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I have only built 14 fret to the body 25.34 scale guitars. I have a couple of OM cut-away rims that I was considering making 12 fret necks. Couple of things I was wondering. What scale is best for 12 fret necks,,,, long or short? And what about truss rod length? What issues should I be thinking about?

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Mark Ewing
Columbus Ohio
"Trees are an important and precious thing. We should build good things with them. Building good guitars with heart are the best use for them." K. Yairi.

If you are going to use the same size body as your 14-freter, but join the neck at the 12th fret, then you are going to have more of the scale length over the body, so the bridge is going to be further towards the end block. That is the main reason why 12-fret guitars have a different sound. Even if you use a shorter scale length it is probably not going to be shorter by 2 frets worth, so the bridge will still move south. You will want to shift the bracing along with the bridge, and maybe also the soundhole at least part of the way. Needs some careful planning but it is not hard to work it all out. No definite rules about scale length - it depends what tone and feel you are looking for. Truss rods come in a shorter length, suitable for 12 fret necks. There are some fantastic guitars with 13-fret necks also.

Most of my 12 fretters have been the longer scale with the exception of a Parlor Guitar (size 5) and a 12-string slope-shouldered Dred.

In the case of the Parlor, I used the even shorter 24.5" scale just because that's what the plan called for. In the case of the 12-string, I chose that scale to help to reduce the torsional force from the neck.

Enjoy the 12 fret slothead experience. If you're a fingerstylist, it's a whole new sound and playing world you're going to find.

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JJ
Napa, CA
http://www.DonohueGuitars.com

Actually the Martin Norman Blake model has the bracing very similar to the 14 fret 000 so the wings of the bridge just cross the X brace on the very front corner. I have played a couple of the Blake Martins and they are great sounding though the bridge placing on the X makes me a little nervous. I have a set of top tracings from John Hall of the Blake 000.

Fred

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Fred Tellier
http://www.fetellierguitars.com
Facebook page http://www.facebook.com/pages/FE-Tellier-Guitars/163451547003866

I've been working on a 13-fret 000 cutaway. I decided on a 24.9" scale and had to shift the bridge, X brace, and soundhole less that 1/4" from where they were on the 14-fret, 25.4" scale OM.

The distance from the 12th to 14th frets on a 25.4" scale is about 1.36" so a 12-fret 000 would have the bridge shifted that far.

A 12-fret 000 cutaway is also on my short list - not sure which scale yet; depends on how the 13-fret 24.9" works out. I'm leaning towards the long scale because I want to see how it sounds and plays with the bridge moved down so far.

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Steve Smith
"Music is what feelings sound like"

Todd
When I look at the 12th fret dimensions of the two scales I get 12.45 for the 24.84 scale and 12.67 for the 25.34 scale. There's an obvious shift for the bridge on the short scale towards the sound hole of about 1/8"+. Should the sound hole shift respectively? Location of the X brace intersection seems to be effected as well. Maybe these are nuances that have diminishing returns. Maybe not?

Also I was wondering about string tension and bracing size in comparison between short and long scale? Also is it tradition to use slot-head peg heads for 12 frets? Ive never done one but I would never learn any younger.

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Mark Ewing
Columbus Ohio
"Trees are an important and precious thing. We should build good things with them. Building good guitars with heart are the best use for them." K. Yairi.

New revelation!! Looking at the bridge layout it appears the back corner of the bridge creates an intersection with the outboard side (sweet spot) of the X brace? Is that a standard practice for X brace layout? Short or long scale the hole stays put and the X brace shifts accordingly and goes wider or narrower to hit the sweet spot on the bridge. Am I understanding you correctly.

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Mark Ewing
Columbus Ohio
"Trees are an important and precious thing. We should build good things with them. Building good guitars with heart are the best use for them." K. Yairi.