Shimming an Adjustable Guitar Bridge

The saddle can be found next to the six pins holding the strings in place.

Low action on a guitar often results in an irritating and distracting buzzing sound as the vibrating strings contact the fret marker. Adding a shim underneath the saddle of acoustic guitars can raise the string height and correct the problems with the guitar’s action. The height of the bridge on an electric guitar can generally be adjusted with two screws on either side of it, but acoustic guitar saddles must be shimmed or replaced to raise the string height. Learn to shim the saddle of an adjustable bridge if you don’t wish to purchase a new one.

Things You'll Need

• 1/32 inch shims
• Screwdriver
• Ruler

Instructions

1. Locate the saddle. Look at the part of the guitar’s body where the strings are held. There will probably be a series of six pins holding the strings in place. Find a small strip of white material beside these pins. This is the guitar’s saddle, and the strings arch over it before they extend up to the top of the instrument. The height of the saddle controls the height of the strings themselves.

2. Measure the distance between the top of the 12th fret and the bottom of the strings. Find the 12th fret marker and measure the space between the top of it and the bottom of both the low and high E strings. The lower, thicker E string should sit 3/32 inch above the fret, and the high E string should sit 2/32 inch above the fret. Anything lower than this means your action needs to be adjusted. Make a note of the measurement.

3. Remove the strings from your guitar. The saddle is usually held firmly in place by the pressure of the tight strings pushing down on it. Loosen the strings by turning the machine heads at the top of the guitar to lower their pitch. Remove the strings by hand when they are loose enough for you to do so. Most strings on acoustic guitars are held in place by pins in the bridge. Remove these pins to completely remove the strings. Put the pins to one side so they can be used later.

4. Examine the sides of your adjustable saddle. Some adjustable saddles have screws on either side which can be used to change the height of the bridge without using a shim. If this is the case, turn the screws to the left to raise the height of the saddle by the required amount. Remember, you are aiming to bring your thick E string up to 3/32 inch above the 12th fret and the thin one 2/32 inch above. If your strings were 1/32 inch low, raise the bridge by that amount.

5. Pull the saddle upwards if there are no screws. Adjustable saddles come out easily, and can usually be swung to the side so you can add shims as needed. Move the saddle so you can see inside the cavity. Add in the required number of shims and put the saddle back in place. Be sure you know the thickness of your shims to avoid mistakes.

6. Replace the strings and measure the action again. If it is still too low, or is now too high, repeat the process to correct it.

References

• Fret Not Guitar Repair: Acoustic Guitar Saddles
• Sheehans: Acoustic Guitar Set-Ups ("A Look at the Aetup Process" - Step 7)
• Ovation Guitars: Use and Care Reference Guide