Since the early 1930’s, when C.F. Martin introduced their dreadnought guitar line to the public, the Belly Bridge was an amazing success and it has been used on the majority of acoustic guitars built since that introduction.
Even today the bridge of choice is the Belly Bridge. The reasons for using this bridge are many, but the basic reasoning is simple, elegant, big gluing surface and it’s a great tone transmitter.
Some of the other bridge choices can be the classic Gibson Moustache Bridge or the classic C.F. Martin Pyramid Bridge. Both of these are used on vintage re-creations and hardly ever on traditional acoustic guitars. This of course can depend on your own personal preferences of that of a guitar client.
Stationary Belt Sander
Brad Point Drill Set
Dremel Moto Tool 4000:
Self Adhesive Sandpaper 120 Grit
Adhesive Sandpaper 220 Grit
Wood Chisel Set
Beginning Construction Process:
If you haven’t shopped for your wood for the bridge you should do so. To get more information on wood go to our article Belly Bridge Construction, where I discuss the merits of the bridge, the wood to select and much more.
Also you should have within your position a great Bridge Plan, such as our plans from Georgia Luthier Supply
Step 1: If you purchased lumber for your bridges, start by re-sawing this lumber into bridge blanks. I always saw my blanks about 1/8″ wider and longer and make them a bit thicker too. Talking about thickness, you should have a few different thicknesses around the shop to address differing configurations for your guitars. Or better yet, make them all about 1/8″ or so thicker when you re-saw them. Above all else, make sure the blanks are perfectly square.
Step 2. Make a copy of the Guitar Bridge from your guitar plans and cut out the bridge with about 1/4″ border around the template. Paste this template onto the wood bridge blank with Spray Adhesive.
Step 3: My tool of preference is the Band Saw for cutting around the template. I prefer to cut about .5mm outside of the line to allow for a little sanding to get out the saw marks. If you are rather new to using the bandsaw, you may want to give yourself a bit more leaway, like 1mm.
While you are at it, use a Scratch Awl and place a center punch into the center of each bridge pin hole.
Time To Sand The Bridge:
Step 4: Take the blank to the Stationary Belt Sander. If you do not have a vertical fence installed on your belt sander, here is an article on how to make one of these invaluable jigs: Stationary Belt Sander Fence. Carefully hold the blank tight against the fence and sand all edges to the template outline. On the curved portions you will need to hang the blank over the curved sander wheel.
If you want an absolutely flat surface on the top and bottom of the bridge, the Stationary Drum Sander is the way to go. You can also do this on the Stationary Belt Sander with practice or with a Planer. Some luthiers just use a Block Plane and fix the bridge in a vice to cut it to exact height.
How To Sand The Bridge Ramps:
Step 5: You will find that this will be the most difficult step in the bridge building process, unless you build the Ramp Sanding Jig, which will make it one of the simplest tasks in bridge making.
If this is to be a one time only bridge making venture, there is no need to make the elaborate jig described above, unless you enjoy making jigs (I do, by the way). To make the ramps on the Stationary Belt Sander, carefully hold the bridge on the idler pulley and cut the ramp very slowly and check your work very often. It is easy to get humps and uneven sanding though.
Sanding The Backside Curve:
Step 6: If you look at a typical Belly Bridge you will note that the back edge of the bridge (behind the bridge pins), has a radius to it. You can make this radius by sanding cross-grain of the Belt Sander. Just roll the bridge with your fingers to cut this radius. Again – go slow and check that you are getting an even cut.
If you choose you can do this operation with Wood Chisels and sanding sticks too. It will take longer, but your chances of a screw-up are minimized.
Drilling The Bridge Pin Holes:
Step 7: To drill the pin holes you can use a portable drill or more conveniently, a drill press. Just make sure you use Brad Point bits to keep the bit centered. Also to prevent stock tear-out on the bottom of the bridge, use a sacrificial wood caul beneath the bridge blank. Size the holes to match your selected bridge pins, plus a bit for the strings. I find that if the pin has just a little friction when placed in the hole it will be just right.
GLS Tip: To get your pins nicely in a perfectly straight row, use a fence with the Drill Press so you simply slide the bridge blank to each new location for drilling the next hole.
Bridge Pin Countersink:
Step 8: I find it a nice feature to countersink the bridge pins just a bit. This is easily done with a ball-shaped milling bit, which closely matches the bottom of the bridge pins. Be sure to use a depth stop on the drill press so all of the holes look exactly alike. If you like do a trial and error on a scrap piece of wood the first time. Again to make this easier use the fence setup described above.
Step 9: String Ramps are very important and help to minimize string breakage and extend the life of your strings. I prefer to use a Dremel Moto Tool with a few different sized down-cutting bits installed. Just hold the Dremel like you would a pencil and cut the ramp in at a 45 degree angle. Now round or put a slight radius on the top and bottom of the ramp. Try you best to make them all the same.
The saddle is best left for later. I usually make the bridge, glue it in place, then check the exact scale length and make any necessary adjustments and cut the saddle slot after the bridge is glued in place. We will discuss that in another article.
Do you Need More Help Building Your Guitar
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