Re: ATM - Casting Aluminum

[Chuck Hards <chuckh@companionsystems.com>]

Remember that most (if not all) cast metals shrink by an appreciable
amount during cooling, in the mold.
Pattern makers must figure this shrinkage factor into their work, and
build them oversized to compensate.  I'm going from memory here, but I
think aluminum shrinks 3/16" per foot, when cast.
There are special rulers for pattern work, called "shrink rules", with
the proper amount of shrink built into the graduations.  They are
manufactured by Starrett.
Never let a "shrink rule" get away from you--It can cause a lot of
stress if used for anything other than patterns for the foundry!

Chuck Hards