Recently, a customer brought
a ’74 Gibson flattop into
our shop for me to check out.
It was in good overall condition
and sounded good, too, with
a warm bottom end and silky
highs. But as I was examining
the guitar, my eyes were drawn
to six black bridge pins protruding
from its wafer-thin rosewood
bridge and strings that were sloping
over a rickety, bottomed-out
plastic saddle. I’ve seen my share
of wafer-thin bridges on flattops
built during this time period,
and I’m familiar with the problems
that can occur with them.
Often, the bridge develops cracks
between each bridge-pin hole
and they follow the grain lines.
Thin bridges can also bust out at
the front. This is caused by having
insufficient mass to resist the
forward pressure from the saddle.
Measuring the action, I also
determined that the strings
were low on the fretboard. You
could hear that they were getting
slightly choked off, and this was
hindering sustain and clarity. But
I knew that, with a few changes,
we could significantly improve
the guitar’s dynamic response,
overall volume, and tone. To
make this happen, however, the
flapjack bridge had to go!
Bridge Removal. Before
starting any work—and especially
before using tools that apply
heat—the first crucial step is
to protect the top of the guitar.
For this, I used a thin layer of
card stock with a hole cut out to
allow the bridge to fit through.
To remove a flattop’s bridge,
I use three tools from
stewmac.com: two bridge heater and
fingerboard irons (item #4607)
for applying heat to the bridge,
a surface thermometer (#4603)
for accurately reading the temperature
of these irons, and
a bridge/fingerboard removal
knife (#4464) to help separate
the glue seam. You can get the
job done with just one bridge
heater, but two of these really
expedite the removal process.
I used a hot plate to heat up
the irons, and the surface thermometer
to monitor their temperature.
I kept my eyes on the
gauge and adjusted the hot-plate
setting until the irons reached that
sweet spot of 250 degrees F. Once
the bridge heaters were ready, I
placed them on the bridge, allowing
the heat to penetrate through
the wood and into the glue seam.
After 10 minutes, I picked up
my removal knife and applied
gentle pressure to see if the glue
seam was ready to separate. This
is the time to be graceful and not
force the knife—you don’t want
to tear out the spruce top. At first,
you’re simply probing to see if the
glue has softened enough to allow
the knife’s tapered, stainless-steel
blade to penetrate the seam. With
some patience and careful prying,
the bridge came off like butter.
Fabrication. The next step
involved making a new bridge
that would add 3/16" thickness
to provide more stability and
increase frontal support for the
new elevated saddle. To make my
replacement bridge, I began with
a rosewood flattop guitar bridge
blank (#0160). Actually, I ordered
three blanks, because I was hoping
to find one with a grain pattern
similar to the original. When
they arrived, I found one that, for
all practical purposes, matched
the grain pattern of the Gibson
bridge. Any of these blanks would
have functioned superbly, but the
client and I felt it was important
to try to match the subtle details
of the bridge I was replacing.
And that original bridge still
had a role to play—I used it as a
pattern. I carefully measured and
then duplicated its footprint, pin
holes, saddle slot, and lacquer
line on the replacement blank.
After squaring up the two
sides of the 1/2"-thick rosewood
blank using my Grizzly spiral-cut
jointer, I used double-sided
tape to fasten the blank to a section
of countertop board before
running it through my DeWalt
Planer. These tools make the job
go quickly, but it’s worth noting
that if I didn’t have a spiral-cut
jointer and a planer, my Luthier’s
Friend Sanding Station (#5659)
would work for squaring and sizing
the blank to its target 5/16"
thickness. For the most part, the
Sanding Station offers the ability
to fabricate a complete bridge
without any other tools.
With the rough thickness
established, I used double-sided
tape to attach the original
bridge flush to the front
edge of the blank, and then
marked the bridge-pin holes
and traced around the sides
and back.
A 3/16" brad-point drill
bit works well for drilling the
initial bridge-pin holes. After
drilling, I used a band saw
with a fine-tooth blade to cut
the sides and back edges of the
blank to shape. Finally, I used
the Sanding Station for scalloping
the wings of the bridge
and overall final detailing.
Next month, we’ll finish this
bridge-replacement project.
John Brown is the
inventor of the Fretted/Less
bass. He owns and operates
Brown’s Guitar Factory,
a guitar manufacturing,
repair, and restoration facility
staffed by a team of talented
luthiers. His guitar-tool and accessory designs
are used by builders all over the world. Visit
brownsguitarfactory.com or email John at
info@brownsguitarfactory.com.