David asked/said: "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, This system is archaic. And, was long since abandoned for good reason. There are too many different expansion ratios involved. My solution would be to install standard capstan screws and put action cloth on the stickers bottoms. Once, settled, I suspect the problem will go away. Also, I'd take a long, hard look at the temperature/humidity situation in the piano's area. (Leave a recording Temperatur/Humidity gauge inside the piano for 6 months.) I suspect a combination of bad things, all working together to make your life miserable.<G> Regards, Joe Joe Garrett, R.P.T. Captain of the Tool Police Squares R I
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