Official Luthiers Forum!

i have started my 2nd and 3rd guitars ( my first was at a workshop with Frank Finnochio) Both are OOOs I am using the usual texts for reference the notes I have from the workshop as well as some dvds. One thing I noticed after comparing references and looking inside some of my personal acoustics is that the lower bout back braces are thick around 3/4" wide in some and 5/8" in others. Obviously the 3/4" braces are much shorter than the 5/8" braces. Is there any advantage to one over the other? Also should all the braces come from the same brace wood billet. I noticed after cutting the braces for the back one brace came from a different brace wood billet and had much higher grain count ( it is all Lutz spruce just different pieces)

thanks
Richard

Hi there, I built a guitar with Frank too , it was a great place to start learning the craft. the guitar I built with Frank also had larger back braces meaning :

there are basicly two schools of thought on the way the back of a guitar works within the system of the guitar body . school one ,( which I call the stiff back )is where the guitar body works like a bass reflex speaker , where the back and sides are ridgid, and the top "pumps" in and out like a speaker cone.this is the way the guitar was built in Franks class.( at least mine was, and it sounds like yours was too) . in this system the braces are usualy more stout .
now the second school of thought , ( which my first solo build is following ) i call the flexible back school ,this is where the top and back are coupled in such a way that they work together , sort of like a tennis racket , guitar body with stiff sides , and both the top and back coupling together . in this system the back is, or seems to be noticably more active.in this system you can use lighter braces .

Great sounding guitars can be built either way !

so the answer to your question seems to be , you first need to decide which school you want to be in , that will determine , your brace sizes.If you are unsure , good advice at this time might be to stay with the plans you are using ! Jody

I am not sure but I think Martin set the standard for using wider back braces in the lower bout. My guess is that this was done for structural rather than acoustical purposes much as they stopped scalloping their top braces. It is not likely that they could hand-select perfectly quartered brace stock with no runout, as the individual luthier can do, so they were made fatter to accomodate what came off the saw.

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It's not the miles ahead, it's the stone in your shoe


In Markham,Virginia

Folks, Martin didn't always use the 3/4 x 1/2" bracing on their dreadnaughts. If memory serves, pre-war martins used 5/16 x 5/8 stock for their back braces. Kevin Gallagher might be able to chime in here and discuss the whys and wherefores. Observationally, the older guitars with the taller thinner stock sounded better. That's going to be a combination of how their tops were braced and how their backs were braced.

The same is true for some pre-war Gibsons and the lower two back braces can be approx. 5/8" wide and 1/2" or less tall and shaped like half-rounds.

'37 D-18


'36 D-18


Lower back braces were 3/4" x 3/8" to 13/32". The upper braces used 5/16" x 5/8" stock though.

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Jeremy Douglas

I wonder what that dead bug does to the sound of that '37 D-18!

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Alain Moisan
Former full time builder of Acoustics, Classicals and Flamencos.
(Now building just for fun!)

Isn't that a rattlesnake rattle? I've seen guys put them in their guitars. Have no idea why.
TJK

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It's not what you don't know that hurts you, it's what you do know that's wrong.

It makes the guitar sound better, keeps spiders and mice out and brings good luck, or at least keeps bad luck away. It comes mainly from fiddle players putting them in there.

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Jeremy Douglas

I put one inside my 1950 D-28 to let anyone who tries to walk off with it know what will happen to 'em.