Small gas forge

tnmike

tnmike

Joined
Dec 6, 2005
Messages
289
I thought there might be some interest in this small forge I built last night. It is made entirely out of scrap.(the only thing I bought was the propane torch) The interior dimensions are roughly 4x7 inches. The refractory is one inch inswool coated twice with satanite. I was amazed at how fast the thing came up to temperature with the first coat of wet satanite being wet. I would show it in operation but I wanted to let the second coat dry slowly.

You can block the mouth of the forge with firebrick to get more internal heat.

In case no one has seen them: Harbor Freight sells an adaptor that allows you to refill the small propane bottles from a 40 lbs or less propane tank. The adaptor is US made and is legal. Its pretty slick.

Thats about it ..a quick and easy forge.....very portable and very durable......MIKE
 

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Now you can go fishing and forge blades while you wait for them to bite. Cool little forge.
 
Hey Mike, never thought of that. Now you got to build one that will keep the sodas cold and will make for a great day.
 
Thats pretty slick! I'm a fan of the small forges. I'd say over 90% of what I do can be done in a small forge, why heat up a big one. I've gone from big to smaller, to smaller, to big and now to smallest. A solar forge is next. Mike, when you get the solar one perfected let me know.
 
Those adapters to refill a disposable tank are legal.Transporting the tank after refilling is not.For about $20 you can get an adapter hose to run your camp stove or lantern from a bulk tank (sears,sports authority,outdoor shops,etc),and thus hook up the forge (or any disposable bottle appliance like a torch) directly to a 20# tank without needing the disposable bottles at all.
 
Really a nice little forge Mike! Also, if you want more BTU's every now and then, get a small bottle of mapp gas at Lowe's. It may even fit the same torch head, but I'm not sure. Seems like everyone is coming up with neat little forges, guess I better go try my hand at it. Now to find a tiny battery operated fan for a small portable forced air forge (:o)
 
Nice, tnmike. You say it is about 4" diameter by 7" long and the torch works well. Do you think it would be effective in a similar forge (for heat treating low-alloy tool steels, not forging) but more like 6" diameter x 8" long?
 
The reason I stayed away from a 20 lb propane tank is portability. I wanted this thing to be light and easy to set up.I also dont like carrying a 20 lb tank in the back of my Subaru wagon.

The interior dimensions of this forge are 4x7. The exterior is 6x8. You may can increase the interior dimensions and get up to critical temperatures for heat treating. I havent spent a lot of time yet playing with the burner position to optimize the heat but I can tell you that position makes a difference. The angle that the flame impinges on the interior wall makes a difference as well. Do not simply direct the jet against the opposite wall. You will not get a flame vortex and it wont work as well.

Mapp gas gets quite a bit hotter but its quite a bit more expensive too. I wish you could get it in 20 lb tanks but I dont know where to do that around here.

These little things are fun to build and great to use as well...MIKE
 
That looks quite useful for me and the small utility blades I make occasionally. What would be the max size you could heat in there? Is the back end closed? I've been using a 1 brick forge and mapp gas, but the blades warp because there's always a hot spot in front of the fire hole, and I have to close the hole in the back to get the heat up enough. Also, I know next to nothing about propane and burners and such. Can you give a little more detail on the burner setup?
 
The burner is a JTH7...(I think that is the right number) Bernz O Matic torch ..available at Home Dept and countless other places. The back of the forge is closed although Ive seen some that were open. The interior of mine is 4x7 so you can forge a knife with a 4 to 5 inch blade easily. I block off the front opening with firebrick to control the heat as needed...
 
All of the steel in the body came out of the scrapyard. The bodys itself and the endcap are motor housings dumped by a local manufacturer. They are 12 gauage steel or close to it. The legs are 1/4 plate. The last time I looked there were hundreds of these motor housings on pallets waiting to be loaded onto railcars headed to the steel mill.
 
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