Very Basic Home Heat Treat

Rob Nelson

Well-Known Member
Aloha!

So I have #2 ready for HT (while waiting for #1 to get back from Peters) and since its 1080, I'd like to do this on my own. I've read alot of posts here, read entries from 2 books, watched a bunch of video clips. Of course none of them are precise to what I'm trying to do, so I'm moving cautiously and seeking help.

Using a fire brick on my grill in the back yard as a workspace, my plan is to torch harden using a propane torch for the HT (will a bottle propane torch work?), taking it past non-magnetic (using a cheap telescoping magnet to test), and quenching in preheated mineral oil. Then tempering in my toaster.

Don Fogg on torch hardening "For small blades it is possible and efficient to heat them with a torch. You need a large tip, adjusted to a slightly rich flame. This will show as a blue inner cone off the white hot point in the flame. Moving the flame back and forth over the blade will give an even heat. Be careful to shoot the flame at an angle to the blade so that no spot gets hotter than another. Another use for a torch is flame hardening of the edge. By moving the flame just along the edge at a consistent and fast pace, the edge will rapidly austenize and air harden. It requires practice and a good hand, but can yield consistent results and can be useful in some applications."

With 1080, could I just flame harden the edge, let it air harden, cool to room temp, then temper it in the stove? Your input would be greatly appreciated!

Mahalo,
Chaps
 
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I have seen carbon blades edge hardened with a torch. If done properly, you can even get a really awesome hamon this way. You will need a proper quenching oil to HT it though. You can't air harden 1080.
 
Chap,
Your best bet, assuming the blade isn't huge, would be to hollow out that (soft ?) fire brick and make a one brick forge. The brick will contain the heat from the propane torch and give you an even heat on the blade. It may be difficult to get the blade an even heat just running the propane torch over it. I do believe Don is refering to a oxy-acetaline torch, by "large flame " I think he's referring to a rosebud tip. You should be OK with the mineral oil and I hope you meant "toaster oven".....regular toasters do crazy things when you drop hot steel in them. Be safe and play nice.

Rudy
 
I have seen carbon blades edge hardened with a torch. If done properly, you can even get a really awesome hamon this way. You will need a proper quenching oil to HT it though. You can't air harden 1080.

Murph, would mineral oil do the trick here? Then temper as usual in an oven?
Mahalo, Rob
 
Chap,
Your best bet, assuming the blade isn't huge, would be to hollow out that (soft ?) fire brick and make a one brick forge. The brick will contain the heat from the propane torch and give you an even heat on the blade. It may be difficult to get the blade an even heat just running the propane torch over it. I do believe Don is refering to a oxy-acetaline torch, by "large flame " I think he's referring to a rosebud tip. You should be OK with the mineral oil and I hope you meant "toaster oven".....regular toasters do crazy things when you drop hot steel in them. Be safe and play nice.

Rudy
Rudy, yep, toaster oven.

I looked up firebrick forges; I might be able to swing that. I'm anticipating my typical knife OAL will be around 8-9", so I looked at a 2 brick.
 
Chap,
At 8-9" you would be Ok with the one brick, you don't have to harden the tang. 2 bricks are better, more interior space. I believe Murph has pics of his someplace here. I used a propane torch in a small forge for a couple years, it does work with 10x steels. Good luck.

Rudy
 
Chap,
The torch is a BernsOmatic JT 7 or something like that, really can't remember, I got in the 80's.
I believe Lowe's or Home Depot would be a safe bet. A plumbing supply house would definately have something equal or better. I was surprised at the time how well it worked and how long the bottles lasted. I could actually forge with it.

Rudy
 
If we're still talking 1080, 375-400 max should get you around 59 rc. Temper 2 times and let the blade get to room temp inbetween. Others may have another formula but that worked with my toaster oven. Now I have a real kiln but have not fooled around with 1080.

Rudy
 
I must apologize. I was thinking of an oxy-acetelyne torch, not propane. Here are a few pics of my little propane (two brick) forge.

01a6d754.jpg

c11f7492.jpg

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I completely carved a channel into one and almost completely thru the second. I then mortared them together with Rutland furnace cement. I then use a third brick to close off the rear of the chamber. The reason I didn't carve the channel completely thru each was in case I needed to work a larger piece and needed to pass thru.
 
Murph's set up looks real good. Another thing that you can try is 8" diameter flu pipe lined with two one inch layers of insulating ceramic matting like Inswool, coat it with a refractory cement. Make the hole in the side like Murph did in his insulating bricks and insert the nozzle of the torch. Two bricks on either side will cradle the tube to keep it steady. Block the end with some scrap on Inswool or a fire brick if you want. Use your immagination. A simple propane torch forge is not hard or expensive to build.

Doug
 
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