Diamond Back Forge Question

[bike4fun919 OpbunchKnives]

I'm new to knife making and appreciate all the advise and knowledge I've been able to gather from this site.
I just recently received my single burner Diamond back forge. I've fired it up for testing and will soon be doing my first heat treat. My question is what pressure (psi on the dial gauge) should I have the forge to heat treat my 1084 blade?
These are some knives I have made recently.

https://pix.sfly.com/tQiUPV
https://pix.sfly.com/wBQrJN

 

[kuraki]

No one is going to be able to tell you exactly what settings to run your particular forge at because of the variables involved with forges as a system. In general, people tend to heat treat at the lowest pressure their forges will run at, as even at that pressure they will create hot spots in your forge that exceed your austenitizing temperature.

 

[bike4fun919 OpbunchKnives]

Thank you Kuraki. I thought that might be the case but wanted to get some advise and will learn my forge as I go!

 

[Stacy E. Apelt - Bladesmith]

Some test firing will tell you the range of your forge.

Light the forge with whatever pressure works to get it lit. 5# is a good starting place.

Adjust it so it seem to be running at a medium heat, not a roar and no sputtering. Note this as your basic Lighting and Idle pressure. It could be anywhere between 5# and 8#.

Let it run at idle for 5-10 minutes, then turn down slowly, allowing the forge to equalize as you do it. Find the lowest pressure your forge will run at. It should not make loud screaming noises or be sputtering. Note this as your LOW pressure. This is where you will do HT. I have never seen a venturi burner forge that wasn't actually too hot at this temp. You will learn to move your knife in and out and along the sides to keep it from overheating in HT. Most forges are in the 3-5# range at this point.

Turn up to a big roar. Get it running HOT, put in a bar of scrap steel ( don't waste knife steel) and let it heat up. If it gets so hot it starts sparking, turn the pressure down. Find the point where a bar of steel will get crazy yellow-white hot, but doesn't ignite into a shower of sparks. This is the max heat, and can be used for welding. It could be anywhere between 10# and 20#. Make a note of that pressure.

HT pressure will usually be the lowest setting
Annealing and thermal cycling temps will be a pound or two higher.
Forging temps will usually be from 2# above low to about 5# blow the welding pressure. Start forging at the high end and lower the pressure ( and temperature) as the blade gets more refined. The final forging heats should be just above the HT temp.