10 is NOT 12... or is it?

[nexion218]

I got a little confused yesterday... The Floyd locking nut on my 7 string was a little wonky from the get go: slight burr in the slot "trapping" the high E, to much travel for te string before being locked down (it looks like the classic Jackson tilt back headstock just doesn't give enough break angle for the high E when it is sized up to accomodate the 7 tuners) and if I'm not cautious when locking down, the string might touch the wall of the slot producing a slight sitar like ringing... None of this is a biggie: sanded the burr, I can manage the break angle with a shorter tuning post or a few more winds of the string on the already existing post and paying attention and making sure the string sits in the V while locking down does eliminate the sitar like ringing. Still, my OCD kept bugging me, so I started looking for a replacment nut, hoping that my issues are just a result of manufacturing tolerance or in the worst case scenario I get a spare nut and it wouldn't set be back too much financially.

So off to the Floyd website to look for the correct part number only to find that there is only one 7string locking nut. "Okay then, it's better this way, not even I can can mess this up" - I said to myself... Then I went through the specs only to find that the only 7 string nut Floyd Rose produces/sells has a 10" radius! The guitar has a 12"-16" compund radius board so I am completely baffled here... Do they produce differently radiused nuts as OEM for the big companies? Or if I choose to change the nut, I have to file the inner slots to match the 12" radius? Shimming does not seem to be an option, as shimming just one side would still move the whole thing, which I do not want. Or should I just ignore it as it is such a minuscule difference between the two theoretical arcs of not even 2 inches long that the only thing it interferes with is my OCD-ish attitude?

Also, as I'm writing this, I went back to the floyd pade to double check... ALL their nuts are listed as 10" radius, except for one... which is 15". What gives?

[nexion218]

Re: 10 is NOT 12... or is it?

OK guys, nevermind... I dug up some basic maths formulas and managed to calculate an answer. So I treated the nuts as circle segments outlined by the theoretical arc formed by the but's radius and corresponding chord being the plane of the fretboard. The lenght of the chord in each case equals the nut width (1,875"/47,625 mm), the radii belonging to the arcs being 12" (the desired nut radius) and 10" (the available nut radius) and looked to determine the the heights of the two segments. That gave me the difference between the highest point of the two arcs, which turned out to be 0,0073"/0,187 mm, which sounds like quite a negligible difference to me... So should I decide to change the nut, I think I will be just about fine with 10" one.

Oh, and since finding the actual formula was a sort of an a-haa moment for me, I think it might be useful for others too (I hope I'm not the only one on here who didn't know this already! ):

h=r-SQRT(r^2-0,25w^2)

where

h= the height of the segment
r= the radius
w= nut width