Key Leads and Inertia

[Delwin D. Fandrich]

----- Original Message -----
From: "Ron Nossaman" <RNossaman@cox.net>
To: "Pianotech" <pianotech@ptg.org>
Sent: Thursday, May 01, 2003 8:54 AM
Subject: Re: Key Leads and Inertia


>
> Del,
> You knew this was coming, so I won't make you wait any longer. Do you have
> any rough rule of thumb go - no go diagnostic criteria for deciding when
> keys are too flexible during teardown?
>
> Ron N


Only "rule of thumb" stuff. In the bass if I can hear the key hit bottom
before I hear the hammer hit the string, I know I have a problem. If I can
hold the hammer down and fully depress the key without feeling like
something is getting ready to break, I'm pretty sure I'm going to have a
problem. If the piano is a post "Accelerated Action" Model D sans bottom key
plates, I'm pretty sure I'm going to have a problem. If the piano is a post
AA Model D sans bottom and top keyplates, I know damn well I'm going to have
a problem.

Also, from a purely tonal standpoint, if the piano has relatively massive
hammers and relatively long keys--i.e., something in the 8' to 9' range (the
OAL of the piano, not the keys)--the keys and other various action bits and
pieces are going to bend and flex and compress to some considerable degree.
It is this bending and flexing and compressing that is ultimately the power
limiter. If you're checking a piano for tonal range and you get to a point
where it simply doesn't want to give you any more and you're really not
striking the keys all that hard yet, this is probably why.

One last thought--if the piano is relatively short and/or relatively wide
and you find that power seems adequate or normal from the first tenor note
on up but the bass is generally weak starting noticably with the highest
bass note, you might check the amount of key flare. Some of these things are
pretty extreme and the keys can twist pretty bad. There is an illustration
in the Action Power articles but I'm sure you know what I mean.

Del