Now that we have a new saddle for the Martin, we can move on to making a new nut.
This is old one, which I'm pretty sure is the original one. You can see where someone put paper under it to shim it up. Paper. Just the thing for good tone.
Anyway, I'll use the old saddle to help shape the new one - and I'll also use approximately the same spacing between each pair of strings.
The streaks in the horn are really nice looking I think. I've read that the horn material is fairly hard, but it's not quite as hard as cow bone, which I usually use.
This was a little trial-and-error. I wound up marking the two outermost strings. On the bass side, the outermost string is the octave E. On the treble side, it's one of the paired high Es.
Then I measured and marked the low E alongside the octave E, using the pair spacing from the old nut. Then using the low E and the outside high E as a reference, I marked the other 4 standard strings. Finally I went back and marked the octave strings for each pair.
It depends on the individual string. But in general, I used a feeler gauge about the height of the first fret (I think about .030), and then a second gauge a couple thousandths higher on top of it. Then file down until the file just hits the gauge.
It came out ok I think. It's not quite as dramatic looking as I had hoped. The horn does seem to be a bit softer than bone - it definitely scratches more easily. But it looks much better than the white plastic original.
I have some better pictures of the finished guitar coming up.
The Complete Martin Guitar Restoration Saga
Repairing heel break
DIY chisel for bridge plate removal
DIY bridge plate removal iron, Pt.1
DIY bridge plate removal iron, Pt.2
Steam removal of bridge plate
Bridge plate removed
Tongue brace removal
Crack repair and brace scallop
New bridge plate Pt. 1
New bridge plate Pt. 2
Patching hole in top
Final fitting of top patch
Installing carbon fiber rod
Fingerboard crack repair, Pt. 1
Fingerboard crack repair, Pt. 2
DIY fret bender tool
Refretting Pt. 1
Refretting Pt. 2
Tuner shaft repair
Neck reset - dovetail fitting
Measuring neck set with DIY jig
Gluing the neck with hide glue
Fitting bridge pins
Making bone saddle
Making a buffalo horn nut (This page)