Wednesday, October 27, 2010

Making a (bone) nut from scratch

I’ve made a post on here before about making a nut (out of ebony) by tracing an outline around the old nut (http://diystrat.blogspot.com/2009/06/making-ebony-nut-and-saddle.html), but today I’d like to show you how to make a nut for an acoustic (or electric) guitar from scratch. This is for a couple of reasons:

1. The old nut might be missing or damaged.
2. You may not be able to trust or may not be happy with the shape of the previous nut.

So let’s look at the patient first. Here’s an acoustic guitar missing its nut. Just a quick note here... there are some remnants of glue in the slot and that should be removed with a sharp knife before proceeding further.


Assuming you have now cleared out all the glue, and are ready to start making a nut, you will first need a blank. Here’s mine:


I was going to tell you that the first thing you need to do is thin the blank a little so that it will fit in the slot, but it turns out the blank I had was perfect already. If you DO need to thin it a little, check out the ebony nut post to see how I did it there. Oh, and if the blank is already TOO thin, then forget it – you need a new, fatter blank.


So far we have a blank that is the correct thickness, but not the right width.


Mark the edge(s) with a pencil and cut it down to size with a hacksaw (not while it's sitting on the guitar, as the photo might suggest).


The next step is to shape the blank nut to the same radius as the fretboard, and make sure the strings pass over it at a suitable height above the other frets. This is the step that you can miss out if you just trace the previous nut’s outline, and is also where a lot of people get stuck. However, it’s not hard at all.

You will need a very specialised tool for this next step, namely the “half pencil”.

Here’s a “whole pencil”. We need to split it down its middle.


First let’s remove that pesky eraser thing at the end. A pair of pliers will make short work of that.


A decent sharp strong knife is required now. I don’t recommend using a craft knife for this – it’s too brittle. Here’s the knife I used.


DISCLAIMER: If you don’t know how to use a knife safely, stop here. I will not be responsible for any injuries you might cause yourself.

If you look at the end of the pencil, you may be lucky enough to find where the two halves were stuck together originally (yes, that’s right, a pencil has two halves, plus the lead – they don’t just drill a hole through a long piece of wood and insert the lead that way).


Unfortunately for me, I couldn’t see the join, so I had to guess. My first attempt was a disaster.


Further detective work revealed a faint line down the sides, so I tried to follow that. Success!



The half pencil is pretty rough at this stage, not least because the lead itself will remain mostly intact. That’s fine.


What we need now is our trusty piece of sandpaper sitting on a nice flat piece of, well, pretty much anything hard (in my case a floor tile).


Sand the bottom of the pencil until you have a nice flat surface and you are now the proud owner of a half pencil!


You can see from the photo how much carbon has gone everywhere. It’s probably a good idea to wash your hands at this stage to prevent more unwanted carbon marks. Also, to stop the pencil lead from falling out (there’s really not much holding it in at this stage), I recommend running a length of Sellotape (Scotch tape) along the exposed part of the pencil to hold it all together.

Place the half pencil on the frets and pull it across the fretboard, while drawing a line on the nut (which you’ll need to hold in place for this part).


You will now have a line marked on the nut where, if you were to file down to this line, it would be exactly in line with the other frets.


In fact, you need to make a line a little higher than this. Some people would recommend freehanding it, but I prefer placing something under the pencil and drawing another line. A good safe distance is about 1-2 mm. I thought I had one of those wooden coffee stirrers lying around, but I couldn’t find it, so I used a lollypop stick.


You can tape this to the bottom of the pencil and draw another line to give you a good (safe) line to shape the nut to before you start filing the string slots.


Here’s the nut with the second line drawn:


And here it is filed down to that line:


Next thing to do is mark the position of the string slots. For this I have a nice little position chart. I got it with my nut files, but I’m sure you could find a printable one easily enough online.


Here are the nut files I’m using:


I use my nut files to file slots down to about halfway between the two lines (not quite finished in this picture).


Remember not to file the slots exactly level (horizontal), but rather at a bit of an angle, angled down towards the peghead side of the nut.


You’ll probably also want to shape the back of the nut so that it curves down a bit on the peghead side. This helps the strings to find their way to the machine heads without too much interference.


This next part isn’t entirely necessary, but if you want to make the nut nice and shiny, you can use something like these micro mesh pads from stewmac.com:


First use the roughest one (be careful not to alter the shape/thickness of the nut), then move through each pad until you get to the smoothest one. You’ll end up with a nice shiny nut. You could just as easily use different grades of sandpaper to do this job, or possibly some other sort of abrasive.

Here’s the finish I got after just a few minutes’ work with the micro mesh pads:


I’m sure an even better finish could be achieved with a little more effort.

So now it’s time to test the nut out on the guitar. DO NOT glue it in place at this stage.


As you can see the strings are sitting a bit high, but the good news is that we can simply file a bit of height off the BOTTOM of the nut now – no need to do all that shaping, slot filing and shining work all over again.

I mark the nut with my best guess for how much to take off (remember you can always take more off, but not really put it back), so better to take off a little at a time.


Another test fitting after removing some height and I’m happy with the results, though I’ll play with it for a while before deciding for sure.


Once you are sure you are happy with the nut, you can glue it in place (although this is not entirely necessary, as the strings will hold it in place very well – just be careful if you ever remove all the strings at the same time).

The question is which glue and how much to use. I’d recommend a very weak glue. Cheap white craft glue, even watered down about 50% is more than sufficient. A single drop near each end of the bottom of the nut is enough.

Finally, here is the happy patient, with its new bone nut, made from scratch. Please feel free to leave a message if you have any questions or comments.


5 comments:

Anonymous said...

Thank you VERY much for this information. Now I know how to go about this. Excellent!

Mollymoll said...

Hi Stu. Adam here, we met at Preston's on Christmas day. Great Blog. Very detailed. I'll come back.

stu said...

Cheers, Adam.

DiegoA said...

Are these proper nutfiles or you carved teeths in a feeler gauge?

stu said...

Hey Diego, they're kinda both. Google "Norman Nut File System". I'm not sure if you can still buy them.