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Am doing a guitar with 2.250" string spacing at the bridge and 1.750" nut width. Am trying to figure the width at the 12th fret without doing a full size drawing. I think the rule of thumb is the size at the 12th fret is equal to the string spacing at the bridge. It got me thinking about what happens if the nut width changes. Wonder if anyone would care to clear this up for me? Life can be confusing when your not too bright.
Tom

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A person who has never made a mistake has never made anything!!!

Isn't the 12th fret basically half way? I would assume it's 2" but someone with more knowledge can and probably should chime in.

Charlton

Whatever I am using for my saddle spacing, that is what I use for my 12th fret spacing as well.

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I was recently working on this, too, Tom. Same specs. I modelled the neck with http://www.ekips.org/tools/guitar/fretfind2d/ and printed it out.

Anything that will accept a pencil mark, is as long as your scale length and at least 2.5" wide would allow you to scribble this out and then take any measurement that you want, anywhere along the FB. I do this sort of thing on my bench top all of the time and then just hit it with a scrap of 220 paper to erase it. It would actually take less time to draw it than it would for me to type this reply. If I were out in my shop, I would have sketched it out and have an answer for you but, I'm not.

Respectfully,

Tom,
Just measured one that I just finished, at the 12th fret, with a 1.75 nut and 2.25 string spacing, my fret board width is just 1/64" over 2.25" or 2 17/64". 2.25" would be fine.

Chuck

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In the late-1930's, 14-fret Martins had a 1 3/4" nut and 2 5/16" spacing at the bridge. The width at the 12th was 2 1/4". With that in mind, 2 1/4" is plenty wide......and 1/32" narrower at the 12th (2 7/32") should also work.

The nut width is the width of the fingerboard, not the string spacing.

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John

The consensus seems to be 2.25", so I'm going to fly with that. Thanks all.
Tom

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A person who has never made a mistake has never made anything!!!

2 17/64 (57.5 mm) is spot on for a 3/16 distance of the string to fingerbord edge at fret 12.

Yo, Tom

Wood bees and should bees, spot ons, and half of this length is the bangle of the dange between this to that, is all a crock.

Besides the string spacing at the bridge, we would also need to know the string spacing that you will be using at the nut to answer your question.
Or the amt. of set back at the nut from the edges to the E stings.

And that's assuming your running them strings parallel to the edge.(Not advised)

So throw us one more number and we can throw you back the exact answer.

NOtE: Width of nut and width of string spacing at nut are two different things.
Think about it.

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I would just do the drawing then measure. Once you have the nut width and the bridge pin width, Just do the following.

Measure in 5/32" on the 6th and 1/8" on the 1st for the string location at the nut. Draw a line connecting them to the pin locations. That will be the string layout. Measure out about 3/16" at the 14th fret from the 1st and 6th sting. Draw a line from the outside of the nut at both ends going through the marks at the 14th fret. That will be the fingerboard. Then you can measure the width at the 12th fret.

Anyway, that's how I do it.

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Joe Beaver
Maker of Sawdust

Oh.... You're right! Fail on my part.

2.25

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John Mayes
http://www.mayesluthier.com

That is generally not done, because it can cause problems with pushing the outer strings off the edge of the fretboard. This is because the string is more flexible at its midpoint than it is near the nut.
The earliest 14-fret Martins (OM's mainly) had this combination:
1 3/4 nut
2 1/4 12th fret
2 3/8 or 2.4 bridge spacing
Those can sometimes exhibit the problem outlined above, particularly if the frets are severely beveled and if the spacing at the nut is widened to the max.
I do know that the alignment on these is more critical than the later guitars....so a neck reset must be spot on as far as center alignment is concerned.

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John

Lots of folks not aware of this unless they are players.There are players and those who play at the guitar. I'm in the latter group. I have seen a noted luthier who was not aware why this was done. I was educated about this quite a while ago by a player. Before I was informed I thought it was mainly for design purposes to give visual interest. For folks that don't know, John is a player. Thanks for jumping in John.
Tom

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A person who has never made a mistake has never made anything!!!

I would imagine that Larry Pattis is the player to whom you refer, Tom.

Larry posted very eloquently, in fact definitively, on the subject on this thread ...viewtopic.php?f=10101&t=30776. You can skip the first two pages if you want to get straight to his posts.

I am fairly certain that the relatively recent decision by Martin to list the 12th fret width as part of the guitar specs on their website is due solely to his airing of this issue over the years on various forums.

Murray : No, not Larry. It was someone local to my area but it's so long ago I forget who it was. That's one of the subtle benefits of growing older. I have 5 books, 5 DVD movies and I'm set for entertainment .................................read, watch and then start over and swear you had never seen any of them before this time.
Tom

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A person who has never made a mistake has never made anything!!!

The width is whatever you or your client want it to be based on how much fret space you want outside the strings. The common rules of thumb are to match the bridge spacing at the 12th or 14th fret but there's nothing magic about that. Some people like more space. A few like a lot more. I haven't run into anyone who likes less yet.

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Ya Kent, your right ...the only ones that didn't mind less were a few slide players, and the only place they wanted more was in the raised action...go figure eh.

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The thing that always puzzles me is the arcane discussions on how to offset the neck ever so slightly so that there is marginally more distance between the treble e and the edge of the fretboard compared to the bass E and the edge of the fretboard.

Just increase the width and the taper of the fretboard in the first place, so that there is sufficient clearance on both strings ...

The idea behind that is to keep the bass side space as small as possible without falling off the edge so the thumb wrappers can have their fun, but also to have enough space on the treble side to do pull-vibrato without falling off there. Don't usually push the bass strings up to bend, so the edge space there can be smaller. You can do it either by tilting the neck toward the bass side, or simply marking the treble edge a bit farther away from the centerline on the neck and fingerboard when tapering them.

I use pretty much the same method as Joe Beaver described. Can be done mathematically or geometrically, and with any nut width, bridge spacing, and string-to-edge spacings you want. There are 4 string-to-edge spacings to decide on... low E at nut, low E at 12th fret, high E at nut, high E at 12th fret. The nut spacings can be about 1/32-1/16" less than the 12th fret spacings without falling off the edge, due to the previously mentioned fact that the strings stretch more easily in the middle.

My preference is 1/8" low E at nut, 5/32" low E at 12th, 5/32" high E at nut, 3/16" high E at 12th.

tl;dr, 12th fret width equal to bridge spacing is usually pretty much right.

My preference is 1/8" low E at nut, 5/32" low E at 12th, 5/32" high E at nut, 3/16" high E at 12th.

My experience is that I want to bend the strings upward more than downward, so I like a little more clearance above the low E than below the high E. Anybody else have actual numbers they like?

Using the string spacing at the bridge as the neck width at the 12 fret (midpoint) will keep the distance of the outer strings off the edge of the neck roughly the same all along the neck, because the distance the string is to the right at the nut is matched by the distance it is to the left at the bridge from a line passing through the midpoint of the string and parallel to the centerline of the guitar.