[CAUT] M & H model 50

[Don Mannino]

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Jon,
=20
The one I worked on had a horizontal tongue, so that when the key was
played the arc swung the sticker back.  The capstan moved  slightly
foward. By raising the tongue flange rail, the sticker movement can be
made to match the capstan movement.
=20
Friction measurement is a good plan for finding the correct rail
position.
=20
But, of course, all of this could have simply been on the pianos I
observed, and may not have been common to all of these.
=20
Don Mannino RPT, Director
Kawai Piano Technical Education
 <mailto:dmannino@kawaius.com> dmannino@kawaius.com

-----Original Message-----
From: caut-bounces@ptg.org [mailto:caut-bounces@ptg.org] On Behalf Of
Jon Page
Sent: Monday, January 16, 2006 5:12 AM
To: caut@ptg.org
Subject: [CAUT] M & H model 50


>The problem is that the sticker cloth is sliding forward very badly on
>the capstan during play.  On the one I repaired it was observable by
>eye, and the wear on the sticker cloth was a long mark instead of a
>round dimple.

This effect dawned on this morning. As the sticker is lifted, the arc of
the support arm
pushes the cushion towards the front.  A bolstered cushion would
minimize the sliding
friction but the felt is too short.

Not having a sample in the shop I can only speculate.
What is the optimum travel of the support arm?

Is it lifting to (slide forward) or from (slide back) a horizontal
position?

Or lifted crossing the horizontal position through the key stroke, this
would cause the
sticker to change direction by being pushed forwards at the beginning
and pulled
backwards at the end of the travel.

We need someone to test these different executions for friction.

As far as bobbling hammers go, I'd check the hammer blow and key dip to
insure
jack clearance.  Decreasing the blow and taking up the lost motion might
may be
the cheapest fix.
--=20

Regards,

Jon Page


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