Building a 12 string- suggestions for top and bracing?

[Steve Frost]

A friend asked me to build a 12 string for her husband, so I'm in the planning phase. Actually, my first guitar was a 12 string, built  in 1979 along the lines of the David Russell Young book as far as bracing goes. I didn't use the epoxied butt joint, however- I used the mortise and tenon that Irving Sloane advocated.

At any rate, I won't be replicating that guitar. I'm looking at an OM body size with  the corresponding 25.4 scale. I don't want to go longer than that, as I don't anticipate him tuning down. I figure to go a bit thicker on the top, to about .140", make the X braces taller, and maybe add a third tone bar. Anything else I should consider? I'm open to suggestions,TIA.

[Frank Ford]

My sense is that it's tempting to over-brace the tops of 12-strings, so I wouldn't go too heavy.   Some of the best 12-strings I've run across were conversions from standard straight-braced 1960s Martin dreadnoughts with no extra support at all.  The tops were stable and the instruments sounded just fine.

I don't think I'd do the tops with prewar scalloped braces, of course. . .

[Steve Frost]

Thanks for the feedback, Frank. It wouldn't do to be too cautious, I don't want to end up with a brick!  I had to dig out the Young book to see what I did 34 years ago- I probably have a wilted black and white print of the insides somewhere... Anyway, that plan featured 3/8 W by 1/2 H tapered bracing, with an additional transverse brace right in front of the bridge plate. There were a couple other bracing wrinkles, but it didn't seem particularly over-braced, and considering the guitar has been tuned to standard pitch for 30+ years without issue, maybe I should just go with some straight braces. Anyone else have an opinion?

[Andrew]

The martin a frame brace thingy seems like an idea, should reduce top rotation. Ive never built a 12 string though, just throwing it out there.

[Tim Mace]

I'd consider something like the attached pic!!Stefan Sobell has the right idea....carved top ...if only I could whittle!Check out his site

[Donald A. Fortune]

Hi Steve--  when I build a 12 string, I just taper the top braces instead of scalloping them.

I make then a bit taller but that's it.

Like Frank says '' so I wouldn't go too heavy''

I made the bridge plate under the top about 25% larger in sq. area to accomadate the extra pull of the extra strings.

Other than that the rest of the box can be built like a 6 stringer.

best to you on your build and do a good job....

Peace, Donald

 

[Steve Frost]

Thanks for the ideas, guys. I think I  will brace it like a 6 stringer, and use slightly taller tapered braces as Donald suggested. I'm not sure the OM body needs a third tone bar, even for a 12 string. I appreciate the advice, I'llpost some pix later on down the road!

[Donald A. Fortune]

hey Steve -- sounds good -- post some pics -- Id be interested in seeing your progress--

Peace, Donald