bobble heads

[Alan R. Barnard]

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You've got ten times the experience I have, but these are my random =
thoughts and questions:

If the lower notes ARE checking properly, what is different in the =
regulation of those?

Has this been a problem since the hammers were installed or something =
new?=20

Are the shank-pin-dropscrew-flange screw hole locations/dimensions all =
correct for this M? Seems like the shank length could be just fine with =
the hammer at rest but, based on the pin center, f'rinstance, the swing =
radius could be off with the hammer tail missing the backchecks.

Same with those knuckles you mentioned ... is the hammer-to-string =
distance correct with the hammers at rest?

Tail arc radius too small? Tails too smooth? Backcheck leather glazed, =
worn, compressed?=20

Any "pulley" to those keys or shift of the balance rail, i.e., does =
playing the key push the backcheck slightly away from the hammer?

I don't know what I'm going on about. Grand checking seems a mysterious =
art form to me -- so many things have to be right on. I'm attending a =
weekend PTG regulation workshop in Joplin, MO this weekend ... maybe =
I'll have=20

Alan R. Barnard
Suggesting in Salem, MO
  ----- Original Message -----=20
  From: Wimblees@aol.com=20
  To: Pianotech@PTG.org ; caut@ptg.org=20
  Sent: Tuesday, October 15, 2002 5:47 PM
  Subject: bobble heads


  Problem: Bobbling hammers on a S&S M from C5 on down. I mean, they =
don't even check on a hard blow.  Some of them are checking, but only on =
a hard blow. The rest just bobble. New hammers, shanks and flanges.=20

  Let off is right, drop is right, there is after touch. I changed let =
off, I changed drop.  Keys are level, right amount of dip.  I increased =
dip, decreased dip. I've increased rep spring, and decreased rep spring. =
Dampers are not in the way. Nothing.=20

  This is a 1939 model. There has been some discussion about knuckle =
size.  As I said, these are relatively, (about 3 years old) new h/s/f/ , =
with 3/8" knuckles. Could that have an effect?

  Wim=20

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