Half punchings on balance rail

[Richard Brekne]

I find that if you cut out a 2 mm wide strip of card paper perhaps 0.3 
mm thick,  and try different positions on the key stick you can even out 
the SW ratio quite a lot.  I havent gotten around to looking really 
thoroughly at the whys and hows,,,, but I think that slight differences 
in how the underside of the keystick is shaped, along with other 
keystick-punching contact conditions significantly contribute to 
variances in the actual ratio for each key. This can be compensated for 
by appropriate placement of a thin strip of card paper to alter the 
fulcrum point. You have about 1.5 mm of distance on either side of the 
balance rail hole to play with.  Which is more then enough.

Cheers
RicB

Bob Hull wrote:

>List,
>
>I have searched the archives for comments on the
>practice of cutting a felt balance rail punching in
>half and glueing it to the bottom of the key (behind
>the balance rail pin) in an effort to change lower
>downweight and/or strike weight ratio.  
>
>My search didn't yeild any previous discussions.  I
>have tried this method (experimentally on the bench) 
>which did lower the downweight too much, and lowered
>the strike weight ratio from 5.78 to 5.31.  I'm
>wanting a 5.5 ratio. The piano is a D on which I have
>just replaced the hammers. They are a little on the
>light side, I think, for a D. (#1 sw is 12.1, #40 is
>9.7.)  It is in a small recital hall which doesn't
>require huge tonal projection.
>
>What do you think about this practice?  On another
>note I tried just cutting off 1/4 of the front part
>and it gave more desirable results.  
>
>Comments?  Thank you for all the great help you
>usually give.
>
>P.S.  As you can tell, I'm trying to get a grasp on
>using the smartchart.
>
>
>Bob Hull
>
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