Flange Center Friction Increase

[Paul Chick (Earthlink)]

-----Original Message-----
From: pianotech-bounces@ptg.org [mailto:pianotech-bounces@ptg.org]On
Behalf Of Farrell
Sent: Wednesday, July 16, 2003 6:56 AM
To: pianotech@ptg.org
Subject: Flange Center Friction Increase


I am refurbishing a YC grand action. Hammer shank flange center friction is
all over the place, so I am repinning most centers. Some of the low-friction
centers have the following characteristics: First swing test - 9+ swings,
then each time I test the swings, the number of swings drops by one. So
after the ninth (or there abouts) swing test, I'm only getting one swing.

What is that all about? And ideas?

Terry Farrell

Terry
Isaac Sadisgursky talked about this in his class on center pins at the
Convention.  He demonstrated how a center pin can be too tight in the
bushing cloth and loose through the wood, just the opposite of what it
should be.  This problem can be spotted as you describe--fewer swings as you
go along.  Here's his test: carefully remove the center pin from an
offending flange. Gently place it back in the bushed flange and check the
friction just by pushing the pin with your fingernail.  Now place the same
pin in the wood and push it with your fingernail.  Chances are you can push
it right through the wood.  The problem is caused by using the assembly wire
used in the flange to size the bushing cloth during manufacturing.  When the
flange is installed, the worker slides the wire back to clear the other
member then slides it through and cuts it to length, fitting done.  Isaac
says to watch for centers that are clipped on both sides of the flange.
This will tell you a wire had been used.  He then went on to demonstrate how
to repin a set of flanges in about 45 minutes.
Paul C