I have at least two other posts here (published or otherwise) about melting aluminum or lead or like metals for use in some process. i can say with confidence that i have melted 8+ different metals in some mass quantity. The most common one I've done has been aluminum. this is nothing new to many people. The King of Random, Mr. Grant Thompson has put out several videos on his "Mini Metal Foundry" and that is where I started when I graduated to aluminum. I started melting things "harsher" than ice cream when I was somewhere around 6. I started with candle wax. Shortly after I found my father's propane torch and spool of plumber's solder. I remember sneaking down to the basement around 8pm one summer evening and gathering everything as quietly as I could. On a dark section of the cold concrete floor I unraveled a foot or so of solder, and lit the torch. As it began to melt on the floor, I could see impurities (burned flux) rolling around on the surface of the small puddle. I moved the torch closer to try to burn it off, and three seconds later, POP! Some moisture under the surface of the concrete flashed to steam, fracturing the concrete above and sending small chunks of concrete into my face. Lucky for me, none of the solder went my way, at least enough to burn me. The oblong, quarter-sized dent is still there as far as I know. I had enough wits to realize I needed more equipment (or if nothing else, a set of safety glasses) than just the solder and the torch. I wound up the unused solder on the concrete and put everything back where I found it. I was 8 years old at that time. This would not be my last fright with molten metal. 

Fast forward nearly fourteen years later, and I've built four backyard foundries and three experimental ones. I've been burned by something foundry related at least six times that I can remember, and only carry a scar, albeit a very faint one (Thanks Mom! would've been worse without your guidance!), from one instance. My first foundries were small-scale ones designed to work with the same propane torch that scared me so very long ago. Molded using simple Plaster of Paris and stuff from the recycling bin, I was able to melt everything from Tin, Zinc, and Lead, to small lengths of Copper and decent amounts of Gold, and Silver. my first attempt at a proper Mini Metal Foundry was an old Helium Tank, cut off at both rounds to aid in cleaning, and lined with concrete. Fueled by lump charcoal, that worked to a degree. but it was never able to effectively melt aluminum. A year or two later I went out and bought everything I needed for the charcoal version of the Metal Foundry. Three weeks later (I messed up the Sand/Plaster/Water ratio pretty bad) I had a full "seasoning" burn. I took Grants suggestion and went to a couple of thrift stores and found an old hair dryer. I knew from years of reading Hot Rod Magazine (and related) that you would get a hotter burn with more oxygen, so I set the hair dryer to it's "cold" setting, though this had diminished effect in the middle of the summer. Regardless, it worked marvelously. My first melt I was able to go through nearly three pounds of cans. I had more, but I burned through the Propane bottle I was using as a crucible. I still have one of the ingots from that melt. 

After this, I shelved the project for a month or two until I acquired a graphite crucible, and all of the parts for Grant's "Jet-Torch". Since then I can confirm that I've melted well over 25 pounds of aluminum. I should really do a count to see how much I've worked with... 

I made an adapter for my car's air cleaner, it's a little rough, but it works plenty fine. I plan on re-doing it once i get a better greensand. This was made using the lost foam method and a section of a lower control arm off of some Asian import I was given from a friend.  Couldn't have asked for a better end result. 

Most recently, I've been prototyping a Bedroom Foundry. 

 

Disclaimer: This prototype melting machine (hereby "The Foundry") is being designed as a CONCEPT. Aluminum melts as very high temperatures, and operating the foundry inside a building, residential or otherwise, raises the risk of an uncontrolled combustion, and is therefore, not advised. The author claims no responsibility if you choose to replicate their work, and it results in personal injury or the loss of property. 

 

The bedroom foundry is a combination of a lot of what I've learned over the years. It's designed to be as compact as possible and to melt, realistically one thing: Cans. In my end-all be-all world I'll have a shredder and a pellet-stove type deal where you feed cans into a shredder then they are continually fed into a crucible with cleaning pills added periodically. Right now, it consists of a steel gallon-sized paint can, steel-wire stand, propane bottle, and propane torch. the refractory lining is Grant's regular Plaster/Sand mix with some extra coarse steel wool added for stress relief. My test crucibles have been soup cans, but again, I burn through them pretty quickly. I have only had one such occurance, and that can probably be stretched if I tried a few things. For example, pre-heating the foundry sans crucible. I did just come up with that right now. The foundry runs off of a standard 2lb BernzOmatic propane bottle, and utilizes a MagTorch MT245C torch [this one] as a burner. I poured the lining around a Quart measuring cup, then cut through it with a 7/8" hole saw. The fit is excellent. The steel wire stand is actually a motor mounting assembly out of an old central heating furnace. I plan on re-making a design quite similar to this when I construct version 2. 

One of the issues with an indoor smelting system that some people will no doubt point out is the fumes generated by the smelting process. Cans are lined with a clear varnish prior to filling to aid in shelf life and anti-contamination. It's a very neutral coating that does not allow the liquid to corrode the inside of the can. Ever wonder what makes the soda able to clean up the rusty bumpers? Acids. mainly. Hence the reason that they tint your teeth. Ingestive health effects aside, the lining burns away, along with any packaging glue and stickers that may reside on a wayward can, and ends up in the air. It's currently winter here, so the differential temperatures work in my favor when I'm testing this, as I work with the foundry about 10 inches away from a window. However, this will become a much more significant problem during the summer months. Utilizing the whole animal, I salvaged the smaller blower motor out of the same central furnace, and soldered it up to a PC power supply receptacle, aiding in it's usefulness and portability. it moves a lot of air and is still quieter than the foundry when running. the next issue lies in how i'm going to mount the extractor. i decided a vertical mount would be easier to construct, so the next issue was creating a fume hood that could connect to the fan. I solved this by utilizing a handful of 1.5" PVC fittings I had from the previous foundry,  an old funnel, and a single 3D Printed adapter. I could just as easily used an existing section of PVC fitting, but it would've been bulkier and would have destroyed the larger portion of a fitting. Also, when all you have is a hammer...

If I had thought about this post, I would have taken better documentation... The fit was very close, only about 1mm smaller in the fan-flange side than I would have liked. A minor issue, I know, but It would not have worked as effectively had I not chosen to glue that section on permanently. I used your run-of-the-mill Permatex 5 minute epoxy to do this. The PVC side fit wonderfully, the final fit may seem looser due to available leverage, but it snugs up comfortably and comes apart without difficulty. The funnel was modified by cutting the small taper off and sectioning the larger taper at the joint. I then took a 1.5" PVC male socket to 1.25" PVC female threaded  NPT adapter and pushed that inside, while I used a 1" section of 2" PVC to act as a collar around the outside of this whole assembly. this left enough room on the adapter to socket into a 1.5" street elbow that feeds into my shiny new 3D printed flange. The funnel-PVC assembly stays snug enough that I don't feel the need to permanently attach anything. 

This is about where I'm at now. I'm musing about bringing the propane bottle as crucible idea for this project, as I'd run out of cans long before I'd run out of empty bottles. I'm also Printing an Open-Bionics Brunel hand structure and plan on using it with a set of micro servos in order to make this a "hands free" foundry. Maybe down the road Hal will be analyzing the bucket of cans and melting them on his own, while I float out in the cold, dark, vacuum of space, sipping a macchiato, in a space swimming pool, on my way to Titan, or Europa, the location is yet to be decided. Hal wants to go to Jupiter for some reason. I just want a fancy coffee once in a while...

 

UPDATE: 03-06-2018

I cut the Window board out of a section of 3/4" particleboard. the idea is to mount this in the window then attach the output of the extractor to it. thus removing fumes, not damaging screens, and still keeping the wildlife out. Taking window openings, height and offset of the blower into account, I had a board two feet in length and about 10 inches in width (I didn't modify whatever it was, I just ran with it.), with a 2 inch hole 7 inches from the right, and 19 in from the bottom.  this will get painted black to shy away the neighbors eyes and not look like a sore thumb, but it should be quite fun.