The Shop > Metal Stuff
Oil fired crucible furnace
vtsteam:
Thanks tekfab! :beer:
I'm hardly in a position to recommend crucibles since my experience before was poor, and my current crucible has only been used for 3 iron melts. So I can't say long term if it will hold up for me, under my conditions of use.
But it looks good so far and is far better than the "3000 degree" (advertised) clay-graphite crucibles I started with, so I have hope for it.
Personally, I would try to get the same brand crucible that Ironman uses, which is Vesuvius. And I believe more specifically it is the "Diamond" hard variety -- though not sure about that exact term.
The crucible I have now is an A6 MorganMM Salamander Super and the label said A&0130H0165&-SUX4-3GN-IL, and made in INDIA. It was close to $75 delivered.
But whether that is good or bad, I don't know yet. Let's get 20 more castings under our belt and see how it does!
But for casting aluminum, I would never use an expensive crucible. I would just continue to use a cast iron plumbers pot, or a made up one from steel, lined with a little fireclay and sand mix.
vtsteam:
Mayhem, thanks, man! :beer: I may be building a forge like you did soon. How is your lathe doing?
awemawson:
I've always been concerned with iron dissolving into molten aluminium when using a steel or iron crucible. So I always used a clay/graphite one. Even small quantities of iron in aluminium make significant alterations to it's mechanical properties. Though I am aware very many home casters do use steel.
http://www.aomevents.com/conferences/afi/papers/Taylor.pdf
vtsteam:
Andrew, good to mention. The cheapskate high quality alternative to both schools of thought is a clay lining in a homemade steel pot.
I suppose the ingots could be poured in a greensand mold instead of a steel one -- but the last seems almost universal on the casting forums.
awemawson:
I suppose it really depends on what you are doing with the castings. If they are only ornamental, or so generously proportioned that strength isn't an issue it could be said that it doesn't matter. But if you want to be able to heat treat the casting and get particular machining qualities especially, then iron anywhere near it is a no no. As that article says, once the iron is in the aluminium effectively it's staying there for good!
I always avoided use of steel crucible, and used a dip wash coat on the various tools I used such as stirrers and skimmers. Problem is that the over metal that is poured to ingot may be used for something more fussy than the current one, but you've already contaminated your stock
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