those pesky nose bolts, now locate guide rail.

[Nick Gravagne]

Hi Fenton (Mr. B3!)

Your question presupposes that you want to locate the damper guide rail
(DGR) in its original location.

After your new board is made and dry-fit to rim for bridge location and all
around fit, put everything aside and go to the hobby store or local gunsmith
and pick up a small container of BBs (unless you have some random small ball
bearings rolling around somewhere). You will use these in a fashion similar
to dowel centers.

Do not plug the original DGR holes in the belly bar. Now place the 5 or 6
BBs in the DGR holes and light tap them down to seat(or use 1 BB at a time
and move to next hole), set your board over top and either with the side of
your fist, or else a small dead blow and block of wood, strike down on the
soundboard top over the area of the BBs. Upon removing the board find the
small indents and drill through from bottom to top with a 1/8" brad point
(usually the right size). Don't worry about EMC unless for some reason the
board is extreme one way or another (which it shouldn't be anyway).

When gluing in the board leave the holes un-plugged. In fact, the 1/8" DGR
holes can act as additional tooling pin locators. After the board is
installed and glue dry, simply chase the holes to clean out the glue and/or
change bit size to accommodate the screw. Make sure you drill deep enough.
Should your bits get clogged they clean up easily with water, especially if
you use hide glue.

This all assumes you want the DGR located in the original position. Usually
and for the most part we do. As other fine posts have indicated, if the
plate and bridges are re-installed exactly (or very near so) to original
locations the DGR will be where you need it. I have yet to re-install the
original damper wires without having to make or tweak the neck bends for
damper head left-to-right centering. 

If for some reason you know that the original DGR needs to shift to the
right or left some specified amount (say 1mm), you may still use the
procedure above, but this time drill very small reference holes as near
vertically as you can, and as precisely in the center of the indent as is
practicable. Use the small holes to measure left or right for the 1mm. If
this is the case you need to plug the original holes.

Works for me.

Regards,

Nick Gravagne, RPT
Piano Technicians Guild
Member Society Manufacturing Engineers
Voice Mail 928-476-4143

Nick Gravagne, RPT
Piano Technicians Guild
Member Society Manufacturing Engineers
Voice Mail 928-476-4143
 

-----Original Message-----
From: pianotech-bounces at ptg.org [mailto:pianotech-bounces at ptg.org] On Behalf
Of Fenton Murray
Sent: Thursday, September 04, 2008 9:50 PM
To: Pianotech List
Subject: Re: those pesky nose bolts, now locate guide rail.

As long as we are locating things, how about some ideas on locating the 
damper guide rail.
My last job I pluged the holes, made a new rail and started over. I've 
frustrated myself trying to exactly locate the little number 8 screws, or 
whatever they are, drilling precisely in the right spot through the new 
soundboard, to catch the old hole.
Tips, techniques?
Thank you,
Fenton