Our last tech article was about setups, and finished up with restringing the guitar. At this point, you need to begin adjusting. There are several adjustments to be made, and they should be made in this order: the truss rod, string height (action), and then intonation. You should always follow this order, with one caveat: floating tremolos. If you have a floating trem, check out this section before making other adjustments.
Also noticeably absent is adjusting the nut slots. This would be done prior to the string height adjustment, but since it requires special tools, it has been left out. This is an area where a novice can get in trouble in a hurry; there''s a fine line between "it can go a little deeper" and "oops!" Cutting a slot too deep is something that is not easy to fix, and most good guitars have their slots cut relatively well from the factory. Often, subtle improvements can be made, unless it is a guitar where the maker really dials it in, such as Anderson, Suhr, Grosh, etc. If you''re convinced your slots should be cut lower, consider taking the guitar to a qualified tech, since this is something that will only need to be done once.
You can become knowledgeable about this subject and learn to make adjustments to your guitar yourself, but it might take a little while to master it. If your guitar needs a setup, you might as well try your hand at it. The worst thing that could happen is you''ll get things a little out of whack and have to take it to your tech, which is exactly what you would have done in the first place. Nothing ventured, nothing gained. Over time you''ll get the hang of it, and will save yourself some money over the long haul, so roll up your sleeves and give it a shot.
- Truss Rod Adjustment
The truss rod''s purpose is not to adjust the action, but to adjust the neck''s straightness. Ideally, you want a perfectly straight neck, where the tops of all of the frets are on a level plane. However, due to the elliptical vibration pattern of the strings, having a straight neck creates more buzz than most people can live with. This is because the strings'' excursion is greater at, say, the seventh fret than it is at the second fret. So most necks need to have a slight forward bow - or relief - where the curve of the neck mimics the elliptical pattern of the strings.
If you start with a perfectly straight neck with no strings on it, then string it to pitch, you might find that the string tension would introduce exactly the right amount of relief. On the other hand, it might not, so the neck needs to be adjustable. Because necks are generally made of wood, they are highly affected by fluctuations in humidity and temperature changes.
Once the guitar is tuned to pitch, the idea is to adjust the neck so it has a slight amount of relief, which will probably be between .004" and .015". Generally, the more level the frets are, the less amount of relief you will need. The following is how to adjust relief:
Hold the guitar in playing position. Assuming you''re right-handed, fret the G string at the first fret with your left hand and fret it at the 14th fret (or thereabouts) with the pinky of your right hand. Now use the first finger of your right hand to tap the string somewhere near the middle (halfway between the two points where you''re fretting it) and look at the gap between the bottom of the string and the top of the fret where you''re doing the tapping (tapping will help you see the gap more clearly). This gap is the relief. If you consider that your high E string is probably between .009" and .011" in diameter, this will give you a frame of reference. If the gap under the strings is approximately the same as the thickness of the E string, you''re in the ballpark.
If the relief is not in the ballpark, then you need to adjust the truss rod. If you have too much relief, you need to tighten the rod to force the neck back. If you don''t have enough relief, you need to loosen the rod and allow the string tension to pull the neck forward. Try making adjustments in 1/8 to 1/4 turn increments to get a feel on how far you need to go.
A word of caution here - do not over tighten! If you''re trying to tighten the truss rod and it doesn''t seem to want to move, understand that you can break or strip the truss rod. If you are in this situation, use caution. Try to loosen the rod first, and then tighten it. If it still seems like too much force is required, take it to a qualified tech. You do not want to break the rod.
If your truss rod adjusts at the heel like on vintage Fender necks, the neck needs to be removed to make truss-rod adjustments. To minimize the "trial and error" approach dictated here, I find that if I get the neck dead straight with no string tension, normal string tension will tend to bring the neck into the ballpark.
- String height adjustment
Once the truss rod is dialed in, you need to set the string height. Again, the more perfectly level the frets are, the lower the action can go before fret buzz becomes a problem. If you like low action and your frets are level and in good shape, you can adjust all of the strings so they are 1/16" at the last fret. Hold the guitar in playing position and adjust each string so that the gap between it and the top of the last fret is right on 1/16". You''ll need a machinist''s ruler for this, and be sure to slide the ruler right up against the string; otherwise it''s easy to misread the height.
If you want higher action, or if you have some fret problems, you''ll have to adjust accordingly. Note that saddles typically have two screws to adjust their height, so make sure you adjust both screws so that the saddle remains level - you don''t want the saddles angled if you can help it. Tele bridges with vintage-style brass saddles are a notable exception.
Once you have the action adjusted, play the guitar and fret every string on every fret, listening for excessive fret buzz. Don''t go crazy - when you start to really listen for fret buzz you can bet you''ll hear some. Some fret buzz is pretty much a fact of life, and you won''t hear it when the guitar is plugged in and turned up. If the buzz is pretty consistent across the neck, and not excessive, then try bending the plain strings at least a whole step all along the neck and make sure they don''t fret out. If they do, you''ll have to raise those strings slightly. Note that necks with a 7.25" radius are more prone to this problem than necks with flatter radii.
If your testing reveals excessive fret buzz, or inconsistent buzzing along the neck, then you''ll either have to raise the action a little, or level the frets. Inconsistent buzzing along the neck is a sure sign of needing a fret level.
Once you get the action adjusted to a level that feels goods and where the buzz is manageable, it is time for the next step.
This is a whole lesson in itself, and we aren''t going to get into the finer points of tempered tunings and the merits of systems like Buzz Feiten''s or Earvana''s. Suffice it to say, you can read about this subject in all its detail on the Internet.
For our purposes, we''re going to discuss straight-up, old-fashioned intonation. Intonation involves changing a string''s length to compensate for string height. Basically, fret positions are determined by a given scale length, such as the 25.5" scale as used on most Fenders, and if you then actually make the strings 25.5" long, they''ll be out of tune when you fret them. The reason for this is because they are hovering above the fretboard, the act of fretting them actually stretches them, and you know what happens when you stretch a string: it goes sharp. The higher the action, the more pronounced this out-of-tune-ness becomes.
So string lengths are altered to compensate for this, and this is done with intonation adjustment. Here''s the procedure:
Hold the guitar in playing position, and tune it using as high a quality tuner as you can get your hands on - the higher the quality, the more accurate your adjustments will be. Once all of the strings are tuned, adjust the intonation one string at a time. Tune the open string, and get it as perfect as you can. It may help to use the 12th fret harmonic instead of the open string. Now, fret it at the 12th fret, and compare the reading. Was the fretted note sharp? If so, you need to make the string longer, so adjust that saddle towards the butt of the guitar. Now re-tune the open string, and then check again. Keep at it, lengthening the string if the fretted note is sharp, shortening if it is flat, until the open string and the fretted string both read in tune. Do all of the strings, and you are finished.
A couple of tips: as you''re checking the tuning for each note, continually pick the string (not too hard, just steadily), every couple of seconds. This applies to both the open notes and the fretted notes, and will help you get a steadier reading on the tuner. Also, as mentioned, use the most accurate tuner you can. We have a Peterson 490 strobe tuner, but you don''t have to have something this accurate for general intonation setting. Peterson has a new tuner called a StroboStomp that is a really good tuner at a reasonable price. It simulates strobes, so you can really see very small changes in pitch. Needle-type tuners are going to give somewhat questionable results, but they will certainly get you close.
At this point, people with floating trems would still have the wedge sticking out of the back of the guitar, so this would be the final adjustment. Basically, since everything else is completely adjusted, you would tune all of the strings one final time, and then simply screw the two claw screws in a few turns at a time, until the wedge begins to feel loose. Once the wedge will slip right out, you''ll know you''ve stretched those springs to the point where they''re exerting the right amount of force on the bottom of the trem to balance the string pull. Take the block out, hold the guitar in playing position, and check the tuning (don''t tune the strings with the machine heads, just check whether they''re in tune). If they''re slightly flat, tighten each of the claw screws a quarter turn, and check again - if the guitar is sharp, loosen the claw screws a quarter-turn. Keep going in quarter-turn increments until the guitar is in tune.
Finally, once all of the adjustments are made - and assuming you don''t change string gauge - understand that the only adjustment that will change on its own is the neck relief, due to humidity fluctuations. Six months from now, if the action is too high or too low, it''s not because the saddle height changed by itself - it is because the neck moved. A simple truss rod adjustment to correct the relief should bring everything else back into adjustment. You may find that once every year or two is enough to do a complete setup, with just the occasional truss rod tweak needed in the interim.
Also, if you have a tremolo you don''t use, and you want to completely lock it down so it can''t move (without blocking it), this is easy to do. Just put all five springs on the trem and tighten the two claw springs all the way down. That will take care of it.
Have fun, and good luck!
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