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>
This PTG archive page provided courtesy of Moy Piano Service, LLC