epoxy alone

[Clyde Hollinger]

Del, Ron and others,

Agreed.  Thanks for all your helpful responses.

Clyde (with a "C," Ron) <G>

Delwin D Fandrich wrote:

> ----- Original Message -----
> From: "Ron Nossaman" <RNossaman@cox.net>
> To: <pianotech@ptg.org>
> Sent: June 08, 2002 6:21 AM
> Subject: Re: epoxy alone
>
> > Glyde,
> > In the case of the Conn, it should be fine because the existing bolts are
> > holding it from separating more. It would probably be just as fine if you
> > didn't do anything to it at all. This is likely the case with the
> Wurlitzer
> > too. Given a piano where the lags have pulled out and there's a gap all
> the
> > way across the top, I wouldn't trust a repair without bolts. Looking down
> > into these gaps, I usually (not always) see a relatively clean separation
> > at the glue line with little splintering of the wood. That means you won't
> > have a wood/epoxy/wood joint when you glue it back up. You'll have a
> > wood/old glue (that failed)/epoxy/old glue (that failed)/wood joint. Why
> > wouldn't the old glue that failed the first time not fail again this time,
> > with an indestructible layer of epoxy hanging on to it like grim death?
> > Epoxy alone might work, or might not. It might work temporarily or
> > permanently. It might just barely hold, or be something you couldn't break
> > if you wanted to. How would you know how well it's working until it fails?
> > I wouldn't trust it. I am reasonably certain that 4-7 3/8" carriage bolts
> > won't fail under a load that can be overcome with a couple of C-clamps,
> and
> > as long as I am unable to properly clean the old glue from the joint, I
> > think I'll keep using bolts.
> > Ron N
>
> I agree. Most vertical pianos built in the past 40 or 50 years have used
> heat-setting (that is via RF energy) adhesives to bond the pinblock to the
> back assembly. The process works well when constant attention is paid to
> details such as open time, even spread, consistent RF power, cleanliness of
> the electrodes, consistent (and adequate) press time, moisture content of
> the wood, etc.
>
> Unfortunately, many piano makers didn't (don't) always do this and have
> ended up (still end up) with joints in which the adhesive has dried but only
> partially cured, or boiled and lost its adhesive strength, or.... By using
> just epoxy you will end up with a joint that is only as strong as the
> already-failed original adhesive.
>
> When in doubt -- through-bolt.
>
> Del