MadModder
The Shop => Metal Stuff => Topic started by: MetalCaster on August 04, 2013, 12:24:04 PM
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Here is a furnace and crucible I built to melt aluminum.
Aluminum is pretty easy to melt and pour, just don't breathe the fumes, and wear some good personal protection including face protection, and boots perhaps.
I used the soft fire bricks from Budget Castings, but you can also use the hard bricks. The good thing about the soft bricks is that it is easy to cut holes in them with a hole saw or any other type of saw. for the burner, etc. Don't breathe the brick dust.
If I had to do over, I would just stand the bricks on end, and put them in a circle, perhaps cutting the sides to fit together, and using a little furnace cement.
I have even melted aluminum by just stacking fire bricks in a circle temporarily.
The crucible is welded together from heavy steel.
Some have mentioned that a steel crucible will contaminate the aluminum, but I have not seen any signs of that, and a heavy-wall steel crucible is very tough and long-lasting.
The pouring shank needs to positively lock into the crucible so that you can tilt the crucible beyond horizontal without any danger of the crucible falling out of the pouring shank.
I will look for a pouring shank photo (the one I use).
I use propane to melt aluminum.
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I made a coated ceramic blanket top for this furnace, and I am not too pleased with it, and will make another one out of soft fire brick.
The furnace below is my temporary furnace from stacked fire brick.
You can also see the pouring shank I use.
Lifting tongs are just two rods with hooks on the end.
Notice the "L" shaped retainer on the pouring shank.
I also added a short piece of vertical round rod on the end of the "L" bracket to keep the crucible from sliding off the end of the shank.
And I added a 6" handle about 8" out from the crucible, pointing straight down, which I grip with my right hand.
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And here is the final furnace.
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If I were only going to melt aluminum, I would use a steel crucible only.
I wanted to do some bronze work, so I bought a clay-graphite crucible, and made some lifting tongs and a pouring shank.
I need to rework the retainer on the pouring shank, it does not work correctly.
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A flywheel I poured in aluminum 356.
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I use petrobond sand, which is an oil-based sand.
If I were going to make a limited number of parts, I would try some water-based sand from Budget Castings, and use good venting in your molds.
To use petrobond effectively, you really need some type of muller, or some way to get good mulling action.
Petrobond will dry out, and addtional oil and sometimes alchohol must be mulled into it.
I am not entirely pleased with the maintenance that petrobond required, but have not tried water based sand yet.
If you use water-based sand, don't get it too wet or the water inside the mold will flash and eject molten metal back out of the mold like a volcano.
Be safe above all else and do your homework if you intend to cast metal.
So far I have not had to use any additives to the aluminum I use. I just melt it, skim and pour as quickly as possible to minimize disolved gasses getting in the mix.
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I use a diffeent sprue/basin/runner/gate arrangement now, shown below.
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Why the dead end runner?? *curious*
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Any lose particles of sand, dirt, etc. anywhere in the system will get swept directly into the mold cavity, unless you have a trap, in which case the initial wave front of molten meltal will sweep out the spure/basin/runner system and trap all the particles in the trap.
I always blow out the mold lightly with compressed air, but you generally always disturb a slight amount of sand when you assemble the cope and drag, and no sense having sand inclusions in your part.
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Smart, never seen anyone do that before though. =)
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"Basic Principles of Gates & Risering", American Foundrymen's Society Cast Metals Insitute, ninth printing, 1993.
I got mine used as a paperback online.
Gating and risering methods vary from book to book.
I am trying to zero in on one that is relatively simple to make and use, and one that will work well with a variety of mold types/sizes.
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There is a bit on using a swirling gate in this video,
Lee.
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That is a terrific video.
Lots of cool ideas there.
I have not seen the swirling thing, but I have seen the big central riser arrangement.
Very nice video, thanks for posting that.
Those guys really have it down to a science.
The degassing is not required if you don't have a gas problem, but it may help with microporosity or something.
I don't do much aluminum, so I guess I won't try degassing.
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MetalCaster
If you use a small amount of Borox, the same Twenty Mule Team stuff, it will make the brass flow nicer and more of the trash to rise. Nice looking casting.
Nelson Collar
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Metalcaster,
I have been reviewing the post on casting furnaces.
I am an old man, there are many things I do not understand.
What is the mystery about your identification?
You do not want people to know who you are yet you
can not keep from posting.
I do not understand.
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Building my furnace? I found a local "boiler" repair company who buys the castable refractory by the truck load. Purchased left over from them.
There is two grades here from what I remember, one ultra high temp for steels and other metals, and one lower for aluminum less than 2k F.
Mine has sat now for about ten years in the weather, cast in a old hot water heater. I am not the greatest caster there is and had about a 40-60 percent failure rate in my castings. I suspect it was overheating the metal and poor sprue forming. Pouring metal while "all alone" is not a real good idea either. I had two trolleys put up, till one jumped the limit switch and busted a $4k gearbox. (got from a scrapper for weight, but could not replace it cheaply) Funny, the camera I had on it always showed "green glow" instead of the red-orange normal.
I talked to the wife about tying it into the barbeque grille as a smoker-wood burner, it is just sitting there. I had last machined a bottom drop pot with a taper plug valve. Keeps the slag on top. A old modified pressure cooker was how I debubbled my lost wax castings. (what would fit in there)
I had hoped to go hang out with some "better foundry workers and learn from them".. there is a great post over on Hamb. I am not too old to learn.. yet. My career expertise was electrical, instrumentation, I am interested in about everything from Solar to magnetics and still have not outgrown the fast car-motorcycle lure, not killed me yet..
If anyone is casting in the south-east or within close driving distance?? Lemme know.. thou I might be sleeping in my car-truck..
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Dawai, where are you located? I'm in E. Tennessee, near Jonesborough.
Chuck
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Metalcaster,
Have not heard from you. Hope you are well.
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Metalcaster,
Have not heard from you. Hope you are well.
Metalcaster is no longer a member of this forum. You won't get a response from him here.
Eric
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Thanks, I just did not understand some of his posts.
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What sort of temperature do I need to achieve to melt Aluminium?
I quite fancy having a go at a small casting and althought I have used lead in the past (lead soldiers) I fancy trying my hand at Aluminium.I have some very fine sand (not builders sand) and is it that I just need to add water to it to make "Green Sand" or is there a bit more to it?
Thanks in Advance.
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Ooompa, there are several inexpensive books on the subject:
http://www.amazon.com/Charcoal-Foundry-Build-Metal-Working/dp/1878087002/ (http://www.amazon.com/Charcoal-Foundry-Build-Metal-Working/dp/1878087002/)
http://www.amazon.com/Backyard-Foundry-Workshop-Practice-No/dp/1854861468/ (http://www.amazon.com/Backyard-Foundry-Workshop-Practice-No/dp/1854861468/)
http://www.amazon.com/Foundrywork-Amateur-Workshop-Practice/dp/1854861689/ (http://www.amazon.com/Foundrywork-Amateur-Workshop-Practice/dp/1854861689/)
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Casting Videos, if you enjoy youtube like I do? search "user" "myfordboy" There is another fella in England also that really impresses me with his casting and pattern making skills. (forget the user name). At the end of each segment he "cooks something" over the flame, getting around the local restriction on fires, a cooking fire is excluded from the local zoning laws here too. Wife said he is just a bachelor.
I rigged my LED television through a $50 blueray player, plugged in the networking cable, and now I watch Youtube on television, it is a pain to search for things thou, have to scroll the "ONE letter at a time like the kids do phone texting". If that remote disappears or dies, all that fun is over.
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. (forget the user name).
Dawai, I think you mean Doubleboost, he generally cooks bacon on his cooling furnace!
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...a cooking fire is excluded from the local zoning laws here too.
You can't even have a barbecue? :bugeye:
And they want to put in zoning here....... :loco: