Dumb beginner question about beveling

[Bend]

Hello knife makers!

I am an extreme beginner and I’m in the middle of making my first knife. I have a very basic (and I’m sure very stupid) question. When grinding the bevels before heat treat how much of an edge should you bring them to? I ground till the edge was very thin and basically sharpened. Will this edge be damaged or deformed during heat treat? Should I dull or sand it down to make it less fine? Sorry for the stupid question.

[samuraistuart]

That most certainly is NOT a stupid question. It is extremely valid and a question that every maker needs an answer to. This is also a question where you will get differing opinions. I'll try to steer you the best I can.

The thickness of the edge PRIOR to heat treating really depends on the steel itself. If we are talking carbon steels like 1084, 1095, O1 and such, the THINNEST edge for an oil quench is 0.020" thick. That is really the thinnest you can get an edge before it will "bacon" warp. Like an "s" curve! Ask me how I know! But I do NOT recommend going that thin prior to HT. To prevent edge warps, take it down to 0.030" for a safer minimum. 0.040" is even better and safer. A dime is about 0.050" thick, a good reference and a good edge thickness, too. You will have a little more to grind off after heat treating, but that's just part of the process.

Stainless steel is a different animal. Because they are plate or air quenched, the edge can be taken down to almost final dimensions. I have sent a few AEBL and CPM M4 blades to Peter's heat treating that had edges sub 0.010", and they came back perfect.

Back to carbon steel (I am assuming that is what you are using), I have found that the longer the blade, and the taller the blade, the thicker the edge needs to be in an oil quench. Long, tall, Santoku-like blades seem to have more edge distortion than shorter blades. Also, if you use a fast oil on a steel that doesn't need fast oil, like O1 or 52100, then there is more edge distortion.

[epicfail48]

Depends on the steel you're using and exactly how you're heat treating it. Steels like 1095 are 'sgallow hardening' steels, and have to drop in temperature extremely fast in order to get as hard as they should, and the temperature drops faster the thinner the cross section is. If you're quenching in something that's right at the edge, like warn canola oil, grinding the edge down to about the thickness of a dime will give you the best chances of reaching full hardness.

Deeper hardening steels like O1 and most stainless steel are formulated to reach full hardness with slower quenches, think 2-3 seconds to drop from 1500f to 900f instead of 1 (not exact numbers). Steels like that, you don't even need to grind in the bevels before hand, you're pretty well certain to harden the blade throughout.

Personally, I don't bevel before heat treatment for any steel I use, mostly 1095 and AEB-L stainless. For the 1095 I actually use an engineered quench called Parks 50. Expensive stuff, but it cools the steel nearly as fast as a straight water quench with less risk. Fast as it cools, getting 1/8" thick stuff to harden completely is a non-issue. AEB-L is technically an air hardening steel, so there again, 1/8" thick hardenes with no real effort. I hate grinding bevels, so this way I only have to do it once.

If you're just starting out though, and working with plain carbon steels like 1095, 1075, that stuff, I'd take the edges to about the thickness of a dime before heat treat. Get used to the steel, how it responds to heat treat, then decide if you want to bevel before heat treat or not. No substitute for experience when it comes to HT after all

[Bend]

Thanks you all so much! This is my fisrt time posting on this forum and I can tell that it is going to be an invaluable help in my knife making journey.

[dtec1]

bend welcome chek your private message's I just send a welcome message