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This is my design for a metal melting foundry that also works as a forge.
Materials needed:
1 old beat up standard propane tank
Portland cement
Silica sand
Wood ash
Perlite (not vermiculite)
Fireclay

External parts:
Forge burner
------ I used the burner from this instructable
https://www.instructables.com/id/how-to-build-a-gas-forge-burner/
High pressure gas regulator
Crucible (shown at end)

Tools needed:
Reciprocating saw (for cutting the propane tank)
3" hole saw drill attachment (optional)
1 3/8" hole saw
Chisel
Small drill bit
Hacksaw
Drill

Step 1: Prep the Tank

Completely empty the tank of all propane by fully opening the valve. Using your chisel or a hacksaw, slowly cut the brass valve off. Which should expose a roughly 3/8" hole. Fill the tank with water and let it sit for a few minutes then empty it out. Don't throw the valve away because it's solid brass, which you can melt down later!

Step 2: Cut the Propane Tank

First you'll have to cut the top off the tank. Do this first by drilling a small hole in the tank at the desired height, mine being right where it begins to taper in. Then take the chisel and use it to punch a hole big enough for the reciprocating saw blade to fit, and then use the saw for the rest of it.

Step 3: Drill the Large Exhaust Hole.

Using the 3 inch hole saw, cut out the hole right in the top of the tank. My hole saw ended up breaking since it was old and this was the second foundry I've made, so I finished it with the reciprocating saw.

Step 4: (optional But Recommended) Lid Structure Addition

I didn't get a picture of this but basically weld a bunch of random screws onto the inside of the lid to help support the refractory brick.

Step 5: Mix the Refractory and Cast

For the body of the foundry:
Mix 15.6 c Portland cement, 15.6 c perlite, 15.6 c sand, and 15.6 c wood ash. Thoroughly mix and add 33.5 c water. Then add 31.2 c Fireclay and mix until there are no dry pockets. It should be the consistency of very very very soft cookie dough. Pour it into the body of the tank and press a 6 inch diameter by 7 inch high cylinder (basically a large paint can) into the mix until it is right up to the top of the tank.


For the lid:
Mix .8 c Portland cement, .8 c perlite, .8 c sand, and .8 c wood ash. Add 1.25 c water and mix. Add 1.6 c Fireclay and mix. Before you pour the lid, find a 3 inch cylinder to put through the ventilation hole. I used a large spray paint can. Then pour the mix and pack it in, but be careful of the screws welded on!


If you have any leftover cement, make refractory bricks!

Step 6: Drill Gas Supply Hole

Around the center of the tank, drill a 1 3/8" hole through the metal and the concrete. This is to put the burner in.

Step 7: Crucible

You can either buy a ceramic or graphite crucible, which I don't recommend as mine exploded after a while, or you can weld together a metal one which I have now. It's just a 3" ID schedule 40 steel pipe around 5 or 6 inches high. They're based off of the crucibles made on this site: http://backyardmetalcasting.com/crucibles.html

Step 8: Use It!

You can use it to melt anything from aluminum to copper and more as this reaches temperatures of up to 2400°F. You can use it to forge, cast jewelry or other metal parts, and you can melt glass too! Be safe!

PS: if you don't have access to propane as fuel, you can use charcoal with a hair dryer blowing into it instead. It isn't as hot but still works for aluminum and other low melting point metals up to around 1400°F.
<p>Great looking work! It is all excellent. I do like the cautions, and of course will heed them.<br><br>BUT, at the risk of seeming ignorant (I'm simply uninformed), I'm in the US, and am not familiar with the abbreviation used in step 5: Step 5: Mix the refractory and cast<br>Mix 15.6 c Portland cement, 15.6 c perlite, 15.6 c sand, and 15.6 c wood ash. Thoroughly mix and add 33.5 c water. Then add 31.2 c Fireclay and mix until there are no dry pockets. (and it goes on...)<br><br>What does the lone &quot;c&quot; mean Cubic Centimeters (usually CC)? Cups? (can't be cubits, the project is too small.) ;-) <br><br>Someone please inform me as to the meaning the author is conveying with &quot;c&quot; please. And if you mix too much, what's a safe disposal method for the mix excess?<br><br>I've seen many other projects based on used gas cylinders, and many use &quot;rock wool&quot; or other fireproof fiber insulation, along with firebrick I'm assuming that <strong>this</strong> insulation goes to higher temps. I only need at most about 2,200&deg; F for forging and later about 425&deg; F for tempering metals in blades, hammers, and tools like chisels. <br><br>Clear up this little confusion for me someone!</p>
Good instructable! Just FYI, if you want to go to work on the cylinder quicker after emptying it, you can just fill it with water, empty and go to work. You will still smell the odorant, but the flammable vapors will be gone and safe to work with immediately, no need to wait a week. I have welded and cut on a lot of them and that is the procedure I use.
Thanks for the tip! I'll change that step
<p>dry ice works really well at displacing vapor. As it sublimates it goes to the bottom of the tank and forces the residual propane vapor out the top - actually, it displaces everything in the tank. Nothing gets rid of the mercaptain tho except time, sigh.</p>
Huh that's interesting. I'll have to try that if I make another one
<p>Something else to try. Before I reseal a tin of oil based paint I flood the inside with propane. Would use butane but it's not something that's readily available. Only place I found that would sell it to me wanted something like $50 a gallon. Anyway, it displaces the air in the tin the same way dry ice displaces anything in a propane cyl. The paint won't form a skin on top - think spray paint.</p>
<p>I would strongly suggest nitrogen over propane. Nitrogen is non-reactive and will displace oxygen thus protecting your paint. It is also not explosive....</p>
<p>NOT disputing. N works just fine as well as He, Ar, Kr, Xe or any of the inert gasses BUT you need a dedicated high pressure bottle to contain it and a regulator (who really wants to just crack a valve on 2250 - 3000psi bottle for a tiny amount of content). Just look at all the spray cans you have sitting on the shelf filled with butane, they're explosive as well. What's one more, unpressurized can? Research Propane and you will find it is just about the safest of all reactive gasses. Lookup dust explosions, flour in a drinking straw blown at a candle will explode!</p><p>As a kid and freon was used in cans we used to collect the ones that washed up on the beach and throw (from behind a beached log) them on a beach fire - depending on how full they were there were lots of sparks or no more fire depending on the orientation of the solder seam. Grew up and pursued various careers one of which dealt with plastic explosive, bi-component and other explosive compounds. </p>
<p>In Russian but idea is clear:</p><p><a href="http://www.icct.ru/node/79" rel="nofollow">http://www.icct.ru/node/79</a></p><p>Well worked out, practical article. Here is video of process:</p><p>https://www.youtube.com/watch?v=R6z2q1aaTV8</p>
That was what I originally wanted to make but it was a little out of my skill set. Induction foundries are pretty cool
Step by step tactic maybe? That is modular (steps like) PRACTICAL design, extremely well described and depictured. Unfortunately, in non-native language, but electronics has no national boundaries ... COMPONENTS do )) but there is your native hardware only (mostly). <br><br>I bet you'll try and win. There is a lot of people in inet who make their first steps in power electronics successfully ... and not much. )) The game is worth the candle I suppose.
<p>Good Job</p>
Thank you!
<p>It might possibly be easier to drill the gas supply hole before putting in the refractory mix. Just use the same procedure as you did for the top vent (spray can) and then put the rest of the mix in to fill it up. What little of the mix that gets between the big paint can and the small paint can can be knocked out and filed smooth. This could save alot of drilling and cement dust generation that is really not good for you to breath. Love this idea, very similar to how I refinished the inside of my forge. </p>
Yeah that would work too. Thanks!
You are welcome. :)
<p>When someone comes up with a good Instructable like this it always brings out the nay-sayers who try to discourage anyone from building the item. They don't seem to understand that the photos in the Instructable are proof that the author actually built the item and that it actually works. Don't let the nay-sayers get to you. They will always try to denigrate your effort and accomplishment, but their opinions really do not matter.</p>
Thank you for the kind words!
<p>This would also be useful for enameling small items and firing small hand painted tiles or cups.</p>
<p>This would also be useful for enameling small items and firing small hand painted tiles or cups.</p>
<p>This would also be useful for enameling small items and firing small hand painted tiles or cups.</p>
<p>TIP!!!!</p><p>Leave the water in the tank while cutting it.</p><p>Propane is nested into the pories of the tank!!!!</p><p>I made one and works fine</p>
<p>steel is not porious </p>
<p>Why do you think you can't weld a gas tank to fix it unless it is full of gas or water.... All metals are porous to some degree. because of their lattice like atomic structures. </p>
<p>Who told you that load of BS? Steel , and iron, are indeed porous!, and will hold explosive amounts of flammable material, for way longer than you'll want to wait!</p>
Good tip. Thanks!
I have to recommend not using cement in any refractory mix. It does not end well and is unsafe. To find good refractories and refractory mixes, check out some blacksmithing forums. A good one I've found is iforgeiron.com
Most of the mixes I found have Portland cement in them and say that as long as they're fired properly they will last a good amount of time. This is the best mix with clear instructions I could find http://www.imarketingcenter.com/refractory.html
Yeah it's easy to mess up. Hopefully people know safety. Thanks!
<p>Ok,if it works for them. Most of the guys I've talked with have some interesting stories of people messing up and hurting themselves by doing things wrong. I'm just trying to make sure people aren't making uneducated decisions that might hurt them. I mean, there's a story of a kid who regularly poured gasoline on his forge to boost temperatures. Suffice to say, he isn't around anymore. And if you guys just want to make a forge, it doesn't need to be complicated. Forges have been simple holes dug in a ground for hundreds of years, and as long as they have a fuel and an air supply they work fantastically. Good luck!</p>
Thanks for the tip! I'll check out other mixes
<p>Thank you, the plan looks simple. Now to find an old gas bottle!</p>
Good luck and have fun!
<p>Hi chaotech creations, I am keen to also make this forge and was looking at the picture with the pipe and PVC tube mounted to the side of the tank. Is this for forced fed air and in addition to the gas burner hole? </p>
No that's the setup you would have if you were using charcoal instead of gas
<p>i missed the step on how the burner is installed.</p>
You just stick it through the gas supply hole and connect it to the pressure regulator, then connect that to the actual propane tank.
<p>I sold Propane for years, it is heavier then air, so if you leave the tank upright not all the gas will leave. And the brass valve won't spark but could develop enough heat for ignition if cut too fast or a cut off wheel was used. I would still invert the whole tank on the handles with the valve open for several hours to let the last vapor drop out before attempting to cut a valve. Once the valve is removed and the tank flooded and drained, I would consider it safe.</p><p>Personally I would just screw the valve out of the tank in one piece. My usual method is to use a 2 inch or wider rachet strap, anchor one hook, wrap the tank completely, fasten the second hook and tighten. This will keep the tank from spinning while you use a wrench to take the valve out. I found the anchor points at the back of my trailer work well or the bumper on my pickup. Have a really stubborn valve you might add a second strap.</p>
<p>Thanks for some good tips.</p>
Yeah all the valves I've taken off have been too stubborn to unscrew, so I had to cut them out. Thanks for the safety tip!
<p>sweet I want one </p>

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Bio: Hi! I'm an 18 year old guy that likes to work with metal! Subscribe for cool projects! Next Instructable: DIY Mini Lathe Chuck
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