[JackB1]

Originally Posted by Robin, Wales

Have you found that the string spacing is different between your original Martin nut and the Graphtec replacement? Graphtec tend to cut all their nuts with equal spaces between the strings. Martin use equal or proportional centres. The result is that the treble strings are closer together on a pre-cut Tusq nut and the bass strings further apart.

I can play a 1 11/16th Martin nut but struggle with a 1 11/16" pre-cut Tusq nut - despite the overall string spacing being 37mm on both.

No the string spacing on the replacement nut was identical to the original Martin nut. So was the width. I just needed to sand down the thickness a tad and then the height needed to come down quite a bit.