Bridge removal
By Larry Fisher
"Michael Concordia" <piano-roll-one@worldnet.att.net> writes:
> the bass bridge is still firmly glued to the soundboard yet has to be
> replaced I have removed the screws and have tried a little vinegar in
> water solution applied to the joint with no positive results. Any
> ideas on how to go about this without damaging the soundboard?
The effect of water and vinegar is slow but will eventually weaken the joint enough to accomplish your goal. Here's a few tips I've found work well.......
The vinegar and water solution should be hot
Make a small trench at the glue joint using a wood chisel or one of those special funny looking chisels from the supply houses. If the plate is in the way, use something to score the glue line. This will focus the solution better on the glue joint.
Stuff rags in the surrounding area to keep the solution off any other glue joints. Wipe off solution from areas you don't want it as you apply it to the joint.
Using a large pipe wrench or huge lock jaw pliers, get a firm grip on the bridge and start rocking it bach and forth as space permits. If you're replacing the bridge all together, there will be no need to worry about cushioning the jaws of your tools, just be sure to retain the original dimensions of the bridge for replacement purposes. You'll hear some creaking and cracking of the wood as you rock it back and forth. Continue to add more solution as it become looser. Some of the soundboard will come off with it but usually not enough to worry about. I've only encountered a few splinters here and there. Since you won't be glueing the same piece back on that came off, and if you have lots of wood splinters from the soundboard come off with the bridge, fill the voids with automotive fiberglass (Bondo), sand smooth and reglue your new bridge on.
Another method that I can think of requires lots more paper work.
Measure and diagram everything about the bridge. Make a print of the pinning, and then proceed to totally mangle and destroy the bridge with every tool you can throw at it. A skill saw could be used to slice pieces off until nothing remains but the stumps, and then you could grind or file them down with a SureForm (I think is the brand name) file. I suppose you might be able to get a router to reach the depth from the plate, but then maybe not. If you could, you would have the opportunity to get a really nice machined smooth surface for your new bridge to be glued to.
It's only a piano. It's only a bass bridge. You need to remove the old one, put on the new one of proper dimensions, and get the string vibrations to the soundboard with as little loss (of vibrations) as possible. To do all this with as little financial loss is a whole 'nuther matter.
Lar
Larry Fisher RPT
specialist in players, retrofits, and other complicated stuff
phone 360-256-2999 or email larryf@pacifier.com
http://www.pacifier.com/~larryf/ (revised 10/96)
Beau Dahnker pianos work best under water |
(Message sent Tue 5 Nov 1996, 17:23:23 GMT, from time zone GMT-0800.) |
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