Bass hammer checking

[Ron Koval]

Here is yet another of those "red faced" moments:

Patient: old Kranich & Bach grand (strike one)

took the action out to do some bench work to make playable only, for a 
friend (strike two)

Upon return, (oh, it should only take me an hour) I ended up having to 
re-regulate just about everything 'cause the keyframe was so flimsy or the 
keybed wasn't flat! All the work on the bench was wasted!

(strike threeeeee, yer out!)

Anyway, without careful premeasuring, etc.... it's easy to end up with 
surprises when the action is back in the piano.  Check dip, and all the 
other perameters, I bet something doesn't measure like it did on the bench!

Ron Koval



Date: Thu, 14 Mar 2002 18:45:04  0000
From: "Phillip L Ford" <fordpiano@lycos.com>
Subject: Bass hammer checking

Yesterday I worked on an older Baldwin with a Schwander action that
had a characteristic that I've encountered on other grand pianos,
some having it more than others.  The hammers check perfectly on the
bench or when the action is pulled out in your lap, but won't check when
the action is in the piano.  This behavior is usually only noticeable in the
low end of the scale and becomes most pronounced at the bottom.  On some
pianos it seems that you can't get the hammers at the bottom end to truly
check no matter what you do; make the checking shallower, make it deeper,
groove the tail, rough up the check leather, change the back check angle,
reduce rep spring strength to almost nothing, etc.  When I say 'truly check'
I mean behave as in the rest of the piano.  The hammer is held
some distance below the string when the key is down and rises
when the key is released.  Apparently some sort of 'checking'
is going on because even on a hard blow the hammers don't bounce back to
the strings.  But the tail isn't really being held by the backcheck when the
key is down.  What's the reason for this?

Phil F
- ---
Phillip Ford
Piano Service & Restoration
1777 Yosemite Ave - 215
San Francisco, CA  94124



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