Spring behavior

[Jon Page]

At 09:35 PM 10/25/2002 +0200, you wrote:
>Repetition I found a little less fast (but efficient) with these whippen. 
>The weight of the Teflon screw is felt in the lever when
>playing. The springs seem to be not as responsive. I've see one that was a 
>little noisy too (a very little).
>That is more a matter of feel. Bechstein, I believe have used these 
>whippen before coming back to butterfly.
>But sure they are very stable. Isaac OLEG

The springs come in way too strong from the manufacturer and by the time 
you relieve the tension sufficiently
the spring is contacting the backside of the Teflon nut; not the best 
distance for optimal loading.

I fashioned the jaws on an old pair of lineman pliers into a curve (wide 
wire bending pliers, so to speak).
On the 15mm wide jaw face, the curvature is 1mm in the middle.

I plan on purchasing a Strain Gage soon to actually measure the difference 
and then be able to calibrate the
tension out of the piano. This pre-tensioning is proposed for wippen assist 
spring tension as well.  I hope
to reduce the time needed to afine-tune the tension once installed and gain 
the best spring curvature with visual
inspection.

The angle of the wip assist spring retaining cord is too acute and does not 
allow for fluid motion during the
wip travel. Spring tension is greatest at rest (constrained) and decreases 
during play.  Having the loop more
towards a 90 degree position retains a more constant tension through the 
wip travel and provides a more fluid motion.
Duplicating the arc of the loop on a piece of paper with a compass will 
show mechanically how the tension changes
with the currant configuration and how it remains more constant with a 
minor modification.

Actual real figures will develop once I obtain this new tool...
the ultimate goal will be for this to measure Touch Weight in an efficient 
manner.

Regards,

Jon Page,   piano technician
Harwich Port, Cape Cod, Mass.
mailto:jonpage@attbi.com
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