Re: Removing A Bass Bridge
By Larry Fisher
> Subject: Removing A Bass Bridge
>
> I'm reworking a Monarch upright player
>
> ... , I'd like to have the bridge duplicated. How do I
> get the bridge out without destroying the sounding board? Is there a
> trick to it? The sounding board already has a few cracks that need to
> be fixed, and I don't want to add any more.
The bridge is usually attached to an apron, and the apron is then attached to the soundboard via a riser, or stick. Three screws typically attach the apron to the soundboard. These three screws are visible from the back of the piano and are "surrounded" by soundboard buttons. Two of the three screws will be easily removed. The third usually requires some careful planning. I've drilled a hole through the backpost large enough to clear my longest screw driver blade to reach the screw. This is by far, faster than trying to use one of those right angle screwdriver things. When the bridge is replaced, and you no longer need the hole in the backpost, simply plug it with a dowel or leave it for the next time bass bridge removal is needed.
Once all the screws that hold the apron to the soundboard have been removed, if the apron doesn't fall off on it's own, (lots of times this happens) then you'll need to use an offset chisel to fracture the glue joint at all the points you can reach where the stick or riser is glued to the soundboard. If this doesn't break it loose, dribble conservative amounts of hot vinegar and water on the glue joint and start pulling. You'll hear the wood fibers crackling and breaking, but I've never had any serious wood damage using this method. Once the glue joint breaks free, sever any remaining wood fibers and save this piece of wood to reglue later.
Label the apron, high end, low end, note one, note 30, whatever, to keep you from gluing the replacement bridge on backwards. Remove the screws holding the bridge to the apron, shock shear the glue joint and mail the bridge to Schaff for duplication.
Glue the new bridge on the apron, and tighten the screws. Remove slivers of wood from the soundboard that might buzz, or make sure they're well saturated with glue before you reglue the apron to the soundboard. Likewise with the matching surface on the riser or stick. These two pieces are a mirror image of each other, and their uneven surfaces should fit quite nicely together. Screw together as before and allow to dry.
Tips......
New screws tighten better.... they're not all rounded off from rust, age, etc.
Use new soundboard buttons, the old ones are probably going to break anyway.
I use wood glue, carpenters glue and have had beautiful results. Some swear to using hide glue, I swear at it. It's all a matter of what you're accustomed to using.
Keep a damp rag handy for wiping excess glue. There will be a place behind the apron you won't be able to reach very well. If you reglue with the piano on a tilt cradle, the glue won't travel very far.
Clean your old glue joints of all the old glue.
Regarding hide glue, there have been some threads regarding it's usage and some people really enjoy it's properties. I don't enjoy using it, and have used carpenter's glue for every bass bridge repair I've ever done. It's always been a successful repair, and it's always pleased the customer, and so I'm not about to change something that works.
Some of the soundboard will come off with the apron. Careful removal will produce minimal amounts of splintering. If someone has a better method, I'd sure like to hear it. Hot vinegar and water is a procedure I've used to break massive glue joints like the ones used to hold the pin block in an upright, but I've never had to use it to soften an apron glue joint.
Larry Fisher RPT, Metro Portland, Oregon's
Factory Preferred Installer for MSR/PianoDisc Products
phone 360-256-2999 or email larryf@pacifier.com
http://pacifier.com/~larryf/homepage.html
the piano's keyboard smiled at me & said, "I dare ya to tune me!" |
(Message sent Mon 29 Apr 1996, 15:54:44 GMT, from time zone GMT-0800.) |
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