oxy acet question

[tomh]

I am having trouble getting my steel to temp on knives bigger than 4 inches. I am using a # 4 tip. I was wondering if someone could tell me what pressure you use on the gases, since I don't think my torch is getting hot enough and I can't think of anything else it would be.

Thanks!

[Ed Caffrey]

With a #3 or #4 tip, you should have the Acetylene around 10-12psi, and the Oxygen around 18-20psi.

Bigger blades will take you longer, and will be harder to achieve an even heat. A trick to try is to turn on your forge, then using the torch, heat the spine of the blade just until its a very dark red, then run it in/out of the forge a few times, then when the edge just starts to turn a dark red, go back to the torch on the edge and heat as normal.

There is so much thermal mass in the spine that often times it requires that you pre-heat that area before going to the torch....otherwise you will never get the edge up to critical temp.

[tomh]

thanks for the advice Ed. I got the bowie straightened from the warp, now I gotta get it hardened.