[Farmall] O-12 parts

[Chris Klossner]

  One thing to keep in mind casting parts out of aluminum is shrink.
Cast iron is  about 1/8"  shrinkage per foot of casting.  Aluminum is
closer to 1/4" per foot.  Brass is slightly higher than  iron.  It may
not seem like it would matter much on small parts until it comes time to
machine it out and holes start getting closer to edges.  On big parts
that do not require as much finishing.  Like a steam engine gear  where
the teeth are  1 1/2" deep.  The 1/4" Shrinkage on the diameter is only
1/8" on a side so it is a still major improvement over a worn gear.

  Chris Klossner
 http://home.att.net/~klossner