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My objective here is to use a standard sized ooo body,
12 fret neck
25.4 scale length
1 3/4 nut width
2 5/16 sting spacing
can somebody tell me what the neck width @ the body joint should be?
Peter

Easy.

2-5/16" @ the 12th fret.

Neck width at the 12th fret should be the same as the bridge's string spacing.

It's that simple?
Thanks, Grumpy!

Peter,

Although Mario is probably right, he usually is, I would still just draw it out full scale. It dosen't take very long and then you also have a great reference sheet. You will need to know your string spacing at the nut as well. Typically about 3/32 in from the edges.

Shane

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Canada

excellent idea Shane, I'll do that.
Thanks,
Peter

Hi Peter,
you could determine that dimension yourself by first establishing what you want for string spacing at the bridge (in this case you're using 2-5/16"). Lay out the strings on a piece of paper. Some builders (or players) want the distance from the E string (either low or high) at the nut to the edge of the fret board to increase ever so slightly as you go up the fret board until you meet the body. For instance, if the string is 1/8" in from the edge of the fret board at the nut, by the time you get to the body you might increase that dimension by 1/32" or so. Some players prefer that distance to be the same all the way up. There's nothing like having your own drawings to prove things out and being able to take measurements from.
Craig S.

I'll get on it, thanks Craig.

Would it remain 2 5/16" from the 12th fret to the end of the fretboard, or woud the taper continue to the end? I've always wondered which was the most common way. (Showing my green horns here!)

Y'all would try to over complicate the Lord's Prayer, wouldn't ya's.....

The taper continues for the full length of the fretboard.

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Horton, MI

Kevin, the taper would continue to the end. Otherwise, when you fretted your outside strings past the twelfth fret, you'd run off the edge of the fretboard.

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Joe Breault
Merrimack, NH
Perpetual novice

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Well, it can be more complicated. I never heard of a player who wanted the E strings parallel to the edge of the board, but it is possible to have the string spacing at the bridge be a bit more than the 12th fret width; I've done 1/16" more at the bridge. Depends also on the nut width and the scale (which affect taper). But you won't go wrong matching bridge spacing to 12th fret width, and you will save the Grumpster from a major headache.

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Howard Klepper
http://www.klepperguitars.com

When all else fails, clean the shop.

The rule only works out if you're using a string spacing 1/4" wider than your nut, or if you don't mind your strings not being parallel to the taper of the board. I would mind that. The board is tapered to match the path of the strings (unless there's some other reason I've not heard yet).

The width at the 12th fret is (nut width + string spacing @ bridge + double the distance from the board edge to the string)/2

The not-too-crazy choice of a 2 5/16" string spacing and a 1 11/16" nut width (with 1/8" string to board edge) should have a 12th fret width of 2 1/8" but instead we'd be 3/16 over that using the 'rule of thumb'. That's almost a quarter inch of fretboard on either side of the string at the 12th!

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Bob Garrish
Former Canonized Purveyor of Fine CNC Luthier Services

Bob, did you draw this out with the string sizes included? And remember that the string spacing won't be the nut width. I ask because I've never seen tis rule fail, and I've done weird nut widths anywhere between 1-9/16" and 2-1/4", and bridge spacings of 2-1/8", 2-1/4" and 2-5/16".

Maybe I fluked something, but it always ends up with pretty even spacing all the way up.

Bob, making the edges of the board parallel to the E strings would be quite unconventional. The board widens more than the spread of the E strings widens. As you go from the D and G to the E's, the path of the strings gets proportionally further from the centerline. The board edges mimic the line another string would take if it started at the edge of the nut--i.e., the increase in spread followed by the strings from D or G to E is proportionally followed by the edge of the board. More or less, depending on tastes, etc.

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Howard Klepper
http://www.klepperguitars.com

When all else fails, clean the shop.

Well, at the risk of total embarresment-here's how I have done it for 30 years.
I make the fretboard 3/8" wider than the nut at the 12th fret.
In other words if the fretboard is 1-3/4" at the nut I make it 2-1/8" at the 12 fret.
Then I set the edge of the high and the low e string in by whatever amount I choose from the ends of the fretboard-this then gives me the "spread" at the bridge-then I divide the spaces evenly.
Works for me.

There is certainly no hard and fast rule with this one but just for the record, Martin uses the following relationships:

Nut / 12th / Bridge Spacing

1 11/16" / 2 1/8" / 2 1/8"

1 3/4" / 2 1/4" / 2 1/4"

1 3/4" / 2 3/8" / (OM) 2/3/8"

1 13/16" / 2 5/16" / 2 5/16"

1 7/8" / 2 5/16" / 2 5/16"

Mario: Yes, my math is correct. The masters in math and job description mean I'm pretty careful about math I post online
That said, the calculation is based on the fact that I make my fretboard edges parallel to the E strings and find it most aesthetically pleasing; no customers who have gotten boards made to match string spread have complained over a pretty big number of fretboards...but that brings me to:

Howard: Well played, sir. That's a perfect logical and aesthetic reason for doing it differently than I do. Respect! So, assuming you use an equal string to string spread, the taper is actually on a a line from the magical place all the string paths would intersect, though the edge of the nut (and twirling, twirling twirling towards freedom).

As it turns out, the formula for your way is this...

N=nut width
X=string spread at nut
S=string spread at saddle

S * (N/X) + N
-------------
2

(IE: If the nut is Y% bigger than the spread of the strings, it scales the saddle by Y% and then takes the average)

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Bob Garrish
Former Canonized Purveyor of Fine CNC Luthier Services

it scales the saddle by Y% and then takes the average

Now it's getting interesting. Why would you want to scale the saddle spacing?

Here's a set of numbers for you to crunch right quick. My string spacing is 1.433" at the nut, and 2.25"(center to center) at the saddle, what would you cut the fretboard to be a the 12th fret?

I need the total nut width. Let's assume you put the strings 1/8" from the edges (so it'll line up well with the two methods)

With my method (constant offset, string to edge), your 12th fret width would be 2.092"
Using the 'common intersection point' method, your 12th fret width would be 2.163"

Here's an illustration. The black lines are the strings, and the three horizontal yellow lines are the nut, 12th fret, and bridge. The two dots on either side of the nut spacing are 1/8" from the strings (so that's the 'actual' nut width, N, where the string spacing at the nut is X (1.433)). The red lines, as you can see, are the 'extra string' lines through the common origin of the strings, and the two edges of the nut. The blue lines are the 'constant offset from strings' that I use.

The scaling is because we have the nut total width and the nut spacing, and the fretboard starts at the nut total width. So, we need some sort of 'virtual saddle' total width to match the taper to. The logical options are to either say 'OK, well the nut extends X beyond the strings so let's make the 'virtual saddle' do that' (which is what I do) or 'The nut is X% bigger than it needs to be and/or the nut is the string to string spacing times Y wide...so lets make the 'virtual saddle' like that' (which is what Howard does).

I hope this is sort of understandable, in context of the picture and everything else. And, yeah, the frets are going to be really close together on this neck (with the 2" scale length )

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Bob Garrish
Former Canonized Purveyor of Fine CNC Luthier Services

Sorry, that 1.433 spacing is for a 1.6875" nut width.

Hope that changes the figures...

Okay, doing the math your way, i come out to a neck width of 2.0955" at the 12th, pretty well what you came to also, for equal spacing all the way up. But from experience, few players would be able to play that instrument. That's a 0.110" spacing from outer string to the fretboard edge, on each side. Assuming we have the neck dead-on straight. Take off at least 0.050"(likely more) for the fret's bevel. That leaves the player exactly 0.060", on a perfectly centered fretboard, in leeway. Most players push or pull the strings either toward the bass or treble edge a least that much. Add highly polished frets and/or coated strings, and you have a client cussing you loudly every time he/she plays up the neck.