The Georgia Luthier Supply Bridge Clamp will bring simplicity to the installation of the traditional belly bridge or modified bridges with similar bridge pin spacing. It works without the use of supplemental clamps and provides for a quick and easy method of clamping and completing subsequent glue clean-up.
- 1/4″ x 1″ x16″ Aluminum Bar Stock
- 2 Plastic Knobs w/1/4″ x 20 x 1″ Long Threaded Studs
- Sheet Cork 1″ x 10″ x 1/8″ Thick
- (2) 3/16″ x 2″ Bolts w/ Hex Head
- (2) 3/16″ Hex Nuts
- (2) 3/16″ Lock Washers
- Hack Saw or Band Sand w/Metal Cutting Blade
- 1/4″ Tap To Thread (2) Holes in Aluminum
- Weldwood Contact Cement For Cork
- Drill Press or Hand Drill
- Appropriate Sized Drill Bits 13/64″ For Tapped Holes and 1/4″ Holes For Bolt Holes
This handy clamp is really quite easy to make. If you would rather make the aluminum base from a single solid piece of aluminum, a piece of 1″ x 3/4″ x 6″ long aluminum is enough to construct the base. If you have access to a metal cutting bandsaw blade, this may be a great option. For now though we will proceed with the construction of this clamp using the 1/4″ thick aluminum bar.
Cut the aluminum bar into the following sizes:
- (1) piece 6″ long
- (2) pieces 3-1/2″ long
- (2) pieces 1″ long
Glue the 2 pieces of 3-1/2″ long aluminum bar together using superglue. Next glue these 2 pieces to the 6″ long piece, centering on pieces on the longer aluminum piece. This will leave a 1-1/4″ overhang on each side of the long piece.
Carefully mark the bridge pins of the 2 “E” strings of the bridge on the bottom of the clamp. I have located these (2) holes 3/8″ from the edge of the clamp. Note they are not centered on the 1″ width of the aluminum bar. I have the holes located 2-1/8″ apart or 1-1/16″ from the centerline of the clamp. These holes should be 1/4″ and drilled completely through the (3) layers of aluminum. If you use a lubricant during drilling your drilling will go much faster and with less heat buildup.
Next, the holes for the plastic knobs with studs have to be drilled. You will want these knobs to approximately be centered on the bridge wings. I have mine located on the center of the 1″ dimension and 13/16″ from each end of the 6″ bar. Use a 13/64″ drill bit to drill these holes (verify with the thread tap you will be using). After drilling use a 1/4″ x 20 tap to thread the (2) holes to accept the stud knobs.
We will now build the supplemental clamping pads for the bridge wings. These are the 1″ x 1″ x 1/4″ aluminum pieces that were cut earlier. To receive the threaded end of the knob stud, drill a 5/16″ hole about half-way through each pad. Center this hole on each pad.
The Cork Protection:
To protect the bridge from damage it is necessary to apply cork or some other material to the clamping surfaces of the bridge and pads. I use 1/8″ cork and glue it to the bottom of the clamp and the bottom of the (2) bridge wing pads. For great results use Weldwood Contact Cement. It is perfect for use with cork. After the padding is dry, drill the hole through the cork on the bottom of the clamp.
An option to consider is to glue an additional pad of cork on the bridge wing clamping pads and after dry, shape the bottom of the cork to more closely match the curved shape of the bridge wings.
See our article on using this clamp here.