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MMD > Archives > April 2012 > 2012.04.10 > 08Prev  Next


Rebuilding Late Ampico A Action Stack
By David Sharpe

I am rebuilding a late Ampico A stack (with right-side-up valves and
soft pedal compensator rail) and I have three questions (so far).

1.  I tried to get valve facings from Player Piano Parts Inc. but they
do not have them.  Does anyone else sell pre-punched valve facings for
the primary and secondary valves in an Ampico A stack?

2.  There seems to be a thick rubber washer around the bottom head of
the long bolt holding the three tiers together. (This is now hard and
brittle.)   Perhaps this was to compensate for expansion and shrinking
of the tiers.  Do people replace this?  With what?

3.  The stack has two 7/32" nipples, one on each side of the bottom
tier, leaking atmosphere directly into the stack.  There were 4 or 5
inches of tubing connected to these but they seem to be simply
mufflers, not leading anywhere.  Why is there so much attention paid to
getting the stack absolutely air tight when there are fairly large
permanent leaks?  Do these leaks not affect the vacuum level of the
pneumatics near them, especially when it changes quickly?

David Sharpe
Western Massachusetts

 [ The bleeds allow the suction to decay quickly after an accent.
 [ After many years, when the action stack is leaking everywhere,
 [ then those bleeds can be plugged.  ;-)  -- Robbie


(Message sent Wed 11 Apr 2012, 01:41:06 GMT, from time zone GMT-0400.)

Key Words in Subject:  Action, Ampico, Late, Rebuilding, Stack

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