Which piano has the rolling knuckle? David Ilvedson, RPT Pacifica, CA 94044 ----- Original message ---------------------------------------- From: "Richard Brekne" <ricb at pianostemmer.no> To: pianotech at ptg.org Received: 3/16/2009 10:45:50 AM Subject: Re: [pianotech] capstain/wippen angle >Hi Mike ! >THIS was the clue I needed... Yes I understand the roller capstan then >would move closer to the whippen center if it started below the magic >line, then get farther away as it passes. Now I just have to think a bit >on how the whippen heel is moving through this. Any given point on the >heel is not going to change distance from the whippen center through the >key stroke. So as the key raises towards the magic line, the roller >capstan would roll towards the whippen center as its distance from the >center decreased. Then at the magic line it would cease rolling and be >as close to the whippen center as possible, continuing upwards it would >reverse direction and begin to roll the opposite direction... away from >the whippen center... Almost like a pendulum motion if the starting >point was just as below the magic line as the ending point is above. >So..... how does an angled capstan that does'nt roll at all counter this >tendency... I can see I am going to have to re-read these posts and do >some thinking on it :) >Sorry bout the misquote... I'm sure Dale is ok with it. >Cheers and Thanks >RicB > Ric, > I wish I had reasoned out the quote you attribute to me - but it > belongs to Dale Erwin. I hope he won't mind if I attempt to answer > your question. Whether it ends up closer or further away depends > on where, in relation to the magic line, the motion occurs. For > example, if you start below the magic line and end an equal distance > above it, the roller will move towards the wippen center until you > reach the magic line, then move away, ending up right where it > started. The "best a tilted capstain could achieve" would depend on > how wide the capstain is. > Mike > Richard Brekne wrote: > Been trying to visualize this a bit and have the following to > ask you all about. > Consider a capstan that was a brass roller instead of what we > have today. So that as the key move and the capstan raises the > whippen this brass roller simply rolls along the underside of > the heal. Wouldn't this result in the roller-capstan starting > off further back on the heal (closer to the whippen flange) > then it ends up ? I.e. the opposite of this increasing leverage > concept ? And if that is the case.... then wouldn't it be more > likely that the best a tilted standard capstan could achieve is > to more or less compensate for that ? > Cheers > RicB
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