Thread: Gas forge for heat treating?

Well got her going today, held temp just fine, but the burner is not working well or correctly. The flame is burning when it hits the front of the oven and not when it comes out of the burner nozzle. The mig tip isn’t entering the tube at the center off about an 1/8”, definitely not helping things but not sure if that’s the only reason, I guess I need to try some different sizes too. I tried adjusting the tip fore and aft but that had little effect. At really low pressure it burns right at the end of the burner. I also played with some different choke settings with no difference in where the burn was occurring.



With the pressure up, combustion is happening at the front under the muffle:


With the pressure turned way down, couldn’t hold temp, losing about a degree every 15 seconds at around 1475.

I cannot tell where the burner goes in?

First picture, the black pipe at the bottom on the left. The one above it is for the thermocouple.

Thought so....Should it not come in from the back top-middle side at a tiny angle toward the front?
Makes the heat go round and round?

I’ll use that sort of design for the smaller forge, this one is specifically for heat treating.

Did you mold the refractory into a flare or nozzle where the burner enters the forge? The flare or nozzle slows the gasses coming out of the mixing tube and stabilizes the flame so that the combustion stays at the burner.

No, I haven’t. I wanted to make sure it all would work before I wasted material on something that didn’t. I was also thinking that the back pressure from the forge itself would be enough.

Those frosty burners work well, you could hose clamp a quick and dirty sheet metal cone just to test your burner.

Most all of my burners are crap without a cone of some sort..

Originally Posted by jfk742

The mig tip isn’t entering the tube at the center off about an 1/8”, definitely not helping things but not sure if that’s the only reason,

This could well be a big part of the problem. I'd say, cut the burner off of the shell and see if you can get it working outside of the forge with a nozzle. At most you will be out a pipe nipple. Also Frosty claims that you really want a reducing tee and not a straight tee and reducing bushing. I've never played with that design so........

I’m stumped, built both burners at the same time, same specs same material. I even swapped the T’s to make sure it didn’t have anything to do with the one that has a slightly off center hole for the pilot.

This seems to burn fine in open air:


I did the refractory in the forge and formed a 1in12 tapered flare as best I could to see if I could get the flame burning at the tip of the burner instead of the mouth of the forge, if anything I made it worse. With playing with all the adjustments I can’t even get it to burn correctly even at low pressure with the intake near completely choked.

I’m about to just hack it off and start again, only thing stopping me is that the other burner while using the same T and pilot setup burns pretty darn well in open air even without a flare, but maybe that’s the problem...