Thread: Budget Crucuble ideas wanted - Aluminium melting

Are you preheating the crucible to cherry red to develop a layer of rust on it before using it to melt the Al?

From Foundry Tutorial Book

Finally, aluminum dissolves iron. The iron does not benefit the alloy; in most cases the aluminum becomes brittle and harder to machine. Furthermore, it can easily dissolve right through an unprotected steel crucible. Steel crucibles and tools should be heated empty to a red heat before use, to build up a protective layer of iron oxide. This oxide layer will last longer if the aluminum is not fluxed, or fluxed lightly, and if the layer is not disturbed. For casting applications which need purity, consider using ceramic crucibles to avoid the problem entirely.

3 mm thick steel pipe with an end welded closed is sometimes used.

a good soot layer will help ,.
with propane or WMO you can run your flame " sooty " that means there is bugger all oxygen in the furnace to destroy your tin can crucible
with coal ive seen people run a cut down sacrificial can a round 1 inch high protecting the crucible can so it takes the brunt of the oxidizing but the aluminium will still remove iron from the inside and alloy with it ( not the best ) and pin hole the crucible

best advice is 1soup can per pour , you might get 2 , 3 looking after the flame , but its not worth it , 1 can per pour , or bye a decent crucible ,
stainless steel pot is worse than a can
maybe a 1/4inch thick steel pipe with a bottom welded on , but it will still only last 30odd pours

a decent crucible is well worth it

i dont know about the refractory poured homemade crucibles , refractory reflects heat ??

hope you saved the powder from that fire extinguisher as a parting compound for your sand casting

looks like bobL is a fellow Alloy Avenue dot com poster

First a big disclaimer - I don't do foundry work myself so someone with more experience may wish to comment on what has been said in case I've gotten it wrong.

Firstly, there is a Gingery book called "making crucibles" (ISBN 1-878087-27-4), where he makes crucibles out of a clay mix. Looking through the book it does not seem hard, so it may be something to try. The book is only 60 pages - I think I got my copy from Plough Book Sales: Home

Second ( but more dodgy) thought. I have heard (don't know how true) of people using clay flower pots. Use a little bit of fire clay to stop the hole in the bottom and you have a clay vessel that is hopefully metal tight. I wouldn't want to try this for iron, but for AL (provided that the pot and clay was well dried/ baked) I can't think why it would not work.

Personally I'd be trying the former as once you are set up making them would not cost much. They may even be something that other home casters would be willing to swap for.

Michael