I've done maybe a half-dozen bridge repairs on bass bridges that have damage similar to the one you picture - and worse. All the repairs I've done have been on mid to low value pianos where the owner wished to minimize costs, but yet have a serviceable repair done. All but one were on vertical pianos.
My method is fairly easy. I use West System epoxy thickened with their #404 High Density Filler. You don't want to make the thickened epoxy too thick - just thick enough so that it will stay in the bridge cap crack. You want the epoxy thin enough for it to soak into the wood a little bit so that you get a good epoxy/wood bond. Peanut butter consistency is too thick for this repair IMHO - that is why something like JB Weld is not a top choice for such a repair - I would be concerned that it might not adhere well to the wood because you can't really work the epoxy into the wood surface for bonding as it is way down in the crack.
1. Best perhaps to lay the piano down on its back - although I've only done that once - others were done with the piano upright with complete success.
2. Remove bass strings from hitch pins and bridge pins in affected area.
3. Remove bridge pins from affected area.
4. Trowel thickened epoxy into bridge pin holes and crack - squish it into the crack/wood as well as you can.
5. Push bridge pins back into holes getting them as close as you can to their original positions and attitudes.
6. Wipe up epoxy squeeze-out.
7. Clamp where possible to squeeze crack closed to whatever extent possible (nothing critical with this step - just do what you can).
8. Wipe up epoxy squeeze-out.
9. Let cure at least overnight - better two days.
10. Remount bass strings, chip to pitch, tune.
11. Collect $$ and watch client smile while you do it!
Below is a picture on one of my first (maybe even my first!) bass bridge repairs. I know you can't really see much, but at least you can see that the repaired bridge looks somewhat normal. The bridge pictured was cracked open MUCH more than yours - it looked like the Grand Canyon over the entire bicord segment of the bridge.
Now If I only hadn't put that darn bass bridge back in the wrong place!!!
I really don't have records of how much time it took me to do the job, but my recollection (such as it is (or isn't)) is that at most it took two to three hours to remove the strings, apply epoxy, set bridge pins and clean up. Then the next day or two later maybe an hour to put strings back on and get it up to pitch. IMHO, this results in a bridge repair that looks okay and functions VERY well. No reason to think the repair won't outlast the life of the piano.
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Terry Farrell
Farrell Piano Service, Inc.
Brandon, Florida
terry@farrellpiano.com813-684-3505
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Original Message:
Sent: 09-26-2018 20:05
From: Sheffey Gregory
Subject: kawai upright bass bridge
This bass bridge [see attachment] is on a 1994 Kawai UST 8 which belongs to a non-profit. Ideally, the bridge should be replaced, but that is not financially possible. The only bass bridge repairs I've done are where the cap had separated from the root. And I'm not even sure a glue and clamp job would work. I am hesitant to run screws in the side of the bridge for fear of damaging pins. Has anyone done a repair on this type of damage? Success? Special considerations? Horror stories?
[This will also posted in the FB group "Global Piano Technicians" ]
Thanks,
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Sheffey Gregory, RPT
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