Acoustic Bridge Replacement
When an acoustic guitar bridge is damaged to a point it needs replacing most of the time a direct replacement isn't available. If it is a very traditional and common style of bridge, pre-made replacements can be considered, but usually differences in size, shape and pin location are such that it won't work well. This is the time to pay a qualified repair person to make a new bridge from scratch that will exactly match the original bridge. Yes, it can be expensive, but if the guitar justifies the work it is the best choice to make. Assuming there are no other issues that need to be addressed making a replacement is a fairly straight forward process (for a qualified professional).
The original bridge will be removed and used as a guide for the new bridge. The outline is carefully traced and the location of each bridge pin is transferred but the new hole is most often drilled "undersized" so that near the end of the repair the holes can be reamed to fit the bridge pins properly.
Not only is the outline matched but the dimensions in height for the center section of the bridge and the wings of the bridge would be made to the original specs. Over time an acoustic guitar top will "settle in" and pull up slightly under the pressure of the strings. Many acoustic guitars also have radius to the top and were never made truly "flat" to begin with. Therefore the new bridge will need to have the bottom surface fit properly to the top so ensure a good bond.
Reasons why an acoustic bridge might need to be replaced:
- Cracks have developed between the bridge pin holes that are too large to be fixed.
- Cracks have developed at the ends of the saddle slot that are too severe to be repaired.
- The original bridge was planed down at some point to improve the saddle height above the bridge. (see "Other Critical Info" below)
- This was a cheaper alternative to a neck reset and at one time was considered an acceptable fix.
- On acoustic guitars with doweled, epoxied "butt joints" this may have be the only reasonable option instead of a neck reset.
- The original bridge needed a reglue but it was never done and therefore has warped beyond repair.
Other Critical Information
If the original bridge has been planed down in thickness the first thing I will do is check the neck angle. I see no reason to replace a bridge in this situation unless the neck angle is fixed first. If the neck can be reset to have the proper angle the new bridge can be made to the original and "correct" height.
Another very important thing to check before estimating a repair is the location of the saddle. If there is a problem with the location I'll evaluate how much the saddle should be moved and note if that makes it too close to the pins. If the new location isn't a problem, the process moves forward pretty much as explained previously but...If moving the saddle places it too close to the bridge pins there is a ripple effect to the problems.
It is possible to also relocate the bridge pins on a new bridge as long as they are still supported inside the guitar by the bridge plate. The new bridge will be made slightly larger than the original so the bridge pins don't end up too close to the back edge of the bridge. Any finish under the bridge will be removed so there's a very strong bond between the bridge and the top. The bridge pin holes that have been drilled in the top wood and bridge plate will need to be plugged before the new bridge is glued on.
All in all the process can get pretty involved and therefore pretty expensive. Keep an eye on the bridge of your acoustic guitar to see if a small gap develops along the back edge and get it reglued by a professional before it gets worse. If you aren't sure it's coming loose take a small feeler gauge or even a piece of paper to see if it slips under the bridge. If so, take it to a pro and get an estimate on the repair and seek their opinion.