Old Knabe Pinblocks

[Delwin D Fandrich]

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  ----- Original Message -----=20
  From: Brian Trout=20
  To: pianotech@ptg.org=20
  Sent: Thursday, August 05, 1999 7:14 PM
  Subject: Old Knabe Pinblocks


  Hi All,
  =20
  I have a job in the shop waiting for me right now.  It's a Knabe =
grand, 7'4" I think, late 1800's, with a full plate.  The pinblock is =
sloped, and also curves from bass to treble.  If you've seen one, you =
know what I'm talking about.
  =20
  The pinblock is to be replaced.  I guess what I need is some advice as =
to how to attack the beast.  I want to do it right.  The main problem I =
seem to run into is that to remove the pinblock completely, it's almost =
impossible without tearing off the top front parts of the case.  (The =
pinblocks I've seen like this one were screwed in before the case =
assembly was finished, and not intended to be removed.)
  =20
  Have any of you come up with a better way to do a pinblock replacement =
on these?
  =20
  =
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----

  Brian, et. al.,

  This has been an interesting series of posts to follow.  Having done a =
couple of these in the past, perhaps I might be allowed to comment....

  First, these things look far more intimidating than they actually are. =
 What you are faced with is simply a task that will require somewhat =
more, and more demanding, woodworking that is usually called for.  =
Believe me, though, if I can pull one of these things off, most anyone =
else out there can as well.

  I have not tried filling the holes with epoxy and re-drilling.  It =
might work, though.  Epoxy, by itself, does exhibit a fair amount of =
creep under load, but in this case it is just being used to reinforce =
the wood fiber surrounding the pin.  Basically what you would end up =
with a fiber-reinforced plastic pinblock.  Which may or may not be a =
good thing.  I'm not really qualified to evaluate the idea.  But, far be =
it from me to stand in the way of progress.=20

  I have, however, encountered pinblocks that have been plugged and I =
have encountered pianos in which portions of the pinblocks have been =
routed out and inserts installed.  Some have held up well, others have =
abjectly failed within just a couple of years.  I have encountered =
inserts that have pulled loose and pinblocks in which the plugs weakened =
the structure -- no, the glue holding the plug in does not make the =
structure as strong as it was before you drilled out all that wood -- =
sufficiently that the blocks had actually broken.  So, for me, both of =
those options would be out.

  My choices would come down to an epoxy repair of some sort or, my =
preference, replacement of the original block.  Taking the rim apart at =
the bass end -- you shouldn't have to get into the treble end at all -- =
just isn't that difficult.  Neither is putting it all back together and =
doing a bit of re-veneering.  Cutting the original block loose from the =
stretcher is also not terribly difficult.  The only real challenge is =
shaping the actual pinblock panel and fitting it to the plate.  This can =
be done fairly quickly using a variety of power and hand tools.  And, =
yes, we do cheat and do the final bedding to the plate using an =
epoxy/wood flour matrix.

  I am currently updating my old class outline on replacing these =
blocks.  I'll be happy to send you a copy -- once it is completed -- if =
you're interested.

  Regards,

  Del

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