Posted by RDavis on Tuesday, October 29, 2002 at 9:23PM :
In Reply to: Alloy Casting posted by Judd on Tuesday, October 29, 2002 at 7:44PM :
I once visited a company on my lunch break
that casted all different size and shaped letters, the type on buildings for names and address. I was impressed at how easy it all seemed to be and I bugged them with many
questions. Of course some things are cast better as two seperate halves and some as
a solid shape with the inside being machined.
You didn't give a clue as to what purpose
this item would be for so the level of difficulty would be impossible to judge.
I know that with alum., its thickness and such must be calculated into the amount of shrinkage that will occure once it has
cooled.
Engine blocks of all types (car, lawnmower,boatmotor,etc) seem to be of adequite alloy composition for strenght.
2 man portable electric smelter pots were used by the letter casters. They always seemed to want the casting form to stay stationary. Very fine damp sand was used for a smooth finish. A slight tapper(draft) must be built into all surfaces of the pattern that come in contact with the mold sand including support webbing so the pattern can easily be removed leaving a unblemished impression in the mold sand.
Thats all I know or that I think I know about casting alum.