Tuning Pin plate bushing removal

[Jon Page]

At 10:20 AM 11/26/98 EST, you wrote:
>In a message dated 98-11-25 20:44:24 EST, you write:
>
><< Dear List:  What is the easiest way to remove tuning pin plate bushings
> when restringing, but not reblocking.  I haven't had a lot of luck for
> ease with a chisel.  The ones that didn't come out with the pins are
> really tight in the plate.  The ones that I removed today took me way
> toooooooooooooo long ( like 1 minute each on the average ).
> 
> John R. Fortiner >>

John,
First look to see if the pin block hole is centered in the bottom of the
plate hole. Probably not since the hole is drilled thru the bushing into the
block at an angle so the block hole is closer to the back of the plate hole.

Pull the plate, punch the old bushings out and clean/wax the s/b.
Install the new bushings.  Another reason to pull the plate is to apply
epoxy to the block to insure a solid flange fit, also to inspect the block and
make certain there are no separated laminations or the startings of them.

If the block holes are centered fairly well, the ream the bushings with a
17/64 drill bit or there-abouts.  Ream from the bottom, holding the drill
at the same angle of the pin.
If the block holes are towards the backside of the plate hole then ream
from the top with the drill angled same as the pin.

This is done in an effort to align the bushing hole with the block hole. If
you drive a pin into the block with a bushing which has a 90 degree bore,
the pin will start out straight and then pull itself to the angle as it enters
the block. So depending on the location of the block hole at the bottom
of the bushing, some wood could be crushed in a manner which may not
be ideal for long term pin torque. The bushing could actually cause the 
pin to make the pinblock hole oblong by not allowing it to get close enough
to the backside of the plate hole, hence reaming diminishes this effect.

If the pins are extremely close to the back of the plate hole, a new block
should
be seriously considered. Another approach would be to elinimate the bushings.
To avoid pin contact with the plate where it meets the block, ream the
plate hole
from the top at an angle so as to slope the plate hole slightly. Use a bit
which is
the same size as the hole or 1/64 larger. I usually do this on any plate where
oversized pins are being used. Of course the plate is out of the piano. I
don't
even want to think of the consequences arrising out of reamimg the plate
while it is in the piano.

Jon Page
Harwich Port, Cape Cod, Mass. (jpage@capecod.net)
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