Paul Tang asked about a slow Duo-Art 'steamboat' pump in yesterday's
MMDigest.  If the pump is original, I'm sure it needs complete
rebuilding.  Any attempt to soften and seal the cloth usually results
in a mess that doesn't end up working all that long anyway.  If the
pump hasn't ever been rebuilt, has the stack been rebuilt?  If not,
that probably needs a complete overhaul also.

I rebuilt a Steck upright Duo-Art with a 'steamboat pump' probably
15 years ago.  I rebuilt the pump as it was originally designed.
The problem I had was that it never developed adequate vacuum.
The difficulty was with the flap valves, the leather 'straps'
on the inside and outside of the bellows that act as a check valve.

I worked extensively with the glued leather backing (felt), spring
tensioners, type of leather, etc., but I never could get it to work
all that great.  This had never happened to me before.

The steamboat pump leather strap valves are around 3/4" wide and
cover a long slit or cut in the wood.   There were a lot of them.
(I am thinking it was around seven flaps on each side of each bellows.
If seven is correct, that was fourteen per bellows times six bellows
for a total of 84.)

I finally consulted with my friend Craig Brougher on my dilemma.
He advised that the design be changed to a more conventional style.
Most conventional pedal or other pumps have one or two of leather
straps acting as check valves, on the inside and outside of each
bellows.  They are typically are around 2" wide and cover round holes
around 1" in diameter.

I filled in all the slit openings, made everything nice and flat,
then drilled round holes and installed wider leather valve as you
would typically see these done.  It worked great, and the piano
continues to work great today in my sister's home.

Gary Rasmussen
Mason, Ohio (Cincinnati area)