Edge thickness before heat treatng

T

trailrunner531

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Sep 16, 2013
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I recently finished grinding the bevel on my first knife-making attempt. The metal is A2 steel and I'm doing a flat grind. The blade is about 1.25" across at the widest point. Currently the edge is about 1.5mm thick with a 22-deg bevel angle. My understanding is that it cannot be too thin going into heat treatment or else it might warp. I'd like to minimize the amount of grinding necessary to get a sharp edge after treatment and tempering. So my question is, how thin is too thin before heat treatment? Should I leave it at 1.5mm and go ahead and heat treat, or can I get away with grinding it a bit thinner?
 
Question, first.

What is your set up for heat treating?(forge, kiln, torch, outsourced, etc..?)

With A2, I suggest outsourcing. If so, you can take it down to .015-.020"(.38 - .50mm)... maybe even thinner.
 
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I'll look into out-sourcing it but I might rather have the experience of doing it myself even though my setup will be pretty crude. Homemade forge and blower with a pile of charcoal. I was going to heat tot he nonmagnetic point and then quench in used motor oil, then temper in my kitchen oven.

I know this isn't anywhere near the best way to do this, but I'm enjoying the project so far and I'd like to just work with what I've got. So given the charcoal forge and oven, what edge thickness should I shoot for?
 
You would be better off outsourcing this one and making the nex one out of 1084 and ht as said above. JMHO. Best if luck.
 
I agree with Cody. Heat treating A2 without proper equipment will yield poor results at best. This steel requires higher temperatures in the 1730-1800 range, and needs to be held at those temperatures for a soak time of 25-45 minutes, this would be virtually impossible in anything but a proper electric heat treating kiln. The cost of sending it away will be more than worth it to have a properly working knife. The most magical high end super steel will still be a crappy knife without proper heat treating.
 
Yup... short story... A2 is not a steel for beginners to HT. Send it out, and do your own experimenting with 1084, or similar eutectoid steel.
 
I don't mean to hijack this thread, but I have some 52100 coming in on Tuesday, and am sending it out for heat treat. How thin do you guys think I can safely grind the edge on that?
 
trailrunner531 said:
Fine, you convinced me :)

Any recommendations for a heat treater?
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I have had several A2 blades done at Tru Grit. Be sure you request stainless steel foil and might as well have them do Cryo while it is there. It comes to $16 + postage
 
SilentMethod said:
I don't mean to hijack this thread, but I have some 52100 coming in on Tuesday, and am sending it out for heat treat. How thin do you guys think I can safely grind the edge on that?
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I like to go down to around the thickness of a dime (~0.040") before heat treat, some guys will go thinner though.

Bruce
 
Next blade get 1084 (or lower 10XX steel) and heat treat yourself for the experience. But ditch the motor oil and use canola oil. It's cheap and quenches faster than motor oil.
 
FullyTorque said:
Next blade get 1084 (or lower 10XX steel) and heat treat yourself for the experience. But ditch the motor oil and use canola oil. It's cheap and quenches faster than motor oil.
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+1
...AND it will be a lot more pleasant when using the kitchen oven for tempering.

Chris
 
I use Peters' for all my HT, and usually grind right down to final dimensions beforehand, regardless of steel type.
 
SilentMethod said:
I don't mean to hijack this thread, but I have some 52100 coming in on Tuesday, and am sending it out for heat treat. How thin do you guys think I can safely grind the edge on that?
Click to expand...

I usually go to about .020 or so. 52100 isnt that bad to HT at home. I do it in my forge often and quench in canola oil with great results. Tempered at about 415F usually gets me around 61 or so hrc with 52100 using the forge and oil. A normalization is mandatory with this stuff bringing the first cycle up above 1600F.
 
I was wondering about this too. My first couple knives are ready for HT. I'm using O1 and have the edges at .02"-.025" right now.
 
You're in good shape. I take my 01 blades down thinner than that, but I use decarb protection.
 
One more question before I send my knife off to heat treating. On the website it says to indicate the level of hardness you want. I'm a newb so I honestly don't know. My knife is going to be used mostly for bushcrafting and wood-processing tasks on backpacking trips. Given its use and being made of A2, what should I say as far as hardness? I'm not even familiar with the terminology that's used. Thanks for your help.
 
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