Pinblock Separation Repair & Pitch Change

[Farrell]

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3/8".

Terry Farrell
  ----- Original Message -----=20
  From: Richard Strang=20
  To: 'Pianotech'=20
  Sent: Thursday, October 30, 2003 3:50 PM
  Subject: RE: Pinblock Separation Repair & Pitch Change


  Thanks for the info, Terry. I have to go make that very repair to a =
piano shortly and was contemplating whether or not to lower the pitch =
first. It this case, the separation is about 1/2"  in the bass and about =
1/4" in the treble. Those pesky little termites are in there, too. I =
think they are causing the problem. They are not in the pinblock, =
though, so the piano is in tune, though 200 cents flat.
     I was also wondering what size bolts to use, 1/4", 3/8"? What do =
you recommend?
  Thanks.

  Richard
    -----Original Message-----
    From: pianotech-bounces@ptg.org [mailto:pianotech-bounces@ptg.org]On =
Behalf Of Farrell
    Sent: Thursday, October 30, 2003 8:09 AM
    To: pianotech@ptg.org
    Subject: Pinblock Separation Repair & Pitch Change


    Differing opinions regarding the benefit of lowering pitch prior to =
drawing a pinblock/backpost separation back together have been expressed =
on this list. I am one that generally feels more comfortable lowering =
pitch. I thought it might be of benefit to put some numbers on potential =
pitch changes.=20

    Yesterday I did one of these repairs on a late model (1980s) Baldwin =
Acrosonic console. It had an approximate 1/4-inch separation between the =
pinblock and the backposts and deadwood back assembly. The separation =
had been "repaired" in the past with something that appeared to be =
silicone bathtub adhesive - surprisingly (?) the separation appeared to =
have widened since the application of the silicone. The piano was tuned =
at that time (and presumably tuned at standard pitch).=20

    Prior to my repair the piano was fairly uniformly 75 cents flat. I =
dropped the pitch to between 200 and 250 cents flat prior to any =
clamping. I yucked in West System epoxy thickened with #403 Microfibers. =
(A fine fiber blend, is used as a thickening additive with =
resin/hardener to create a multi-purpose adhesive, especially for =
bonding wood. Epoxy thickened with microfibers has good gap-filling =
qualities while retaining excellent wetting/penetrating capability.)  I =
drew the gap closed slowly going back and forth among the six 3/4" pipe =
clamps (of which two got bent pretty good!). The separation appeared to =
close very close to 100%.

    I then checked pitch again. Piano was fairly uniformly about 75 =
cents flat. Therefore, it appears that closing the 1/4-inch gap resulted =
in a pitch increase of approximately 150 cents.

    I will be going back to the job on Friday morning to install a few =
through bolts, remove clamps, pitch raise and tune. If there is anyone =
out there that perhaps has not seen this repair done (or whoever for =
whatever reason) wants to see a few photos, I will take them Friday =
morning. Let me know.

    Terry Farrell
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