jack in the mortise

[Isaac sur Noos]

Tried a method given by Roger Jolly (I guess) to bend (twist) the post
and lock the bend with a dab of CY glue.

Did not had much success when I tried it, it may depend of the
strength of the post indeed.
A heat gun is the first tool to buy if one works on pianos ! a model
with thermostat and 2 speed of course, and having small noses or
accessories you can modify to have a smaller zone of heating.

Very useful also for all hide glue application, warming the part
slightly is a good security against dry glue joints.

I find often that the lever is twisted itself, it is not only a post
problem. Untwist a lever with heat is feasible, I've seen a fairly new
Steinway where most of the jacks are higher in the window on ones side
than the other, a very difficult to regulate piano then. the weight of
the roller is more one side of the lever, I believe this cause undue
friction on the whippen flange pin, slowing the repetition.

So some have experimented a good method to straighten by sanding or
whatever the actual contact and friction zone on the jack and the
lever ?
I have on some occasion burnished with a metal tool the jacks top and
the lever window, I generally rub them , but changing the edge of the
jack and eventually filing the top can be helpful if accurately done.

Isaac OLEG




 -----Message d'origine-----
De : pianotech-bounces@ptg.org [mailto:pianotech-bounces@ptg.org]De la
part de Dave Nereson
Envoyé : mardi 13 janvier 2004 09:05
À : Pianotech
Objet : Re: jack in the mortise



----- Original Message -----
From: daniel carlton
To: pianotech@ptg.org
Sent: Monday, January 12, 2004 8:36 PM
Subject: jack in the mortise


i have a question regarding centering the jack in the mortise (using a
hammer tap on the head of the jack).  do the jacks need to be
positioned in the exact center of the mortise or can they get away
with being off-center?
another question.  it seems that bending the center pins like this
sometimes causes resistance toward the end of the jack's travel.  this
concerns me because it seems that it can affect the regulation and
feel.  is this just my imagination.  is it any big deal?
any info and advice is greatly appreciated.

thanks

daniel carlton

    It doesn't have to be precisely in the center, as long as it's not
rubbing the side of the "window".  Yes, bending the pin can cause
resistance in jack travel and no, it's probably not a big deal for
your average piano player, but for fine regulation of fine grands, it
might be.  And for this reason some techs recommend straightening the
repetition lever post instead.  It's claimed that this is what causes
the jack to rub the side of the rep. lever window in the first place.
The rep. lever post dries out and warps, or twists slightly as the
wood ages or acclimatizes, and then the rep. lever is no longer
exactly parallel above the wippen body.
     I don't know how one goes about straightening those posts -- pull
'em off and re-glue 'em?   --heat 'em up with a heat gun and try to
twist them?  They're pretty thick -- I haven't tried straightening
them as I don't know an effective method for doing so.
    Anybody else?
    --David Nereson, RPT