Bridge Pin Height Regulation, was: More, More (was Re:TharShe Blows!)

[Farrell]

No. Drill, swab with epoxy, drive pin.

Terry Farrell
  
----- Original Message ----- 
From: "gordon stelter" <lclgcnp@yahoo.com>
To: "Pianotech" <pianotech@ptg.org>
Sent: Friday, May 23, 2003 10:49 AM
Subject: Re: Bridge Pin Height Regulation, was: More, More (was Re:TharShe Blows!)


> Drill, impregnate with thin epoxy, drill again and
> drive pins?
>      Thump
> --- Farrell <mfarrel2@tampabay.rr.com> wrote:
> > Comments below:
> >  
> > > 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 ?
> > 
> > If the bridge pin is only a tad smaller than the
> > hole, there will only be a small volume of epoxy
> > filling any void space between pin and wood. If the
> > wood absorbs the epoxy, then there will be none or
> > little epoxy filling the void by the time it cures.
> > Just a concern.
> >  
> > > > 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. 
> > 
> > Another thing to keep in mind with epoxy - it relies
> > on a mechanical bond between wood and epoxy and
> > between metal and epoxy. It is recommended by West
> > System that when bonding with epoxy to metal that
> > the metal surface be sanded rough, coated with thin
> > epoxy, and the epoxy sanded into the metal for the
> > most secure bond. A nice new shiny bridge pin is not
> > likely to establish a good bond to epoxy. I can chip
> > epoxy off any glossy surface real easy when I get
> > waste on it - my floor, table top, etc.
> > 
> > Terry Farrell
> > 
> > > 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
> > 
> > 
> 
> 
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