Blacksmith gas forge

[2Tim215]

My new gas forge for small, large and funny shapes - thoughts???

[pkrankow]

You are not done insulating.

Looks interesting to say the least, but I don't have a good sense of scale.

The door post between the two opening may give you grief at some future time, but eliminating may also give grief.

Phil

[2Tim215]

Yes I still have to insulate the door and put the small door on. The reason for the small door just off the large door is so that i can slide the long end of curved work through the large door and out the small door. I tried having them at opposite ends and found that this method worked better. Base is 650mm across and forge is 500mm high. Insulated with 2" ceramic fiber, 1" soft fire brick and 1" castable. Small door is 150X150 and large door is 150X 300. Also, the small door allows me to work small work without losing to much heat through the large door if I only had the large door.

[Frosty]

Here's my thoughts for odd sizes and shapes. It's a variable volume forge, the lid is on a scissor jack though I'd recommend a trailer screw jack, the side walls are fire brick on their sides and the partition walls are light firebrick on side. The partition bricks can be reconfigured to make almost any shape or size chamber under 20"x20" and the height can be altered by laying bricks flat or stacking them.

It's a few years old now and works well enough to prove the idea though it does need tweeks but those are for the next one.

Frosty the Lucky.

[2Tim215]

Hi Frosty

Nice forge - have seen similar ones on the net, but couldn't get bricks at the time, now I have more than I need but forge is all ready done. Would appreciate more detailed pics and dimensions, also info on the changes you would make if you had to re-do.

Tim

[Frosty]

Tim: There're already drawings,descriptions and discussions of this forge on IFI, though I don't recall where. If you have Google Sketchup loaded or want to download a copy, it's free for the basics, you can modify, or just play with the drawing.

The worst thing is the light fire brick, it doesn't stand up to thermal shock very well and the things are kind of expensive to keep replacing. 3,000f split fire brick lasts a lot longer but has a much higher specific heat so takes more fuel to bring it to temp. And, if I crank the burners to near max, 3,000f isn't enough range, the bricks will start melting, even coated with ITC-100.

The present answer is to just not crank it, Normal working heat is in the high orange low yellow and with careful prep low yellow is plenty to weld.

My last tweek was to replace the soft brick lid with pleats of Kaowool and it's holding up fine so far. My next major tweek is rebuilding the lid making it several inches wider so exhaust heat doesn't warp the frame so much making it not seat on the side and partition walls properly.

Everything on the interior is generously coated with ITC-100 so flux doesn't do much damage and it's reasonably efficient for it's size. However, if I have all four burners on and turned up it'll put a heavy coat of frost and ice on a 100llb. propane tank.

Frosty the Lucky.

[prburner]

Here is another take on the variable size forge. Mount the burner to a table base and stack up the bricks any way you want. Burner and plumbing stays put. You can use pottery kiln shelves for a roof on larger forges.

Tom

[Nathan Hall]

Looking at your picture, it appears that your burner is welded in place. if that is the case then you may have trouble with that when you shut it down. heat rises and burner may not last quite so long when subjected to that. You may be fine if you leave your blower on till its cooled down a bit though.