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gas forge for welding


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I've done very little forge welding, and so far it's all been in a charcoal forge. I'd like to build a dedicated propane welding forge for making billets and cable damascus. Can those of you who do a fair bit of that sort of work recommend some appropriate internal dimensions? I'd like to keep the forge reasonably small to economize on fuel and materials, and I don't see why welding up billets should require a lot of space. But I don't want to get too carried away and end up making something that turns out to limit me in ways I didn't anticipate. So I thought I'd better get some input from folks with more experience.

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Matt,

 

Here are two excellent tutorials on forge building to help you make up your mind and give you construction details.

 

http://www.dfoggknives.com/forge.htm

 

http://www.indiangeorgesknives.com/building_a_forge.html

 

I built a vertical forge using a cheapie air tank for a shell and I'm very happy with it. It's powered by an Ellis design forced air burner and is very economical to run. Achieves welding heat quickly and easily. The hot zone is about 7.5" across so that is plenty big enough for my purposes.

 

Ken

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My welding forge is horizontal, single burner. The floor is flat, made of fire brick. The top is curved and lined with 2 inches of Kaowool. The whole thing has a layer of Seraset and ITC100. The dimensions are 8" wide x 6" high x 18" long. With the sloped sides you get about 6" usable, side to side. The 18" length is nice since damascus is one of the few times when you actually want to take a long heat on a piece (long length, not long time :huh: ).

 

I have worked on a vertical forge made for damascus. It was oval, about 12 inches high and perhaps 24 inches along the axis of the oval. It worked just fine too. You generally want a hard floor, since flux eats up Kaowool, but I have seen a forge that just had a steel plate in the bottom. When it got too crusty, the owner just lifted the hood off and took the plate out side and hit it with a hammer.

 

Geoff

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Hi Matt ! Thought i would pitch in my 5 cents on this !

Though i have a very limited experience in forge welding and i have done it successfully a couple of times, I use the same forge for welding and for forging ! (i am in need of more space and money... lol). I made this forge from very inexpensive hard firebricks powered by a 3/4" propane burner that i also made, remade and re-remade. As you can see the forge gets to temp very easily (after 5 minutes) at low pressure around 5-8 psi. And you're right about the space thing i don't believe you need a huge forge for welding unless you weld big billets or parts ...

And thanks Geoff for the trick about the plate at the bottom ! Getting tired of replacing bricks from being crusted by the melted borax !

 

DSCF1649.jpg

 

DSCF1638.jpg

 

Steven

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Thanks, Steven. Nice design, but I'm already pretty well committed to ceramic wool (with a hotface) for the lining. (I already have the wool. :) ) What sort of burner are you using? Naturally aspirated, or forced air? If it's natural, is it a Reil or something else? And what size orifice are you using? 0.030" MIG tip? Or did you drill one yourself?

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Hi Matt !

The 3/4" burner is loosely based on The Reil naturally aspirated design.

I use a .035" Mig welder tip. I had tried a .023" at first but i wasn't able to get a clean and stable burn and had constant sputtering from it. So i switched to a .035" tip (i gotta find a 0.030" to try it) and my problem was solved and saved a lot of gas.

I found that using a bit of teflon tape on the nipple threads (the rest of the gas plumbing uses propane certified sealing compound) solved most of my problems... i had small amounts of propane leaking between the threads and the nipple.... problems solved.

 

Yeah i guess if you have the ceramic wool use it ! The worst part is, i got 40sq. foot of 1" kaowool (almost for free) after this forge was built and i never got around to using it ! Here's a pic of the burner if it can help you !

 

VenturiBurner1.jpg

 

Steven

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And have you forge welded with that combination? (Burner and forge, I mean.)

 

I built my first Reil style burner recently with a 0.035" tip in a 3/4" tube, and I'm finding that it runs a little rich. Have you noticed any such problems? I'm planning to try a 0.030" tip and see if that helps.

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Hi Matt !

 

Although i don't spend as much time forging as i would like i have tried and successfully welded twice in this forge. The one time it did not work i had omitted grinding the surfaces of the 2 welded parts (i'll never rush again, through those steps). I had cleaned them roughly with acetone and some sanding but i now know this isn't enough to get a good weld. So the short answer would have to be yes i did twice. And i was much more surprised to see that i got up to welding temp at around 7-9 psi...

 

For the part about the burner running rich i have to agree with you it sometimes does ... i have noticed that filling your propane tanks (i use a 30 pound tank) from the same source is a good idea. I know (i am no propane specialist) but propane is usually a mix of propane and butane (depending on where you are located in the world). I have noticed from trying to fill up from different sources you get different results, even with the same setup without any modification. Give a try for the 0.030 tip.

 

One other thing i learned through reading (Burners for forges, furnaces and kilns by M.Porter) is that getting your tanks completely empty, before refilling, is important. Because of the difference of weight of those 2 (butane and propane) and the mix is different depending on where you get the propane (due to climate and location in the world). if you don't, you end up after 5-8 fill ups with a greater amount of butane or propane which your burner won't like at all.

In my case it was a matter of trial and error and time of course. Someone with more knowledge confirm this if i have this mixed up or not.

 

Steven

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