Learning how to level guitar frets is a delicate procedure and determining the exact level for the string action requires quite a bit of skill. Guitar shops offer this service, but the process can be done as a home project by the brave guitarist.
You'll need to buy or borrow some basic equipment, including:
- Several grades of jewelry files
- Extremely fine sandpaper or steel wool
- Ruler with micro measure markings
- Soft, clean cloth
- Play the guitar to determine the action. Determine how low you want the string action. If the strings are leveled too low, the guitar strings may buzz. Strings that are too high make it hard to play and add interesting techniques. The hardest part of how to level guitar frets is to pick just the correct amount to level from the neck bridge and the exact amount to remove from each fret. Consider the types of playing you'll be doing. Playing with a bottleneck means leaving the action higher than you'd use for normal playing. Think about the type of strings that match your playing. Heavier strings can stand a little bit higher frets and still work well.
- Take all but one string off the guitar. Adjusting the action, also known as leveling the guitar frets, is a good time to switch out the strings to new models. The strings are off for the process anyway, so you'll save some time.
- Disconnect the one string from the tuner. You'll be reattaching this string to test the action, so leave it attached at the base.
- Start filing the main bridge height. This might be the only adjustment you need to make. Use the second finest file to take just a bit off the long bridge that holds the strings in place at the top of the fretboard or at the saddle at extreme bottom where the strings lift to reach the neck. Use a ruler with micro measurements. You need to take only a small amount from the bridge to change the action.
- Check the action. Re-attach the one string and play the guitar to determine if the leveling has moved the action the way you like.
- Measure the fret height with a long straight-edge ruler. Put the ruler across all of the frets to determine if all are aligned equally. If they are, you're ready to adjust all of the frets. If they aren't, lower the highest frets to match the height of the rest.
- Begin filing the frets with the finest-grade file. Don't take off too much. It's always possible to remove more, but putting additional height on the fret requires replacing each of the frets.
- Work evenly and carefully. Avoid any slips into the wood neck.
- Test the action again. When you've finally reached the point where the action sounds the exact way you like it, stop filing.
- Remove the last string and clean the frets. Roll the steel wool or sand paper into a tiny tube and lightly rub the frets to remove any irregularities made with the files. Be careful not to rub too hard or you'll take off more fret metal.
- Clean the frets. Use the soft, clean cloth to remove any excess filings or grit from the frets and neck of the guitar. Don't apply oil or polish to the neck or frets. This will interfere with the playing action.
- Put on new strings. Put one of the string packages in a safe place for future reference. Changing the string size and quality may result in the need to adjust the action again. Buying the same brand and make of strings will help in avoiding this problem.
- Test the level on the guitar frets. Time to play. Test the frets on the entire neck to make sure all are even and clean.
Erlewine, Dan. (1990). "Guitar Player Repair Guide."