Tuning Pin Bushings

[Jon Page]

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At 08:42 PM 11/11/2000 -0700, you wrote:
>Having problems removing the bushings from a piano that wasn't having its
>plate removed - I went to a pawn shop and purchased a ROUND shanked
>screwdriver with a shank diameter very close to the ID of the plate
>bushing holes.   Then, I simply cut off the tip of the screwdriver and
>ground it to look like a tuning pin spoon bit reamer.  You don't have to
>do a lot of grinding to do this as the bushings aren't really that deep -
>only do about 1/2 - 3/4" worth.  Works for me.
>
>John R. Fortiner
>Billings, MT.

For something like this, I would have tried to clean the bushings before 
removing them.
A drill bit with a stop collar would suffice. My worry is that the old pins 
probably have been
pulled towards the rear of the hole. A new bushing may not compact easily 
enough for the
pin to 'register' properly in the pin block.

Drilling an angle in the bushing with the plate in is like treading on thin 
ice.
Unless you cut a section of thin pipe to be a drill bit collar/stop.

The important concern is to make an effort to mate the hole at the bottom 
of the bushing
with the hole at the top of the pin block. Otherwise the tuning pin hole 
could end up slightly
oblong from the effect of the bushing not compacting enough for the pin to 
chase the bore.
Bushings will compact but it is dependant on the location of the 'old' pin 
bore. Hopefully
the old pins did not touch the plate or were too close to it because the 
oversized pins
could end up so.

Below, is my answer to a similar question posted on the Mechanical Music 
Digest yesterday:

  When dealing with tuning pin bushings, the punch has a point which marks the
  center on the pin block when the bushings are installed. I drill the 
block at the
  drill press out of the piano. With the plate out as well I turn it over 
and drill from
  the bottom at the angle at which the tuning pin will be drilled. This 
maintains the
  center at the 'bottom' and establishes the correct angle in the bushing. 
If you didn't
  drill an angle in the bushing, as the pin is driven into the pin block it 
will assume
  that angle and you could be left with a slight space between the pin and 
bushing
  at the rear as the pin changed angles. Depending on the density of the 
bushing it
  will force the pin towards the rear (away from the front) which could 
affect block
  longevity because you just made the hole slightly oblong.

  You could also drill the block in the piano through the bushings if you 
have a table
  mount drill press setup for it. However you do not want to drill from the 
center at the top
  because the angle will cause the pin to be close to the plate at the 
bottom. As the pin
  hole wears, the pin will move closer to and might eventually touch the 
plate and if
  oversized pins are going to be installed in the future there will be a 
problem.
  The same holds true for pianos without bushings.

  On pianos without bushings, I also drill the plate hole at a slight angle 
starting at the top.
  I select a bit which is the same size as the hole and angle the drill so 
as to relocate the
  bottom of the plate hole further towards the rear but not make the hole 
wider. (The top
  of the hole is moved back as well but not as much as the bottom on the hole).
  This is done in an effort to ensure that the pin does not ride the plate. 
It is especially
  effective when restringing and using the old block with larger pins. How 
many times have
  you needed to replace the block because the pins were riding the plate? 
This is an option
  which may circumvent the need to replace the block for certain pianos.
  No flames please from the zealots who replace every block as a matter or 
course.
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That last line was for a few readers of the MMD, these player guys can be 
rather head-strong,
with questionable rationale; it's as if they are in their own little 
universe (revolving around them :-).

So that's my thoughts on bushings/plate webbibg.

Chiao, (that reminds me, breakfast time  . . .)
Jon Page,   piano technician
Harwich Port, Cape Cod, Mass.
mailto:jonpage@mediaone.net
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