Making a New Bridge Plate:
This simplest way to make a new bridge plate is to make a pattern from the old bridge plate. This may be easier said than done as when you remove the existing bridge plate as shown in the article Removing a Guitar Bridge Plate, you will find that it comes out in pieces.
If it is not possible to piece together the existing plate you will need to construct one use the following method.
Take a piece of cardboard that is about 8″ x 6″ and hold it up against the point where the X braces intersect inside the guitar. Prop the cardboard with a stick that is propped against both the cardboard and the guitar back plate.
Place the Inspection Mirror on the bottom of the guitar, facing upward, along with the LED Work Light. Carefully mark the centerline of all the braces on the cardboard with a pencil.
Remove the cardboard and cut the cardboard out. Try to fit inside the guitar and keep trimming the cardboard until you have a perfect fit. This may take a couple of tries.
Material of the New Bridge Plate:
The best wood material for the bridge plate will be a good quality tonewood that is very hard, as it has to withstand not only the strain of the strings, but the resistance of the string ends from pulling through the wood.
I have the most luck with a piece of Indian Rosewood. The grain should run perpendicular to the grain of the top wood. Thickness should be about 1/8″.
Sizing The Bridge Plate:
For normal top plate conditions the bridge plate extends about 3/4″ to 1″ in back of the back side of the bridge and 1/4″ to 1/2″ in front of the front line of the bridge. Now this is for normal tops. For bellied tops, that is a different matter.
Depending of the severity of the belly you may need to extend the front of the bridge plate nearly all the way to the X Brace intersection, and to the rear of the bridge by 2″ in lieu of 1″. This is needed to straighten out the belly of the top and provide a better connection between the top and bridge plate.
Place your cardboard template on the bridge plate blank and cut to size with a band sand. Sand the edges straight with the Stationary Belt Sander and check the fit. Re-sand until you have tight joints against all the braces.
Finally ease the edges of the bridge plate a bit by sanding a slight chamfer on each edge of the plate. (About 1 mm). Final sand the plate with 220 grit sandpaper.
Tags: guitar bellied top, making a new bridge plate, repair a guitar bridge plate, warped guitar top
