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Breakover angle at nut

PostPosted: Wed Oct 05, 2016 11:57 am
by George Reiswig
I use two instruments that both have some fairly heavy wound strings. On my baritone acoustic, the 6th string is a .070", and on my standard-scale Lowden where I regularly tune the 6th down to a B, I use either a standard .056" or even a .060".

These strings are thick enough that they don't easily bend over the angle of the nut if I do the windings around the tuner the way I am accustomed to doing them: with the lowest winding being the "exit" winding such that the string goes from basically the bottom of the post to the nut. As a result, the action is increased. I can force a bend at the nut once tuned, but for example on my Lowden I change tunings a great deal, ranging from that low B up to E. A permanent bend there causes issues.

Or...I could change the way I wind the string around the tuning post, so that the exit winding is higher, decreasing the angle over the nut. This does seem to help a bit, but it got me thinking about whether there are other factors that might be affected doing this? Is there an optimal break over angle? Is there a generally agreed proper direction to wind the string around a tuning post?

Re: Breakover angle at nut

PostPosted: Wed Oct 05, 2016 2:25 pm
by Brian Evans
I don't know about optimal angle, but I do know a friend recently built a guitar with too shallow a break angle too shallow a headstock angle, really) and had a buzz that was very hard to diagnose and fix. A lot might depend on headstock angle to start with, and distance from the nut to the post - all variables in every build.

Brian

Re: Breakover angle at nut

PostPosted: Wed Nov 16, 2016 9:15 am
by Glenn Ohman
I think it should more or less match the break angle at the headstock.

Glenn

Re: Breakover angle at nut

PostPosted: Wed Nov 16, 2016 12:30 pm
by Rodger Knox
Minimum "effective" break angle is about 6°. Less than that is not enough, and with the OP's heavy string issue I'd guess "optimal" would be between 6° and 8°.
I also wind the strings down the post, which is pretty typical for those who pay attention to that kind of thing, but that's just to increase the break angle. I see no reason you shouldn't wind the strings up the post to reduce the break angle as long as you don't go too far.
Normally, more break angle does not cause problems, but with heavy strings that may not be true.

Re: Breakover angle at nut

PostPosted: Wed Nov 16, 2016 1:53 pm
by Steven Smith
Per my training, the breakover angle on the nut should vary from perhaps 5 to 7 degrees at the string entry to a few degrees less than the breakover angle of the headstock. This is facilitate smooth string movement through the nut and to prevent buzzing.

Re: Breakover angle at nut

PostPosted: Wed Nov 16, 2016 3:10 pm
by Gordon Bellerose
The shape of the nut might also affect the way the string works there.
Is this a "Fender" type nut? Very thin, with a bit of fret board in front?
Or is is a "Gibson" type, resting against the front edge of the fret board?

If it is a "Gibson" type, you should be able to shape the slot so that the fret board side is flat along the plane of the fret board, and the trailing edge slopes down toward the tuner. This gives the string a nice rounded "ramp" in which to work.