Fast course on elasticity: materials are elastic. That means they deform when pressure is applied to them. Pressure is force per unit of area, so the smaller the area of application, the larger the pressure.
Japanese planes compress more the wood they are planning by having only two points of contact with the wood.
Stanley planes on the other hand are flat, so the force is divide on a larger surface and the respective deformation is smaller.
What has to do this with the cutting ability? Easy, the answer is stanley 60 1/2.
By compressing the wood on front of the cutting edge, you are effectively lowering the angle of the blade.
How much is this deformation in a real piece of wood? To my physicist approximation, something between 1 and 10 microns for a Young modulus of 11GPa.
Questions?
Now you can tell your wife you need one plane for every kind of wood and every thickness you want to plane. The consequence of this is that depending on the stiffness of the material and its size your optimal sole configuration will vary.
And if you are waiting for the post why japanese chisels are better, I tell you right now: they are more beautiful, which according to Plato is the same as more truth and better. Go figure.
EDIT: as per Jason's request varying the size of the flat on front of the mouth:
I think that you've found something new here my friend. Excellent insight!
ReplyDeleteCan you run this sim with a variable parameter for pressure zone width? The flat spot on the sole right before the cutting edge varies according to weather condition, wood being planed, etc. I would like to see the results from using different (I don't know what it would be called....pressure gradient?) to simulate sole conditioning. I use a wave ala' Jim Blauvelt, but others just use a 5-10 mm flat zone.
DeleteThis could be a great visual confirmation of why some methods of sole conditioning work better than others.
But I already knew it from shaving with a straight razor though my cheek is no pine board. There on the epidermal surface not only does the pressure deflect the surface but tensions it a well helping out the "razor's edge," as Maugham has put it.
ReplyDeleteRegards,
E.dB.
that's very very interesting... I guess the grain of the wood can be considered as hair, somehow. I want a microscope.
DeleteDid you read Alex's new entry http://bit.ly/1VvL2yG? He's got a very fine microscope for dialing in on the razor's edge.
ReplyDeleteyep, read that. I have mostly this problem with knives and one or two blades, the Y edge never goes away, so I think it does, use it a bit, and you feel it breaking under your fingers. And that's a sweet microscope.
DeleteBeautiful analysis! I've been looking at Yann Giguère's site mokuchiwoodworking, he apprenticed with Dale Brotherton on the west coast (both of whom met with Yataiki while in Iowa) and hosts kezuroukai east, so I'm wondering how once actually wins a planing competition with dai conditioning...
ReplyDeletethis is something I want to write about... unless my dai is really nicely conditioned I have no need to go beyond 6000 sharpening. In fact, I seldom go beyond 3000. But lately I managed to condition the sole quite fast and well, so going to 12k is paying off.
DeleteOnce I did a few trials with a Stanley nr 4 with a similar sole patern as a Japanese plane. I used a file to remove a bunch of iron excpet just in front of the mouth, at the toe and at the heel. I was purely looking at how a tight mouth prevents tearout when planing against the grain. I must say, the Japanese patern sole didn't make any difference in my test.
ReplyDeletethat was something I wanted to say but didn't since haven't looked at it enough. Steel has 20times the Young modulus of wood. That means basically it won't deform when in contact with the wood you are planing. I think the fact that the japanese is a wooden sole has a lot to do with this whole thing working. More to come on this subject, I'm figuring out how to simulate disjoint materials at the moment. Thanks for your comment!
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