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MMD > Archives > November 2001 > 2001.11.20 > 14Prev  Next


Rebuilding and Testing Player Piano Valves
By Harald Mueller

Hello!  Around Christmas I might really start to rebuild the pneumatics
of my first player piano (a Hupfeld Phonola).  After reading Art Reblitz'
book a few hundred times, I am quite sure I need something to produce
vacuum for testing.  However, I do not have (and actually do not want
to build) a rotary pump with 4 pumping bellows, 1 reservoir bellows,
mechanical gears and housing.  No thanks!  I want to rebuild the piano!

In the Reblitz book a "suction box" is mentioned, but I do not know
what that is supposed to be, and whether it has a German name, so that
I could get it somehow over here.

Of course, I also had the idea of using a vacuum cleaner, which I would
modify as follows: Add an electronic speed control; add reservoir
bellows (I think I can do one(!) bellows before tackling the piano
itself); put a spill valve on the reservoir (actually the opposite of
a "spill" valve -- it's not superfluous air that has to "spilled", but
air must go into the bellows if the vacuum gets too low); maybe adding
a regulator that slows down the vacuum cleaner a little when the spill
valve opens; and adding a home-made vacuum gauge (some transparent hose
filled with water -- I hope the water doesn't get sucked into the
bellows and vacuum cleaner with lightning speed the first time I start
the whole thing).

The problem I can see is the noise: Mr. Reblitz asks a few times
to "listen for a hissing sound in the stack."  I am quite sure that
I could not hear anything when a vacuum cleaner is running nearby.
I could, of course, put the vacuum cleaner a few rooms away and connect
it with a long hose, but I'm not quite sure what my wife would say if
she constantly trips over the hose when she goes to the washing machine
or gets something else from the basement (where my workshop is).

The second question I have: How do you cut round pouches, etc., from
leather?  Mr. Reblitz mentions "arch punches", which I have never seen
over here (not even in the tool catalogues for professionals).  Is
something like a compass with a cutting tip okay? ... Of course not,
because it would make a little hole in the center.  But what if the
center pin is replaced with an inverted cone (with a, say, a 120-degree
tip; but a real tip, not a rounded one) that hopefully keeps the center
stationary while cutting, but just leaves a little dent in the leather?

Thanks for any enlightenment!

Harald M. Mueller
Grafing bei Muenchen
Bavaria, Germany
http://www.haraldmmueller.de/


(Message sent Tue 20 Nov 2001, 08:02:18 GMT, from time zone GMT+0100.)

Key Words in Subject:  Piano, Player, Rebuilding, Testing, Valves

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