more beginner questions

[Dave Nereson]

----- Original Message -----
From: Gerald Posey <poseyviolins@charter.net>
To: <pianotech@ptg.org>
Sent: Sunday, March 10, 2002 3:53 PM
Subject: more beginner questions


> I'm working on regulating the action of a Heintzman baby grand.  All my
> reference drawings show two separate springs for the jack and escapement
> lever but this piano has only one that seems to do both jobs.  There is a
> little tiny screw at the end of the escapement lever(away from the
roller).
> What does it do?  I made all of the measurements for key leveling and dip,
> hammer travel and "where the jack trips".  But the touch feels "vague"
like
> theres no power.  When they say , "the jack trips" do they mean it begins
to
> move or it is all the way out of the way?
> Thanks
> Gerald

    Before you regulate anything, you have to have some drop and some
repetition spring strength.  The little screw at the end of the repetition
lever (escapement lever, or balancier) could be for adjusting the height of
the repetition lever above the tip of the jack or it could be for adjusting
the strength of the repetition spring.  If it's a spade-head type, and turns
a little button on the bottom of the repetition lever, which you probably
would have noticed, it's for the former.  If it's a straight-slot type, and
more of a set screw recessed in the wood, it's for the latter.
    I'm giving particulars before basics here, but:
    The tip of the jack should be below the top of the repetition lever by
"just a hair", or a few thousandths of an inch.  With the hammers at rest,
depress the tip of a jack with a finger and let go.  The hammer should dip
down, or "wink", but then return to where it was.  If it doesn't dip at all,
turn the button on the back of the rep. lever clockwise.  If it dips too
much (more than 1/16 " or so), or if it dips and stays dipped, turn the
button counterclockwise.  This isn't all there is to it, but . . . .
    Strike a key and make the hammer rebound off the string or regulating
rack and be caught by the backcheck.  Now, without letting go of the key or
letting it come back up, just release your pressure on the key, but still
keep it touching the front rail punching.  In other words, you're holding
the key down with minimum pressure required to keep it down (hammer still in
check).  The hammer should rise up to its let-off point, if there's any
repetition spring strength, with a "positive", or "assertive" motion (not a
sluggish, gradual rise, and not a sudden, springy, jumping motion at the end
of which it bounces, or "dances" . You shouldn't feel a little thump in the
key when it rises.).  If it jumps and dances, decrease the spring strength
by turning the set screw counterclockwise.  If it's a sluggish rise, turn
clockwise.  This is assuming you've already checked hammer shank pinning and
taken care of any tight or loose ones, and that any slots the spring rests
in aren't gunked-up with goo.
    There's much more to this, but it requires a lot more explaining and
some "hands-on".
    As far as the jack tripping, it starts to trip as soon as its tail, or
tender hits the regulating (let-off) button, but the key goes down several
millimeters before it's all the way out from under the knuckle (roller).
The hammer should go up to about 1/8" to 1/32" from the string, depending on
various factors, before it drops away (lets off), after which it should drop
about 1/16 ".  There's a lot more to be said about let-off and drop, but no
space here.  As Wim said, the jack hitting the let-off button and the rep.
lever hitting the drop screw should happen at the same time.
    As far a "vague touch", are all the action screws tight?  Is the
keyframe properly bedded?  Are the hammers aligned to strings, wippens
aligned to knuckles and wippen cushions directly over their capstans?  Are
the capstans polished and the wippen cushions clean?  Are the jacks properly
aligned to the knuckles?  Is there gunk on the knuckles?  Are the backchecks
catching the hammers or is the leather on them worn out so that the hammers
"bobble"?  Are the backchecks retarding the hammers on their way up? (With
hammer in rest position, restrain it with one hand and press the key with
the other hand, and rock back and forth to see if the hammer tail rubs on
the backcheck).
    This is just a start.  Post is getting too long.  Past my
dtime.   --David Nereson, RPT, Denver