How to Lower the Bridge on a Mandolin

The bridge adjustment screws are partially concealed by the bridge top.

On a mandolin, the bridge is the fixture over which the strings are fitted. The bridge elevates the strings above the body of the mandolin, so they sit just above the neck. The height of the bridge determines the clearance between the strings and fingerboard. Too much clearance means it is harder to press the strings down onto the fingerboard. This can impede your playing. Too little clearance means the string will buzz against the frets. While string height is a matter of preference, it’s essential to lower the height of the bridge so there is sufficient clearance without impeding your playing.

Things You'll Need

• Microphonic tuner or correctly tuned digital instrument
• Feeler gauge

Instructions

1. Tune the strings of the mandolin, either using a microphonic tuner or another, accurately tuned instrument as a note reference. A digital instrument, such as a keyboard is preferable as they don’t go out of tune. Tighten the tuning pegs to correct flat notes and loosen them to correct sharp notes. It’s essential that the strings are in tune when you measure the clearance, as slack strings can sag onto the neck, giving a misleading measurement.

2. 

   The first string is the thinnest one.

   Place a feeler gauge between the 10th fret and the bottom of the first string. Measure the clearance and note it down.

3. Place the feeler gauge between the 10th fret and the bottom of the eighth string. Measure the clearance and note it down. Ideally, the clearance on both sides of the fretboard is equal, but the bridge may have slipped due to careless handling.

4. Relax the tension of all strings so they sit slack against the fingerboard. The tension of the strings applies down-force to the bridge. In order to lower the bridge, you must relax this tension.

5. Place the mandolin on a flat surface, with the neck pointing to your left.

6. Rotate the treble-side bridge thumb-screw 180-degrees counterclockwise. This lowers the bridge slightly. The treble-side of the bridge is farthest away from you when the neck is pointing to your left.

7. Rotate the bass-side bridge thumb-screw. If the bridge was tilted slightly, making for unequal clearance, you must compensate for this when adjusting the thumbscrew. If the clearance of the eighth string was greater than the first string, rotate this screw slightly more. If the clearance was less than the first string, rotate it slightly less.

8. Tune all of the strings back to the correct pitch.

9. Measure the clearance of the first and eighth strings again. The clearance will have decreased. If the clearance on each side is still unequal, detune the strings and lower the highest side of the bridge by turning the thumb-screw. Retune and check the clearance again. This is a fine-tuning process that may take a few attempts, but it’s essential that the bridge is level.

Tips & Warnings

• If there insufficient scope for satisfactory adjustment from using the thumb-screws, remove the strings, sand down the top of the bridge and use a slotting file to create new string grooves. Some cheaper mandolins have non-adjustable bridges, in which case sanding is the only way to lower the bridge.

References

• Fret Not Guitar Repair: Mandolin Bridges