[pianotech] Square Grand Jack Leather & Felt

[Joseph Garrett]

Terry the Farrell said: 
"The toe of the square grand jack has a piece of leather on its underside.
Right below that is a piece of felt on the base of the jack (what do you
call that - the piece with two screws through it for adjusting lost
motion?). Ultimately, I'm trying to decide whether to replace these pieces
of leather and felt. What I really want to do is understand their function
(beyond keeping these parts from slapping loudly together).
 
Seems to me, in a properly adjusted square grand action, they really
wouldn't even be needed. Yes? I can see if let-off was set too low, or if
key dip was set too deep (too much aftertouch), this leather & felt would
keep things quiet. But if aftertouch and let-off are properly set, seems to
me there really isn't a role for these cushioning pieces. Am I correct, or
am I not?
 
Pictures below:
 
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Thanks!
 
Terry aka Grasshopper,
You are incorrect Grasshopper! The leather is there to "align" the jack to
the Vertical Position. This is necessary in the juxtaposition  to the
Butts! The felt is there to quiet things, (as is most felt in most
actions!), and to give a base for the verticality of the jack. If just the
spacer, (i.e. "leather"), was used, it would be noisy. Again, if it ain't
busted, don't fix it! While we're at it,....on the hammer butt felt, there
is a piece of woven material glued to the base of the felt and the butt.
That is there to curtail the felt from squishing away from the pressure of
the jack. IF you replace a butt felt, make sure you put that piece of
material on as well! I use extra thin action cloth or Bridle Strap Tape
material. Or...??? you choose.<G> And, PLEASE, use hide glue for
everything!????<G>
Joe

Joe Garrett, R.P.T.
Captain of the Tool Police
Squares R I