----- Original Message ----- From: <pmc033 at earthlink.net> To: <pianotech at ptg.org> Sent: Thursday, November 19, 2009 6:00 AM Subject: Re: [pianotech] regulating S&S (ex-) reproducer actions > Hi, David: > I'm not a rebuilder, but I'll put in my $.02. The difficulty > with a > longer key lies in the geometry. The hammers check because > the arc of the > backcheck intersects the arc of the hammer tail. The extra > length of the > key makes the radius longer than a regular key, and so the > arcs don't come > together until the key has moved a greater distance thru that > arc. Draw a > simple diagram with two different key lengths showing a side > view and > you'll get it. > Also, beware the spring strength. If you have a short blow > distance, the > spring doesn't "wind up" as much, so it will take a greater > tension to lift > the hammer. > FWIW. > Paul McCloud > San Diego Yes, and for this reason, I left the spring strength a bit on the weak side, so it wouldn't prevent checking. Thanks for the replies. --David Nereson, RPT
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