Action flange crushing

[Dave Nereson]

----- Original Message ----- 
From: "Phillip Ford" <fordpiano@earthlink.net>
To: <pianotech@ptg.org>
Sent: Tuesday, November 16, 2004 2:19 PM
Subject: Action flange crushing


>I am continuing to investigate action screw torque.  One thing that has 
>turned up on some correspondence is the admonition not to crush the flange. 
>Any thoughts on why this is a bad idea, other than aesthetics?  Would the 
>flange have a tendency to get loose sooner as a result of some crushing? 
>Is the magic circle of sound detrimentally affected by flange crushing?
>
> Phil Ford

    I had a case where, after tightening action screws, one of the hammers 
became sluggish in returning.  I loosened the screw a quarter or half turn, 
and it freed itself up again.  Tried tightening the screw again and it 
became sluggish.  All I can figure is that the pressure of the screw was 
distorting the flange just enough to cause the "ears" (that the pin goes 
through) to not be quite parallel -- like a bent axle from too heavy a load.
    But the other reason not to overdo it, especially during dry weather, is 
that when it gets humid, the part will swell and crush wood fibers.  Then 
the next time they shrink, and action screws are tightened, they might split 
or be damaged further.
    --David Nereson, RPT