I am at the next step in the restoration of my calliope.  It has a
Simplex unit valve pneumatic stack which was "chopped" from a piano.
The roll player is powered by an electric motor, so the vacuum is
needed only for the stack.  It had a separate vacuum box, but the motor
in it is ruined from being in a flood.  My question is, what amount of
vacuum should be used to run the stack?

Larry Claus

 [ While the wind pressure is at the maximum pressure you will ever use,
 [ enough suction should be provided to reliably move the keys, plus
 [ a safety margin of perhaps 50%.  Be sure to verify the operation of
 [ the Rewind and Play pneumatics, since they may need more suction than
 [ the player stack needs.  -- Robbie (a calliope operator)