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Hi I am about to start an all mahogany OM. Can you give me some guidance as to target thickness for the top as a starting point before voicing? in mm if possible!

Cheers, Bob

Recall vaguely that Mahogany might have roughly the same stiffness as Spruce. I did make a 0 sized guitar out of Walnut and I was about 2.1-2.2mm. Also depends on your bracing, thinner top heavier bracing. Not much but it is all I got, good luck.

.125 in thick is a good place to start

_________________
John Hall
blues creek guitars
Authorized CF Martin Repair
Co President of ASIA
You Don't know what you don't know until you know it

I've done lots of mahogany tops. I treat them exactly like spruce and they have been very successful that way.

Thanks for the input guys, appreciated.
Bob

That's what my measurements suggest as well. The mahogany I've looked at has not had much higher Young's modulus along the grain than spruce, so you need to leave it about the same thickness. It tends to be denser than the softwoods, so the top will probably be heavier.

For my ukuleles, spruce tops are around 2mm and mahogany somewhere between 1.8 and 1.6mm. This is based on flexing the top longitudinally until it feels "right", whatever that means. Intuitively I'd expect a mahogany guitar top to be thinner than a spruce one, but I can't offer any reason why.

You can compensate for a thinner top with heavier bracing, but at some point it will sound more like a banjo than a guitar. Stop thinning before you reach that point