Mammoth Ivory Nut install on a Gibson Les Paul 120th Anniversary Edition
I see lots of Gibsons in our workshop. They are very often great guitars with issues that really shouldn't be there! This particular guitar is a Gibson Les Paul 120th Anniversary made in 2014 and was brought in for setup.
- 2.75mm action at the 12th fret Bass side 2.5mm Treble side
- Truss Rod needs tightening
- Intonation Needed
- Possible Nut issue - Too low on 5th & 4th string
Nut Height Problems
In order to establish if there is a problem with nut height there is a quick method.
Place your finger at the 3rd fret and look at the gap between the string and 1st fret. There should be a small gap.
If there is no gap then it is possible the nut is too low. It is also important to be aware of any fret issues.
After I had adjusted the truss rod and checked for any fret issues I could see the nut was far too low on the D string in particular. With the truss rod adjusted correctly there was almost no resonance from the open string. I looked at the options for amending the problem and talked to the customer about a replacement for the nut. This would usually be a piece of bone, which I would carve from a blank, or a Graphtech / Tusq pre moulded replacement.
Mammoth Ivory can vary hugely in colour from light cream through to almost chocolate colour streaks running through it. Having not worked with any other type of Ivory I don't know how particular colouration variance is to Mammoth. I don't imagine there is going to be any noticeable tonal difference from Bone but it certainly looks a little different. This particular blank is a beautiful aged (10,000 years approx.) cream.
The nut took about 2 hours to make and there was a reasonable amount of prep time to ensure the nut slot was perfectly smooth, clear of glue and lumps. Most of the shaping work is done using small files and a dremel is used if there is a significant amount of material to come off.
The majority of the shaping is done in a vice and when the shape and final width of the nut is correct it can be fitted with a small amount of glue.
The string spacing is very important so I use a Stewart MacDonald tool called a string spacing gauge in order to ensure accuracy. The gap between the strings edges should be the same which means the relative centres slightly increase as the string gets thicker.
One of the most important parts of making a nut is to have good files of the correct gauges. On this particular one we used 0.010", 0.013", 0.017" 0.026", 0.032" 0.048". You could use a thicker gauge file for all the strings but I do prefer the aesthetics of a nut with optimally cut slots.
To polish I use various sand papers starting with 1000 and then going through grades 1500, 2000 and 2500. Final polish is done using a dremel with Encore Scratch remover.
Strings & Setup
- 1.5mm action at the 12th fret Bass side 1.25mm Treble side
- Truss Rod - 0.010" at 7th fret with 1st and last fret held.
- Intonation Perfect
- Replaced Nut with Mammoth Ivory