Glue collars

[David ilvedson]

> Date:          Thu, 01 May 1997 10:05:07 -0400 (EDT)
> From:          JIMRPT@aol.com
> Subject:       Re: Glue collars
> To:            pianotech@byu.edu
> Reply-to:      pianotech@byu.edu

Jim,

I agree.  I have a number of Kawai uprights that had nice glue
collars but were clicking like crazy when the glue joint failed.
The problem was no way for the glue to escape via a hole in the
hammer or groove on the shank.




> Fred;
>   I agree with you on the overrating of glue collars in judging the quality
> of a hammer glue joint.  A glue collar can indicate several things among them
> being:
> 1.  An extremely close fit of bore hole and hammer shank.  In this instance
> the moulding scrapes off the glue as it is being positioned on the shank,
> leaving very little glue inside the moulding for bonding to the shank.
> 2.  Glue that is too thick, or cold, for the intended purpose whose viscosity
> allows it to 'roll' up the shank as the hammer is positioned.  Again leaving
> very little glue in the moulding for bonding to the shank.
>   I believe that it is better for a bore hole to be a 'little' too large
> thereby accommodating a good glue bond, rather than being a 'little' too
> tight thereby not accommodating a good glue bond.   There are exceptions and
> different techniques that address the hammer hanging process, as pertains to
> glue joints, and a good, neat, small glue collar is just one indicator of a
> good glue joint but it doesn't follow that if there is a good collar that
> there is a good joint.
>    One repair method for the original problem voiced, that started this
> thread, of loose heads is to use CA glue in the very thin formulation.  I
> don't necessarily recommend it but the method will work well as an expedient
> repair..  The old glue collars need not be removed, and in fact might
> facilitate the bonding with the CA.
> The thin viscosity will allow the CA to migrate into the loose joints and
> bond the moulding and shank, eliminating all clicking noises.
>   Just some thoughts.
>  Jim Bryant (FL)
>
>
ilvey
Pacifica, CA
ilvey@a.crl.com