1/8" in thick grind questions.

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spareparts

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May 12, 2010
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I want to do a handful of small utility and paring knives in 154cm and S305VN. Blades will be about three inches long, 3/4" at the widest point and 1/8" thick. I plan the finished grind to be a flat grind to a zero bevel (of course won't go to zero before heat treat).

On thinner steel like 1/8", how much grinding can I do pre heat treat without fear of warping or other issues?
 
I've always wondered, how do makers of very thin knives not get extreme warpage? Do they use something like liquid nitrogen? I'm talking about rock hard kitchen knives mainly!
 
Warp isn't an issue with these stainless steel, as they cool much slower than carbon steels. If one uses quench plates, warp is almost never seen.

On blades that small, I would suggest you reduce the thickness from .125" by a third to half. .060" to .080" will be perfect for a paring knife. Go to the kitchen with a micrometer and measure several of your favorite paring knives.....how thick are they?

With the dimensions given of .125" X .75", you would have a 10° wedge for the blade bevels. That will cut, but not nearly as smooth as the 5° wedge of a .060" blade. A secondary bevel should be there, even if it is just a microbevel, as it strengthens the edge. About 15° included is a good secondary for a pareing knife.
 
I have had a few thin stainless blades warp slightly toward the tip when quenching with plates. Of course, they had a distal taper, therefore the tapered portion of the blade never touched the plates. As a result, you get an occasional "drift" from straight.

Some folks grind the bevels after heat treat on thin blades. Easy to do with a variable speed and fresh belts. Makes hand finishing the blade a little more difficult, but there is usually a give-and-take in everything we do.

Robert
 
I don't mean to hijack this thread, but is this the case for single-bevel knives (e.g. yanagiba or kiritsuke) as well?

- Chris
 
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