Epoxy in bridge pin holes, new or old bridge.

[gordon stelter]

Hi Terry,
    I think that impregnating/coating the bridge with
epoxy as much as you can without it looking like a
"candied apple" is your best bet to stop future bridge
pin loosening. Other pins popping up "hither and yon"
during placement in epoxied holes probably has a lot
more to do with internal cracks than normal porosity.
    I suggest: Put epoxy in a few (20?) holes at a
time. Don't worry about a little "slop-out". Waft
gently with a warm breeze from a heat gun. This lowers
the viscosity considerably, so that the epoxy will
penetrate the wood better, the pins will go in easier,
and squeeze out will be much easier to paint around
the wood surface. Go to next section.
    If you do this correctly the epoxy will make the
bridge look like it is nicely varnished and, I
believe, help with vibratory transmission.
     When it is fully cured, take a razor blade and
use it like a tiny cabinet scraper to make the bearing
surface perfectly flat ( remove nibs, brush marks,
etc..)
     Then, take a regular pencil with a soft lead and
see how easy it is to NEATLY lubricate the top!The
razor makes the epoxied bridge top just "rough" enough
to accept the pencil graphite beautifully!
     Thump
 
--- Richard Brekne <Richard.Brekne@grieg.uib.no>
wrote:
> 
> 
> Terry Farrell wrote
> 
> > >Arrrggggg! I have done that same technique on an
> old bridge as part of
> > >refurbishing the bridge. I'd be afraid to do that
> on a new bridge. I
> > >suspect there is always some resonable concern
> regarding how much epoxy is
> > >absorbed into the wood and out of the void
> between pin and wood before the
> > >epoxy hardens. My plan is to swab the hole with
> unthickened West System
> > >epoxy and drive the pin into a normal tight hole.
> > >
> > >Terry Farrell
> > >
> 
> Why would a (very) little epoxy absorbing into the
> wood be a problem ?
> 
> 
> > Ron Nossaman wrote:
> 
> > I suppose it depends on what you think you want.
> If you think you want the
> > pin bottomed in the hole, you can't use epoxy
> unless you arrange an escape
> > route for the excess that will prevent the pin
> from bottoming - or blowing
> > out somewhere else from hydraulic pressure as you
> drive it to full depth.
> > That's going to be either an oversize hole, or
> drive it dry. If you think
> > it isn't necessary for the pin to bottom in the
> hole, the epoxy can escape
> > into the excess depth of the hole without making
> the hole oversize or
> > blowing out elsewhere, or you can drive it dry.
> the one thing you can't do
> > with an oversize hole is drive it dry, bottomed or
> not, and expect it to be
> > functional.
> 
> This is all true enough as far as it goes. I do use
> essentially oversized holes...
> that is to say if the pinis just slim enough that it
> can be pushed in and taken
> out dry with the fingers, then the holes are
> obviously oversized. The (very thin)
> epoxy can find its way up the sides of the pin to
> form and allowed to form a
> collar at the top. Clean off as necessary. Judicious
> use relative to the amount of
> epoxy put into the whole limits overflow / waist.
> One little trick that takes care
> of this and any bleed off into neighboring holes is
> to use a piece of piano wire
> to gauge how deep the hole is... which tells you how
> much epoxy you need to drip
> in.  Pins being of the same length then will then
> end up << bottomed out >> in the
> epoxy and will be one hundred percent solidly
> coupled to the bridge on all
> surfaces. Cant hurt me thinks.
> 
> As will every thing... practice makes perfect and
> you get the hang of how to
> accomplish this one successfully fairly easy. But
> what I like most is the long
> term. Seems to stay solid for like ever. Getting a
> pin into an undersized hole
> without damaging the wood in one way or another is a
> good trick, and one that it
> would seem to me easily takes as much time and
> carefullness as dealing with the
> kinds of problems the epoxy solution presents.
> 
> When so many types of falsness are so easily curred
> by CA treaments, or epoxy
> treatments, it seems to me like a good idea to begin
> this way. Especially when the
> end result seems to last quite a bit longer.
> 
> >
> > So it seems to me that the first thing you need to
> decide is if you want
> > the pin bottomed in the hole or not.
> >
> > Ron N
> 
> This way you dont have to make that decision, tho
> the pin ends up bottomed out in
> the epoxy. I'd like to know what this concern about
> the epoxy soaking into the
> wood is all about tho.
> 
> Cheers
> RicB
> 
> --
> Richard Brekne
> RPT, N.P.T.F.
> UiB, Bergen, Norway
> mailto:rbrekne@broadpark.no
> http://home.broadpark.no/~rbrekne/ricmain.html
> http://www.hf.uib.no/grieg/personer/cv_RB.html
> 
> 
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