This discussion got me thinking, which can be a bad thing. I worry all the time about string break angles over the saddles of acoustic guitars and archtops and resonators - I'm pretty aware of this as I build and set up these styles of guitars. But frankly I had never given the nut end much thought. Long ago I built my first guitar pretty much based on what people had been doing for a few hundred years, seemed to work fine. My criteria at the nut were pretty simple - I didn't want the strings to pop out of the slots (and I really don't like deep slots), I didn't want the strings to bind when I tuned them, I wanted a fairly straight path from the nut to the tuner post, I wanted the guitar to fit into an available case - pretty simple requirements. I was somewhat influenced by the repairs that I make to instruments with broken heads. I also am pretty traditional - I like the heads of my guitars to look "right" for the style of guitar. I have to admit I'm not a big fan of Fender heads in general, but if I'm building a Fender style of guitar I'll probably put a slab head on it. From time to time there will be a discussion on some internet forum about the effects of nut break angle - the usual (unsubstantiated) claim will be for more or less "sustain" (the holy grail of electric guitars). I mostly blew these off - I'm an engineer and I either want to see the math or some sort of well designed experiment that attempts to "prove" whatever point the poster is trying to make. I'll add here that in the world of acoustic guitars there is some very interesting experiments trying to validate those phenomena that we think we hear. So, anyway, this got me thinking. What is the typical break over angle at the nut on different headstock designs. Out to the shop with an arm load of gutiar cases. What I did was very basic - I just measured the angle of the string from the nut to the tuner post as best I could (without going thru a whole lot of effort). I zeroed my little digital protractor and clamped a couple of blocks of wood across the arm so they would sit on the strings. I made an effort to fit it into the top of the slot and measure the angle as the string breaks towards the tuner. Something like this Anyway, here is what I got. Telecaster clone, two string tees, readings from low E to high E. 15.4, 8.6, 10.5, 10.5, 12.5, 12,5 Les Paul clone - low E and D string. 14.0, 12.5 Slot head 00 - low E and D string 24.0, 19.5 Mmmmmmmmm...... What is the optimum angle here? The tele is all over the place, but of course that is largely determined by where and how tall the tees are. The low E has lots of break angle because the tuner is close to the nut and the string wraps are fat so they go farther down the post. The 5th string has the least break, you can see that from the picture. The tees give the other pairs of strings the same angle, maybe they should be put in some other position to optimize these strings. Or not. The LP has pretty much what I would have predicted. The strings follow the 16 degree angle of the head, but the height of the tuner post lessens the angle a bit. The slot head is similar - still a 16 degree head angle but lots of break because the posts are down in the slots. (This brings up an interesting question - Rickenbacker 12 strings have a combination of slot and paddle head tuners, every other string. If one of them is better than the other, more sustain or whatever, why would a manufacture not just use the "best" one?). There is a lot of really good math out there for analyzing the forces at the bridge of a guitar - there are rotational components and components into the top and shear components - the same math would apply at the nut. But you know what, each of those guitars above sounds pretty darn good and the string work pretty darn good too. They tune fine, the strings don't pop out of the slots, I've got jigs for making 16 degree heads. I guess I don't see any reason to change.