Official Luthiers Forum!

I'm about to start my first 12-string guitar, and looking for advice. I've been told the Stella with tailpiece is a good way to
go, so that I don't have to beef up the bracing. I guess I'm looking for a set of plans, or a book, for guidance.
I've built 4 dreadnoughts so far, and am about to finish 2 3/4" size Martin designs from LMI plans, so I'm starting to think I know a little, which is when, of course, somethings going to rise up and bite me in the butt.
Lots of questions, like bracing, top thickness, neck.....
I'd appreciate any comments
Dave Davis
Vtown

Welcome to the OLF Dave!!!

Check out member Haans who is active posting on the OLF. He has built 12's I believe with ladder bracing and there are pics IIRC of his very cool guitars.

Dave: You might want to touch base with Alan Carruth who worked out some sizes based on The Cube Rule and the pull weights of a 12 string set compared to a six string. Alan built at least one 12 string based on these figures and I understand it worked out quite well. I think the data may be here on the OLF so a search may turn something up,if not search out Alan.
Tom

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

Thanks for the mention.

I built that 12 about two years ago, iirc. I figured that a 12 pulls about twice as much tension as a 6, so the top needs to be twice as stiff. Since the stiffness goes as the cube of the thickness, I just made the top 25% thicker, and the bracing 25% taller, and a little wider, than I would have done for a six. Other than that, and the larger bridge plate and bridge, of course, I didn't change anything from my normal Small Jumbo pattern.

The result was a guitar that has twice the energy to drive it, and a top that only weighs about 25% more than the one on a six would. It was the only guitar I've ever made that I could not sing over. I saw the owner at Montreal in July, and he was smiling: so far, so good.

Welcome Vtown.
A lot depends on the strings you plan to use. Most 6's are built for light or at most medium strings, but 12's can be all over the place from extra light to HEAVY. Mine run from mediums to very heavy. The other factors are scale length and what the instrument is tuned to. Regular 25.34" scales can be tuned down as far as C#, and long scales with heavy strings can drop to B.
If you are going to try ladder bracing, here are a couple of patterns.



If you are going to use the ladder, a thick top is necessary...anywhere from maybe .140 to .160", again, depending on the strings and scale. You might be able to go a little thinner with a tailpiece. Bracing can be around 7/16-1/2" wide and around 5/8" thick. My pattern for ladders tends to be somewhere between the Holtz and the Stella.

Hope this helps...