Bridge gain delamination

[Roger Jolly]

Hi Patrick,
                I am assuming that the splits are only in the vertical
laminations.
I have successfully repaired a number of Baldwin vertically laminated
bridges with separations.

You need a few cabinet makers wooden handscrews. ( the wooden clamps with
two handscrews)  The points of the jaws will allow you to slip down between
the side of the bridge and the plate.  Or you can modify them on a band saw
so that you can get a good grip on the sides of the bridges..

Remove enough strings to give you room to work.  Dry clamp the offending
area and see if you can draw the split together, usually no problem.

Remove the bridge pins that have hair line cracks.

I use West System thin epoxy. Swab the pin holes, and the split.  Install
new bridge pins.
Tighten clamps.  Clean excess with acetone.  Leave for 24hrs to cure.

If you have not used wooden handscrews. You need to practice a little
before you start.  They have a good deal of clamping power once you get
used to them, and are less prone to marking or denting your work.

Replacing the bridge pins is a personal fetish for this type of repair. But
the pin will act like a pump and fill your small cracks from the bottom.

I presume the bridge cap is not cracked.

Hope this is of help.

Roger






At 11:57 AM 31/07/00 -0400, you wrote:
>Dear List:
>I just returned from a piano evaluation, for a customer looking to buy a
(32 year
>old) small model 350 Kawai grand, walnut veneer, for $4500. Everything
looked AOK
>EXCEPT:
>the bridge gain (cf. Mason, he also calls it the bridge core; I'd call it the
>bridge body) is separating along the diagonal joint 3-4 notes above the
>tenor/treble break. There's minor cracking of the bridge surface at the
bridge
>pins, but there's clearly been some glue joint failure at the joint in the
body of
>the bridge (the sides of the bridge are no longer flush, the joint line is
too
>prominent). No tonal deficiencies because of it (yet).
>I'm (optimistically) thinking I could fix this in the home by running
screws with
>washers through the separated parts, soak epoxy into the slight but real
>separation, etc. I'm hoping that with 2-3 sessions the bridge should be AOK.
>Have any of you had success with this kind of repair on other Asian pianos
(I've
>seen this as a problem area on all of their long bridges)?
>Or should I tell my customer to back out of the deal?
>Comments, Jim Jon Ron Roger et al?
> 
Roger Jolly
Saskatoon, Canada.
306-665-0213
Fax 652-0505