How to Make a Bone Nut

I’m going somewhere on the subject of nuts (eventually) so I reckon it’s time to show how I go about making a bone nut. This is a relatively involved and image-heavy post so I’ll split it over two. Sorry for the cliffhanger later on.

How to make a bone nut for guitar or bass

I’m showing this on a Fender Strat but the process is mostly the same for any guitar or bass.

It starts off with a bone blank. You don’t actually need to whittle down a cow’s femur yourself. You can buy blanks that are close to the dimensions you’ll need. You'll get these in the usual luthier's supply places and, as usual, Stew Mac is a good place to start.

Thickness the nut blank

Of course, the blank's not exactly at the dimensions you want so the first thing you’ll need to do is thickness the blank so it fits the slot. I have a granite chopping board (that I checked for flatness) with four grits of sandpaper stuck to it (120, 220, 320, 400) and I use this to size the nut so it fits snugly into the slot. I do mean ‘snugly’, but the way. The ideal fit should be an easy press fit that holds in the slot without falling out.

Thickness sorted out, now you need to get the rest of the slot-fitting sorted. If you’ve a Fender, there’s a good chance your nut slot will have a radiused bottom (higher in the middle). I’ve covered this before when talking about fitting pre-cut nuts so you can recap on shaping a radius on the bottom of a Fender nut if you want. Getting the bottom cut to shape will allow your blank to sit perfectly in the slot and is important before proceeding.

Actually, on that subject, pay close attention to the nut’s fit in the bottom of the slot. Make sure the nut sits nice and flush at the bottom.

Marking out the nut blank

Once the basic fit in the slot is good, I move on to marking out the edges of the nut. Use a very sharp pencil to mark the neck’s profile along the face and bottom of each end of the nut.

The next step is to transfer my fret height to the face of the nut. I use a ‘half-pencil’.

The half-pencil is an old carpenter’s trick. Take a pencil and sand or plane it until it’s essentially split along the graphite core. The exposed flat plane rides along a surface and accurately transfers the height of that surface to something else. Because you’ve split the pencil to the core, it’s marking/writing at exactly the height of the surface it’s on. Hope that makes sense. An image might help.

The half-pencil is a great trick

I lie the half-pencil along the frets and run it across the fingerboard. This makes a mark on the nut that’s the equivalent to the fret height. Later on, I'll use this line as a guide while roughing in nut slots. Not everyone does this half-pencil trick, but I find it speeds things up.

using the half-pencil to transfer the fret height to the nut.

The last step of marking out is marking the rough position of the ‘top’ of the nut. For this, I use a radius gauge. I’ll match the fingerboard radius and pencil a rough top line a little above the half-pencil fret-top line. I’ll usually just eyeball this and leave it higher than needed as I’ll be cleaning it up later. Super-tight tolerances are not needed for this line right now. Aim for enough to — at a minimum — easily accommodate a string.

A nut marked out roughly and ready for rough-cutting

You can see the top line in the image above. Bottom line is my half-pencil fret-height and the top line is my (rough) nut top. You can see it gets a little higher as it moves from the 1st to 6th string. I've marked this one relatively close to the final size. If you're following along, I'd recommend you leave the temporary top mark a little higher.

Rough cutting a nut blank

This is where I have an advantage over someone DIYing a nut. I’ve got some power tools to speed the rough cutting. A scroll saw or bandsaw makes it easy to cut the blank close to size. Then, a disc sander makes short work of getting things even closer.

I use these tools to get the nut almost to the sizes I’ve marked. Then I’ll test fit and use my ‘sandpaper-board’ to get the nut ends to within a hair of the side of the neck. I’ll take this last, tiny amount off when I do final fitting and polishing but I do like to get it very, very close now. For you guys reading this, you might have to do some cutting and sanding with hand tools to rough cut your nut.

Checking the rough-cut nut for fit. I like the ends very close to the final dimensions.

Marking string positions

More marking up. This time it’s string-slot positions. Before we get to that, though, we have to mention something important regarding string-spacing at the nut. Those gaps between the string slots are not all exactly the same size. Because each string’s diameter increases as they move from treble to bass side, we adjust the slot spacing between them to compensate. Otherwise, the fatter, wound strings would feel cramped.

You can string up an instrument loosely and layout the strings by eye. This is actually a perfectly sound way to do it and will usually give good results. Just get them where they look right and mark their positions. Actually, laying out by eye like this tends to automatically add that slight increment in gap-size. This is because you’re visually compensating for the fact that the strings are getting thicker.

Using a string-spacing ruler for slot positions. It’s really easy to do by eye on the guitar though.

For speed, I’ve got a couple of string-spacing rulers. The one used in the image, I’ve had for many years and I’ve no idea if it’s still available to buy. Stew Mac has a string-spacing ruler (shown in the background) that allows for many more increments and I’ll use that when needed but, most of the time, this simple one gives me the ‘standard’ string spacing.

Of course, I’ll usually refer to the previous nut and, unless I’m correcting a problem, I’ll match the spacing on that.

I grip my nut in the Stew Mac Nut/Saddle Vice thing (and it’s really handy) but you can easily do this with the nut on the guitar too.

Use a pencil to mark each string’s position.

And there we’ll leave it until next time. Tune in next week for the slot cutting, the fine setup, and the clean-up.

I told you there was a cliffhanger. Suspenseful, isn’t it?

This article written by Gerry Hayes and first published at hazeguitars.com