Acoustic Guitar Maintenance - Bridges
The majority of acoustic guitar maintenance tasks also apply to electric guitars, so don't forget to check the main guitar maintenance page to make sure you don't miss out on anything.
This section however will deal solely with acoustic guitar maintenance tasks, starting of with...
Adjustment of Bridges
While working on the bridge is not the most common of tasks there may come a time when you feel it is necessary so it is well worth your while making yourself familiar with the issue.
The main reasons for making any adjustment to a bridge will be for correcting intonation, dealing with fret buzz and for improving the playability of the instrument without introducing fret buzz and rattling strings. Remember when making any adjustment to a bridge it is best practice to make little adjustments at a time, check the intonation and string height for any sign of fret buzz or dead strings by playing a chord or single note on every fret on the neck, and adjust again of necessary. Do this until the height and position of the bridge is set correctly.
For most acoustic guitars the possible bridge adjustments are limited to changing the height of the bridge saddle. The exception is arch top guitars which can have adjustments for height and position of the bridge on the guitar top.
For arch top guitars with adjustment wheels on each side, adjust the height by raising or lowering the sides, making small adjustments to both sides by going back and forth rather than changing one side completely and then moving to the other.
If you can't adjust the bridge to the desired height without introducing dead frets (where playing a note just give a dull thud rather than a ringing tone) or buzz then you have a number of options.Raise the action until the fret buzz does disappear and make do with the height of the strings if you can.Try a heavier gauge of strings. String the guitar with a slightly heavier set will pull the neck slightly raising the action slightly. Note you may need to adjust the truss rod when changing to a different gauge of string.Adjust the truss rod to provide a slight relief using the same gauge of strings if you don't want to opt for heavier strings. See my page on
Adjusting Truss Rods
.Address the buzzing fret by leveling the offending and neighboring frets. See my page on Leveling Frets.
Placement of movable bridges
Some acoustic guitars, again the arch top is a good example, have movable bridges which can accidentally be moved by getting knocked or when changing strings. It is important for the position of the bridge to be correct otherwise the intonation will be completely out, making the guitar sound out of tune up the neck.
Check for bridge position marks on the top of the guitar, perhaps a discoloration of the finish or even a line of dirt. If there are no tell-tale marks on the top of the guitar from the bridge you will need to do some measuring. First measure the distance from the top nut to the 12th fret. Then place the bridge saddle on the guitar top the same distance from the 12th fret. For example, in the case of a 24 1/2" scale guitar the 12th fret will be 12 1/4" from the top nut and the bridge saddle will be 12 1/4" from the 12th fret.
Check correct placement by playing a harmonic at the 12th fret and comparing to a fretted note on the 12th fret. Both should be the same and true. Do this with a couple of strings to ensure the bridge is aligned properly and not sitting crooked on the guitar top.
Sometimes a bridge comes loose and needs repaired by re- gluing. The repair process is simple enough but still takes considerable care. However, whether this should be considered acoustic guitar maintenance rather than repair is debatable!Remove stringsUsing fine sandpaper clean all traces of old glue from the guitar soundboard and bridge.The outline of the bridge may be visible on the guitar top, but to ensure the position of the bridge is defined, place the bridge exactly where it was originally placed and trace the outline using a sharp pencil.Apply hot hide glue to both the bridge and, carefully, to the top of the guitar. Place the bridge precisely where you have outlined, pressing firmly but taking care not to make the bridge slide on the guitar top.Place wood blocks on top of the bridge and under the bridge, inside the body of the guitar, using bridge clamps to secure them for 24 hours.Wipe away any excess glue from around the bride immediately the bridge has been clamped.
Note: Some bridges may also be bolted to the guitar top. To remove these the nut will need to be removed from inside the body of the guitar before attempting to remove the bridge.
Check out the other pages on Acoustic Guitar Maintenance by clicking the links below.
Next - Acoustic Guitar Maintenance - Saddles>
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Watch out for updates covering bindings and braces.