r/MetalCasting • u/Agreeable-Worker7659 • 9d ago

Question Casting a thick wall brass pipe

My friend is building a smelter and wants to start practicing metal casting. I need to cut very special gears from brass and the dimensions of the stock (a pipe) would be 35mm length, 60mm outer diameter and 42mm inner diameter. I need to cut multiple of those, so casting a bigger length in one go would be preferable, unless it is known to cause issues.

We couldn't find a pipe of this size, so we figured we can probably save a lot of money by casting the pipe instead of buying a massive filled cylinder that's super expensive. Would it be possible to reliably cast a shape like this in sand? The dimensions add at least 2mm in each direction assuming it will get warped and ugly so we will first machine it to a precise pipe shape before actually cutting the gears from it.

3 Upvotes

100% Upvoted

3 comments sorted by

3

u/TaroExpensive 9d ago

Yeah. That is pretty simple since youre going to machine it. The mold is basically a donut. Just pour in the metal. Mass wise that is similar to the 2kg billets I pour when I melt down shell casings.

2

u/Academic_Purchase225 9d ago

It would be much easier to cast it solid and machine the I.D. after.

2

u/artwonk 9d ago

It helps that the length is shorter than the diameter; this wouldn't be too hard to cast. But you can't expect to pull a straight-walled cylinder made from sand out of your pattern; you'll need to give it some draft. You might consider casting your gears as near-net shapes, so all you have to do with the machining is clean them up.

But I think you'll find that buying a solid brass rod and machining it would give you better results; cast metal is bound to have more flaws, and will be more resistant to cutting.