Slippery keys, center rail studs, etc.

[Avery Todd]

Anton,
   Welcome back to the list. It was good to read your post. I agree with
what you are saying about the sharps burying below the whites. That's, of
course, definitely too much.
   However, I want to question your comment about bedding the keyframe.
It's always been my understanding that the bedding screws *only* contact
the keybed enough to keep them from knocking, hence "only tight enough to
still allow a strip of newspaper to be pulled out from under them without
tearing", or (on some pianos) "turning them down with a tuning hammer only
far enough to stop them from knocking when bumped with the palm of your
hand on the portion extending out above the keys", i.e. Steinway. If the
screws are turned down far enough to allow 3/4 of a turn up and still be
bedded and not knock, it seems to me they would be exerting quite a bit of
pressure on the keyframe and the guide pins in the cheek blocks. If this
were the case, it seems that it would be extremely difficult for the action
to shift freely when the "soft" pedal is used.
   As a result, being able to move the action this much, this way, would
change the key height, dip and quite a few other things. I would think
(hope) that one would rarely run into a piano where this was possible. Have
you found this type of situation often?
   Even though it's not quite as "quick a fix", don't you think that it
would be better to just go in and correct the sharp dip with punchings and
then correct the resulting changes in the backcheck regulation? Of course,
this would also change the aftertouch on the sharps, resulting in having to
change the hammer blow distance if it made the aftertouch too
shallow........etc., etc. So there we go. Wouldn't it be nice if it were
just always done correctly the first time???? <G>
   I also don't see how turning the glides "up" could warp the keyframe.
Turning them "down" too much, maybe.
   Anyway, it's nice to have you back and want to thank you again for your
wonderful recital here. Also for what I learned from you from your
perspective as a performer who can also speak "my" language. I hope I get a
chance to work with you again in the near future.

>Returning to a subject I brought up previously, I keep finding pianos where the
>sharps go too deep; even if they don't "bury" they are too close for comfort.
>At one top piano company, with outstandingly well maintained pianos, about two
>thirds of their instruments were wrong in this respect.  A quick fix in this
>case is to screw the center rail studs on which the action glides up; usually
>about 3/4 of a turn is enough, unless the keys are really burying quite deeply.
>If you are sceptical about this, put a touch block on a key and feel the
>adjoining key as you screw one of the center rail studs up and down.  This
>can >of course only be done if they protrude sufficiently from the bottom
>of the >action that they will still be in contact with the key bed, and if
>there is a >fair bit of aftertouch and touch depth, because as you lower
>the center rail >you will reduce both of these.  You also have to check
>that afterwards the >action does not knock against the keybed in places,
>though I have found that if >you do the exact same number of turns at each
>stud and it was not knocking >before it usually remains OK.
>
>I have heard that this ought never to be done, because it can warp the action
>frame.  I question whether this is true; after all, when fitting the action to
>the keybed, these studs have to be adjusted anyway, and a half or full turn
>would not be unusual; and you want a fair bit of pressure on the key bed
>just >to prevent knocking.  I would be interested in reading some comments
>on this.
>
>Anton Kuerti URPT (unregistered piano technician!)

_____________________________________
Avery Todd, RPT
Moores School of Music
University of Houston
Houston, TX 77204-4893
713-743-3226
atodd@uh.edu
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