May 23, 20179 yr I'm farely new to blacksmithing. I just started as a hobbyist and made a couple of little things in a friend's propane forge. I've been doing some research into it and I want to go for propane as well but I don't know what to make my shell for my forge out of nor do I know what to make my exhaust out of. My forge design is the picture below. (Mind the bad handwriting)
May 23, 20179 yr Why a square shell? Tubular is easier to line with kaowool. Not know what you plan to make using it makes it hard to suggest a shell. However if you lived in the USA I would suggest going to a "Party Store" and asking about empty Helium tanks--the light gauge sheetmetal ones not the welding tanks, all the places I know toss them out. They come in several sizes. Getting started you probably want a smaller one than the larger. Shoot I have a couple in the shed right now; stop by and pick one up! (I tend to grab them whenever I see them at the scrapyard or in a dumpster.)
May 23, 20179 yr If you don't have a party store near, go to any mechanic shop/garage that does air conditioning work and ask if they would save and let you have an empty freon tank. If you put your location in your profile you might be surprised how many IFI members are close to you and would give you a tank. Shoot I have three of them in my shop right now.
May 23, 20179 yr Author Thomas, I didn't know that non-refillable helium cylenders came in more than one size. Could you provide any more information on this, please?
May 23, 20179 yr from searching on: helium tank party store "Our large 14.9 cubic foot Balloon Time helium tank fills up to50 9-inch latex balloons, or 27 18-inch foil balloons. Our small 8.9 cubic foot helium tank fills up to 30 9-inch latex balloons, or 16 18-inch foil balloons." Let me go check what's in the shed: 9.75" diameter
May 24, 20179 yr Author Thanks, Thomas, So the larger cylinder would be about the same size, as a two gallon Freon cylinder, and the small size would be roughly coffee-can size, but nicer looking?
May 24, 20179 yr Author calebB, I will assume the square shape of your proposed forge is a copy of one you have seen; most of us old guys prefer tube forges for a lot of reasons that I won't go into here, On the positive side, one of the better commercial forge designs around (Diamondback brand) is a box shape; their owners find them durable and hot running, so I will shelve my preferences and simply deal with where you are going. In the first place you can buy ceramic fiberboard to line such a small box shape for about $70, which is good. You can top mount a 1/2" "T" burner in such a forge, which make an excellent match between burner and forge. And finally, you can mount the side with your exhaust opening in it with hinges and a latch, so that larger pieces than such a small forge has any right to hold will fit in it. You can also place large casting crucibles in that forge, and move them in and out easily and safely. I don't like any of those facts; they offend my druthers, but you go ahead and make the most of them, anyway. Mikey, the grumpy old man
May 24, 20179 yr 8.9 cubic feet? You must have MASSIVE coffee cans where you are at....Heavier walls too.
May 25, 20179 yr I actually work at a an air conditioning company so I have access to plenty of empty freon tanks. I picked up 2 yesterday. One of them is a blue canister that we call "New 22" and a pink 410. The 410 canister walls are a bit thicker. My next question would be how to; A. Cut the canister. And B. Build my forge. If someone has a design/schematic that they wouldn't mind sharing that would be great!
May 25, 20179 yr I use a reciprocating saw with a metal cutting blade to cut my propane tanks - after the valve removal and thoroughly flushing with water to remove all traces of residual propane and oil. There's 1637 different ways to build a forge. And they all work - to one degree or another. The design for you depends on what you want to do with it. If it were me, I'd cut both ends off the canister. If it was too short, I'd weld two pieces of canister to get the length I needed. Cut a hole or holes for the burner(s) in the appropriate spots on the upper side. Weld a piece of pipe as a sleeve over the holes to hold the burner(s). I'd put in a layer or two of ceramic blanket. Rigidize the blanket. Make a cylindrical plug with a flat side to it (which would become the floor when the canister was laid down) out of cardboard. Fit that in the center of the canister. Make a cone shaped mold piece the size of the burner flare and fit it to the cardboard plug at the burner hole(s), and cast Cast-o-lite 30 between the plug and the ceramic blanket and carefully around the cone shaped mold piece. When that was set, I'd remove the cardboard plug and the cone shaped mold piece, fit legs to the outside so the flat of the interior was on the bottom. Fit two pieces of angle iron horizontally to the top and bottom of the open ends as a track such that fire bricks could be slid into them to be able to close the ends. Build burners. Plumb the burners with regulator and gauge, ball valve, idler circuit with needle valve. Check the plumbing for leaks and fire it up. But that's just what I'd do.
May 25, 20179 yr Have you read Wayne Coe's write up? http://www.waynecoeartistblacksmith.com/uploads/Build_a_Gas_Forge.pdf Not the only way to go of course. Wayne also sells materials for building/repairing propane forges.
May 25, 20179 yr Author There are also two other free sources: Pirated PDFs of Gas Burners for Forges, Furnaces, & Kilns can be downloaded for free; it gives step by step instructions for building a gas furnace from a five gallon propane cylinder, along with all the nuts and bolts information you need about hooking it up, two different method of building an idle circuit, etc. Combine that information to Reil's instructions on building a mini-forge on his burner pages, and you can't go wrong. Finally, forget about using an angle grinder with a cut off wheel to do the cutting on burners and forges, and substitute a hand held rotary tool with cutoff wheels to do the job easier and SAFER. Use the EZ cutoff disk manifold with 1-1/2" disks, and actually doing the work will be child's play.
May 28, 20179 yr Author More about box forge design A box shaped forge should be considerably taller than it is wide or deep; the reason for this is that burners are pretty much forced to be placed at the top of the forge, pointing straight down at the work. therefore, the distance it can traverse before impinging on the work must be kept long enough to ensure the flame finishes combustion before that happens. If you can see flame, even a reducing flame, touching the work surface, than you are producing scale on it. Flames are ongoing chemical processes, which produce heat, and other byproducts during and after combustion. During combustion, free super-heated oxygen is present; when it touches heating steel or iron, super fast forming of oxides (scale formation) is the byproduct. But why does this mandate tall boxes? Can't a larger number of burners allow the box to be tall enough, but still wider and deeper? Yes, but the larger the area being heated the greater the energy losses incurred. So, generally, tall shall remain the rule of thumb for box forges. During and after combustion!?! Yes, because very few flames complete combustion in the primary envelope, which is quite easily observed. Secondary flames are often all but invisible within a heated forge enterior, but we must take what we can get... It should logically follow that the burner is best positioned to keep the flame nozzle from protruding into the forge enterior, where it will only waste energy, while being overheated; even better is to mount a burner within a refractory 'burner block" instead of a metal flame nozzle.
May 28, 20179 yr Author Frosty's use of floor flanges are the best method of creating a burner block in the forge ceiling.
May 28, 20179 yr Author http://www.cotronics.com/vo/cotr/cm_machinable.htm The address above is for what might possibly be the ultimate insulating brick for forge building. It is at least the perfect insulation to place under a high alumina kiln shelf or Kast-O-lite 30 refractory floor.
May 28, 20179 yr All those look interesting to me Mike. I assume you're referring to the silicate foam as an insulating back. It looks like they toughened up an aerogel. I haven't even LOOKED at the prices though. I've thought about shuttle tiles too Thomas, IIRC from the one program I saw back when the Discovery Channel had educational programming. IIRC they said it's a fibrous silicate foam. sort of a predecessor to aerogels but it needs to be pretty tough to withstand the wind pressures as well as heat. I'm pretty sure they'd be on the spendy side for a hobbyist smith. Frosty The Lucky.
May 28, 20179 yr 53 minutes ago, ThomasPowers said: I've wondered about space shuttle tiles... I have a friend who lived in Houston who raved about those, said they were the cat's pajamas.
May 28, 20179 yr Author 1 hour ago, Frosty said: All those look interesting to me Mike. I assume you're referring to the silicate foam as an insulating back. It looks like they toughened up an aerogel. I haven't even LOOKED at the prices though. I've thought about shuttle tiles too Thomas, IIRC from the one program I saw back when the Discovery Channel had educational programming. IIRC they said it's a fibrous silicate foam. sort of a predecessor to aerogels but it needs to be pretty tough to withstand the wind pressures as well as heat. I'm pretty sure they'd be on the spendy side for a hobbyist smith. Frosty The Lucky. I am waiting for an answer back on prices. "A salesman is going to call." Silica bubbles are used in light weight structural concrete, aluminum foam, ceramics, and now as ceramic foam sheet and blocks. My main interest so far is for use under high alumina kiln floors; the idea being to prevent eventual break down of 2300 F ceramic blanket or fiberboard, while supporting a free standing floor. This would eliminate the need to catch kiln shelves in niches Quote made in the steel shell, which would facilitate swinging doors in tube forges. However, if the price is reasonable, the thicker foam bricks could likely be used in box forges by coating the inside face of the brick surface with a mixture of 95% stabilized zirconia and 5% bentonite clay. I recomended that mixture to Doug, becuase he had scored some stabilized zirconia flour (very small particles, which are supposed to give over 93% reflectance ). He used the formula as a thin tough heat reflective coating in a ceramic blanket insulated oval forge, with a Mikey burner. It worked perfectly People who can't afford stabilized zirconia as a coating for the hot face on foam brick, can certainly afford high alumina powder to mix with the clay. So, why not use Kast-O-lite 30? Well that might work, but what high alumina powder and silica foam would likely share in common are very low coefficients of expansion; that kind of match up is always a good idea for surfaces subject to sever thermal cycling.
May 30, 20179 yr Thanks Mikey! I try to contribute what I can, but with so many people with much more experience and knowledge on this site, my contributions are minimal. But that's why I just love this site - so many people with so much experience and knowledge - and a terrific willingness to share it. Just amazes me every time I'm here.
May 31, 20179 yr Arghhh, something got into my Stephen Gensheimer burner as it was unhooked awaiting the next forge (which is ready for it), Now I have to clean it out and get an extra long tip cleaner that will reach the orifice. Next time I will store it in a plastic bag inside a plastic bag inside a plastic bag....
May 31, 20179 yr On 5/24/2017 at 10:48 AM, Mikey98118 said: Thanks, Thomas, So the larger cylinder would be about the same size, as a two gallon Freon cylinder, and the small size would be roughly coffee-can size, but nicer looking? If we're talking pink "Party Time" helium tanks, the big tank is the size of a propane tank like you'd use for your BBQ grill, while the smaller pink tank is about the same size as the typical freon tank - my impression is that it was slightly lighter gauge steel, but I could be mistaken.
May 31, 20179 yr Certainly lighter than the old propane tanks; but I haven't chopped a new tank yet---but noticed that empty they seemed a lot lighter than the old ones do.
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