DIY Aluminum Foundry - Do's and Don'ts

I have been using my previously DIY build foundry (forge) to melt aluminium/aluminum for a number of months now, so it’s time to share my experience sand lessons learned in melting aluminum with my self made forge.
I will look at a number of topics:
1) The DIY crucible
2) The aluminum scrap used to melt
3) Molds I am using for pouring aluminum
4) Safety precautions with a aluminum foundry
5) “Light my fire” or better: ignite your forge in a safe way
6) "Cooking" time
7) Gas pressure (whether or not to use BBQ standard propane gas pressure of 37mbar) with a small test on length of gas nozzle/burning pipe
8) Pouring aluminum
All of this in context of being a newbie and doing this for 4 months!
You can find the video’s on the build here:
DIY GAS FORGE/FOUNDRY for melting aluminium - EPISODE 1: The Foundry - • DIY GAS FORGE/FOUNDRY ...
DIY GAS FORGE/FOUNDRY for melting aluminum - EPISODE 2: The Gas burner - • DIY GAS FORGE/FOUNDRY ...
DIY GAS FORGE/FOUNDRY for melting aluminum - EPISODE 3: Testing! -
• DIY GAS FORGE/FOUNDRY ...
You can find me on Instagram: / extreme.diy.in.belgium
Music courtesy of free KZbin Audio Library

[@neepsmcfly4176]

Just starting. Literally at finding materials stage and I wanted to say that I appreciate you showing your mistakes and learned lessons. From what I've seen so far the criticisms and corrections generally appear to be respectful. That's awesome as I don't learn so well from blow-hards who really just want me to know that they know what they're doing. Keep up the Great work!

[@ExtremeDIYinBelgium]

Awesome, thank you!

[@WhiteDwarfVR4]

Smart Crucible design, I might have to use something like that.

[@BADD1ONE]

I designed a crucible just like yours. I had a previous one. The metal was cheap. Ruined the bottom of my forge. I'm making another now. 1/4" steel pipe 6". Much better material than the previous.

[@ExtremeDIYinBelgium]

If you don't use a crucible that is based on graphite composite material, and you want to use scrap, then indeed you need to use some solid steel and accept the fact it will degrade over time... And for the moment, for me a steel DIY crucible is OK, as I am not melting aluminum every week.

[@olfoundryman8418]

In the spirit of improving your product:- A few more "dont's" Don't use a metal crucible, use a clay graphite one and use decent crucible tongs and a proper pouring shank with it. Don't melt down swarf/chips - too much surface oxide Don't melt down wrought aluminium sections, cans, or pressure die castings Don't viciously stir the metal, it just makes more oxide. Preferably do not stir it at all. Don't mix alloys Don't try to make machining stock this way - all you will get is some chewing gum sticky porous rubbish not useful for anything decent Don't have gaps between the brick lining in your furnace as it will cause a lot of heat loss.....Martin

[@tnmonty501]

would it help any to preheat the aluminum in a container on top of the crucible?

[@jarredsegal6842]

I wouldn’t turn down painted aluminum depending on thickness obviously Pop cans give a lot of slag but the casings from lights can render a lot of aluminum with minimal slag

[@ExtremeDIYinBelgium]

just melted an old (unpainted!) aluminum greenhouse into 38 kg of nuggets... :o)

[@jarredsegal6842]

@@ExtremeDIYinBelgium working on another 200lbs of 400w metal halide ballast Painted but comes with 400 lbs of copper windings The paint is worth burning off and the copper pays for the time it took to break apart the ballasts

[@swdweeb]

Only trying to help... 1) do not use steel crucibles. The aluminum reacts with the steel speeding the erosion and causing crucible failures. Use graphite/clay crucibles, 2) do not waste your time melting swarf (the shavings that come off of a mill or lathe) it is nearly all oxidized and will create inferior castings. There is also so much waste it is a complete waste of propane. 3) Use sand molds or ceramic molds if you want to cast anything but ingots. 4) ok 5) ok 6) turn up the propane. I melted aluminum in 15 minutes in my homemade propane furnace. 7) see #6 8) That's not hot enough. Although aluminum melts under 700C pouring temperature is around 720C. Unless all your doing is pouring metal in cans with holes in the bottom then you can pour at whatever temperature you like.

[@ExtremeDIYinBelgium]

Thanks for the extensive comments! On the crucibles and molds: you are totally right, but the whole point was to use scrap you have laying around or that you can get far cheaper than acquiring all the "professional" stuff. On melting shavings from the mill/lathe: I already had the impression this was not optimal and you confirmed it. On turning up the propane: yes, and that is what I am going to do, but as said I tried to use an existing BBQ propane valve which had only 37 mBar. If I hear that you can melt in 15 minutes, then probably it will not be more economic on propane if I am burning 45 minutes to get to the same point... How high is the gas pressure you are using?

[@swdweeb]

@@ExtremeDIYinBelgium I'm going on an internet conversion here since all of my pressure valves are rated in PSI (pounds per square inch). I run about 17 PSI or what appears to be 1100-1200 mBar I would argue that the time spent locating steel pipe, cutting it, welding it and then only being able to use it safely 10 times is more expensive than buying a graphite clay crucible that will last you many more melts than that.

[@ExtremeDIYinBelgium]

on the PSI/mBar: that's a big difference... planning to acquire a variable regulator to do some testing, but I already knew I was far too low... and besides the fact that the DIY crucible is a cheap working solution for me (the pipe was on top of the pile of scrap metal, so easy to find, had already the correct length ;o) ), I think that my DIY crucible will probably live a lot less longer when I am getting my burner at a higher temperature with increasing the gas pressure...

[@apatbond2864]

Your gas presure not enough

[@ExtremeDIYinBelgium]

Yes, I am aware of that. I am using the gas pressure valve of my BBQ (only 37mBar out of my head) so it takes longer but probably a bit more economic on propane. I will however be using another gas pressure valve in the future...

[@jamestrevarthen6609]

Absolutely the most boring music or whatever it is I've ever heard what arel you spoke about what you were doing