MIMF

A couple of years back, I vaguely remember a post for a formula for laying out a neck. I think it was, neck width at the 14th fret is equal to the highest to lowest string spacing at the bridge. I also seem to remember that this works irregardless of the string spacing at the nut. Am I remembering correctly? Any other rules-of-thumb for neck layout that you'd care to share? Thanks!!!

That rule is a good place to start, but it's the 12th fret and not the 14th. I always lay it out first using that as a starting point and then double check twice to make sure it looks right, and take into account the players' preference too.

Yes, the rule of thumb: "the width of the neck at 12th = string spacing at saddle"
is a good guideline, but it is not perfect every time. I got burned by using it too literally - the customer wanted more FB width. Awfully hard to add width to a neck after the fact.

As the others said, the rule is a guide but I never cut wood based on it. When I do a new spacing combination, I always draw the strings from nut to saddle then draw the appropriate fingerboard under it. When I'm sure it's right, then I cut wood. I do my fingerboard drawings on a good piece of poster board and save them so I never have to do it again for that combination.

Mark, thanks for the correction, and thanks to everyone for the good advice!

It's all proportional. If you know the string spread at the nut and bridge, you can figure out the string spread at any point; you just then add the edge-to-string distance. You need to first figure out the convergence point of the two outer strings.

So if your string spread is 2-1/4" at the bridge (I'll call B), and 1-1/2" at the nut (I'll call N), and you have a 25-1/2" scale (S) with 1/8" between the edge and string on both sides, then the convergent point from the bridge I'll call C1 would be

C1 = B / (B-N) * S
C1 = 2.25" / (2.25"-1.5") * 25.5" = 76.5"

C2 would be the convergent length from the nut, and you subtract S from C1

C2 = C1 - S
C2 = 76.5" - 25.5" = 51"

To find an arbitrary width (W) along the fretboard relative to the nut it is a simple ratio. You have that length to C2. So if your fretboard end was at 18", then C2 would be 69"

Thus

76.5" / 2.25" = 69" / W (we then cross-multiply)
W = 2.25" * 69" / 76.5"
W = 2.03" (this is the string spread 18" from the nut)

You then just add 1/8" on each side and you have about 2.28"...

It looks more complicated than it is, I just tried to show each step so you can see how I derived the answer...

So if you just used the strign spread at the bridge you'd be at least 1/32" too narrow; I actually taper the width between teh edge and string so it's slightly more toward the heel...

Mark Swanson wrote:That rule is a good place to start, but it's the 12th fret and not the 14th. I always lay it out first using that as a starting point and then double check twice to make sure it looks right, and take into account the players' preference too.

Additionally according to the version I heard, the width of the strings at the 12th is the width of the neck at the nut. Mainly I follow whatever the plan says but as an amateur the actual spacing is whatever it ends up being.

I don't see that one, Simon. A standard width for a neck at the nut is 1-3/4" wide and most guitars have a string spacing over 2" at the 12th fret. Are you talking about classical guitars?

You can go here: http://www.buildyourguitar.com/resource ... fbcalc.pdf

and plug in some standard measurements or your own numbers and get the answer.

The theory is explained elsewhere and also here.

Robert Smallwood wrote:You can go here: http://www.buildyourguitar.com/resource ... fbcalc.pdf

and plug in some standard measurements or your own numbers and get the answer.

The theory is explained elsewhere and also here.

This is what I have been using since I built my first neck. It's a great little tool.

There is also a great fret spacing calculator on the same site.