Gas Forge Question on Diameter

[Jaret]

I have read the details in the gas forge section.

I have a question. I want to build a 2 burner forge. What would be the ideal diameter. I am using it for knife making and some small decor. I was thinking an old bbq type propane tank. A 20lb propane tank, and old expansion tank, or something along that line.

Any thoughts?

J.

[HWooldridge]

Any of those will work fine. I built a rectangle type from sheet metal with inside dimensions of 5" tall, 10" wide and 15" deep. It has two 3/4" blown burners and will get pretty dang hot. It will not forge weld consistently so it's right on the edge of weld temps but I could like improve that with some kaowool between the shell and the insulboard.

[sawyer04]

I have a 10 inch diameter by 17 inch long rolled out of 303 stainless. I power it with a 3/4 inch home made burner installed at the center at the top edge. The burner creates a vortex when it gets hot. Works well for blade work.

[Frosty]

Most guys go at this question from the other direction, namely I have a forge X size how many burners do I need?

Two 3/4" burners will bring up to 700cu/in to good forging heat and if you do a good job of making and tuning them and insulate the forge, welding heat.

Two 1" burners will do the same for 1,400cu/in.

Now, a lot of bladesmiths who absolutely positively NEED reliable welding heat on demand hedge their bets by using one 3/4" burner per 250 cu/in which is just fine. Overkill is a good thing, it's better to have it and not need it than need it and hot have it.

Anyway, figure the shape and volume of your forge and see what you need for it.

Frosty