Correct Nut Slot Height
John Carruthers shows us the proper way to adjust the Nut on a Stratocaster. This video is step 3 of a 4 part series. Videos include adjusting the Truss Ro. As a matter of fact, the effect that the slot depth at the nut has on the playability of the guitar is dramatic. Suppose first that the slots were very deep, so that the gap between the strings and the first fret became very small. Then an open, unfretted string would buzz on the first fret. As you know, there is a lot of confusion regarding zero frets or fret-height nut slots vs raising the nut, and flat necks vs relief. I'm trying to diagram this and illustrate it, which is very difficult because the increments are miniscule, so these numbers are very helpful. As to action height, I've seen Martin repair estimates where they refer to 3 and 2 and 3 1/2 and 2 1/2. These are 32nds of an inch measured from the top of the 12th fret to the bottom of the E strings when the nut slots and truss rod are where you want them as both of. The first thing you want to do is take your feeler gauge and check the distance between the string of the first fret and the fret itself. If your string reaches the feeler gauge (.018 inches is the best gauge to use for optimal nut action height) you are all set. If it doesn’t, you need to file down the nut.
Hello! Today we are going to go through the process of setting up a Les Paul style guitar with a tune-o-matic bridge and tailpiece. We will cover all the steps needed to make your guitar play better than it ever did from the factory and some tips and tricks along the way.
Evaluation
The first step in any setting up of an instrument is the initial evaluation. You want to go through the guitar and find out as many problems you are going to face here at this point so you don’t get halfway through the setup only to discover you overlooked something and have to waste time going back to correct it and repeat all of the steps over again.
Electronics
This is the best time to plug in the instrument and check out all of your pots, pickups, jack, and switches to make sure everything is working properly. This will allow you to take care of any electronic issues now that will save you time in the long run.
For example, a lot of grounding issues arise with guitars with a tune-o-matic bridge. The “string” ground (yellow arrow in the picture above) usually runs from the treble side post of the bridge or tailpiece and into the electronics cavity where it will be soldered to ground on the back of one of the potentiometers. These wires lose contact or become loose quite often. So, checking this now and correcting it is going to save your butt instead of you having to pull off your strings and bridge to pry out a bridge post or ferrule to replace the ground wire 3/4ths of the way through your setup.
Neck Relief
At this point, it is a good idea to straighten out the neck of your guitar. Doing this will help flush out any fret or nut issues that can be taken care of now before the new strings are put on and the setup started.
To straighten the neck you want to check how much relief there is first. You can use a straight edge ruler that is long enough to lay across the top of most of the frets of the neck or a notched straight edge that rests against the fretboard. Lay the ruler down the middle of the neck.
If there is too much relief, there will be a gap between the bottom of the ruler and the frets or fretboard near the middle of the neck. You will then need to grab your truss rod tool and turn the truss rod nut clockwise until that gap is gone on the bottom edge of the ruler.
If the neck has a back bow, the ruler will rock back and forth at the ends because the neck is bowed up in the middle. You will want to adjust the truss rod nut counter-clockwise until the ruler is resting flat and even across the frets and/or fretboard. you want to make sure the ruler is not rocking back and forth anymore and there is no gap along the bottom edge of the ruler and the frets and/or fretboard.
If you don’t have a straight edge or notched ruler, you can use a capo, a .005″ feeler gauge, and your hands to check the relief of your neck. Place the capo at the first fret. Then with the thumb of your right hand, fret the low E string down around the 17th fret.
Take the .005″ feeler gauge with your left hand and slide it between the bottom of the E string and the top of the 7th fret. You want this much relief in the neck. Adjust the truss rod until the feeler gauge fits between the bottom of the string and the fret.
Frets
Now with the neck straight we can check if there are any fret issues before we continue the setup. It is important to take care of any frets issues now so we can make sure that we can setup up the guitar as best we can without any buzzing or dead spots on the neck.
We will use the fret rocker tool to check all the frets on the neck and make sure there are no high frets. You also want to make sure that none of the frets are loose and popping up out of the fret slots. If there are loose and uneven frets then make sure the loose ones are reseated and glued down. Then you will want to level the frets and crown them before moving on.
Nut
This is also the best time to check the string heights at the nut and see if the nut needs to be replaced or shimmed. I can’t tell you how many times we have gotten Les Pauls straight from the factory where the nut slots were cut soo low that multiple strings were resting on the first fret when the neck relief was adjusted straight. If there are issues like this at the nut or you prefer a different material, then now is the time to have it taken out to be either replaced or shimmed.
Extracting and making a nut for a Les Paul is an art and can be tricky. It is strongly recommended to have a skilled technician perform this if needed. We will go through the steps of replacing a nut on a guitar in a later article so be sure to watch out for that one in the near future.
Remove Old Strings and Clean Up
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After the evaluation process is finished, and we didn’t run into any of the issues listed above, then we can continue by removing the old strings and giving the guitar a good initial cleanup.
It is a good idea to slacken the strings before you cut them off. This will help reduce any stress or potential damage to the headstock from the sudden loss of tension.
Also, the tension of the strings is what usually keeps the bridge and tailpiece secure to the body so be careful. I usually like to hold the strings with my left hand right above the pickups and cut the strings there. That way I can have both ends secure in my hand when I cut it and keep the strings from flying around causing damage. It also allows me to keep the bridge and tailpiece from popping off and causing dings or scratches to the top of the body.
Now with the old strings off and the bridge and tailpiece off to the side you want to clean up the guitar before we put the new strings on.
I like to polish up the frets and clean and oil the fretboard first. You can use 0000 steel wool or a 320 grit Klingspor pad to polish the frets and break up any dirt that might be on the fingerboard. Then a conditioning oil is applied and allowed to soak in for a couple of minutes before being wiped clean.
While the oil is soaking in you can take this time to clean up the body, back of the neck, and headstock with your preferred choice of cleaner and polish.
I also like to tighten up any loose screws or nuts at this point, especially on the tuning pegs which can cause tuning issues if they are not secure.
After everything is secure and cleaned up we can put the bridge and tailpiece back on and throw on the new strings!
But before we put on the new strings, there are two options involving the tailpiece that we need to discuss.
The first option is adjusting the tailpiece as far down as it can go and pass the strings through normally. It is said that this improves tone and sustain.
This usually can be done without any problems, but be aware that your strings might be prone to breaking at the saddle prematurely if there is too much string break behind the bridge and causing too much stress on the string at this point.
The second option is called “Top Wrapping”. This is where the string is fed in through the front of the tailpiece and wrapped up over it and then over the bridge to the tuners. This method is said to make the strings feel a little “slinkier” and more comfortable for the right hand due to less of a break angle over the saddles.
Everyone has different preferences and the argument for the difference in tone is negligible with both methods, so give both ways a try and see what works or feels best for you. You can also try adjusting the tailpiece all the way down and then top wrapping the strings to try and get the “best of both worlds.” But experiment a little and see what you like!
New Strings and Neck Adjustment
New Strings
Ok, now with the guitar all cleaned up we can restring it with a fresh set of strings.
When restringing you want to have only a couple of string winds around each post and start with one above the string as it passes through the string hole in the tuner. This will pinch the string and help keep it from slipping and causing tuning issues. For the unwound strings, you may want 3 to 4 wraps around the posts to make sure you have the correct string break behind the nut for them since they are smaller in diameter than the wound ones.
Less winds the better since the angle of the headstock is already at 17-degrees and the break angle of the string behind the nut is achieved with only a couple of winds on the tuning post. This will decrease string pressure in the nut and help with tuning stability.
Put on all the strings and tune up to pitch. Grab each string individually and pull it gently up and around in a small circular motion near the middle of the fretboard to “stretch” the string and make sure the wraps around the posts are tight and are not going to move or constrict later causing tuning issues. Then retune the string to pitch. Do this a couple times for each string.
Adjust Neck
With the new strings on and stretched we can adjust the neck. We did this step already in the evaluation phase so most of the time the neck is already straight and ready to go, but if not, repeat the process we went through above until the neck is straight and there is a .005″ gap of relief between the bottom of the E strings and the top of the 7th fret.
Most guitar necks have a little bit of normal “warping” to them. One side more often than not has a little more bow than the other. So when adjusting the neck, you want to check the relief on both the low E and high E. Most times you will find that the Low E side has more relief than the high E side of the neck. This is usually ok unless the high E string is resting on top of the frets. Then you will need to add a little more relief to the neck until the high E has clearance over the frets. This is going to cause a larger relief gap on the low E side of the neck, but you’ve got to compromise a bit to ensure that the instrument is going to be set up as well as it can be.
If your neck is considerably warped, then we definitely recommend taking it in to get professionally evaluated to see if a more drastic repair is needed.
String Action
With the neck straight we can adjust the height of the strings which is called the string action.
Adjusting Bridge
Adjusting the string action on a Les Paul style guitar is pretty simple. The bridge sits on top of 2 thumbwheels which are threaded on to a post or into a ferrule installed on the top of the body. You rotate one of the thumbwheels clockwise to lower that side of the bridge or counter-clockwise to raise it. Some posts have a slot in the top of them where a flat head screwdriver can be used to easily adjust the bridge up or down.
You can use your fingers on the thumbwheels to adjust the action most of the time or pliers with some tape wrapped around the tips so you don’t eat up the metal plating on the thumbwheels. The adjustment is easiest if you detune the strings a little to reduce the string tension pushing down on the bridge.
But the best tool to use is the ESP multi spanner tool. It is a double-sided steel wrench where opposite sides of each end is toothed in order to turn the thumbwheels to lower or raise the action of a tune-o-matic bridge or tighten and loosen nuts. This tool is a must-have and saves you from tearing up the skin on your hands or slipping with the pliers and scratching up your guitar when trying to adjust the action.
Using a ruler or a string action gauge card and holding the guitar in playing position, measure from the top of the 12th fret to the bottom of the string. This is how you get the string action measurement. A good place to start for the action of a Les Paul is 4/64″ on the low E string and 3/64″ on the high E.
Depending on the guitar and playing style, the action can be adjusted slightly lower or higher from this starting point.
Bridge Saddle Radius
The bridge saddle radius should match or be slightly flatter than the radius of the fretboard. Most Les Paul fingerboards range between a 10″ and a 12″ radius. Using radius gauges, measure the fingerboard radius and the saddle radius and see if they match.
If the radius of both don’t match or they do and you want to flatten the radius a little, you can take the same files used to cut nut slots to cut the string notches in the saddles a little deeper in order to achieve the intended radius. When cutting the saddles, make
One common problem you will find is that the factory bridges will start to collapse or bow in the middle due to the soft metal they are made out of and tension of the strings pushing down on it over the years. So if you find the saddle radius to be extremely out of spec or you’ll cut into the intonation screw if you try to lower the string notch any further, then you will most likely need to replace the bridge on your guitar.
String Action at Nut
A critical adjustment that is easily overlooked is the string height at the nut. A correctly adjusted nut can help improve playability and intonation on the first couple of frets especially for barred or open chords.
To measure the height of the strings at the nut, we measure from the top of the first fret to the bottom of the string with our ruler. We then will use the proper nut files for the string gauges used to cut each slot in the nut to the desired depth. It is best to start slow and a little higher to make sure you don’t go too deep and cause the string to buzz on top of the first fret when played open.
It is also important to cut the nut slot in a slight downward angle. If the nut slot is flat, then the string will rattle and buzz when played open.
Another trick is to slightly cut the backside of the slots at an angle for the D and G strings towards their respective tuner posts. This will help alleviate any more friction of the string inside the slot which will help increase tuning stability.
A good place to start is at the factory heights which are 2/64″ for the Low E and A, 1.5/64″ for the D and G, and 1/64″ for the B and high E strings.
From here you can lower each slot until you feel each string is low and comfortable enough for your playing style. I wouldn’t go any lower than just above the 1/64″ mark for all the strings except the B and high E strings. These two strings can go down slightly further and still play and ring out normally.
After each slot is cut to the desired height, clean up any dust or debris from the area and apply a nut sauce or lubricant to each of them to help keep the strings moving freely and prevent any binding in the nut.
String Height At Nut
If you accidentally make one or more slots too low, then shimming the bottom of the nut or building up the nut slot will be needed in order to correct this.
Intonation
The final major adjustment is setting the intonation for each string.
Each saddle in the bridge is threaded on to a screw that can move the saddle forwards or backwards to adjust the length of the string in order to set the intonation correctly for each one. This will make the notes below and above the 12th fret as in tune as they can be with each other.
Using a strobe tuner is recommended, but most will do the job.
First, start by hitting the string open. Lets say the low E for example and tune it to pitch.
Then fret the low E string at the 12th fret and play the note. If the saddle is in the correct position, the notes should be the same pitch.
If the fretted note is higher or sharper than the open note then the saddle needs to be moved back. Use a small screwdriver to adjust the saddle. Retune the open note and check the fretted note again. Adjust until the 2 notes are the same.
If the fretted note is lower or flatter, then the saddle needs to move forward. Adjust the saddle and repeat the steps above until the notes are the same.
Repeat for all the strings until each strings saddle is in the correct position and proper intonation point.
Most of the time the saddle is easily adjustable with the note tuned up to pitch. On some bridges, the strings may need to be detuned a little in order to easily adjust the saddle forwards and backwards.
Sometimes a saddle will be adjusted as far forward or backwards as it can be and the intonation will still be off. Each saddle can be taken out of the bridge, the screw taken out, and then flipped around and reinstalled in the bridge in order to squeeze out a little more room for adjustment.
To do this, you want to slacken the string and move it over to the side of the saddle. Then you can take some needle nose pliers and remove one side of the retaining wire that helps keep the saddles in the bridge. Now you can remove the saddle, take the screw out, flip the saddle around, put the screw in the flipped side, and reinstall the saddle into the bridge.
Position the retaining wire back into place and
After the intonation is set, apply some of that nut sauce or lubricant to each strings notch in the saddle to help reduce friction at this contact point for better tuning stability.
Pickup Height Adjustment
Pickup height adjustment is usually a pretty simple task on a Les Paul guitar. If your guitar has humbuckers or P-90 style pickups there is usually 2 height adjustment screws used to change the height of the pickup in relation to the strings to achieve the best tone.
For humbuckers , the screws are located on either side of the pickup on the pickup ring.
For P-90 or soapbar pickups, the adjustment screws are located on top of the pickup cover next to the pole pieces. There is usually foam or springs under the pickup to help keep it secure when it is raised up towards the strings. A lot of times there is not an adequate amount of foam or tall enough springs to raise the pickup up to the desired height and to keep it from flopping around and making noise. So, more foam or new springs (sometimes a combo of foam and springs) need to be installed under the pickup.
Some guitars have P-90’s or soap bar pickups that sit on and are secured to the top of the body with a special tab and pickup cover called a “dog-ear”. For these style pickups, a special shim is used which can be found online, in order to raise the pickup and cover up
When adjusting your pickups, you want to make sure that the pickups are evenly matched volume wise. You want to do this through your amp with both volumes up and wide open. You also want to make sure that the notes ring loud and clear without any distortion or warbling which can happen if the pickup is too close to the strings.
Machine T Slot Nuts
The pickup height is measured by fretting the outer two E strings at the last fret and measuring from the top of the pole piece directly under that string to the bottom of the depressed string.
For the neck pickup, 6/64″ on the bass or Low E side and 5/64″ on the treble or high E side is the optimal place to start.
For the bridge pickup, 4/64″ on the bass side and 3.5/64″ on the treble side is usually best.
Every pickup, guitar, and ear is different so please use these measurements as a guideline and use your best judgement for adjusting the height of your pickups for achieving the best tone possible.
Final Polish and Cleanup
And that about wraps things up!
Make sure all the truss rod and cavity covers are on and securely screwed back in to place, give your guitar a final wipe down, and go enjoy shredding on your newly fine-tuned axe!!!!
Nut Height
Fine tuning the nut height is one of the very last steps I take in a setup, and should be done with the action and neck relief set as the guitar will be played. This will deal with the locking nuts on tremolo equipped guitars. If you have a non locking glued in nut then adjusting it's height is better left to a professional that's already spent the $160 a full set of fret files will cost. [Although if your problem is the string slots are cut or worn too deep you can carefully build up the string slots with super glue, the alternative is to have a new nut installed]
Nut height is probably one of the most crucial aspects of how your guitar feels within the first 5 frets, but it also effects the feel of the whole fretboard to some degree. Quite simply the nut should be as low as it can go without causing string buzz on the first fret. For a quick judge fret each string at the first fret and look at the clearance it has over the second. Compare to the gap between the top of the first fret and each string with the string open. Near 100% of all new Ibanez guitars have nuts that are way too high. Most of the new Jems I receive have nut height at the first fret low E around 1mm, about .7mm too high!! I've been complaining about it to the company for years and the only thing that's happened is they've gotten higher. I'm guessing factory spec must be for them to be set 'way too high', so in that case, they're all perfect! But if you want a much better playing guitar you will take the time to lower the nut to the correct height. The Jems and sporadically other models will be unique in that their high nuts have nothing to do with how many shims are under it, but the fact the nut rout was never cut near deep enough to begin with, but that's the topic of another much more tedious section.
The first thing you want to do is evaluate what you have now and decide what probably needs to be done. Do you see plenty of shims under the nuts? Great, lowering it will be much easier. No shims? Are you getting fretbuzz at the first fret? Either your nut is too low, your neck does not have enough relief [or is in backbow], or the neck does not have enough relief for where the nut is set. If you have the nut set nice and low with a decent amount of neck relief and you straighten the neck too much, the nut is now too low for the straighter neck and you may get buzz on the first fret. This is why you set the nut height with the relief and action adjusted to your preference. This section will deal with a simple height adjustment where only the addition, removal, or rearrangement of shims is needed to get the desired height.
Before starting you should know that the fretboard radius will not perfectly match the radius of the nut. The nut will probably be radiused a little flatter than the frets. If you have the low and high E's as low as they should be set you'll get 1st fret buzz on the D and G strings and/or A and B strings. Because of this the nut needs to be a little higher to clean up the middle strings and to compensate I will split the difference between both the high and low side of the nut. In other words instead of putting a big shim under the low side to raise it enough you want to put half as much under the low and high side to raise it evenly until the D/G are clean. You'll also find some that may have radiuses flatter than the nut causing the center to be high.
The very first step is with all strings in tune and fully stretched, pinch each string to the fretboard hard right where it leaves the nut. This will remove the strings tendency to rise a little as it curves off of the nut and that little bit is enough to make the difference between having buzz or not when done. It should also be noted that for rock guitars having some mild first fret buzz is acceptable as long as there's no more first fret buzz than you get fretting the second fret.
To adjust the nut height I usually find it easiest to remove all the shims under the nut and start from scratch. With the nut pads removed block the trem to it's highest angle to take as much tension off the strings as possible [this also allows you to quickly unblock it to perform checks on your height adjustment]. It is quite common [and perfectly normal] to find all the shims as half shims built up on each side, and these are quite easy to remove. Unscrew both Allen bolts that hold the nut on in the back a few turns [not necessarily all the way] from here there are two ways to lift the nut, push up on the nut using your wrench seated in the nut bolt from the back, or you can use a 3mm Allen wrench in an outer nut pad bolt hole as a lever to pull the nut up [if you're pulling the bass side shims put the wrench in the E./A pad bolt hole with the long part of the wrench also pointing to the bass side, pull up on the wrench using it as a lever to lift that side of the nut], if you do either technique while holding the guitar on it's side any half shims on that side will just fall out [visually inspect to verify they're all out]. To visualize, if you holding the guitar as if you would be playing it and raise the treble side of the nut all the shims on the treble side will fall out. Flip it over to do the bass side. If they're all gone great. More than likely you'll find a full shim or two left though. These are a little trickier to remove and before you do I suggest unblocking the trem to make sure they need to be removed or if you've already got it low enough. If it's close tighten the nut bolts [using common sense!! They only need to be tight enough to hold the nut in place, too tight and you'll crack the wood!!] because the nut will lower slightly when you tighten it, Recheck.
To remove a whole shim I'll start by backing off the string tree to free up a little more string tension. To get one out you'll either have to remove the nut mounting bots completely, or remove the string tree completely, and on some pesky 'don't want to budge' shims you might have to do both. Most of the time you can just slide the nut toward the bass side then lighten the pressure on the nut and slide it back, leaving the shim stuck out enough that you can now just lift the bass side using the Allen wrench in the pad bolt lever trick to work it the rest of the way out [or grab it with some pliers if you get tired of playing with it]. I've got plenty of shims so I'll just jam a .5mm shim under the nut to force it out the other side enough to grab. Some will just not want to move [some will be virtually glued in] at all and those you can remove toward the headstock. Remove the string tree, lift one side of the nut, use something to 'catch' the shim [I use the point of an Exacto knife] and work it out a little, do the other side, back and forth until it out enough to either get some needle nose pliers on or grab by some other means, then just pull it out. All JS1000/10th/90th/2000 models must have their full shims removed this way as they have an arch molded into them at the truss rod channel.
Correct Nut Slot Height Chart
With all the shims removed re-install the string tree and unblock the trem to see where the nut height is. Play each sting to check for any choking or buzz at the first fret. If there is none, is it low enough for you? Or do you think it can go much lower [compare to the second fret gap with the strings fretted on the first] If so, move to the section on lowering the nut rout.
Hopefully it will be too low, buzzing everywhere, and now ready to build up to the correct height. This would be a good time to talk about nut shims. The shims come in 3 thicknesses, .1mm, .25mm, and .5mm. .5's are monsters and will only have a place if the original nut rout was extremely deep. .1's and .25's are your shims of choice for fine tuning the height, and most specifically, .1mm will be your best friend and offer the most precise fine tuning of the height. Sort through the shims that you've removed, a .1mm will bend if you blow on it hard enough, a .25 is fairly pliable with your fingers and you can bend it, just not like paper, a .5 is one thick tough suckah, you'll know it when you see it.
T Slot Nuts And Bolts
To build the nut back up is a matter of determining what it needs, and some of this will be trial and error. Is it choking on the treble side and not the bass? Shim the treble. Choking on the bass but not the treble, shim the bass. If all strings are choking start with putting the same size shim under both sides and test again. If you have a quick method for blocking the bridge [and I always use my spreader clamp to just clamp my bar to the body [my bar has an Ibanez Sure Grip foam wrap on it so it's essentially a padded bar. I started using it for this reason and fell in love with it, to the point I hate the feel of a normal bar any more]] you will find this very fast to shim, check, adjust, check, until it's right. Using the technique of a wrench as a lever in a pad bolt. I'll always start with a .25 shim and stick one under the low side and under the high side. These don't have to be fully inserted, just stuck under the side to give an idea of where it's at and what it needs. Once it stops choking/buzzing on one side, raise the other until it's clean. You can further tweak by then removing any thicker shims such as a .25 and replacing it with a .1 or two .1's until the nut is as low as it will go without choking or buzzing on the first fret. Remember the note earlier about the nut radius not matching the fret radius exactly. If the center is too low to clean up the center strings split the amount of additional height needed between the bass and treble sides. If the center is too high then you'll just have to shim the low and high side as low as possible and live with it [or have the fretboard/frets re-radiused]
When you are satisfied with the results take out the shims on both sides and analyze them. If you have a .25mm shim on each side use a whole shim instead of a half, the same with any additional shims until the only half shims I'm using are the ones that give the final tweak where using a full shim would raise the opposite side too high. If you don't have the full shims and are using halves [and there is nothing wrong with just using halves, you'll never hear a difference between using a half shim on each side as opposed to a full shim] get the halves together so they are like inserting a single shim, and fully install it under the nut until you can't feel the edge protruding past the nut, making sure they are seated flush against the L where the nut meets the fretboard. Repeat on the other side and tighten the nut snug. Test again to make sure that tightening the nut didn't lower it enough to cause any buzz and re-tweak if necessary. Some will be trial and error, some will be educated thinking, sometimes pure luck will get you there, but taking the time to get the nut height as low as possible will pay big dividends in how the guitar plays and feels.