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MMD > Archives > April 2016 > 2016.04.13 > 02Prev  Next

Player Piano Rebuilding Hints
By S. Lee Walker

To all rebuilders: I have some information! I now have in my
possession a copy of the DUO-ART repair manual:

  Piano Preliminary Instruction Pamphlet.
  Operation of DUO-ART Dynamic Control
  And How to Test and Adjust.
  ALSO The DUO ART Reproducing Piano
  Service Manual, Printed 1983, Revised Edition"

This manual is loaded with schematics and photos.

Next, let's talk about the value seals in the Simplex double valve
system as well as any similar value which used the force fit collar
on a .093" diameter brass shaft.  In several articles in the MMD
Archives there has been problems in getting a good seal.

Here is something you might try but not a "quick fix."  My wife used
in her dentures implants which used O-rings.  These O-rings snap on
the steel post and hold the denture in place.  Size 4.44 mm (.173" OD),
1.57 mm (.062" ID), 1.53 mm (.060") thick.

These O-rings are supplied by the dentist only and are not like
commercial O-rings.  I built a valve assembly using them and by
testing, had no leaks.

I've been reading articles in MMD about how many hours it takes to
repair players [which is] very work-oriented needing many man-hours.
I don't see how you can make any money using old techniques.  I am
by trade a Certified Designer and in my design work I used catalogs
for off-the-shelf parts.  "Why make it if you can buy it!"

Player pianos and player units are reaching 100 years old.  The aging
of wood and several rebuilding sessions probably destroyed the original
dimensions.  I experienced this problem and had to resize the complete
stack.  I also found the gasket surfaces to be uneven or so wavy so as
to not permit a tight seal.  With all the new woodworking tools you can
make a new player probably faster.

I been playing around with the drywall screws. They have a coarser
thread and more mass to make a better grip and will not strip the
thread -- good for dried out wood.  They are however, limited in sizes.

Buy some incense sticks and light the end.  When you're testing
the stack for leaks run the stick around the gasket area.  If the
burning end gets brighter, there's a leak.  (You may need to fit on
your head a lamp with a magnifier.  This way all hands are free.)

If you have a good leak-free stack the atmosphere force will push down
on the stack and be added to the seal.  You can't tighten the screws
to make a better seal -- the screws will strip.

Let's talk more about slotted countersink wood screws.  These wood
screws require some attention when installing.  The shank portion that
has no thread it is sized to keep it from bottoming into the thread,
for if it does it will not turn and will give you a false indication
that the gasket is tight.

If you continue turning, the shank will not let the thread go any
further and then it strips the thread.  This holds true if, for example,
the pouch board thickness is less than the shank then it will bottom
leaving the countersink head not clamping down on the pouch board.

Lee Walker
Indiana [delete ".geentroep" to reply]

(Message sent Wed 13 Apr 2016, 22:28:24 GMT, from time zone GMT-0700.)

Key Words in Subject:  Hints, Piano, Player, Rebuilding

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