Mysterious blocking notes

[Don Mannino]

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Aaron & List

Check for over-centering in this action. If the hammers over-center =
much, and you adjust the action for correct blow, letoff, drop, etc., =
you can have just the symptom you describe. Especially during fast =
repetition, the hammers will drop down below the regular rest position =
and the note will seem to jam. Tapping the key once or twice will =
encourage the jack to reset, and the note will then play normally again.

If this problem is just beginning to happen it can be hard to induce. If =
(maybe I should say "When") it becomes worse you will be able to =
duplicate it easily.

The gradual compression of the roller contributes to the problem, and I =
think is the reason it will gradually get worse.

The ultimate solution is to mount hammers that are bored for the piano's =
string height, but you can also set the regulation a little out of specs =
to improve things: lower the capstans until the hammer shanks are off =
the rest rail the proper distance (as per Steinway regulating =
instructions), then give extra key dip to provide enough aftertouch. =
This should get the piano playable.

Bolstering the knuckles will help too, of course. As will increasing the =
rep spring strength or raising the backchecks a bit.

Of course, this may not be your piano's problem at all . . . . . .

Don Mannino RPT



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From: 	Aaron Bousel[SMTP:abousel@rocler.qc.ca]
Sent: 	Wednesday, December 18, 1996 3:32 PM
To: 	pianotech@byu.edu
Subject: 	Mysterious blocking notes

List,
I've sent this twice in the past two days.  Hoping it will go through =
now.

I have a customer with a S&S 'M' with an elusive, mysterious action =
problem.
First some background:  It is serial number 490934 built in 1984.  The
action is cloth bushed, except for a Teflon plug that holds the =
repetition
spring in place.  It has those screws with the reduced and knurled =
bodies
(just below the head) that sometimes break.  (This is irrelevant to the
problem, but might help someone identify the action.)

The complaint is that, on occasion, apparently at random, certain keys =
won't
go down.  Or more precisely, they will go down but require an additional
amount of force to start them.  Typically, he will be playing a passage =
and
the note or notes resist his touch.  If he stops and goes back to those
notes, they seem to work fine.  Needless to say, the piano smelled me =
coming
and played fine when I tried to duplicate his experience. =20

As he found the problem to be worst on notes C-52 and D-54, I began my
investigation there.  The only thing I noticed that was different about =
the
action parts in that area was that the wippens seemed too far forward, =
i.e.
the capstan had worn the wippen cloth very near the back of its length, =
and
the jack tail was hitting the let-off button very near the front.  I =
checked
all pinning, lubed jack tops, and generally went over these two notes =
with a
fine tooth comb.  I used travel paper on the wippen flange in order to =
move
the whole wippen back just a bit.  Put it back in, and of course it =
worked
fine.  But, it worked fine for me before, so I had no confidence that
anything I'd done was of any use.  Tuned the piano and while checking it =
out
after the tuning, I THOUGHT I felt a bit of resistance on G-47.  Going =
back
to the note, I couldn't reproduce the sensation.  At this point I had to
leave so I explained that I'd tried some adjustments and as I was coming
back in two weeks to tune his upright, I could look into again at that =
point.

Two weeks later he said it seemed much better, but G-47 stuck on =
him--once.
G-47 didn't exhibit the same alignment problems I saw at the end of that
section with C52 and D54.  I did everything to G-47 I had done to the =
other
two notes, except shimming out the wippen flange.

That was a month ago.  I just got off the phone with this customer and =
he
said that just last Saturday A-49  'blocked' on him.  He went to the
Steinway dealer here, who has sold him a Dampp-chaser (which I've been
trying to do for awhile now) but I doubt that this is a humidity =
problem.
For the moment he's going to let the Dampp-chaser work for awhile and =
see
what happens.

The sensation I felt was as if someone had pushed a tri-chord damper =
just a
bit down into the string and then tried to play the note, an initial
resistance, then it lets go.  I don't think that it has anything to do =
with
the dampers, that's just a good description of what it feels like.  You =
may
have noticed, as I did that it only seems to happen on the naturals.  I
checked out the keyboard and everything looks fine, keys moving as they
should, not chucking.

Has anyone ever come across this before?  I would sure be great to be =
able
to come back to this guy with something concrete.  Thanking you all in =
advance.

Regards,

Aaron Bousel
Ormstown, QC  Canada
abousel@rocler.qc.ca



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