overcentering justified?

[David Love]

Perhaps your string height measuring device is improperly calibrated.  Or,
you measured the flange center pin height incorrectly, or both.  The only
other possibility is that the strings run downhill to the bridge by the
amount of the difference.  That doesn't seem likely.  

David Love
davidlovepianos@earthlink.net


----- Original Message ----- 
From: Bob Hull 
To: Piano tech
Sent: 8/21/2003 8:03:08 AM 
Subject: Re: overcentering justified?


When I measured the distance from the key bed (workbench) to the hammer
flange center pin and subtracted it from the string height near the hammer
strike point, why did it  give me a 2" (50.8 mm) difference?  This is a
different indication of bore distance from when I put a line level on a
hammer shank and compared a 50.8mm bore distance to a level on the strings.
The 50.8mm bore shows that when the hammer is raised to the string the
bubble indicates a slightly undercentering.  The old 48 mm bore shows a
shank that has almost exactly at the same level (slight rise) as the
string.  

Since the string ht. was measured at a distance about 130mm (length of
shank to center of hammer molding) away from the center pin ht.  it seems
like it should have indicated
the same distance as the level/bubble comparison test.  ???

Why didn't it?  Any ideas?