Virtual Capstan

[Carl Meyer]

----- Original Message ----- 
From: "Ron Nossaman" <RNossaman@cox.net>
To: "Pianotech" <pianotech@ptg.org>
Sent: Sunday, June 22, 2003 10:11 AM
Subject: Re: Virtual Capstan


>
> >Ok, so putting the magnet(s) behind the capstan makes the action heavier
as
> >the key moves, in it's stroke. I can understand that.<G> Why not put the
> >magnet "IN" the wippen heel? It would take more work to install, but
> >wouldn't change the basic "ratio", (?). In this way you could define how
> >much the magnet(s) effect the actual "touch".
> >Best Regards,
> >Joe Garrett, RPT, (Oregon)
>
>
> If it doesn't change the ratio, it won't lessen touch weight. That's why.
> Putting the magnet in the heel would be no different than putting in a
> non-magnetic weight. The magnetic lift and mechanical advantage from the
> second class lever of the wippen is the only thing that makes this work.
So
> far, it looks like I am the only one who has actually taken a little time
> to try and work out the leverages involved. Forget action terminology for
a
> moment (pun intended), and go back to basic mechanics.

Lets ignore action terminology AND basic mechanics and focus on basic
magnetics.  I know enough about that to be slightly dangerous.  Magnets have
a north and south pole.  Due to the shape etc. the magnetic lines of force
can be shaped.  Also by any proximity to magnetic material.  When a north
pole come face to face with a south pole it wants to kiss it.  Not so  for
north to north or south to south.  It will repel it. Either north or south
will be attracted to any iron or magnetic material that is not magnetized.
When I started reading these post I was confused to whether they were being
used in the attraction or repelling mode.  I first thought that it was going
to prevent loss of contact between capstan and whippen so it would be in the
attraction mode.  Remember the old grands with a direct conection of the
whippen to the key through a clamped center pin in the rocker capstan?  I'm
wondering if they were and advantage to prevent dynamic lost motion.  Anyone
with experience as to the repetition of those designs?

Now here's where down the road a problem may lurk.  In a full keyboard the
magnets will  be closer to its neighbor than its intended mate on the
whippen.  What effect will that have either statically or dynamically I sure
don't know.  With all those magnetic lines of force sneaking around pull
some whippens to one side or will the neighbor counteract the effect from
the magnet?  I don't know that either.

A permanent magnet for a  capstan and a thumb tack under the whipen cushion
would perhaps keep them in contact dynamically.Yes?

I just had a wild idea based on your comments, Ron.  Gotta try it before I
reveal it so I don't embarass myself.

I'd like to know from youse guys.  What are we really trying to accomplish?

Eliminating the helper spring?

Reducing down weight?  In what way?

Reducing friction?

Making it cheaper??????

I'll be in touch.

Carl Meyer Ptg assoc
Santa Clara, Ca.

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