Action Geometry, my thoughts

[Jon Page]

At 11:09 PM 06/09/2000 -0400, you wrote:

>In a message dated 6/09/2000 8:03:14 AM, Jon wrote:
>
><<If you change the time the grand damper lifts without changing key dip, the
>key end lifter
>felt height ends up at the same height, so the damper is lifted to the same
>height.>>
>
>Jon;
>  Y'all needs to rethunk dis here thing guy. :-)  While it may be true of the
>underlever...is it needfully true of the "damper"?
>Jim Bryant (FL)

Jim,
You're right. I had my attention focused on the underlever.   A damper which is
adjusted to lift sooner will have a 'longer' wire extension and will be 
higher than
a 'short' one adjusted to lift later.  Underlever same height, wire 
different length.
I could not see the forest for the trees.  It was just too obvious for me 
to notice :-)

That was a poor analogy to the motion of the jack and wippen in relation to 
a change in
knuckle placement on the shank.

Now that you have me second-guessing what I have said, let me rehash my 
remarks:
 >So by delaying the jack to letoff button contact time, the jack will 
still end up in the
 >same juxtaposition to the knuckle because the wippen is still being moved 
through
 >the same distance.
Although I have not taken exact measurements of the 'jack location at 
check-in';
ei: removing the stop felt and marking the position of the jack on the 
repetition lever
then changing the shank for a different knuckle execution and comparing the 
results.
What I have noticed is that by changing to a different knuckle radius, the 
jack (which
was too far away from the knuckle) did not end up any closer to the knuckle at
check-in but only by moving the capstan was any significant alteration 
accomplished.
There could/must be some slight difference caused by the lever action of 
the jack with
letoff timing when a different knuckle is introduced, I'll make that 
measurement next week
when I get into another rewhatever. I'm still working this up as I go along.

My objective in all this is to have the jack remain close (real close) to 
the knuckle
when the key is fully depressed. This has minimized after touch and aids in 
repetition
since the jack has less travel.

Thanks for catching my oversight, I hope everything else makes sense and 
I'm going
in the right direction but it has produced some nice playing actions.

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