Enlarging existing bridge pin holes

[David Love]

Correction here, I don't insert the "old pins".  Don't know why I wrote
that.  I insert new pins.  The reason I'm not using the old pins, and
the reason I don't, is because they are often notched by the strings and
I prefer to start fresh.  Also, pulling them out usually mangles them a
bit.  

David Love
davidlovepianos@comcast.net 

-----Original Message-----
From: David Love [mailto:davidlovepianos@comcast.net] 
Sent: Sunday, May 01, 2005 12:43 PM
To: 'staff@smithpiano.com'; 'Pianotech'
Subject: RE: Enlarging existing bridge pin holes

I always at least recondition the bridge top using epoxy on a
restringing job.  I don't know Nick's specific method (I think I use a
method outlined by Bill Spurlock), but I generally sand out the string
grooves and recut the notches, insert the old pins with epoxy.  (BTW
since I tend to clean off all the old dag with denatured alchohol first
because I like the look of wood, it can make it difficult to see where
you are cutting the notch relative to the pin line.  I take a flashlight
and shine it toward the notch from a position parallel to and even with
or slightly below the bridge top.  The notch will be illuminated while
the top will be is slight shadow.  It makes it very easy to see exactly
where your cut is.)  My method is changing a bit now as I go to a lower
viscosity epoxy and apply, let harden and sand before I reinsert pins
but I'm still developing it.  In this case, I don't want to fill a lot
of space with epoxy on the odd sized pins.  Since the change is from
.122 (original pin) to .135 (#10 pin) and is only in the bichord section
of the bass, I'm not too worried about the change in diameter effecting
the offset.  And the change in the string position at the damper will be
so insignificant as to be hardly measureable.  

The upper end is getting new caps and the plain wire section of the
tenor is already #9s.  I don't like to use #6 pins and usually go to #7s
in the treble, 8s will work on this job as well.  I also don't like to
sand down the tops of the pins.  All the work to get them snug and them
heating them up while applying side pressure with a belt sander seems
counterproductive, even if you like the look.  

The concern I have with drilling out and enlarging these holes is that
the upward force of the drill at the edge of the hole tends to want to
take chips of wood out around the pin.  I've experimented with a couple
of holes on the backside of the bridge just doing it by hand and
pressing down just hard enough that the drill goes down a little faster
than it wants to cut.  That seems to help.  Unfortunately, it requires a
precise matching of the angle so as not to go down crooked and create an
oblong hole.  I'm going to try a reamer as soon as I get them which will
enlarge by scraping rather than cutting and hopefully prevent this
problem.  I may taper the tip just slightly so as to get it started in
the right direction.  Fortunately, there are not that many holes.  

David Love.
davidlovepianos@comcast.net 

-----Original Message-----
From: pianotech-bounces@ptg.org [mailto:pianotech-bounces@ptg.org] On
Behalf Of Brad Smith
Sent: Sunday, May 01, 2005 11:17 AM
To: Pianotech
Subject: RE: Enlarging existing bridge pin holes

Hi David,
Is there any reason that you must use the #10 pin, other than the
'in-between' size of the original?
Nick Gravagne has great articles and an excellent PTG class on
reconditioning an existing bridge; re-notching, etc.
Using West Systems epoxy to fill cracks, and size the existing holes,
and
then drilling with one size lower drill bit to enable use of original
size
pins.

I just did an M this way, worked very well.  Size #7 pins in the long
bridge; epoxy; drill out with the bit intended for #6 pins.  Install new
#7's.
Buzz them down with carefully with belt sander.    And, I used the
hanging
Dremel tool with the flexible shaft thing. (Drill bits from Pianotek).

Of course, you'll have to weigh the decision, since you are not going
back
in with the odd size 9 1/2 pins.
If you put enough epoxy into the holes, to then drill with #8 bit, and
install #9 pins...it's likely you would end up with more epoxy remaining
in
the drilled out holes.  This stuff is so strong, I would do it with
confidence.  Others may favor the enlarged hole and complete contact
with
fresh wood using #10's.

Also, what are the consequences of using big fat #10 pins...or using
slightly smaller #9 pins. Will it affect side bearing, or relationships
with
dampers?
Perhaps not enough to worry about.

I'm not sure how critical the type of bit is, obviously it's part of the
puzzle.
Most important is the lightweight shaft that allows you to drill and
follow,
without influencing, the angle of the original holes.
For that reason, you would want to avoid completely filling the holes
with
epoxy.
And, making a bridge pattern from acetate or Mylar is vital, should
anything
go awry.
You might even wish to start a size lower than your final bit, to
re-establish the holes, and then complete the sizing with the final bit.
Maintaining control, and working "intentionally" are most important.

Nick's class also covers a great way to fix bunged up notches; or cracks
that have distorted the notch termination on an otherwise good bridge.
This stuff, done right makes an old bridge look as though you've
recapped
it!


Best regards,
Brad Smith, RPT
www.smithpiano.com



-----Original Message-----
From: David Love [mailto:davidlovepianos@comcast.net]
Sent: Thursday, April 28, 2005 11:41 AM
To: 'Pianotech'
Subject: Enlarging existing bridge pin holes


I am repining a bridge and because the bichords are a strange in between
size (about 9 1/2), I need to enlarge the holes to accommodate a #10
pin.  I have not had much luck doing this in the past in a clean way and
am wondering how others approach this.  My thought is to reinforce the
bridge cap with a clear coat of epoxy first before drilling it out,
reaming out any excess that might create large globs inside the hole
before it sets up.  Any thoughts on this?  And what is the best way to
approach redrilling an existing hole: high speed, low speed, by hand?

David Love
davidlovepianos@comcast.net



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