The old Steinway capstans (hex type) were sloped around 15 degrees, the ones after that were sloped around 8 degrees. I think the most efficient angle for the capstan is so that it is perpendicular to the heel when the key is halfway through the stroke. Thus the angle will vary depending on the angle of the heel that you are using. Even a straight heel will tend to set up best with a capstan at about 3 degrees. Either way, the contact will not be frictionless, and the amount of friction will be inversely proportional to the degree of coincident convergence of the two arcs. The lowest friction will be achieved when the contact point coincides with the point that is tangent to both circles. David Love davidlovepianos@earthlink.net > [Original Message] > From: Jim Parker <jhparker@rose.net> > To: Pianotech <pianotech@ptg.org> > Date: 6/28/2003 4:47:52 PM > Subject: Re: older steinway grands > > I'm not sure I would ever straighten a sloping capstan. Steinway did that > for a reason. The sloping capstan matched with a sloping whippen heel > yields zero friction between the two. That is because they roll on each > other due to the matching involute(?) curves rather than the capstan > sliding against the whippen heel as it rises. This was explicated > beautifully by Chris Robinson many years ago at a convention class I > attended. At the time replacement whippens from Steinway with the sloped > heel were unavailable and Chris was cutting his heels to get it. Later > Steinway again began offering the original type heels for rebuilds on older > instruments I believe. > ----- Original Message ----- > From: "Jonno Clarke" <jonnotune@hotmail.com> > To: <pianotech@ptg.org> > Sent: Friday, June 27, 2003 12:07 PM > Subject: older steinway grands > > > I wonder if anyone can help me with the question of what to do about older > Steinway grand actions, the type that have the sloping back capstans. I > always find that when fitting new (Abel) hammers to these pianos that the > touch becomes rather on the heavy side - would it help to remove the > capstans fill the keys and re-tap and then fit the capstans like on newer > pianos ?. The client doesnt want to fit new whippens and the be fair there > is really nothing wrong with the old ones. The problem is that the hammers > are worn out and need replacing. Help please ! > > _________________________________________________________________ > Stay in touch with absent friends - get MSN Messenger > http://www.msn.co.uk/messenger > > _______________________________________________ > pianotech list info: https://www.moypiano.com/resources/#archives > > _______________________________________________ > pianotech list info: https://www.moypiano.com/resources/#archives
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