What method should I use to caste/mold a perfectly symmetrical 10lb lead sphere?

Question

It needs to be a very accurate casting. What materials should I use? I also would like to make a few exact copies of this sphere as well.

Answer 1

Such a ball would be approximately 9.1 cm in diameter (though lead is one of those elements whose density varies quite significantly depending on where it is mined, but let's use that as a good guess).

Build a jig to hold an iron ball of approximately the correct size on rollers which then spin it at high speed, and use a file to round it out, followed by emory cloth attached at a fixed height for the final polished finish. Use your iron sphere as a positive to build a mould around it, then cast the lead in your mould. This has the advantage that the difficult machining step only has to be performed once, and after that you can cast as many copies as you need from it, as long as the mould keeps its shape. Take great care with the lead, it is toxic and current guidelines advise against allowing it to touch your skin.

If you're trying to make cannon balls for your pirate ship, note that the force of the powder charge will probably deform your cannon ball in the barrel and cause it to jam, so you musn't try to machine the ball to the exact dimensions of your cannon.

Answer 2

just use your hands