older steinway grands

[David Love]

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 !
>
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