Enlarging existing bridge pin holes

[Sarah Fox]

Hi David, Ron,

FAIW, I "inherited" a small, unusual drill bit of the type you may be
needing.  If you could untwist a standard twist bit, so that the flutes were
straight and parallel, that's what it would look like.  I have no idea where
you would find such a bit, and I have no idea what it's called, but at least
it exists somewhere.  <shrug>

Peace,
Sarah


----- Original Message ----- 
From: "Ron Nossaman" <rnossaman@cox.net>
To: "Pianotech" <pianotech@ptg.org>
Sent: Thursday, April 28, 2005 12:27 PM
Subject: Re: 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
>
>
> I haven't done this a lot, but I've had the best luck hand drilling
> with a modified drill bit. With a diamond whetstone, I ground the
> cutting edges parallel to the length of the drill. This makes a
> scraping cutter that doesn't grab and pull itself into the hole like
> a standard drill bit. Or you could order a spiral reamer of the
> appropriate size.
>
>   http://www.trianglereamer.com/highspeedsteel_reamers2.html
>
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