Blade and edge design and curly wood shavings?

[pinnah]

[Reposting this from the Maintenance sub-forum. Figured more people who make feathersticks will be reading here.]


Why is it that some knives more easily make nice curling wood shavings while others do not? Grind? Edge profile? Blade shape? Handle? Steel? Blade thickness?

I ask because I was totally surprised this morning when I was making some feather sticks to start a fire. A knife I had written off over the past few years (my Buck 110) totally surprised.

[David Martin: you can say "I told you so." ]

I recognize that my technique has a lot to do with it. And that I'm not same person today that I was 1 or 2 years ago.


This morning's fire making prompted me to dig out several knives and to make some feather sticks side by each. Here they are in reverse order of effectiveness.

Opinel #9 (and 10) - Flat convex grind. 12C27. They tended to either skip or dive. Perhaps the round handle makes them hard to control but I don't think that's the main issue. At the end of the stroke, they tended to pop the shavings off the stick.

Buck 500 - hollow grind. 440C. The handle is just too small for my XL hands to control when applying firm consistent pressure for the cuts. No way to really get a feel for the blade as the knife just moved around in my hand too much.

Schrade 51OT - Flat grind. 440A. This felt similar to the Opinels, either skipping or diving. The wide flat handle gave better edge angle control. Still, it had the tendency to roll out and pop off the shavings at the end of the stroke.

Schrade-Walden H-15 - convexed sabre grind. 1095. This knife made longer curling shavings with greater ease. STill a bit tricky to control at the end of the cut. I wonder if the issue is the thinness of the blade and the higher position of the shoulder - sort of on the spectrum towards full flat.

Buck 110 - Hollow grind. 440C. This is a 2 dot version that has a swell of thickness just above the edge. It gave great control of the edge angle and consistently ripped off perfect curls.

Mora Companion HD - Modified convexed scandi. 1095. The handle is by far the easiest to control. Unmodified, this knife dove deep into wood and didn't make curled shavings well. With the shoulder convexed and a 20-dps micobevel, it is the best that I have, but not by whole lot compared to, surprisingly to me, my old Buck 110.


Not listed here are several more recent Bucks and a Case both with 420HC and thinner hollow grinds. They were bad enough at this that I've gotten rid of them.

I'm wondering if the thickness of the old 2 dot 110 behind the edge is a factor here.

Thoughts and insights?

 

[daizee]

I would expect that you need a significant shoulder at the top of the edge bevel to steer accurately. This could be a traditional V edge or a thick blade with a serious convex edge (rather than the nearly flat convex of the Opinel).
OR a scandi on thin stock, where the shoulder of the primary grind IS the shoulder of the edge, and is far enough from the cutting edge to give leverage, but not so far to be useless.

Does that correlate with your experience? I'm lousy at feathersticks, so my technique is clearly the weak link.

 

[Rick Marchand]

It is all about control with tasks like feather sticks. I have seen folks make them with Scandi grinds, convex, flat, v-grinds, chisel... etc. There is some geometry that lends itself well to controlled "planer" type cuts in wood(scandi or chisel). That is why you see the majority of woodworking tools with this grind. But, I think it really boils down to the technique of the user. The way you hold your knife and the approach angles you use are different with each of the more common edge geometries.

 

[Quirt]

Pinnah what angle are you using on your two dot Buck 110?

 

[jdk1]

This is an interesting topic. I discovered that my ESEE 6 actually was not very good at making curls, unless I used the serrations. But, this below converted khukuri, which is quite thick, made wonderful shavings when the tip was planted and the wood was dragged along the edge. The only thing I could conclude was that the very sharp and nicely convexed edge was better than the equally sharp V edge and FFG ESEE 6. I was very surprised.

 

[pinnah]

It is all about control with tasks like feather sticks. I have seen folks make them with Scandi grinds, convex, flat, v-grinds, chisel... etc. There is some geometry that lends itself well to controlled "planer" type cuts in wood(scandi or chisel). That is why you see the majority of woodworking tools with this grind. But, I think it really boils down to the technique of the user. The way you hold your knife and the approach angles you use are different with each of the more common edge geometries.

Rick, I ran the same question by the crowd in the Maintenance sub-forum. There was a general consensus there that the wider shoulder above the cutting edge creates a fulcrum that is more forgiving of technique variances and thus "easier" to maintain the right the right edge angle with.
http://www.bladeforums.com/forums/s...Blade-and-edge-design-and-curly-wood-shavings

I've seen this same thing with skis and bikes... "Best" is a funny attribute and very much tied to the user's technique, which may have strong built in preferences to one design or another. Knives don't make shavings. Only knives used by people do.

Pinnah what angle are you using on your two dot Buck 110?

Quirt,

I use a 17-dps back bevel and a 20-dps primary bevel on pretty much all my knives, including the old Buck.

I really must emphasize how different this 70's vintage "2 dot" Buck 110 is from Bucks made after the early 80s (they went to a traditional full hollow grind) and more particularly after from around 2000 (they went to a thinner hollow grind).

There is a very noticeable swell in the thickness just above the edge. You can notice it in this picture as it shows in a clear change in the reflection. What you can't really see in this picture is that blade continues to swell out beyond the reach of the 17 degree back bevel. That is, on the flatter Opinel, the 17-dps back bevel is not very high because the blade is so thin but on the Buck, the back bevel goes up higher and then the blade stays thicker for a longer period of time after that (probably in the 16 then 15 dps range).

My sense is that for a few millimeters above the apex, the blade is more like a convexed Scandi Mora than it is a traditional hollow grind, hence the better wood shaving performance.

Buck 110 and Opinel #10 by Pinnah, on Flickr

 

[Quirt]

Thanks! I have the same two dot Buck. Thought I'd sharpen it up and give it a try.

So Pinnah how did you get the patena on your opinel?? Also what wood is that??

 

[B34NS]

What Rick said.

I feel the majority of instances I've seen it performed, it's usually in the standard grip on the handle. Which means you loose control of the blade when apply force through material. Unless the material can't be used as lever, try using more of a draw knife technique. We used to employ the same technique for making chocolate shavings and curls in the kitchen.