Official Luthiers Forum!

 Is there a general rule of thumb for thickness of sides and backs. I am going by what I saw in the Stew-Mac catalog for steel strings .095-.1 for sides and .115-.120 for backs. I am new to this what are reasons that you would change this- wood type? Are classicals the same?

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Mistakes are mandatory-learning from them is optional. http://www.opensourceluthiersupply.com

I build classicals and in general I take the sides to 2mm (~.078") and backs can range from 2mm to 2.5mm (~.078- .098).

Different woods can be more difficule to bend than others so there is no general rule of thumb.  Another important aspect is whether the wood is quartersawn or not. 

Steel strings are under tension much more so than classicals so my dimensions are specific to classical guitars.

I am with Todd. I have a few old martins and worked on many. I some were as thin as .065 and as heavy as .080 the backs .090 to .120
    I do most with .075 sides and ,090 back
john

I'll third the past two suggestions. I have built with thicker woods, but afterwards found I could have gone much thinner. I try to shoot for about .70 to .80 for sides and .85 to .95 for backs. Some woods I go a little thinner, some a little thicker, but not by much.

 

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Reguards,

Ken H

.75 sides, .85 backs, .110-.125 for tops depending on stiffness, size, and bracing...you really have to have each piece in your hands to decide...I agree with John about the Martins...they got really thin at times but they know how to sand and not go too far!

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http://www.presnallguitars.com

Dang I just saw this thread (after posting my own!)...I didn't realize you guys commonly use sides down to .075. I thought .090 was more standard? I was concerned about my current build which has sides between .075 and .080...guess I'm right in the ball park?

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http://www.PeakeGuitars.com

Parse, the advantage of a .90 side is that you can sand the box with anything short of a die grinder and not ruin anything...but, as you progress and hone your process, you don't need to sand/scrape too much on the completed box anyway...and thin sides bend easier and I think make for a more "open" sounding guitar...although the top/back contribute much more to the sound than the sides!

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http://www.presnallguitars.com