Story and Clark/QRS console bubbling hammers

[Paul McCloud]

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Dave:

            You need to determine if there's enough aftertouch.  As you
go through let-off and the key bottoms out, check to see if there is a
little forward motion of the hammer, and that the jack it out from under
the hammer butt.  If not, your key dip is still too shallow.  Putting a
thinner punching may get you closer to the correct dip, but you need to
be more precise with this adjustment.  Setting the letoff point will
help some, but you must be sure that you have enough dip to make it
work.  I recently worked on a Mason Hamlin large upright which had a
similar problem with bobbling hammers.  Actually it wasn't so much
bobbling, but the piano had a kind of "loose" feel.  By raising the
balance rail, the dip increased and the checking worked much better.
Hope this helps.

            Paul McCloud

            San Diego

 

-----Original Message-----
From: pianotech-bounces@ptg.org [mailto:pianotech-bounces@ptg.org] On
Behalf Of Piannaman@aol.com
Sent: Friday, December 05, 2003 7:46 PM
To: pianotech@ptg.org
Subject: Story and Clark/QRS console bubbling hammers

 

Hello again, 

It's been a week for pain-in-the-posterior piano problems.  A couple of
months ago, I was called to come and see if I could figure out and fix a
problem with bubbling hammers on a Story and Clark console piano with
QRS pianomation installed.  When I got there, almost every hammer was
bubbling.  Key height was fine, but the dip was way to shallow.  I
replaced the fat front rail felt punchings with more meager ones, did a
bit of regulation, and the problem was gone...at least for the time
being. 

I got a call from the lady a couple of weeks ago complaining of a few
more bubbling hammers.  I got a chance to go out yesterday, and with a
small amount of let-off adjustment on a few notes the problem seemed to
be cured--until I pushed the sustain pedal down.  I could not make all
of the hammers check when the sustain pedal was engaged. 

Can anyone tell me if there is some connection between pedal/damper
function and the QRS mechanism?  It doesn't seem as though there should
be, but I have never installed or worked on one of these. 

The problem seems to be that when the sustain pedal is down and the
dampers up, there is not enough strength in the springs to push the
hammers back quickly enough to catch on the backchecks.   

My thought is to check the tightness of the whippen and hammer centers.
The action feels far more sluggish than it did the first time I worked
on it.  I suspect moisture or something else has invaded the bushings.
Maybe graphite coated center pins???  I certainly hope not.  Been there
before. 

Any thoughts or recommendations for possible courses of action would be
appreciated. 

Thanks again! 

Dave Stahl


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