[pianotech] capstain/wippen angle

[paul bruesch]

Steingraeber und Söhne

On Mon, Mar 16, 2009 at 3:06 PM, David Ilvedson <ilvey at sbcglobal.net> wrote:

> 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
>
>
>
>
>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://ptg.org/pipermail/pianotech_ptg.org/attachments/20090316/b5ddaac8/attachment.html>