Making A Bone Nut
Learning to make a proper nut for your guitars is an important part of ensuring that your guitars come off the bench sounding and looking great. The good news is that it is something that anyone can learn to do and learn to do very well with a practice and patience.
This tutorial is how I am making nuts these days. Some of the tips and techniques that I will detail here came from David Collins and I thank David very kindly for all that he has shared with me. If you notice any mistakes these are my very own contributions to this tutorial...
The first step in making a nut for a guitar is to clean and true up the nut slot. No matter how careful we are when building our guitars nut slots often are not uniform in size…
Today we are working with a guitar that I built 4 years ago. It has had a lot of use lately and I decided to make it my primary guitar at least for a while. I have just completed a fret dress and now I want to make a new nut to improve on the original string spacing and make it more to my own personal liking.
The old nut was removed which is very easy to do and can be accomplished by placing a block against the nut face and lightly tapping the block with a small hammer – I used my fretting hammer. The nut will break free and begin to lean backwards. Working it carefully forward and aft and the nut will soon release all the way.
Here we see the nut slot on this guitar:
I have already used some small, sharp chisels and files to true up the slot and to remove the dried glue from the last nut. I would have taken a picture of this process but hey a guy only has two hands you know…
This nut will be a bit more difficult in as much as the nut itself has to conform with the curves of the headstock. This is a look that I personally do not like and I am no longer building guitars with dramatically curved nuts. But it is a good mule for our purposes today.
Here is another shot of the nut slot now cleaned up and ready to start fitting a new nut blank:
Recently I found a new source (new to me…) for nut blanks and these came from Chrislin Trading Company: www.chrislintrading.com
The packages contain bleached and unbleached nut blanks and I am very pleased with the quality, service, and pricing of Chrislin Trading Company. I should mention too that I needed some oversized blanks for a special application and I could not find what I needed anywhere else. Chrislin Trading had the goods I am pleased to say.
Regarding bone nut and saddle blanks often you will find both bleached and unbleached blanks available. The difference is the whiteness of the blanks and it has also been said that bleached blanks, all things being equal, can be slightly softer than unbleached blanks.
Today I am selecting an unbleached blank to match the unbleached original saddle on this guitar AND because I personally like unbleached, natural looking bone. If it’s true that unbleached bone is harder that’s a bonus.
The very first thing that I do is to true up one face of the bone blank to designate the face of the nut. In addition I am looking to remove material from the blank to get it close, but not all the way, to fitting in the nut slot. A nut should fit well in a nut slot and not have any slop or ability to move forward or aft:
Again I am not looking to remove enough material at this time to make the nut blank fit in the slot but I am removing the obvious excess and getting the nut blank to be close to fitting.
What you see below is a piece of tubular aluminum that both faces were worked on a certified flat surface plate covered with 120 grit sand paper. As such this “beam” is now nearly perfectly flat on both faces and comes in very handy for a number of guitar building tasks. These beams also make an excellent surface to true-up anything that is small enough to fit on the surface of the beam that you wish to make near perfectly flat. In this case once the beam was trued on the certified surface plate I have placed 120 and 240 self-stick sandpaper on the two respective sides.
My newly designated nut face is now flattened on the 120 side of the beam:
Next I will make pencil marks on the face of the nut blank so I can visually see as I am flattening the blank:
Anything that you have available to you and that you know is very flat can be used for this step.
Now we will turn over the beam and sand our newly designated nut face on the 240 side of the beam:
Once this is completed we now have a flat and smooth nut face and a pencil is used to mark this surface for future reference. The nut face will not be worked again and will be as it is now when the completed nut is installed on the guitar:
Moving along… the next thing that I do is to sand in the headstock’s set-back angle into the bottom of the nut blank. If you do not locate your nuts on the angled back headstock this step can be substituted with simply flattening as we did above the bottom of the nut blank AND making sure that the bottom is 90 degrees to the nut face.
For this guitar the nut is located on the set-back headstock so this will require a 15 degree angle on the bottom of the nut blank. Be careful to place the angle in the correct direction in respect to the newly designated nut face…
I adjusted the table on my belt sander to 15ish degrees and sanded this angle into my nut blank.
Once this is accomplished it time to start fitting our nut blank to the guitar’s nut slot. Once again we intentionally left the nut wider than the nut slot so that we could sneak up on the fit and get it right the first time. You can see the nut in the slot and it will only fit at this point if not seated and angled back. This is exactly what we want for now:
Next we will be removing material off the back side (toward the headstock) of the nut blank until we have a snug fit. The sanding beams are great for this step too.
With very little practice you can learn to read your nut blanks by trial fitting and noting where material needs to be removed. Using the sanding beam and adjusting your fingers to concentrate on the area of the back of the nut blank that needs to have material removed will help you zero in on a good fit.
A good fit is when the nut blank can fully seat but not move forward or aft. Since nut slots are rarely perfectly true sliding the nut blank from side to side in the slot can also yield a better fit in certain positions.
Once the blank will seat AND the face it perfectly 90 degrees to the fret board you are nearly there.
The 15 degree set-back angle is not always 15 degrees either. So now it’s time to hold the blank firmly down with your thumb and check the fit from both sides to be sure that the angled bottom of the nut is making contact with the nut slot. If not remove the blank after noting which edge is high and use your sanding beam, or what every you have, to concentrate on the high side of the nut bottom frequently trial fitting until the nut is fully seated:
Once our nut blank fits well in the nut slot it’s time to use the half-pencil to transfer the fret height onto the nut face. The half-pencil is exactly that, a pencil that one half of it has been sanded away on a belt sander. The line that we make, though not required, is helpful to me when initially cutting the nut slots in as much as it provides a reference line to not exceed.
It’s very useful for many things that we do to be able to draw a line that we can see but to also have the line be very thin and precise. You can easily and quickly sharpen even a mechanical pencil with some 220 sand paper:
Once you have the ability to draw thin and precise lines while holding the nut blank firmly in the nut slot use the sharpened pencil to trace the contours of the fret
board, neck, and headstock overlay onto the nut blank:
At this point I know from experience that I can remove some material and height from the nut blank. I have drawn a line to not exceed and used the trusty belt sander to remove excess material. If you are wondering why I don’t transfer the radius of the fret board onto the nut blank top read on we will address that later:
The nut blank is now placed in the nut slot in the exact position in accordance with the lines that we have drawn on the nut blank:
One additional step at this point with the nut blank in the slot and positioned correctly is to trace the head stock overlay where it contacts the back of the nut blank. A line is made on the back of the nut blank for future use:
The shape of one’s nuts can vary widely… and I am sure that we all have shapes that we will find pleasing. For me I like to remove some material off the top and back of the nut blank and this is now done free hand on the belt sander. One of the advantages of doing this step now is that when you are cutting the nut slots with your nut files you will have less material to cut through:
Here is where things get interesting… The nut blank is properly located, NOT glued, and the low and high E strings are installed on the guitar. These strings will hold a well fitted nut blank firmly in place for what comes next:
The tape that you see on the head stock is optional. My method for stringing a guitar benefits from some protection to this part of the head stock in as much as we don’t want to scratch anything now do we…
In the photo above we see the low and high E strings on the top of the nut blank. The string spacing in terms of the distance of the E strings from the edge of the fret board is now determined and marked. Dan Earlywine does this by eye using his years of experience. For the rest of us an engineer’s scale is recommended… Personal preference may also come into play here too. Some folks use 1/8” as the standard, others use something else. I like a bit less than 1/8” and using an engineer’s scale I have positioned the strings where I want them and using my sharpened mechanical pencil I have traced each side of the strings onto the nut blank top:
Update: These days I am using my eye as well as the shape and condition of the fret ends to determine the spacing of the outer strings.
Here we see some of my nut files and the specific files that I like to use for the strings that I prefer. Most of my files are a couple thousandths wider than the respective strings that they will be cutting the slot for. Luthiers with more experience and talent are able to reliably cut a nut slot nearly any size with a much smaller file. For the rest of us carefully selecting your nut files for your most common requirements will be beneficial:
At this point I am going to rough in the nut slots for the two E strings. While initially cutting your slots I find it easier to use my thumb as a stop on one side of the nut file as I move the file slowly forward between, hopefully…, the lines. If you are off a bit you can tilt the files in either direction and “walk” the file into the proper position.
Be sure to note your files orientation too. It’s very easy since we are standing on only one side of the guitar to cut nut slots that are not in the plane and direction of the neck. But again at this point we have lots of material to cut through and most mistakes can be corrected if noticed early enough:
Now it’s time to space out the rest of our strings. The Stew-Mac nut spacing rule is excellent for this task and highly recommended.
When using this tool be sure to note the “bass and treble” designations on the rule and use only the scale that these designations properly correspond with.
A place on the rule is found in which the two E strings appear in the slots and 4 (count them please…) additional slots in the same set of slots are available in between the two E strings. Don’t laugh – I have marked out a 5 string guitar before by mistake…
With your sharp pencil make a mark on the nut blank’s top where the remaining 4 strings will go:
Now using the correct nut file for each respective string rough in the remaining 4 string slots:
I like to tune the guitar to pitch at this point. Even though we are not going to cut the slots all the way yet it’s not a bad habit to get into to tune the guitar and retune as required while cutting nut slots. More on why later:
For now my intent is to cut the nut slots nearly to full depth but not all the way. During this process I will also be increasing the pitch of each string trying to keep the guitar nearly in tune.
Since I didn’t have a free hand or a helper when I did this I don’t have a picture for you. But what I want to talk about next is the angle that your nut slots should be cut in respect to the plane of the fret board.
Frank Ford has a very good suggestion which is to note the head stock angle set-back, in this case 15 degrees, and divide that by 2 and endeavor to cut your slots in the 7-8 degree angle from the fret board plane. This is what I do as well. I also try to angle the file a bit more toward the head stock at the back of the nut slot (side toward the head stock). This is so as to keep the string from riding on a high part of the slot and not making contact with the slot bottom at the face of the nut.
Be very careful though and if you do round the back side of your nut slots never exceed the 15 degree head stock angle or a slip of the file may gouge the head stock…
The goal for a well cut slot is for the string to be in full contact with the bottom of the slot as the string launches into space off the nut face. If the forward most position of the slot is lower than the rest of the slot the string will not make contact at the nut face and you have succeeded in elongating the string and intonation and other problems my occur.
If you don’t know a method for how deep to cut nut slots here is one for you.
You can check if a nut slot is deep enough (or too deep….) simply and quickly by doing the following: Making sure that the string is all the way seated in the slot by pressing the string right in front of the nut and visually observing the bottom of the nut slot be sure that your strings are seated all of the way. It’s very easy to cut a nut slot that is too narrow for your string and the string will hang up in the slot. Since you don’t see the action improving you cut the slot deeper and deeper… In short order your slot is too deep, the string is hung up, and now the nut is useless and you have to start over…
To avoid this unfortunate occurrence while cutting nut slots frequently (I check with every 3-6 swipes of the file) check by doing the following:
Fret and hold the string between the second and third fret. Observe the strings height over the first fret and using your finger tap the string between the nut and first fret. The string should NOT lay on the top of the first fret – this is too low. Our goal here is to cut the slots so that the string is ever so slightly clearing the first fret but not touching it. This is dicey at times in as much as the difference between a high nut slot and a perfect nut slot can be only a very few swipes of the file. Please note: It is all too easy to cut the slots too low so be careful!
When the string is still not touching the top of the first fret while fretting between the 2nd and 3rd fret what you want to see is just the tiniest of gaps between the top of the first fret and the bottom of the string. This gap can be so very tiny that you might not always be able to see it but instead see some light through the gap. Another way to observe this is to listen for a “tink” sound that comes from the string hitting the top of the fret when you press between the nut and the first fret and are fretting the string between the 2nd and 3rd frets.
This is actually in my opinion where cutting nut slots properly becomes a bit of an art that one will develop the touch over time. Don’t be discouraged if you cut too far and have to make a new nut – we all have.
The feel that the player will receive while playing a guitar with skillfully cut nut slots is well worth learning to do this correctly. In fact just making a few nuts with the goal being to learn to make nut correctly is well worth the time and effort.
Update: This old fart now has an Optivisor... highly recommended...
These nut slots are nearly cut to final depth. I have left them a few swipes high on purpose and will do the final cutting once the nut is shaped and the guitar is strung up.
As promised a word about keeping the guitar tuned to proper pitch while cutting nut slots.
Since the head stock of many guitars is angled back and/or strings angle downward after the nut in practice a nut slot may end up crossing the line that we drew on the nut face indicating the fret height. As the string breaks over the nut from the head stock toward the neck there is an ever so slight bending of the string that happens where it leaves the nut face. As the string’s angle changes from the 15ish degrees to the plane of the fret board the string leaves the slot and rises ever so slightly before assuming the plane of the fret board. This is why nut slots may at times be cut below fret height and still be well cut slots.
The pitch and tension of the strings will determine how much of this bending from the nut face the string wants to do. If your strings are slack when cutting nut slots the read that you receive will be inaccurate. The same holds true for strings that are over tensioned.
If you suffer from hypertension take a few deep breaths we are going to do something messy next…
In the picture above the excess nut height is being filed away on the guitar, fully strung. When I first saw this done it made me very nervous but I assure you that this is a great method to accomplish this task safely, accurately, and quickly. Do be aware that you are using a metal file on a finished guitar and always observe the number one rule of guitar repair – do no harm….
Support the guitar and guitar’s neck well and use a fairly fine cutting file. The goal here is to indeed file the nut’s top down to the point where you are actually contacting the file with the tops of some or all of the strings. At first your slots will fill up with dust and then you will start to hear metallic, ugly noises and the bone dust in the slots will be replaced by shiny strings that you are now mutilating… Stop when you make contact with the string – please…
It is not uncommon to use 2-3 sets of strings during the set-up of a guitar. They are considered expendable by many repair and building pros. Remember – buy strings in bulk whenever possible…
Once you have stopped palpating and you have exposed metal of the strings while filing the top of your nut it’s time to put the file down and cut the now useless string off your ax.
If you recall we marked the nut in respect to the neck, fret board, and head stock overlay. Now it’s time to fit the nut ends to the contours of the guitar.
After removing the bulk of the excess material the nut is trial fitted:
Here is where your artist’s eye will come into play. I use a file to shape the hard edges of the nut and try to additionally shape the nut so as to be pleasing to the eye and functional.
Once the shaping with the file is complete I move to 220 grit sandpaper. Be sure to get all of the file marks out with the 220 grit – later grits will not remove file marks as well.
But before I do I have intentionally written on the nut in three places where I do NOT want to sand the nut. These places, if sanded, will ruin the great fit that we worked so very hard to achieve earlier. The marked locations include the nut face, bottom of the nut, and where we traced the head stock over lay onto the back of the nut.
One of my very favorite tasks when working with bone is to get out the Micro-mesh pads and shine my nuts and saddles…
Micro-mesh can make a bone part look jeweled and give it a very polished look. Although using a buffer is faster I find it enjoyable to spend 20 minutes polishing my bone parts. It’s one of those immediate gratification things I suppose….
Do be sure to not sand any of the areas that we marked.
Hey, hey it’s CA (super glue) time… I use medium CA for gluing nuts. A well fitted nut really needs very little glue at all. We do glue them so that in the event that one of our customers changes their strings and their nut falls off we don’t get an impassioned, panicked call at 3:00 AM…
With CA only two very small drops are required and I place these drops in the crotch of the fret board end and the neck’s nut slot. Medium CA will tack in place in about 5-8 seconds so work carefully, use very little, and all will go well.
I like to make a puddle of CA on scrap and then use a tooth pick to apply the CA.
Be sure to also clean out any dust from your nut slot prior to gluing the nut.
Before gluing the nut now is the time to erase any remaining pencil marks and writing on your nut.
Are you getting excited???
And here we are with our nut now made and glued in place. Note the jeweled look that the Micro-mesh created in the surfaces of the nut.
I hope this helps you with your nut making.