Geometry question regarding kitchen knife grinds

J

James Hall

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Sep 18, 2013
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I made a chisel ground kitchen knife a while back about 2" wide from 1/8" stock. The grind went about 2/3 up the blade, and the geometry seems to be holding up well for chopping and the like.

I'm going to try making another from 1/16" stock, but I'm not sure how high I should take the grind. I've been looking at pictures of gyutos that I'm basing my design off of, and the grinds seem pretty obtuse, only going about a quarter of the way up the blade, even for double bevels. How high should I take the grind with this stock with a single bevel, and how would that change if it were a double bevel?

Thanks for the help.
 
This is such a simple math problem, I really am tempted to let you figure it out. If the grind on 1/8" is 1.32" high ( 2/3 of 2"), the same grind on 1/16" stock is .66" high ( half the thickness = half the height) to get the same edge angle.
 
Thanks Stacy, I guess I should've asked something different. What angle should I be shooting for on a general purpose kitchen knife for the primary bevel? I know that the angle on the one I made is decent, but how much better can I do? What would be considered too thin, or too wide of an angle?
 
The primary bevel on a kitchen knife is normally a FFG or nearly one. That is going to be a very low angle, usually 5 degrees or less. This low angle bevel allows smooth cutting and slicing. The thinner the blade, the lower the angle. For practical purposes, this angle is ignored ( since it is merely a product of the blade size and thickness). What is controlled in this bevel is the edge thickness. When final grit sanding is done, a kitchen knife usually has a near zero grind edge. On a heavy use kitchen blade, obviously, it would be thicker, and on a very fine slicer, it can be taken to only one or two thousandths.

It is the secondary bevel angle that makes the edge survive use. On a kitchen slicer that is usually between 7 and 15 degrees per side. What is simplest in testing, is to do the secondary bevel at a low angle, say 10 degrees...and do some test cuts. If it chips, then re-sharpen at a slightly higher angle, say 12-13 degrees.
 
The primary bevel on a kitchen knife is normally a FFG or nearly one. That is going to be a very low angle, usually 5 degrees or less. This low angle bevel allows smooth cutting and slicing. The thinner the blade, the lower the angle. For practical purposes, this angle is ignored ( since it is merely a product of the blade size and thickness). What is controlled in this bevel is the edge thickness. When final grit sanding is done, a kitchen knife usually has a near zero grind edge. On a heavy use kitchen blade, obviously, it would be thicker, and on a very fine slicer, it can be taken to only one or two thousandths.

It is the secondary bevel angle that makes the edge survive use. On a kitchen slicer that is usually between 7 and 15 degrees per side. What is simplest in testing, is to do the secondary bevel at a low angle, say 10 degrees...and do some test cuts. If it chips, then re-sharpen at a slightly higher angle, say 12-13 degrees.
 
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