Propane Coffee-Can Foundry

List of Materials:

• Coffee can or some other sort of container
• Perlite
• Furnace cement
• Propane/propane torch
• Steel pipe as a crucible

Day 1
09/17/05

All started well. I went to my local ACE Hardware store and found everything I needed to get going. The Perlite came in a 2 gallon bag, costing $4.49, and I found myself wishing they had a smaller bag. The furnace cement came in little 8 oz containers, each one costing $2.49. I bought two.

Upon arriving home to commence work, I found a rather large pipe lying in the driveway, about 2 feet long, having the same diameter of a coffee can. I thought, "that would make a much better foundry than a mere can would," so I decided to use it. I cut the bottom off a coffee can and forced it into one open end of the pipe, forming a well-secured bottom. Then I drilled the propane entry hole. Not quite a walk in the park since the pipe wall is 1/4" thick. I then found a scrap piece of cardboard to roll to form the inner core mold.

The Perlite/cement mixture looks like it couldn't hold anything together being as loose as it is, but once packed holds its shape nicely. It does, however, loose a conciderable ammount of its volume after packing. It soon became painfully evident that I didn't have enough cement to finish the job. I mixed what I had and then decided I needed two more containers.

I returned to ACE Hardware to find that they only had one container of cement left. They wont have any more in for five days. I bought the one and went to every other hardware store I could find. None of them had any of the furnace cement. Just my luck. So I returned home and mixed and packed what I had, finding, to my astonishment, that I had used well over half of the two gallons of Perlite. I should have enough to finish the job, I'm just glad they didn't have a smaller bag.

Working Time: 2 hours

Day 2
09/21/05

Construction of the nozzle began today. I took an old weed burner lying in an obscure corner of the shed with me to work. On my lunch brake I headed out to the shop to use some tools. I broke the welds holding on the guard, grinded it down smooth, and cut off a guessed length as to how much I needed. I was going to simply tap the pipe with the same size threads as the end so I could just screw on the propane, but that didn't work. The pipe is much thinner walled than on the end where the threads are. So I went back to Ace Hardware to see what they had that I could use. After sorting through many fittings I found that a 1/2" copper pipe fits quite snugly inside the pipe. I then went back to the shop, cut off the threads, cut a short piece of copper pipe and coupled the two together. I'll have my work buddy weld the pipe sometime to make it air tight.

Working Time: 1 hour

Day 3
09/22/05

IT'S THURSDAY!
Which, of course, means my furnace cement has arrived at ACE. I went immediatly after work to pick it up and, after learning of their 60th anniversary and the subsequent 20% discount, I decided to buy four, just in case, so I wouldn't have to make yet another trip down. I got home and started working on the PCCF. There I was, mixing and packing--then at long last I got to the top of the pipe.

With that much compleated, I decided I had better have a lid, so I started construction on that. I took what was left of the coffee can I chopped (for the bottom of the huge ol' pipe), placed it onto a plastic sheet, cut some 1x2's to fit in a cross inside, put them in, and placed a small piece of pipe the same size as the crucible will be in the center. I made up some more perlite/cement mix and packed it around and over the pieces of wood and pipe. The idea is that the wood, when removed, will leave air vents and the hole in the center will allow for the crucible to drop in.

I waited two hours then went back to see how it was doing. It was doing well, though not yet dry enough to "seal." That should be done tomorrow.

Working Time: 1.5 hours

Day 4
09/23/05

I couldn't resist. Today on my lunch break I took my nozzle, stuck it in the hole, turned on the gas and threw in a match. I watched as a big puff of fire came out... and out. The propane was filling the inside, but no oxygen could get to it, so the gas would rise and burn as it came out the top. I definatly need an air inlet at the bottom. Probably some way of pumping in air--like a reversed vacuum or an air compressor.

After work I spend a little time doing some real work on the foundry, namly sealing it. I took some furnace cement, thined it down with water, and spread it all over the inside. Turned out to be much more time consuming than I expected, but my goodness, does it look sexy.

Working Time: 2 hours

Day 5
09/24/05

I spent the better part of a half hour drilling a hole through the bottom for the air to enter. That darn 1/4 inch wall is a bugger. I then went to DI to find an old vacuum. Lucky for me, they had exactly what I was hopping for--an old hand-held model. I bought the little guy for a whopping $3.00 and took it home to figure how exactly I was to reverse it.

I took it compleatly appart to see what could be done. It has as cetrifugal type fan, which is the best kind for moving a large volume of air, but it only blows one way, so one can't simply reverse the direction of the fan. So, after a bit of thinking, I decided to chop off the handle of the vacuum, remove any interior bracings and other things that would block the flow of air, taped of the vents, succesfully making it blow its air out the handle. I then ran back down to ACE and gathered up some fittings to mount in on the foundry. I chose to go with a bypass valve system to control the amount of air that would be directed into the foundry. It works like so: Air from the vacuum blower goes through a pipe from into a TEE; the opposite end of the TEE is fitted with the valve and the offshoot of the TEE goes into the foundry. That way I can open or close the valve to direct more or less air in.

I assembled everything then set out to test my contraption. After mounting the air supply, I turned on the propane and thew in a match. It flamed up to life, just as before, resembling a campfire. Then, starting with the valve fully open, turned on the air supply. Initially the flames grew much bigger out the top, but after a short while (a few seconds) it gave a semi-loud pop sound and fired up as expected. No flames come out the top anymore. I tampered with the propane and air valves a bit to get what seemed the best roar out of the foundry. Now, looking down in, I'd say it looks like a swirling vortex of fiery doom.

Working Time: 3 hours

Day 6
09/27/05

Still waiting for my work buddy to finish welding that crucible. Darn public school schedule....

So, while I wait for that, I deceded to make my own temporary crucible by pinching off the end of a pipe. After all, I do have a rather warm heat source. And so I fired up the foundry, took the pipe and stuck the end of it down in. After achieving a rather nice cherry red glow I took it out and pounded upon it. After a few cycles of this I folded it over and pounded some more. Viola. A closed end pipe. I then proceeded to drill a hole through the top to allow rebar through, which will rest on the top of the foundry, suspending it inside.

Now for the fun part.
Fired up the foundry, stuck the crucible in, waited, added aluminum... woohoo, it melts!
Though I can't seem to get it to a decent pouring temperature. Perhaps with the lid I will, but I'll let the real crucible get done before I try that.

Working Time: 3 hours

Day 7
10/03/05

At last, the crubible is done.

After finding a small leak and welding it shut, I got to work melting. Putting the lid on does, indeed, raise the temperature so that I can pour resonably well.

And now, it sufficeth me to say that my foundry is complete.

Working Time: Not much

• Days to complete: 17 days
• Total working time: 12.5 hours
• Total cost: Approx. $26.50