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What is a minimum side thickness to shoot for. I have a set of sides that have varying thickness with a minimum of 1.7mm. Is this too thin to safely build with?

Thanks

Hi Canegri,

I'm sure the OLF experts will want more information from you if they are going to be able to help you answer this open-ended question.

Like:
1. What kind of wood are you using?
2. Does the wood have much/any runout (i.e. how straight is the grain, and is it quartersawn)?
3. Does the wood have lots of figure/curl?
4. What type/size instrument are you making?
5. How deep are the sides going to be?
6. What type of kerfed linings will you be using?
7. What method of side wall bracing will you be using?

Answer this set of questions and I'm sure this will allow the good folk of OLF to give you a more useful answer.

Off the top of my head though, I'd say 1.7mm, which is about 67 mil (or 0.067") is too thin to be structurally sound in the long run for an OM or D style acoustic guitar (if that's what you're making). The thinnest I'd go, using straight-grained quartersawn EIRW say, is about 75 mil (but I'd target 85 mil). For koa/walnut/mahogony sides, the thinnest I'd go would be about 85 mil (but I'd target 95 to 100 mil). That's just me though - others may well have different ideas about this.

Actually, side thickness is a pretty frequently occuring question on the forum, so you might like to use the search feature on the archives and see what it throws up.

Cheers for now,
Dave F.

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Cambrian Guitars

"There goes Mister Tic-Tac out the back with some bric-brac from the knick-knack rack"

1.7mm (.070") doesn't leave much room to clean up ripples and/or sand/flatten the sides after the bends. It could be done though, depends on the wood and how carefully the sides are cleaned up afterwards. Structurally it should be fine, is it for a steel or nylon string guitar? What size?

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Laurent Brondel
West Paris, Maine - USA
http://www.laurentbrondel.com/

How does the thickness vary, and how much difference is there between the thicker and thinner parts? If the changes in thickness are abrupt you may run into problems when you bend.

I think the shape of the instrument matters a lot; the more curves, the better in your case. Bend a piece of paper and compare its stiffness to one that is flat to see my point. I believe some classicals are built with sides that are about that thin, some are even thinner. Violin sides are thinner still, but they have a much smaller radius than the typical guitar of course. The part of the sides where the smallest bends are on my mandolins I thin down to about 1.5 mm, yet they are plenty strong thanks to the curves. I like to thin guitar sides to about 2 mm.

If your sides feel too flimsy but you’d really like to use them, you could always laminate them or at least double up the thinnest parts.

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Rian Gitar og Mandolin

I look at this question in a different light. While I hold .07" (1.8mm) is really pretty much the limit for most woods, I also look binding thickness I want as I do not want rout past the side and into the linings, I prefer bindings that are .08-.09 thick and inlay them with about .005-.008 proud of the side and scrape bank to flush with the side. All this is a consideration as well as the ease of bending.

Thanks to all who responded. My books say .08 - .09, so I suspected mine were too thin for OM or D style steel string. Thought I'd check in here, though.

I hadn't even considered binding yet (I'm planning on .060) so thanks for mentioning that critical factor.

Chris

Some of the 'golden age' Martins had sides down to .060".

Colin

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I don't believe in anything, I simply make use of a set of reasonable working hypotheses.