I have a forge I'm building from an old 5 gallon compressor tank. Once lined it will be about 4000 cu.in. in volume. In order to get up to forge welding temp (1200°C) I'm trying to decide on one burner or 2. My burner set up I have a venturi style burner made with 2, 1&1/4" - 3/4" reducers with a 10" long x 3/4" pipe nipple. Burner has a #64 (ish) orifice. Drilled into a 1/4" brass nipple mounted in the reducer. (A ron reil burner) I will be insulating with 2" 6# kaowool. Coated with itc-100. Suggestions always welcome.
I'm not a forging guy, but 4000 cu inches is an awfully big forge. I wouldn't want your gas bill on that. I guess it depends on what you need to heat in it, but I'd try for something more modest, maybe in the 200 cu. in. range. (That's about 10" long by 5" wide.) For something that big, you'll definitely want two good sized burners -- at least.
Myth is right it is big. the number one ruler when making a forge IS BIG IT NOT BEAUTIFUL, keep it as small ( to fit the job )as possible for maximum heat and low propane costs. My big forge will burn up 20 lbs of propane in 4 hours and it starts to get real expensive. That is why I designed it with two burners and an extension for the length to get a hot billet through the rolling mill.
Maybe something not right with the volume calculation or you slipped and added a zero. A 5 gallon compressor tank, lined with 2" of ceramic blanket is going to be an order of magnitude smaller. But that's okay. You have the idea. Example, a cylinder 6" x 16" interior is 452 cubic inches. That's just a little over the recommended volume for a classic homemade Reil burner which I think was pegged at around 350 cubic inches. (or some other classic Chevy engine, perhaps 327). I used two burners in mine, similar design, but rarely use the back burner. A half-round, fitted 2" firebrick blocks it off the back side and I concentrate the heat up front. It's nothing like FORGE's but works for basic heating of steel. If you reduce your interior volume a little, you can get by with one burner, and sip the sweet propane so it lasts all day. Dan
I made my first forge out of a tomato juice can filled with plaster of paris and aluminum oxide powder. It had a single input for a hand torch using MAPP gas (i started with propane but it wouldn 't get the steel hot enough). It worked great on blades that were say 5-6" and shorter and no more than 3/16" or so thick. I couldn't get a 1/4" blade or one longer than 6" (or so) hot enough with a single burner. I don't know how much heat the burners you're using will put out but, with a forge that large, you will definitely want at least 2 burners. I sort of agree with what the guys are saying too. That's a huge forge. It will be a pain in the butt trying to get steel up to heat and maintaining it for a while when it's that big. Maybe use the tank but use more insultation to make the core of it smaller? Just a thought. I'm not expert but I found what everybody's saying to be accurate. Make the forge no bigger than the size you need for the biggest knife you'd make.
Ok maybe my calculations are wrong. I have a 5 gallon compressor tank will be lined with 2" superwool. So my ron reil look alike should suffice with a single burner? Just wondering more or less so I know where to place my burner. However I'm thinking now I should probably place it closer to the front.
Hi, for a 3/4 inch venturi style burner I've always heard about 350 ci is a good size for welding temps... my first forge was a 3/4 burner with 2" insulation in a propane tank shell and could get to welding temps. Now I almost always run a blown burner for welding and general forging.
