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Making a reuseable mold for an at home foundry and casting aluminum? Answered

I've been really interested in at home aluminum casting and wanted to make a forge and try my hand at it. Before I started I've done a lot of research and video watching. It seems it is most popular to use the lost foam method. I was just wondering if it would be possible, and what materials to use to make a simple reusable mold. If I was to cast 10-12 of the same object it just seems easier to make a mold then forming and shaping 12 pieces of foam. Since I'm just getting started i wouldn't be casting anything too complicated or big. Thanks in advance!


The traditional method makes a wooden pattern, you pack sand around half the pattern, set in a case called a 'drag', and then you place another case on top, called the cope, and pack sand around the other half. You lift the drag off the cope, and remove the pattern.. Now you form channels for the metal, called risers. Next you close the two halves of the mould. Then you pour the metal.

Thanks this basically just requires one "master" part that is continuously used to pack the sand and make the mold right? I don't know why I over looked this. I was overthinking things and thinking I would have to make a silicon or plaster negative to reuse. Never though to reuse the original part. Thanks!

If it matters, then you have to make the initial part slightly bigger than the finished part, because you get shrinkage of the metal as it cools.

Like Rick says, Pattern making is a skilled art form. Patternmakers are some of the finest craftsmen in wood that there are.

Keep in mind your casting will be a bit ruff on the outside. Often the item being used to produce the sand negative will be slightly over sized so that the cast part has enough extra material on it for finishing. If you are not happy with the finish of your first part then add a few layers of wax or something before you make your sand negative. Using finer sand and a decent bonding agent helps.

Is a good series on casting at home.

Technically your master is a pattern, (a mold is a hollow thing like a jelly mold.). Pattern making was/is a very skilled subject.

Your patter can't have any undercuts or it won't come out of the sand. However you can make the pattern in several parts so it can be removed IF it must have undercuts.

Watch the video series to get the idea of what a cope and drag are for and get hold of some real oil based casting sand.

The sand can be quite fine and give a pretty good cast but you will need practice to get there.

The pattern could be made from plaster, MDF is very common and as said the size has to allow for the casting material to shrink if your looking for a particular finished size.

If your product is small and you want a fine finish look up lost wax casting, this will give a jewellery quality finish from a wax master what you can make from a mold - usually silicone.

Casting is exciting and fun BUT has obvious danger. i would suggest you as a minimium make a sand tray to put your mold in so any spills stay in the tray.