Questions: Nut Width

by Bob Pittman

Originally published in American Lutherie #102, 2010

Rand Nooteboom from Haiku, Hawaii asks:

Nut width varies from one instrument to the next and so does placement of the outside strings. What is the most reliable method of evenly spacing the remaining strings? Not just marking placement, but also accurately cutting the slots.

Bob Pittman from Brookline, Massachusetts responds:

For marking the spacing, I use the Stew Mac string spacing ruler (www.stewmac.com/shop/Tools/Measuring_tools/String_Spacing_Rule.html) and a .7MM pencil. The pencil is very fine and fits in the spacing ruler slots. The ruler does proportional spacing and I’ve never had a single customer complaint. I start with a nut cut square on all sides and sanded to 400 grit. I cut it to width and fit it into the nut slot. The outside strings are marked, then the nut is put in my nut vise, a Parrot vise with panels cut to 45° on the top edges so I can get at the nut. I mark the remaining slots with the string-spacing ruler and the pencil. With a 3" machinist’s square, I butt the edge up to the back of the nut next to a string mark. I use an X-acto saw and mark the top of the nut on top of the string line. (I think a Japanese-style saw would be perfect for this since it cuts on the back stroke, but I haven’t gotten around to buying one small enough.) I make sure the saw is perpendicular to the nut and flush against the square. With very light pressure, the slots are cut about 1mm deep. I put the nut back in the guitar, and nut files are used to finish off the slots. After that, I remove the nut, shape it on my sander, polish it with Micro-mesh up to 12,000, put it back on the guitar, and the guitar is ready to string up. ◆