Go to the bridge development page.
Go to the "Make your own bridge" page.
How can I buy one of Red's bridges?
Here's how I fit a maple bridge.
Feel free to write if you have questions during this process.
First, mark the feet of the new bridge, using the bottom of your old bridge as a guide.
Work your new bridge's feet down close to this line with files or sanding. The close you
can get, the easier the next steps will be. Then, again tracing from your old bridge, cut the new
bridge to approximate height, leaving 1/16" or more extra height for the time being.
To fit the bridge feet, I use the sandpaper method. To protect the mandolin finish, cut a
piece of medium sandpaper about 1" x 7", and then cut a piece of heavy paper about 1" bigger each
way. Attach the sandpaper, centered, onto the heavy paper with spray adhesive, Elmer’s, or even a
gluestick. Now the sandpaper ends and edges, potentially scratchy, will be isolated from the top.
Some bridgemakers like to add a piece of heavy paper about 2 1/2" long, centered underneath the
first piece.
For now, leave the old strings on the mandolin, but loosen them enough to leave a slight
pressure on the top of the bridge. Lay that two-layer paper/sandpaper rectangle down on the mandolin
across the centers of the f-holes, then tape the ends of the paper onto the mandolin with masking tape
extending over the binding and part way down the sides.
The strings keep pressure on top of the new bridge as you move it from side to side on the
sandpaper. This seems to help a lot, both in sanding both feet the same way at the same time, and in
keeping the bridge standing at the right angle. I use sanding strokes about 1/2" long, and the string
pressure regulates it to about this far, anyway. This seems to work fine as far as getting a good
fit goes. I usually sand from the bass side for a while, then turn the mandolin around and sand from
the treble side.
Take the bridge off every hundred sanding strokes or so and check it at a sharp angle to a
bright light bulb to see how the fit is doing. Since my preliminary foot shaping is with a belt sander,
the part of each bridge foot which now fits the mandolin top is much smoother and easy to see. Sometimes
if I was lucky with the belt sander to begin with, a bridge will surprise me and fit after only 200 or
300 strokes. Other times I can spend 15 or 20 minutes or more on this step.
Some bridges are really recalcitrant and never really look like they come to a great fit, but
sometimes these are among the best-sounding bridges. All that goes to show that there’s a lot yet to be
discovered about mandolin bridges!
Cutting and compensating the bridge top:
If you want to preserve the same string-height as before, mark the top of the new bridge from
the old bridge. Leave an extra 1/32" or more for now— you can always take it down later. Cut or sand
the bridge top down to the line. Mark the string slots in pencil on the bridge top, using your old bridge
as a guide. Make sure the slots are centered not only on the bridge top, but also above the bridge cutouts.
Make narrow file cuts on the pencil marks, and then compensate the bridge with a small triangular
or flat file. I compensate most of my own bridges very simply, leaving the E and D strings all the way
forward and cutting the A and G string slots about 3/32" back. Up-the-neck intonation is excellent. (It
is not necessary to make compensation cuts on the back side of the bridge, except for aesthetic reasons.)
Now enlarge the string slots slightly to fit each string, making sure that the slot bottoms are smooth and
not in a tight “V” which will bind the strings. Slant the slots a little downwards from front to back.
Now try the bridge out. Make sure it has good contact on both feet, refitting as necessary, and
then work the bridge top down to your preferred action. Fine-sanding the new bridge and any stain or finish for it are up to you. Now play, and enjoy!
To drop me a line with any questions,
click here.
Red Henry.
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