Sticking Jacks

[Thomas D. Seay, III]

>   I'm working on an Acrosonic console from the '50s with a sticky
>treble. Most notes in the top third stick after much play (maybe once in
>30 hits). It's very erratic. I eased the keys and lubed the flanges
>which only partially helped. The whippen stays up, not the key, but the
>whippen drops when the hammer is pushed forward just a bit, so I think
>the jack is sticking against the butt. Sure enough, the butt felts
>(buckskin?) are graphited heavily. I replaced one with buckskin dusted
>with teflon. It stuck even worse than the others. I then put in a
>heavier jack spring, and this seems to work, but it gives a heavier
>touch. I've seen this problem in other pianos. Some tuners have glued
>weights to the whippen, etc. Any ideas?
>
>Thanks,
>
>Philip Jamison
>West Chester, PA

Phillip,

My experience with these pianos, especially if they haven't been played for
a while, is that the action centers become very sluggish, usually requiring
repinning or repeated applications of ProTek CLP.

Check the pinning of the jacks. Repin the worst one you can find and see if
this improves things. Also, be sure that you have a very slight amount of
clearance between the jack and the hammer butt with the hammer at rest. If
a slight amount of lost motion is not present, the jack won't go back under
the butt completely. A good test is to play and then release a key very
slowly with the damper pedal engaged, watching the jack closely as it
returns. If there is no clearance, you will see the jack stop about halfway
under the butt. If that is the cass, add just enough lost motion to allow
the jack to return fully under the butt.

Good luck.

Regards,

Tom Seay
The University of Texas at Austin
t.seay@mail.utexas.edu