Here I will be replacing a fixed bridge with a floating
tremolo system. This is a modification that was very popular years back when
locking trems first came out but one I don’t do very often these days. Our
starting point is a Carvin strat type guitar with a typical hardtail bridge.
After removing the bridge and all the electronics I need to
plug the two mounting holes at the front of the old bridge. They are not
exactly where I need my new pivot post bushings and in fact will be right at
the edge of them when finished. The holes are drilled out and some small maple
dowels glued in. Now I can put down some tape and start to layout the position
of my new bridge. A lot of folks would simply layout using the mounting holes
of the old hardware as reference. I instead prefer to layout based on the neck.
First I mark a line from each side of the fretboard. I then pull a parallel line
from the frets and use my compass to divine the centerline. I then measure out
my scale length and compensate for the offset between the pivot center and
average saddle peak to find the line my studs will mount on.
Now I can attach my acrylic template to the guitar to guide
my router. The template attaches with two screws that also will serve as the center
points for my pivot bushings. I carefully align the template and use a self
centering bit to drill pilots for the mounting screws. I drill one, put the screw
in and then drill the other. The layout tape is then removed and the template
attached for the cutting operations.
The neck can now be pulled off and the body clamped to a
bench to begin cutting. I use a plunge router for this with a solid carbide downcut
spiral bit with a guide bushing to waste out the material. I make a series of
cuts at quarter inch increments until I am within about ½” of coming through
the body.
After this operation the template can be pulled and I can
move over to the drillpress. With a forstner bit I will drill a hole through
the back aligned with the forward treble corner of the cavity I just cut. This
will serve as a reference point to align my template on the rear of the guitar
to cut the spring cavity.
I will also drill the two holes for the pivot stud bushings
while I am here. The less walking around the shop I do the better. Notice how
close the new holes are to the ones I plugged.
My back template is aligned and attached in a similar manner
to the one on top. It also attaches with screws which serve as cover mounting
holes in the end. A new hole for the ground wire to the bridge is drilled as
well as holes for the spring claw. After all the machining is done I take the
body over to my big buffing arbor and give the whole body a quick polish to remove
any slight marks that may have been left from the work. Now it is just a matter
of installing the hardware and setting up the guitar. Here is the finished
project. With just a few hours work it is a whole new guitar.
That's great work. Makes it look easy.
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