Champ’s Shop Talk: Ready, set, action
by Devin Champlin
When people are talking about stringed instruments (like a guitar, bass, violin, etc.), the word action gets thrown around. We’re not talking about some sort of movement as the word might seem to imply. Action describes the space between the fretboard and the strings. When you press down on a string, ideally it shouldn’t take too much effort to touch it to the fret. If the action is too high, playing can become more work than it needs to be. High action is a very common issue on a lot of instruments I see, and often people don’t know quite what the problem is, but they just know that their guitar is not as fun to play as it used to be. Fortunately, there are some simple adjustments that can be made at home with a confident hand.
The method will vary depending on what style of instrument you have. First you’ll want to measure where your action is currently sitting. There isn’t one measurement that applies to every instrument or player but I’ll generalize here a bit for simplicity. Measuring in 1/64 inch increments off the top of the 12th fret to the bottom of the string, I like to see about 7/64” on the bass side and 5/64” on the treble for an average acoustic guitar. I set action about the same for an electric bass. On an electric guitar I go lower, usually close to 5/64” on the bass side and 1/16” on the treble. Don’t have a ruler that measures in 64ths? For a rough measurement, try two dimes on the bass side, and one nickel on the treble. That’s close.
Most action adjustments happen at the saddle. On a flat top acoustic guitar the bridge is the wood piece on the top of the guitar where the strings end, usually held in place by pins. The thin strip of material (often bone or plastic) that the strings bend across is called the saddle. For electric guitar bridges there is a wide range of styles, but most can be lumped into two categories: Gibson style, where the whole bridge moves up and down on two adjustable posts, and Fender style which often have height adjustable saddles for each string. Before making any action adjustments, you’ll want to make sure your neck is relatively straight, and your nut slots are properly adjusted. (For more info on neck adjustments, see my article in What’s Up! May 2018).
I’ll start with electric guitars which typically have the most user friendly adjustments. For a Gibson style bridge (also archtop guitar, mandolin, etc) there should be either two thumbwheels under the bridge, or sometimes a flathead screwdriver adjustment from the top. Bring both sides down an equal amount of turns until you get close to the measurements above, then fine tune each side as necessary. For a Fender style bridge (like on a Stratocaster) you’ll need a small allen key. Each individual saddle can be adjusted up and down, usually with an adjuster screw on both sides of each saddle. On a six string guitar that makes for a whopping twelve points of adjustment for string height. Here you’ll want to set the outer strings to roughly the height listed above, and then adjust the rest of the strings to match that height, but also following the curve of the fretboard. Remember to tune the instrument after making the adjustments. Many electric guitar saddles also adjust forward and backward for intonation. I’ll touch more on that in a future article.
Adjusting the action on an acoustic guitar can be a bit more of a project, but still very approachable. First determine how much you want to lower the action. You’ll have to remove about double that amount from the saddle. Take off the strings, and carefully pull out the saddle from its slot in the bridge. You’ll want to leave the top of the saddle, where the strings touch, as is, so you’ll do your work on the bottom, flat surface of the saddle. Measure and mark a straight line across the bottom of the saddle. Lay a piece of coarse sandpaper on a flat surface such as a countertop. Moving the saddle across this, grind until you reach the line, checking every so often to make sure you are staying square to the sides. Replace the saddle and the strings and hopefully everything lines up right.
There are so many factors that go into a proper set up on any instrument. Hopefully this bit of info is helpful and only serves to get you better acquainted with your instrument.
Devin Champlin is a stringed instrument builder/fixer/player in Bellingham. Message him at firstname.lastname@example.org or visit champlinguitars.com.