Key Pin Friction - was Heavy Playing S&S C

[Farrell]

> Carefully polish the key pins, front and center.

And then how do techs evaluate key pin friction? I have never seen anything
in print regarding any definitive procedures to evaluate key pin friction.
The gal that does my key bushing jobs for me says to just push down the end
that is up (usually the back of the key) and see if the key returns.
Hmmmmmmmmmmm. I think that only tells you if the friction is less than some
large amount - like maybe ten or 20 grams. I sure feel the need to be more
accurate than that. Is there some great method used that I am not aware of?

What I have done in the past is to place weights on top of the capstan so
that the back end of the key is just touching in the down position (or as
close as I can get - take a gram off and it rises - this example is
obviously for a key that is front-heavy). One can measure the friction in
the key pins (I'm assuming - or I make sure - here that the center rail pin
hole is eased properly and the key is not rubbing on a neighbor) by placing
a weight on the front end of the key. If it takes a ten gram weight on the
front of the key to make the key front go down, then I guess there is about
ten grams of friction lost in the key pins. I've only done this once or
twice, but it seems like two or three grams of key pin friction is about
right - if you go down to one gram or less, you seem to end up with too much
play in the key pin bushings. Then I ease the key bushings until I get to
whatever my target key pin friction is.

Does anyone else use a similar procedure? Is there a better way?

Terry Farrell
Piano Tuning & Service
Tampa, Florida
mfarrel2@tampabay.rr.com

----- Original Message -----
From: "Newton Hunt" <nhunt@optonline.net>
To: <pianotech@ptg.org>
Sent: Monday, April 30, 2001 12:56 PM
Subject: Re: Heavy Playing S&S C


> Most bang for the time is reduce the friction even more.
>
> Are you doing new hammers?   Then go for a lighter set, just two or three
grams.
>
> Without running the numbers the rest seems in the ball park.
>
> Carefully polish the key pins, front and center.  Polish the capstans.
Carefully
> lubricate all the centers then regulate and take new measurements.
>
> Let us know how it comes out.
>
> Newton