Epoxy Bass Bridge Repair

[Gevaert Pierre]

Hi Gregor,

 

Could you tell me where you can find West System Epoxy in Germany ?

I live in Belgium.

Thanks

 

Pierre

 

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De : pianotech-bounces at ptg.org [mailto:pianotech-bounces at ptg.org] De la part
de Gregor _
Envoyé : vendredi 9 mai 2008 17:49
À : Pianotech List
Objet : RE: Epoxy Bass Bridge Repair

 

Terry,

what do you mean by "you need to leave some epoxy in the gap. You don’t want
to epoxy-starve the joint."?

I found a source for Western System Epoxy handy repair set including that
filler here in Germany. Good to know, I will try it perhaps one day, but not
with that Kawai. I told the customer to ask a collegue who has 7 pianotechs
working for his shop: 4 on master level, 2 with certificate of
apprenticeship and one apprentice, and they have a huge workshop. I don´t do
repairs with woodwork anymore, just tuning, small repairs and selling
pianos. But in this case it probably would have been easier to order a new
brigde from Kawai which fits perfectly without any adjusting: just
installing and it fits.

Gregor

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From: mfarrel2 at tampabay.rr.com
To: pianotech at ptg.org
Subject: Re: Epoxy Bass Bridge Repair
Date: Fri, 9 May 2008 08:57:04 -0400

Epoxy repairs for a situation as you describe can yield very good results.
Sometimes the crack opens up a fair bit – you’ll want to clamp it back into
position – not to clamp in the traditional sense, but rather to simply
position the parts in their original orientation – you need to leave some
epoxy in the gap. You don’t want to epoxy-starve the joint.
 
I use West System epoxy resin, hardeners and fillers:
www.westsystem.com My favorite for a cracked bridge is #404 High-Density
Filler and using the West System two-step bonding procedure described on the
West System web site. The following is from the West System web site:
 
404 High-Density Filler
404 High-Density filler is a thickening additive developed for maximum
physical properties in hardware bonding where high-cyclic loads are
anticipated. It can also be used for filleting and gap filling where maximum
strength is necessary. Color: off-white.
 
You can either push the bridge pins into the uncured epoxy, tidy up and be
done with it, or, for a neater, more exacting job, you can epoxy the gap and
then drill bridge pin holes after the epoxy hardens. I have found that if
cosmetic considerations are not paramount, I apply the epoxy, clamp together
until the wood is close to original dimension, clean off epoxy squeeze out
(acetone) - at that point you will be able to see the outline of the
original pin holes - push pins in place - the wood will have been drawn
together enough to hold the pin in its original position - and then level
off and clean up the little bit of epoxy that squeezes out of the holes as
you push the pin in place. Wait a day or two for the epoxy to completely
cure, go back and install bass strings.
 
I've done this repair numerous times with great success.
 
And of course, on a nicer piano where the budget allows, new bridge and/or
new cap is preferred.
 
Terry Farrell

----- Original Message ----- 

From: Gregor _ <mailto:karlkaputt at hotmail.com>  

To: pianotech at ptg.org 

Sent: Friday, May 09, 2008 5:13 AM

Subject: Epoxy Bass Bridge Repair

 

I crawled the archieves but I did not really find what I was looking for:
does Epoxy work even for bigger gaps?

I wanted to tune a Kawai CE-11 upright yesterday but the bass bridge looked
horrible: a long gap which affected 9 notes. The gap started at the upper
pin row and the pins were vertical. Some strings rattled at the pins. The
gap expanded up to 4 mm above the upper pin row. I did not try but I could
imagine that I could have pulled out some pins without using pliers.

First at all: I never worked with Epoxy. My first thought was to pull out
the pins, fill the gap with epoxy and drill new holes for new pins. Could
that work or is such a gap too much for Epoxy? The bridge is made of one
piece of wood, no cap.

I was shocked about such a gap in a Kawai from 1992 (no grey market import):
no floor heating, no air con and no heater near by the piano. And I don´t
live in an area with huge differences in the climate. Very strange. That
damage is a pitty because everything else in this piano was in a pretty good
condition. But making a new bridge would be definitely too expensive
including transports from the second floor into a workshop and back to the
customer.

Gregor


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