grand action problem

Jon Page jonpage@comcast.net
Wed, 15 Dec 2004 20:20:59 -0500


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 >> If it comes to raising the hammer centers/rail, shim the whole stack 
under the brackets.
 >Moving the hammer rail upwards won't do you any good.

That's what I said.  If the hammer bore is too short, raise the whole stack 
instead of the hammer rail.
Measure along the "Magic Line" to see if this relocation is viable. Scott 
already said there was room
under the block to raise the 'rail'.

 >However, Ric is right.  The most obvious fix is to sand the back-sides of
 >the buttons, so that you can adjust them a bit higher.

No, this would be disastrous if you first don't verify the degree of after 
touch now present.
If there is little or no after touch now, trimming the buttons will produce 
even less a/t;
raising the stack is an easier solution without further compromising a/t. 
You need to establish
practical action elevations for the ratio parameters to work assuming the 
elevations are improper,
this is part if the info we are lacking and can only speculate.

It is very difficult to speculate without more info or actually physically 
seeing the action.
David I. touched on a good speculation... are the drop screws set too low 
restricting the
upwards motion of the repetition lever. Or to use the drop screw as a stack 
height indicator:
If the drop screws are set as high as possible and the hammer still doesn't 
rise enough; then
that would indicate too short of hammer bore and/or improper stack height.

A few years ago I regulated a Schimmel and I think I did have to raise the 
stack to coerce the
action into proper function. If <string height minus hammer bore> is not 
close to hammer center
height then the stack height should be addressed.

As far as the spread goes, lacking the factory spec; set the jack to be 90 
degrees to the
shank at rest (aligned on the knuckle core with proper hammer blow distance).



Regards,

Jon Page, piano technician
Harwich Port, Cape Cod, Mass.
mailto:jonpage@comcast.net
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