[jefrs]

Given enough time and effort one can make any tool (I was taught by a master toolmaker), after all, somebody made those nut files. Even if they are made on a machine, somebody made the machine. Suppose I were to fashion a nut file by grinding down the sides of a Swiss needle file (done that), there's a lot of wasted ones, the temper is ruined, it takes time, and they're not very good: it is more cost-effective to buy them.

The slitting nut files are industrial micro-saws, they are very good at starting the slots in precisely the right place. Their cutting edge appears to be square with no set, so they cannot cut deeply. They will make a complete slot provided the slot is not too deep, or as I've found, the string may bind or even snap the cusp off the nut.

The V-shaped nut files are a very shallow Vee, the string cannot bind in their slots but the bottom of the slot is precisely the correct diameter to seat the string properly. I initially thought they were too wide for anything but thick acoustic strings but no, I've had no problems with light electric sets, no slipping sideways, no tuning or intonation problems, no binding, no buzzing and wheezing.

I've made a lot of different nut slotting tools over the years but I've found nothing that comes close to the ease of use and the precision of professional nut files.

Now everyone has their own way of doing a job, and their own favourite tools for it. If there are six ways of doing it, someone will find a seventh.