Official Luthiers Forum!

Hello all

I am in the final stages of our 12th guitar (my 1st real solo effort) and am now considering doing a 12 string for my next project. I want it to be simple, probably mahogany or walnut body and spruce top, ebony bridge/fretboard, you know the drill. My only questions are regarding the bracing structure.

What do i need to do different with a 12 string's top braces (I scallop mine on 6 strings), if anything?

Does the bridge-plate need to be extended or altered in any way?

I am planning to use a 12 string I have access to as a template for neck width, bridge size, etc. But cannot remove the top to look at such things (the owner would not be real happy). Any advice you guys can give me would be great!

Thanks!

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Jake

~Make a joyful noise unto the Lord~

I used a double X pattern on my 12 string but I see many standard patterns as well. Keep the top on the heavy side and beef up the bracing a little bit as well as the bridge plate.

Depends on the kind of 12 you want. There's everything from wussy-harpy light guage 12's to long scale monster cable 12's tuned down as low as A. That's where you start...what do I want to build?

FYI,
I was at the Martin Factory last November and I asked one of the
Supervisors on the body line..."What is the difference between a Dred
6 string and Dred 12 string body?"
His answer was this:
"The bodies are identical with the exception of the size of the bridge plate"

Gregg

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Gregg

I want to do just a "standard" 12 string (tuned like a six-string, with the additional six octave strings...just like you'd go into a music store and buy). I don't want anything real fancy, like one of those you can tune down multiple steps or something like that.

I'm getting the feeling that i shouldn't change much, save for maybe extending the bridge plate a little bit to the lower bout (i'm guessing that would be the proper approach?).

_________________
Jake

~Make a joyful noise unto the Lord~

There was a good discussion here about this a while ago, try to find it. Seems most people were inclined to beef the braces, or make the top thicker (was it about 10% more or so)

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Build log

Major differences for me were to extend the height of the X-brace from .500" to .625", increase the stiffness or thickness of the top by ~10% and enlarge the BP to accommodate a larger bridge. I didn't purposely set out to change the bracing profile but it probably changed as voicing decisions dictated.

Good luck with your effort...12 strings are fun!

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

Yup, if all you want is a Martin, I'd go about .115-120 on the top and do all that other stuff. My tops run around .180, but my strings run around .070-.015.

I built one a couple of years ago and based the changes on the cube rule: the stiffness of the top plate or of a brace goes as the cube of the thickness. So I made the top about 25% thicker than usual, and the braces 25% taller. It was a killer.

You need to use a wider bridge and bridge plate, of course. I also use a wider saddle: about 3/16", and compensate the octave strings seperately from the regular ones. If you do it right, they will play in tune all the way up the neck.

Thanks guys!

I'll print this off and add it to my shop notes, and definitly use this when the time comes.

I tell you, there is no better place to get information than the OLF, you guys rock!

_________________
Jake

~Make a joyful noise unto the Lord~