David The problem is not the screw but the cloth on top of the screw. As thick as it is, and without it being glued to a surface, every time the humidty changes, the thickness of the cloth changes. I would cut the cloth off the key, and glue a small piece on the bottom of the sticker. Then replace the screws with standard capstan screws. Wim -----Original Message----- From: David Boyce <David at piano.plus.com> To: pianotech <pianotech at ptg.org> Sent: Sat, Dec 3, 2011 3:03 pm Subject: [pianotech] Wandering Capstan Screws Since 1988 I've tuned the old upright of a local GP, now retired. Early on, I regulated for lost motion, only to find next time, that the hammers were, unevely, lifted off the rail. So I regulated the screws back down, leaving the hammers on the rail, without lost motion. Only to find, next time, that there was lots of lost motion. It seemed apparent that the capstan screws were moving, cyclically, up and down in the keysticks. The problem was not the back rail, because if it was shifting, then the movement of the hammers off the rest rail would be more even. I eventually fitted slightly thicker screws, hoping that the added friction would solve the problem. It didn't! I was at the piano today, and took the pics attached. Why do these screws work up and down like this? Best regards, David. www.davidboyce.co.uk -------------- next part -------------- An HTML attachment was scrubbed... URL: <https://www.moypiano.com/ptg/pianotech.php/attachments/20111204/165c6ed3/attachment.htm>
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