[pianotech] double-striking hammers on chinese uprights

[David Love]

Poor regulation can cause it.  Inadequate jack travel, dip, incorrect blow
setting, too much lost motion.   But if that is in order then check the
spoon regulation to be sure the damper spring doesn't engage too early.
Then disengage the damper spring and see if that doesn't solve the problem
(or pull it back with string hook while you strike the key).  Sometimes the
damper springs are over tensioned and can inhibit the key from making a full
stroke through let-off especially on a soft blow.  If that's the case you
will need to carefully ease off the tension on the spring being careful not
to overdo it and compromise effective damping.  One thought anyway.  

 

David Love

www.davidlovepianos.com

 

From: pianotech-bounces at ptg.org [mailto:pianotech-bounces at ptg.org] On Behalf
Of Britney Kirk
Sent: Tuesday, August 18, 2009 7:08 AM
To: pianotech at ptg.org
Subject: [pianotech] double-striking hammers on chinese uprights

 

What causes a hammer to double-strike on an upright?  When I play the key,
it feels like there is an extra force at the beginning of the keystroke.
When the keystroke is at the halfway point, the hammer has already hit the
string and started to come back.  When I have finished my keystroke, the
hammer has returned and hit the string once more. 

 

 I have tried re-pinning the hammer flange and doing a finer regulation.
The only thing that seems to help-- but not actually solving the problem,
and creating other problems-- is setting let-off extremely far from the
string.

 

 

Any ideas?

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://ptg.org/pipermail/pianotech.php/attachments/20090818/dd29a55d/attachment-0001.htm>