1890s WNG Action Geometry

[Porritt, David]

Terry:

 

I played a Steinway B once that David Stanwood had redone and he had
moved the capstans 0.400" of an inch which would be 10.16mm.  It really
played nice.  He did have to move the wippen heels also.

 

dp

 

David M. Porritt

dporritt at smu.edu

________________________________

From: pianotech-bounces at ptg.org [mailto:pianotech-bounces at ptg.org] On
Behalf Of Farrell
Sent: Monday, July 17, 2006 5:03 PM
To: pianotech at ptg.org
Subject: 1890s WNG Action Geometry

 

Phil Bondi and I dove into an 1890s WNG action from a 6' 4" Knabe today
to try and straighten out some basic action geometry. We haven't got all
the kinks worked out yet, but we seem to be getting there. With only a
large capstan move and removal of a couple leads, we went from an action
ratio of over 6.0 down to 4.9. DWs went from 60+ to 50 and less (I know,
too light) and BW in the 36 to 40g range. We have a lot of work to do
yet, but it seems the capstan move described below has gotten us into
the right ball park anyway.

 

Most notable was a very large capstan move that we will likely keep
(unless someone so kindly informs us of a potential problem the change
might induce). The photo below shows the original capstan in the
background. The forward key had its capstan moved 10mm forward and 11mm
lower. The middle key had its capstan moved 13mm forward and 12mm lower.
The second photo shows the modified wippen heel. These lower positions
put the capstan right on the magic line at half blow. The capstan/wippen
heel interface went from a traveling, grinding, sliding affair and a
note with 17g friction to a perfectly interfacing union with no apparent
sliding and a note with 9g friction. We were amazed at the improvement
in friction and interface movement.

 

This strikes me as a rather drastic capstan move. Has anyone else run
across an action that needed such a large capstan move? As our action
ratio is down to 4.9 and key ratio is down around 4.8 with the 10mm
forward capstan migration, we may move it back just a few millimeters.
But still it seems large. Is there some hidden pitfall I'm not seeing?
Comments?

 

Terry Farrell

 

 

 

 

 

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