rounded face for that purpose, or would suggest it be used that way (though I might do so). And yet, as you say Ken, when he sharpens his Mora, he does follow the Tormek method pretty closely, because it is a relatively straight blade. He has a nice slow-and-steady technique and gets good results.

Funny how Tormek says "lift" when the same Wolfgang in the Tormek videos, once posted this on Facebook...



... (although his solution is a bit different).

Makes one wonder.... 

[tgbto]

I think the lift vs pivot issue is pretty much settled. We all know it depends on the individual geometry of each blade, and the clamping position. In the "advanced sharpening" video, Wolfgang explains that sometimes he has to pivot one way or the other. I personally understand it as :

"When beginning to sharpen on the Tormek, just lift and you can't go (very) wrong. When you're more confident with your skills and muscle memory, look at the scratch pattern/sharpie residue and pivot whichever way necessary to achieve desired edge".

Cheers,

Nick.

[RickKrung]

I have been bothered by this "rounding" of the tip when lifting.  I generally do not pivot much anymore at all.  Mostly I have been focused on maintaining a consistent bevel width.  I think I'll have to revisit this a bit where the tip rounding is concerned. 

Rick

[tgbto]

When I don't need to pivot much, I prefer to clamp closer to the handle, so I have a lot of control on the lifting action. And less chances of rounding the tip by lifting a tad too much.

If I need to pivot forward or backward a lot, I find it easier to do clamping a bit closer to the tip.

[cbwx34]

When I don't need to pivot much, I prefer to clamp closer to the handle, so I have a lot of control on the lifting action. And less chances of rounding the tip by lifting a tad too much.

If I need to pivot forward or backward a lot, I find it easier to do clamping a bit closer to the tip.

Where you clamp affects the angle with either method.  (You probably know this already... just thought I'd point it out for others). 

[GKC]

I think the lift vs pivot issue is pretty much settled. We all know it depends on the individual geometry of each blade, and the clamping position. In the "advanced sharpening" video, Wolfgang explains that sometimes he has to pivot one way or the other. I personally understand it as :

"When beginning to sharpen on the Tormek, just lift and you can't go (very) wrong. When you're more confident with your skills and muscle memory, look at the scratch pattern/sharpie residue and pivot whichever way necessary to achieve desired edge".

Cheers,

Nick.

While I agree with the summary that Nick gives here (stick to lifting until you are experienced; then pivot if it helps you get the edge you want), I would not say that lift vs pivot is settled. Tormek has consistently--in old (Farris, Holtham) and new (Knife Sharpening Part 1, Advanced Knife Sharpening) videos--instructed "lift-don't-pivot". Pivoting is described as "the common error" and "the basic error" that causes problems (over-wide bevels and too-acute angles) on the curved parts of blades (see e.g. Knife Sharpening Part 1 at 28-31 mins).

And yet many of us want to pivot, at least in some circumstances.

When I watch closely, the pivoting that I see Wolfgang (who is helpfully candid) suggest in the Advanced Knife Sharpening class (at about 32 mins) is the opposite of pivoting to follow the curve. He notes that it can be helpful to pivot the handle AWAY from the bar (as I say, the opposite of following the curve) while lifting, to maintain the desired angle. I don't think that Wolfgang would describe this necessary, but rather as a way that might be easier or more intuitive for some than pure lifting which, if taken to excess, can lead to rounded tips. (Later in the class, at about 35 mins, Wolfgang also puts the SVM-45 guide on one of its corners so that he can follow the straight edge, but this is a static position, he is not pivoting in a curve. One senses that, as noted in his Facebook post, he sometimes finds the straight-backed collar restricting.)

Though I have and use Rick's pivoting collar (and designed one myself that I see is now sold by the sharpening outlets), I would rather not pivot if I could learn how to avoid it. I am not an expert at geometry, but it seems to me that any angle can be maintained just by lifting: in theory, if done in the correct amount, the lifting could exactly offset the change in angle caused by the movement of the edge traveling closer to the bar as the curve passes over the wheel. That might be more theoretical than doable in practice, but if the theory is at least true, then the practice should get better with experience.

I once asked Tormek Support to help us with a clear answer to whether pivoting was EVER required to maintain either a consistent edge apex angle or a consistent bevel width (whichever is your objective). I got no response at all to my email. Maybe one of the geometricians on this forum can help answer that question.

Gord

[cbwx34]

...
I would not say that lift vs pivot is settled.
...

For me it's settled, it's just getting the new jig to comply.   

Resistance is Futile...   

[3D Anvil]

I don't think there's any way to maintain a consistent angle with a curved blade without pivoting.  The angle is determined by the distance from the USB.  If you don't pivot with a curved blade, the edge will ride up the stone and thus give you a steeper angle. 

Often that's not a bad thing, because curved knives are usually thicker behind the edge as you get closer to the tip.  Gradually raising the angle toward the tip can thus result in a more consistent bevel width ... even if the edge angle isn't consistent.

Nice to have the option, though.

[tgbto]

I am not an expert at geometry, but it seems to me that any angle can be maintained just by lifting

Well there are several issues with this, as explained at length in some other posts :
- Sometimes (often ?) you don't want to maintain the angle but the bevel width. As the blade width varies, especially in the tip area because of curvature and thinning, you might want to increase or decrease the angle. The blade has to be very carefully designed if you want a consistent angle to result in a consistent bevel width.
- Lifting will only increase the angle. Not maintain it. So if you think of a typical blade, when you lift to keep the edge in contact with the stone in the tip area, you're essentially reducing the projection distance, so increasing the angle. For most chef blades this is OK, as the curvature of the tip brings the edge towards an area closer to the spine, where the blade is thicker. So you want to increase the angle to avoid the bevel getting crazy wide. But for other blade geometries this won't work. I have a santoku with an edge that is pretty much straight from heel to tip, but gets thinner at the tip. In that case you want to lower the angle to maintain a nice looking bevel.

I think what Wolfgang shows on the whiteboard in the advanced sharpening video is an excellent support for demonstrating this : surely with all these different shapes (and keep in mind he only shows two axis, the blade width often varies along the thid one as well) you can't expect the same action to end-up having the same result.

Now if you want to maintain the angle (on a typical convex blade), there's only one option : pivoting forward so your tip remains on the line that you were on when sharpening the flat of the blade. Do you want to do this ? Your choice.