This procedure is for lowering string height on the first fret of an acoustic guitar. I filed the nut slots to make them lower. Here is the link to the tool. Faulty Nut Slot Height What’s the ideal nut slot height? Guitars fresh from the factory rarely get this right. The strings of the guitar rest in slots or grooves that are carved into the nut, which is the small (often white-colored) piece by the guitar’s head, where the strings rest before branching off.
After you have built the perfect guitar setting up the action and nut height will make all the difference as far as playing comfort is concerned. Slotting the guitar nut correctly will not only make the guitar more pleasant to play, it will also improve the action and may even effect (for better) the intonation.
The basic idea when slotting your nut is file the slots as low as possible (or to the players personal preference) without going too low and creating any buzz. You also want to consider filing the correct width of each slot, the angle and the spacing between slots. Other factors to consider are the tools at your disposal and the type and material of the nut itself.
In this article I will go through the process and methods used for slotting files as well as cover tools, technics, tips and anything else I found may be helpful to this particular task in the guitar building process.
I’ll start by saying that with a bit practice and very cautious work, slotting a guitar nut can be achieved with a single or a couple of good files, so if you are not a professional planning on building dozens of guitars and if you are already running into more expenses than planned, you can manage with just that. On the other end of the scale you can find amazing file sets designed and built for this exact purpose. ‘Good tools are an investment’ and if you subscribe to this notion you may just go and get one of those sets which may set you back upwards of $80. Here are your options:
These are what the pros use. These will come with 3-8 individual files of usually double-sided files of various gauges to match the different thicknesses of strings. Obviously, you will not want the low and high E strings to have the same size slot. The variety of shapes, quality and price is very wide in this group. There are relatively simple Chinese made with a flat profiled file which can be found for around 17$ on AliExpress or Amazon and there are American Or Japanese sets with a radius file and many more increments between thickness which will be around 80$ or more. Well worth it, but expensive, especially if you are just building a single guitar or kit guitar.
One double edged single file with fairly sharp and thin tip can do the job. You will have to work much harder and be very careful not to overdo the width of the slots, but with a bit of practice, possible.
Tip: It’s not a bad idea to start with just a couple of thin enough files and practice ‘manually’ widening slots by rocking them sideways.
These come as a set of around 15 round rods/ pins which are actually round files, they will have thickness ranging from 0.4mm to 1.6mm to match all string gauges. Personally I find them uncomfortable to work with, especially the thinner ones, they tend to bend very easily. Probably more useful if you only have very minor adjustments to make and not when fashioning a new nu from a blank. Such a set should not cost more than 10$
Probably something you should have laying around anyway. If you are Froogle enough (or just for the fun of it) You can take an old set and cut some teeth into it to make the profile more of a file or saw. This way you can have a file in the exact thickness you need.
Tip: Good quality nuts of exotic materials can be expensive. Get yourself a bunch of cheap plastic and ruin a few of them practicing
If you are using a slotted nut and just making adjustments, then your spacing is already done for you. If it’s not correct, don’t try to fix it. Get a correct one or a blank nut. With a blank nut you will have to figure out the spacing and mark it yourself.
A few things to consider when working out the position of the slots:
Tip: Good quality nuts of exotic materials can be expensive. Get yourself a bunch of cheap plastic and ruin a few of them practicing
After marking the two E strings by measuring from the edge, you will need to subtract the width of the four remaining strings and divide by five. This will give you the space between each of the strings, but when marking the slots, you also want to add half of the thickness of the strings on either side of the particular space. If you are going with this method, you will definitely need a calculator and a digital caliper. Personally, I think going metric at this point would make things easier, but that’s just me.
The easiest and logical to do this would just be using a spacing ruler. This ruler comes with growing proportional increments and after you have marked the two ‘E’s, you just have to slide it along the nut until you find the spot where they align and have the other four slots between them. Mark them and continue.
If you want the even easier (though more expensive) route, there is a Safe Slot Nut Guard that comes as a set with a Spacing Rule and a Neck clamp which will hold your ruler, and even enable using filler guards to show the correct height and protect the nut from cutting too deep.
Ideally the string should be about half way deep into the slot. We don’t want the nut ‘wrapping’ around the string causing buzzing, but we don’t want the string to accidentally slip out of it’s slot when bending it. After you have finished slotting, you can take it out and sand off any access from the to so the strings are not too deep in the nut.
The width of the slot should also fit the string snugly. If it’s too loose, it may buzz.
The bottom of the slot should be radiused to match the profile of the string. The really good slotting files come with the correct radius if you picked the correct gauge file. With the rest of the files, more attention will be necessary when filing.
Always make sure to file in a bit of an angle so the string is not just sitting on a flat slot. Just like the string leaving the bridge has a bit of a break angle so does it need to have a slight angle when leaving the nut. In other words, the highest point of the nut slot is the one closest to the fingerboard so the break point is right at the tip. You can use the same angle the strings take on their way to the machine-heads. This way the intonation will be consistent with the scale and the other frets.
As with any part of the guitar the material used will have some effect on the final tone. How much exactly is hard to say and is a matter of the materials, ear sensitivity and personal preference. Obviously, this is felt most with open string playing
As with any other parts the general rule of thumb is that softer materials will give you a warmer sound and the harder ones a brighter chime like feeling. Sustain will also be lower the softer the material is.
Another consideration is self-lubricating properties of some of the materials which will help with tuning stability, although that can also be helped with added lubrication of sorts.
Metals, Graphite, Graphtec and Corian tend to be very consistent in their behavior, whereas bone which or ebony is a natural material my have variations.
Graphite, bone and ebony are softer and will not have the bright sound of a metal nut, but a warmer tone.
Brass or other metal nuts will give a more consistent bright tone like the frets themselves and will also give better sustain.
Before stringing the guitar mark the maximum depth of the slots. This means marking the height of the frets themselves. Not everyone does this, but it’s a good habit and will give a better sense of where you are going if you are not experienced. There are two methods to do this:
Marking the depth with the ‘Half Pencil Method’
A nice way to mark the exact height of the frets (assuming they are already nice and level) is with a pencil which was scraped, sanded or planed to almost half so the led is showing. This way if you lay it led side down on your frets and push the tip towards the nut, it will mark the exact height of the frets on the front of the nut. You may want to add a 0.01” to the actual height of the slot, but you definitely do not want to go under it.
Using filler gauges when filing
Another method of making sure you don’t run the slots two deep is stacking filler gauges next to the fret to the desired height. Then slip them to the nut and hold them back with an elastic band to keep them in place and also match the fretboard radius. If you have the ‘Safe Slot Nut Guard’ this is the place to use it.
After stringing the guitar or if you are just adjusting a stringed guitar.
Have the guitar with strings in tension. They don’t have to be fine-tuned but enough to hear there is no buzz.
Set your action to roughly the correct height. This means adjusting the truss rod and relief if needed and the bridge/ saddles enough to get good feedback around the first fret. You may want to fine tune the action after the nut slotting.
Move each string sideways from its slot, file it a little, move it back to place and check the height and repeat until you get to the right height. If you marked it in advance, you can file almost all the way and then check. You never want to go too far and start buzzing on the first fret.
There a few theories and methods to determining the height of the open string.
Measuring. For some of us using a filler gauge is the preferred method. In this case 0.001” or 0.25mm is a good place to start.
Another measuring method is using old strings. Cut and bend an old string to use as a guide. Use the them respectively to the correct thickness.
The last method, used by experienced luthiers is the feel and touch method. Press on the string to feel and see if the distance at the first fret feels right. For most players that would be the ultimate test. The lower and closer to the fret, the more comfortable and effortless playing would be.
Since we want the fretboard side to be the highest, we will always hold the file at a bit of an angle down towards the headstock. Something like the angle the string take after the nut. On the length side you want to keep the file straight and parallel to the strings. We don’t want to widen the front (fretboard side) of the nut slot.
If you have a guitar where the strings are flaring sideways (like the two middle ones on most Gibsons) to reach the machine-heads, you would want to widen and flare the back side of the slot to minimize the friction on the string.
Once you have gone back and forth and you are happy with the string height and position and there is no buzz, you can take the nut out for final sanding and smoothing. Once the nut is ready, put a dab of wood glue (some prefer super-glue) and string it. Let it sit with the strings acting as a clamp until dry and you are done.
If you plan on playing with ‘dropped D’ (or even lower) tuning, you will need to leave your bass E string a bit more height for the extra vibration it will have because it is relatively loose.
The same may be true for shorter scaled guitars like kids’ versions.
If you are using a ‘0 Fret’ than your Nut is really more of a guide and the spacing is the most (or only) important factor to the nut. It does have to be slotted lower than the Zero Fret itself but that’s about it.
Most of these have no height adjustment for individual strings and require some routing or filing to fi tin place. Since they are not adjustable it is important to check that they fit the width of the neck and the radius of your fretboard. With this type of installations the only thing controlling the height of the strings is how far we file the neck and it will take some trial and error to get it right. If you went too low you will need a shim to compensate. If you ever want to fgo back to a regular nut from the locking ones there should be no problem, except for a little height adjustment. The main problem with the roller nuts is that in order to correctly position them you would need to rout out or otherwise remove a few millimeters off of the fingerboard and if you ever choose to go back to a more conventional nut, they will be missing.
While there’s no substitute for the work of a good luthier, it’s a good idea to understand the basics of guitar setup. That will help you understand how to care for your guitar, what problems you can address at home, and when you need the help of a guitar repairperson.
You can probably recognize excessive curvature in your guitar neck just by looking at it. If you hold the guitar from the body, without touching the neck, and sight down the neck with one eye, you will see if it is straight or not. If the neck has some relief, the middle string height will start low in the open position, be a bit higher along the middle frets and then get low again by the XIIth fret.
The truss rod is often adjusted by inserting a wrench through the soundhole.
When all six strings are tuned to concert pitch, their combined force can easily exceed 100 pounds of tension. This force would naturally bend the neck into a very large forward bow, much like a hunting bow. To prevent this, a metal rod is installed inside of the guitar neck. This is called a . The is not set to a fixed amount of tension, but the tension can be adjusted by tightening a hex key at either the head or base of the neck. It is adjustable because the needed amount of tension may change over time, due to moisture content of the wood or what kind of strings are used.
The neck should be totally straight, or have a slight amount of forward bow. This forward bow is called , because we relieve the counter-acting tension of the and allow the strings to pull the neck forward—but only a tiny bit.
The truss rod is not meant to be set once and forgotten, and nor is it considered a job only for experts. Most guitars ship with a truss rod key, and the player is supposed to be able to make adjustments as needed.
If there is too much relief in your guitar neck, the string height along the middle frets V-XII will be very high. You can try to adjust the truss rod yourself. However, if you’ve never done this before, it’s great to try it on a cheap guitar first. If you adjust the truss rod too much, you might cause it to break. You should not adjust the trust rod by more than one or two full turns at a time. If the problem you are experiencing is not fixed after two or more full turns, then you should probably stop and ask an expert, or at least wait a day and try again.
You should also not tighten the truss rod very tight. It should not have the same resistance as the nut on a car tire. It should turn fairly easily. If the resistance is a lot and it is becoming difficult to turn, you should probably stop. Do not add more torque.
It is also best not to make too many sudden adjustments. You can try a quarter or half turn of the trust rod and then stop, wait and observe. You can repeat this process until you’ve found the right setting.
After making your adjustment, sight down the neck again and see if it’s improved.
Because they affect the shape of the wood, truss rod adjustments need a bit of time to sink in. Try doing a quarter or half-turn, and checking again the next day.
Sometimes if a truss rod has been overtightened, or heavy strings are replaced with lighter strings, the neck will begin to have a slight backbow. This is never ideal because the guitar won’t play correctly with a back bow.
The solution is to adjust the truss rod and add a bit more to the neck.
Guitars fresh from the factory rarely get this right. The strings of the guitar rest in slots or grooves that are carved into the nut, which is the small (often white-colored) piece by the guitar’s head, where the strings rest before branching off to the tuning machines.
Because guitars are mass-manufactured, and because getting the correct depth for the nut slot is very difficult and exacting work, most guitars do not ship from the factory with perfect nut slot depth.
If the nut slot is too deep, you will notice immediately because when you play that string open, it will rattle against the first fret. There will be a tinny metallic buzz whenever you play the string open. But if you play any other fretted note on such a string, there is no buzz. This is the tell-tale sign of a nut slot that has been carved too deep.
The string should barely clear over the first fret, with very minimal clearance. Only enough to prevent buzzing. This one is a little bit too high.
If, on the other hand, the nut slot is not deep enough—a much more common situation—it will not be immediately obvious to you. The consequence of this is that the strings are much higher than they need to be over the first fret, which means it will take more force than necessary to depress them in the open position. In other words, because most manufacturers do not ship their guitars with perfect nut slot depth, it may sometimes be difficult to finger open chords on mass-produced guitars.
The irony is that this happens more on “cheap” guitars (less than $1500), so it’s usually beginners who suffer the most from this. And they’re the ones most in need of an easy-to-play guitar!
A guitar that has gotten overly dry may have lower action, and thus have the rattling described above. It is best to first get the instrument fully hydrated before deciding if any setup work needs to be done.
Guitar technicians measure nut slot depth settings by using a measurement which is equivalent to the distance from the bottom of the string to the top of the first fret wire. This height is measured in thousandths of an inch. It can be a very tiny amount of distance, especially for the high E string. The high E string is a mere few thousandths of an inch above the fret wire.
The optimal nut slot depth is as follows: the string should rest as low as possible without producing any rattle or other problems. This would probably be about .010 inches (one hundredth of an inch, or .25mm) of distance between each string and the first fret. Very few guitars are set up to this exacting standard. A measurement of .020 inches or .5mm would be far too high—and yet, this is a common sight on new guitars.
To know for sure, you’ll need to buy an action gauge, such as the Stew Mac Action Ruler This small tool can be found on Amazon for a few dollars and every guitar player should own one! You can also buy a much cheaper one: Baroque Action Ruler.
If you suspect your nut slots need adjustment, this job is best left to an expert. Of course you can learn how, but it requires patience, some experience, and special tools.
Some particularly cheap instruments are shipped this way. That is, if you grasp the guitar neck with your thumb and index finger, and slide your hand up and down the neck, you will feel the sharp sensation of frets protruding from the side of the guitar neck and scratching your hand ever so slightly. This is far from ideal. You need a smooth surface in order to play the guitar comfortably.
This happens because frets are hammered in roughly and not smoothed out with a fret file. It can also happen due to humidity and temperature changes that cause the wood to contract. The metal fret wire, of course, does not fluctuate as much.
Due to superior construction and wood treatment methods, you won’t often see protruding frets on a high end instrument.
This problem can be fixed relatively easily by filing those frets until they are smooth and no longer protruding.
This is also not much of a do-it-yourself task; you'd have to cover all of the neck’s wood with blue painter’s tape, and use special filing tools to dress the ends.
When shopping for guitars, carefully-dressed frets are one tell-tale sign of good craftsmanship.
An ideal string height is between .070 and .090 inches above the 12th fret. On this guitar, it’s over .140.
The term action describes the height of the strings above the guitar frets. If the action is too high, the strings will be unnecessarily hard to push down to the frets. If the action is too low, then the strings will rattle against one or more of the frets as they are played. Because the strings and the guitar neck do not follow a straight parallel line, this problem is sometimes more apparent on one part of the guitar neck and the other.
Some players prefer a very low action. With a light touch, much of the buzzing can be avoided. To a point. This is especially true for quality instruments. Guitars crafted carefully with excellent fretwork are much more tolerant of low action than inexpensive guitars with hastily installed frets.
If the action of a guitar is too high (which is the most common scenario) then the guitar will play fine, except that it will be harder to push down on the strings. The higher the action, the harder it is to play.
Most new guitars start with action that is too high.
Lowering the guitar’s action can be done at home fairly easily with a little bit of sandpaper and patience. Be sure the finished saddle sits flat on its bottom edge, unlike this one that was sanded into a slope and now leans to the left.
This is simple enough that a novice can probably address it at home.
You’ll need to take off the strings and remove your . Then, using some medium-grit sandpaper such as 200, sit the saddle on top, facing up as it had been when installed on the guitar, and shave off some of the bottom by pushing down and moving the sandpaper in a back-and-forth motion. Take off a tiny amount: about the width of the line drawn by an ordinary pencil. Now rest the saddle on a flat surface and make sure you haven’t filed a slope into it. If you have, keep working until you’ve got it flat. Reinstall it and string the guitar up. The beautiful thing? If you mess up and sand too low, you can easily shim the saddle back up.
Tip: Using a Stew Mac Action Ruler, measure the string action of the big E string at Fret XII both before and after. This will help you figure out if you’ve made an improvement.
Most guitars can’t go much lower than .070' at the 12th fret.
Sometimes an over-zealous action adjustment can result in a string height that is too low.
Especially if it was done in the summer, with high heat and humidity, and now the winter has set in. The lower humidity and heat will cause the wood of the instrument to shrink slightly, and will result in a noticeably lower string height.
Every guitar is different, but most quality guitars can be adjusted to .070' or .080' action at the 12th fret (Big E String). Lower than that and you start to hear alot of buzz. Due to uneven frets and necks that are not perfectly flat and straight, alot of cheaper guitars have to have even higher action.
This is very easy to fix, and you can do it yourself. Remove the strings, snip up a tiny piece of credit card or similar material to serve as a shim, and stick it under the saddle. Put the saddle back on and voila! higher string action. If it’s still not high enough, do it again—this time with two shims, or—better yet—a thicker shim material.
Since shims are thought by some to affect tone quality, some guitar players even keep two saddles handy: a taller one for winter and a shorter one for summer.
Over time, frets will wear down. This means that as you fret a note, you might hear some buzz when you play that note because the place where the string contacts the fret has worn itself into a groove. This problem does not affect beginners very often, because it is a direct result of playing a guitar that has been well-worn. Normally beginners start with a new instrument. However, if you bought a used instrument (or inherited one) then you might have this problem as well.
The exacting work of installing perfect frets is hard to get perfectly right.
If your guitar frets are not of 100% uniform height from Fret I to fret XII and beyond, you may have playability issues.
This is easier for a luthier to address with a simple file and some painter’s tape, but it can be a little time consuming.
A useful starting point for most guitar learners.