Acoustic guitar bridge setup

On the other hand, instruments that have been left without proper humidity will often become dry, which can cause the top to drop and create buzzing problems.

You may also encounter sharp fret ends that are now exposed due to the shrinking of the fingerboard. During times of low humidity it is essential that you keep your instrument properly humidified. Read more about humidity. As the strings pull to and fro across the nut and saddle they are slowly but surely deepening the groove.

Excessive wear in the nut slots may cause the strings to buzz when played open since they are now too close to the frets. Grooves in the saddle can affect intonation and cause strings to break. It is particularly common for the action on flat top instruments to raise over time due to the tension placed on the top.

The strings continual pull on the bridge and top can create a slight arching which raises the action over time. While a slight arch is quite normal, greater changes in the tops shape may be and indication of structural problems such as loose braces or a warped or cracked bridge plate. If you change the gauge of strings you are using, be it heavier or lighter, there will be a change in tension on the top and neck of the instrument.

When setting up an instrument you must choose what gauge of string you will be using so that the action can be adjusted accordingly. Changing the string gauge will effect your set up. Loose braces, loose bridges, loose necks, cracks and other structural problems may first become apparent when a player notices a significant change in an instruments action. The string is now forming a straight line between the two frets.

By doing this, the nut and bridge—the other two arbiters of action besides the neck —have been eliminated from the equation. If the neck is perfectly straight, there will be a tiny gap—just enough to slip a piece of paper or business card through—between the string and the frets in the middle of the neck.

If the neck has too much bow, or relief, the gap will be wider, and so the truss rod must be tightened. If the neck is back bowed, the strings will lie flat against the frets, and the truss rod must be loosened.

When adjusting the truss rod PHOTO 3 , turn the nut in minute increments—say, quarter turns—checking the relief frequently, and use as little torque as possible.

On an electric guitar, this is a matter of twisting the appropriate screws; on an acoustic guitar, you may have to shim or sand the bridge saddle. TOOLS A machinist rule, a screwdriver or hex-key electric guitar , calipers, a shim stock or stationary belt sander acoustic guitar. Unless you have experience with this modification, leave it to the pros.

Listen for buzzes as well as false notes—for instance, fretting an E note or bending to what should be an E and hearing an F. If so, go back and check your work.

One or two false notes on an otherwise well-adjusted guitar indicate an improperly crowned fret, something best corrected by a skilled tech. With the truss rod and bridge fine-tuned, we enter the final phase of action altering. Although these days, the vast majority of nuts are well made, even some expensive production guitars can slip through the cracks with nut slots cut a bit too high or too low. TOOLS A compete set of nut files, shim stock for raising the nut, X-Acto knife and other miscellaneous tools for removing the nut, electronic tuner.

If any open string buzzes, its string slot is low and the nut must be shimmed up. Of course, this means the other slots must be deepened to compensate for the higher nut.

If all is clear, check the pitch with an electronic tune. A high slot will cause the notes at the 1st fret to sound 10 to 15 cents sharper than they should.

Again, the slots must be deepened. This is serious surgery. Do your switches snap, crackle or pop? For amplified acoustics as well as electrics with active pickups, this means a battery check and, if necessary, replacement.

TOOLS Electronic contact cleaner available at any electronics store , various screwdrivers, socket wrench or adjustable open-end wrench. On some guitars, you might have to poke beneath the pick guard to get to the guts, but with a gentle touch you should be able to access the offending component.

The can of contact cleaner should have a nozzle extension that allows you to spritz any point where dirt or oxidation is causing a noisy connection. Also, spray into the volume and tone pots at their openings, next to the solder lugs and directly onto all switches.

Rapidly flick each switch—or twist each knob—back and forth, and then play for a while, listening for persistent noises. Repeat as needed. Nine-volt batteries can be tested with the old tongue test: if its terminals tingle on your tongue, the battery is fine. All of the adjustments discussed so far should be done prior to changing strings. The only time you would adjust the truss rod, bridge height and nut slots with new strings on your guitar would be when changing to a different gauge.

Otherwise, use two sets—one for adjustments and one for playing. To check the tension on the neck, first make sure the guitar is properly tuned. Then place a capo on the first fret and press down the first string at the 14th fret.

Now check the clearance at the 6th fret. You should be able to just fit a piece of heavy card stock index or business card under the string at the 6th fret. Tighten the truss rod to decrease the clearance. Most setup guides that I have referenced seem to skip over this crucial step.

Ideally the neck should be mounted onto the guitar body with a very slight angle; with no tension in the strings and the guitar laying on its back, the neck should be angled slightly downward so that the top of the fretboard is on the same plane as the guitar body. With a straight edge against the body of the guitar, the neck should decline until the top of the fretboard is inline with the straight edge right before the nut.

It does have a slight angle, but in the wrong direction. With the proper neck angle, the plane of the fretboard should intersect the top of the bridge. This can also be confirmed with a straightedge.

The image shows an example of how a poor neck angle affects the alignment with the bridge. The image shows the bridge after I had already started sanding it which is no secret from the way it looks.

Originally it was even higher. After fixing any problems with the truss rod or neck angle you can start adjusting the action at the nut. This is done by pressing each string down after the second fret and checking the clearance above the first.

The clearance should be adjusted to the thickness of an index card:. Once the nut is adjusted I recommend lubricating the grooves with a teflon based machine oil.

This will prevent the strings from burrowing down further into the nut as they are tuned. It also prevents burrs from forming and catching against the string, causing it to break when tuning the guitar. The height of the saddle is the main component in determining the action. Only begin adusting the action at the saddle after you have completed all of the other steps.

It is adjusted by removing material with sandpaper and a sanding block. The top should be slightly contoured to allow the thinnest strings to sit a little lower. If you change the gauge of your strings you should double check the truss rod and bridge. Thicker strings will produce more tension and will need a bit more force to counter it. Also, they require greater force against the fretboard so you may want to lower the action at the saddle to compensate.

If you plan to try a new string gauge then you should plan on ordering a new saddle also. Going through these steps may take some time but it will be worth the effort. Now that you know what to look for, the next time you walk through a guitar shop check these parameters on a few guitars and you will be surprised at how variable the factory setup can be.

The image shows the final result with the saddle mounted and a fresh coat of varnish over the bridge. Question 3 years ago on Step 9. Question 3 years ago on Step 6. How thick is the "index card" used in the "Adjust Nut" step? Standard thicknesses are 0. By lowering the bridge height it becomes possible to lower the saddle height some more However, this will also cause problems with the sting windings climbing onto the saddle, and ruining the intonation of the instrument and tone What's the point of this step?

Doesn't the height of the saddle determine the height of the strings?