[pianotech] Weighing Off A Schafer Grand

[David Weiss]

Jon,

 

Very informative post.  What is your method for relocating the knuckle?

 

David Weiss

 

From: pianotech-bounces at ptg.org [mailto:pianotech-bounces at ptg.org] On Behalf
Of Jon Page
Sent: Saturday, January 30, 2010 7:50 AM
To: pianotech at ptg.org
Subject: Re: [pianotech] Weighing Off A Schafer Grand

 

Moving the wippen rail will have marginal effect on BW. Check into
relocating

the entire stack back. If there is ample room between the keys and the
keyslip,

there is the option to move the stack back and the whole action forwards to

maintain the strike point.

 

A few years ago, I had to remanufacture an action which involved lightening
the

hammers, moving the knuckle, moving the stack and removing lead. The problem

was a heavy action with excessive after touch.

 

Here's the results on middle C:

 

a. original survey
b. Reshape hammers/taper/re-arc tails, graduate weight
c. move knuckles out 1mm on shank to 18.5mm
d. move stack back 3mm
e. alter FW to target 38 BW

Survey of C4
    UW  DW  BW  F   SW   FW  SBR
a  32   60    46  14  10.9  32    6.4
b  26   52    39  13    9.9  32    6.3
c  24   44    34  10    9.9  32    5.8
d  22   38    30   8     9.9  32    5.4

e  30   46    38   8     9.9  24    5.4

 

Even after relocating the knuckle further from the center pin, the jack was
still

being buried into the stop cushion. So in order to maintain a 10 mm key dip,

I relocated the stack. KR was in a nominal range and did not require
alteration.

Moving the stack is much easier than relocating capstans.

-- 


Regards,

Jon Page

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