This poor old Gibson is in a sorry state of affairs. Two of
the back braces are missing, of the other two one has fallen out and the other
is loose. The bridge has not only come off but has split right through the peg
holes. You don’t need to take a real
close look to see I will not be the first or perhaps even the second or third
person to re-glue this bridge. There are
also a few cracks that in the top that will need cleated. This is one of those
jobs that have come in from another shop so I will be doing the structural
repairs and sending it back to them for the final set up work and anything
else.
There is a bit of good news in this little mess. The two
pieces of the bridge fit back together very well and all the small missing
splinters of wood were retrieved from the inside case and inside the
instrument.
First order of business is to replace those missing braces
and make sure the box is stabile and that nothing else is loose inside. So
using one of the large bottom braces as a reference and a partial pattern I
grab a billet of sitka and trace out the back radius. After planing the billet
to the proper radius with my block plane I cut two braces from it. The top
braces are narrower than the two bottom braces so I measured the width needed from
the glue footprint of the missing braces. I used the same height and side bevel
as the lower braces for my replacements. The braces were then cut to the
required length as measured inside the box and the end reliefs cut in on a
2-1/2” sanding drum. With a bit of final fitting they are almost ready to glue
in.
After I have them fitted just how I like I apply a bit of
dye stain to them so they match the other braces and the aged interior of the
box. Nothing says repair like fresh white wood peeking through an old
soundhole….. Here is what they look like in place.
At this time I also put a few cleats on two cracks in the
top. I opted not to try and glue the cracks themselves as they would have
needed splinted to do the job and that was more investment then the owner
wanted to make.
Now I can move onto the bridge. As I said I am not the first
to repair this bridge, but I will be the first to actually address the root
cause of this malady. The actual problem here is that the ball ends of at least
3 strings have pulled all the way through the bridge plate and the top. When
they get to the bottom of the bridge bad things happen…..If you look at this
pic you can see that the balls of the A, D & G strings have clearly pulled
through. Looks as if the B and maybe even the high E string might have pulled
through too. This may have been what caused the bridge to pop the first time
and definitely what caused it to split right through the peg holes.
A look inside and we can see the bridge plate is really
chewed up as well. This is in part because Gibson chose to use spruce for a
bridgeplate. An excellent course of action would be to replace it with a plate
made of tougher wood like maple or rosewood. But replacing a bridgeplate is no
small undertaking and is complicated in this instance by the fact that this
guitar is ladder braced instead of the more familiar X brace. This really
limits access with knives and spatulas to remove the old plate. There are other
options. In this case I will be using one of Stew Mac’s tool sets to repair the
bridge plate and add some durability as well.
Both the top and the plate under it will need repaired. The
tool has a set of cutters. One to cut out a small piece of wood around the
damaged hole and another to make matching plugs. I want to start with making
repairs to the top itself. Using the cutter part of the tool set I cut out the
bad wood at the peg holes, doing every other hole to start. You cannot do them
all at once as the plugs overlap slightly. The old spruce is brittle and
stringy. I turn the cutter in and then back it out to clear the chips working
my way in very slowly to minimize chipping and any chance of possibly splitting
the top.
The plugs for the top are cut from a scrap of sitka spruce
left over from a sound board. Here you can see the first 3 plugs glued in place
and what a plug itself looks like. Now I can do the other three holes.
To clamp these little plugs in place while the glue sets I
use double stacks of ½” high strength magnets. The polarities must be arranged
properly and I need a strip of masking tape to keep them close enough together
to sit directly on the plugs. Care needs exercised here when working with this
many of these magnets in such close proximity. A wrong move and they can jump
all over the place and cause some pretty serious dents.
While waiting for the glue on the plugs to set up I am
piecing back together the bridge. The large part fit quite well and after some
playing around I got most of the chips I found in the case and instrument to
fit back in rather good too. With a couple of clamps holding the little puzzle
together I wicked in some thin CA to hold it back together. After that set I
filled any small remaining voids with rosewood dust and some more CA . But the
bridge still had another problem. As part of a previous repair a split that had
formed under the saddle slot the last time the bridge popped was failing. I
could quickly tell this repair was done with yellow glue. It appeared as if
they simply filled the crack with it. It must have caused problems still after
wards as then from the top someone had tried to wick in some hide glue. The
saddle was actually slightly glued in the slot when I started. This is likely
because the string balls were still pulling against the bottom of the bridge.
Simply gluing the bridge back on did not fix that.
So I gently flexed the bridge at this crack a few times and
loosened as much of the old glue as I could that way. I then used a variety of
picks, blades and improvised tools heated up on my Bunsen burner to pick out
and dislodge as much more of the old glue as I could. Then the gap was filled
with a medium CA. After a bit of flexing the fracture and adding some more glue
I was satisfied that the void was full. I clamped the bridge down onto a caul
lined with wax paper to press it back flat while the CA dried. A bit of
scraping and sanding after that and it looked pretty good for a jigsaw puzzle.
I sanded the bottom of the bridge flat on my small surface plate and scraped
all the old glue from the top. Now I could glue the bridge back onto the guitar
and continue with repairing the bridge plate.
The repairs needed done in this order to be possible. That
is because the tool indexes on the peg hole. After the top is repaired the
holes are no longer there to use the tool from inside. By gluing the bridge
back on I can now align pilot holes for the tool accurately and begin work on
the bridge plate. The process is basically the same as what was done for the
top, doing the work in two stages of three holes each. Here is a shot of the
tool in use. Turning the handle outside the guitar turns the cutter inside and
draws it into the wood. It is equipped with a depth stop. One thing I am doing
different on the inside is I am using maple plugs instead of spruce. The maple
will be much harder for the string balls to pull through and make this a long
lasting quality repair.
After the bridge plate was plugged, pilot holes were again drilled
through and the holes reamed to fit new standard size bridge pins. The pearl
buttons were installed over the bridge bolts with some molten beeswax. A quick
coat of lemon oil and here we have it, almost as if it never happened. So the
next time you are going to re-glue a bridge, check and make sure that it is not
the string balls pulling through that are causing an issue. All the glue in the
world will not stop it from coming back off if that’s the case.
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