1890s WNG Action Geometry

[Overs Pianos]

>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?

Yes.

>  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?

I doubt it.

>  Comments?
>
>Terry Farrell

It seems to me that you guys are heading in the right direction with 
this action. The balance pin lines must be set further back towards 
the key fronts than usual with this keyboard, to require such a 
positioning of the capstans. However, if the jack clears the roller 
sufficiently with the key dip and hammer blow distance that your 
looking for, it doesn't matter where the capstan/heel location falls 
relative to the wippen body (but it must be on the line of centres at 
half blow, which you have already addressed). The regulation 
parameters are all that matters. The down/up weight figures you quote 
prove that the setup you've come up with is going to yield a good 
result. Look forward to hearing what you end up with in final figures.

As a postscript, we had a wonderful time in the US, at Rochester and 
later in Boston. I hope to write a report-post on our trip very soon 
for the list. Some of you have emailed me since our return to Sydney 
and I haven't got around to replying yet, for which I apologise. Will 
attend to this also very soon.

Best regards,
Ron O.
-- 
OVERS PIANOS - SYDNEY
    Grand Piano Manufacturers
_______________________

Web http://overspianos.com.au
mailto:ron at overspianos.com.au
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