Official Luthiers Forum!

Maybe someone can give me a quick answer:
I bought some 6mm (0.23 inch) carbon fibre to reinforce the inside of jumbo steel string guitar (are they called flying buttresses?), it seems pretty flexible and I can't imagine it doing much good.
Is 6mm too thin?
Have I bought the wrong type of carbon fibre? This is what I've got http://www.elitemodelsonline.co.uk/Prod ... 60mm-x-1mt

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We are all in the gutter but some of us are looking at guitars.

Joe, the .023 carbon fiber sheet is typically used sandwiched between two pieces of spruce, vertically, to create a brace. It adds no strength unless it is glued within or on wood. Carbon fiber flying buttresses, run between head blocks and the junction of back and side, are ordinarily hollow tubes. I suppose you could create a box beam with your CF, gluing it around a rod of spruce, but it would be a lot more work than using a tube. The CF tubes are sold for building kites by dealers such as goodwinds.com.

Here's a pic of a couple CF reinforced brace blanks I made, following the methods of Mario Proulx. There's a nice piece about this by Chris Paulick in the OLF "Tutorials" section.

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Tim Allen
"Never hurry, never rest."

Tim, thanks for your reply but I think you misread 0.23 inch for 0.023. In other words 6mm for 0.5mm. The carbon fibre I have is a rod I bought from a model making shop.

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We are all in the gutter but some of us are looking at guitars.

Here's the only one I've done with buttress supports. The supports are 1/4" CF tubing. Not to dissuade anyone but I probably won't do another one unless I can convince myself that it is really useful.

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Steve Smith
"Music is what feelings sound like"

Thanks for the picture, Steve. I was going to have the rods attaching to the lower bout. I guess your design is better and that would make the rods stiffer. 1/4 inch is pretty much 6mm, the same as mine.
Why would you not do it again?
Have you finished that guitar already?

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We are all in the gutter but some of us are looking at guitars.

This guitar went on the shelf for over a year but I pulled it down several months ago and it is now ready for final sanding and finish.

I probably won't do it again unless I feel there is a need for the added structure and the extra time needed to incorporate it. Several years ago I was enamored by some of the new techniques showing up on the forums, this was one of them. Since then I haven't really seen any of the established luthiers pick up the practice.

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Steve Smith
"Music is what feelings sound like"

Steve, what you said has made me rethink what I'm doing. My next build will be number 5, so not many. I still haven't built a guitar I'm completely happy with. I think it's easy to get carried away thinking that if you add this detail or that detail everything will sound suddenly wonderful and your guitars will be as good as can possibly be.
I'm thinking now it's best to get back to the plans and stick with it and concentrate on getting the basics mastered and look more in depth at what I'm already doing rather than try something new.
Thanks for putting me back on track.

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We are all in the gutter but some of us are looking at guitars.

Joe, I came to the same conclusion about 6 months ago. As much as I like to try new things I realized that I needed to focus on building traditional guitars that sound the way I want them to sound.

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Steve Smith
"Music is what feelings sound like"

Exactly.

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We are all in the gutter but some of us are looking at guitars.