12-String top radiused?

[nnickusa]

I'm looking thru my collection of plans and noticed that the 12-string plan by Antes calls for a flat top. I'm guessing that with the extra pressure of the 12 strings that may be to counteract that pressure?

So, a question for you guys that have built 12's, would you still radius the top, or would a flat top be preferred?

Thanks in advance, again....

PS: I've serached the forum, and haven't turned up anything to suggest an answer......

[Shane Woonton]

I'd do exactly what you would normally do for a 6 string. The same laws of physics still apply

Cheers,

Shane

[Bob Connor]

Building a 12 string at the moment with a 25' radius top.

Regards

[kiwigeo]

25' radius on the 12 strings Ive done.

[Tod Gilding]

Hi Nick, I have been under the impression that the radius stiffens the top. So I would think that the radius would counteract the added tension more so than the flat top. Just my two bobs worth

[kiwigeo]

My 12 strings have 3 tone bars and a brace along the back of the bridge patch.

[DarwinStrings]

Keep in mind Nick that a flat top joined at 40% RH has now where to go if it gets down to 20%RH.

Jim

[nnickusa]

All sensible replies. I have seen reference made to not radiusing tops at various times, and wondered if there were a rationale behind 12's. I believe Antes drew from real instruments, so maybe it's particular to the one he was looking at.....I dunno...When I build one, I'll use a radius....

[tim mullin]

I only have one 12-string under my belt -- built for myself in 2009, intending to fix all the things I didn't like about my Martin D12-28. It was successful, but until recently no one has come looking for one (the owner of a recording studio in Nairobi played it a month or so ago and after only a few seconds asked the price -- if he buys it, I'll build another just like it).

The guitar has a flat-top -- same as my other guitars. There is always a slight doming that occurs on all my guitars under string tension, and most people would think they are built domed. I haven't made a single adjustment to that guitar since 2 days after the strings went on, and all settings have stayed exactly where they should be -- despite spending 4 months at sea in a shipping container finding its way between NZ and Kenya.

Compared to a 6-string dread, the Sitka top is 0.005-0.010" thicker (i.e., about 0.110" rather that 0.100"), the X is no more than 2 mm taller, and there is a scalloped brace across the bottom of the bridge patch -- I think that's also on the Ante's plan? That's it. It's been a cannon since day 1.

Lots of great guitars out there with flat tops -- a radius is by no means essential, even on a 12.

[Nick]

Hey Tim, good to see you managed to get your access problems sorted
Nice clean looking twelve string too, Rosewood B&S?

[tim mullin]

Hey Tim, good to see you managed to get your access problems sorted ?

Temporarily -- I'm currently in New Zealand for Christmas. Heading back to Nairobi mid-January, and there my access remains blocked

Nice clean looking twelve string too, Rosewood B&S?

Thanks. Yes - Indian RW B&S. Fingerboard and bridge are Madagascar.

[woodrat]

It is interesting that everybody does things differently...I have always built with a radius in my tops and will continue to do so but one thing I noticed when I visited Brook guitars in the UK in 2011 was that they built with flat tops....they build them very dry they say and therefore there is always a slight induced dome in them at RHs higher than they were built in....

[nnickusa]

Nice guitar, Tim. Thanks for your input. And, yeah, Antes has the lower cross bar, as well as bracing that is slightly more substantial than my usual, so that ought to be OK. Also, I only put a dome of about 3mm to the top for a dread, so it's almost flat, too.

I read in Kinkade's book that some folks build flat in real dry conditions, so the idea of a flat top doesn't terrify me too much, and my dry room is getting down to around 35% these days, given it's pretty dry around here this year.....

Might get into it some time. I do miss my old 12......

[tim mullin]

Nice guitar, Tim. Thanks for your input. And, yeah, Antes has the lower cross bar, as well as bracing that is slightly more substantial than my usual, so that ought to be OK. Also, I only put a dome of about 3mm to the top for a dread, so it's almost flat, too.

I read in Kinkade's book that some folks build flat in real dry conditions, so the idea of a flat top doesn't terrify me too much, and my dry room is getting down to around 35% these days, given it's pretty dry around here this year.....

Might get into it some time. I do miss my old 12......

I'm pretty sure it's the Antes plan I have back at the shop -- and I brace the 12 and the 6-string dread MUCH lighter than on his plans, but I did add that extra brace and a larger than usual bridge patch. Just build as you're accustomed and beef things up a little bit - the 12 doesn't require going crazy with extra stiffness.