And very low friction...wippen cushions showing little wear David Ilvedson, RPT Pacifica, CA 94044 ----- Original message ---------------------------------------- From: "David C. Stanwood" <stanwood at tiac.net> To: pianotech at ptg.org Received: 8/6/2006 3:53:08 AM Subject: Re: 1/2 punching >Ric Wrote: >>Since all this is up, I might as well reveal (since I am an open source >>kind of guy) that I'm working on a scheme useing center pin wire along >>these lines to cause a clear and distinct dual ratio characteristic to >>key travel. Since the initial part of the key stroke benifits greatly >>by reductions in dynamic weight, yet the last 3 mm of key travel could >>well benifit by an increase in stack action travel for key travel, if >>the key could be made to act as a low ratio key for the first half of >>its travel and then act as a higher ratio key for the last half of >>travel then both these benifits are served. >Another blast from the historic past: Chris Robinson has a set of slides >showing the capstan position with the magic line overlaid on the image at >rest, half, and full stroke with a long ago Steinway factory installed 22 >degree angled capstan and angled heel for what he calls the Involute gear >effect. With this set up the capstan/heel contact point stays on the line >rather than moving up through it as with the capstan at present day 90 >degrees with straight heels. What's interesting in relation to the >present discussion is that the point of contact, while staying on the magic >line, actually moves front to back along the magic line. So the ratio is >low to start with and higher to end with giving a sort of "wip" effect. I >was very impressed when I saw this in his class. >David Stanwood
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