Split treble bridge

[Bill Spurlock, RPT]

On 12-2-94 Fred Scoles wrote about "a bridge split about 3 inches long which
runs along the top (speaking length) bridge pins and extends virtually to the
bottom of the bridge." "The part which split appears to have also warped since
the split is at least 3/16" wide on the treble end; and the break was not
"clean", as it has many splinters." This was on the top four treble notes of a 4
year old vertical, and Fred wondered about repairing with epoxy v.s.
replacement.

 Fred, I suspect that an epoxy repair might be better than new, since epoxy
tends to permeate any faults in wood and stabilize it against future
humidity-caused movement. (I would NOT use CA glue for a heavy-duty structural
repair like this.) So, if crack repair rather than replacement of a bridge
section is dictated, I wouldn't be afraid of doing it. Just document that you
are repairing a piece of wood that failed originally, and make it clear that the
same piece of wood could fail again.

On the other hand, you might consider routing off the top of the bridge and
capping it. This repair can be done in fairly reasonable time, without removing
the plate. You'll need an offset-base laminate trimmer to get close to the case
side at note 88. Make a pattern of the bridge top, then stick some hardwood
strips to the plate with 3M Mounting Tape (double stick) for the router to slide
on. Taper or shim as needed so they are parallel to the existing bridge top.
Note the elevation of the router slides to the existing bridge top. After
pulling all bridge pins and soundboard-to-bridge screws, rout off about 1/2" to
3/4" of the bridge slightly longer than the damaged area. Use an angled end stop
for the router to create an angled cut  where the cap will join the existing
bridge, so the cap and bridge join with an angled splice rather than a joint
going straight across the bridge top. (Don't worry about the crack going almost
to the bottom of the bridge--just epoxy the new cap on. The epoxy will fill the
bottom of the crack, and with a good thick cap the bridge will be structurally
stable.)

Once the cap is glued on, it can be routed down to match the original height if
necessary, using the same hardwood strips on the plate. Drill, notch and pin to
complete the repair.

Have fun,

Bill Spurlock