MIMF

I'm wondering if anyone has thoughts on OPTIMUM top and back thickness, tops either spruce Or Mahogany.
I'm fairly certain this is one of several critical dimensions.
Anyone know what Martin use?
Thanks

There are no optimum values because each piece of wood is different, even consecutive slices from the same billet. So optimum thickness is individual for each instrument.

For spruce (which I find too brash sounding for a soprano) I thickness the top to around 2.2 mm and work down from there, probably ending up around 2 mm on average. Mahogany I thickness to just under 2 mm and end up around 1.8.

My soundboards aren't uniform thickness because I'm looking for a consistent "springiness", and that often requires some parts to be thinner than others. I never cease to be surprised at how the stiffness of wood can vary, even over something as tiny as a uke top.

Ken Timms makes a better Style O than Martin currently does, taking his dimensions from a 1920s Style O. I believe he thicknesses to between 1.7 and 1.8, but will vary that for the individual properties of each mahogany top.

Many thanks Chris.

Another point, you need to trade off between top thickness and bracing. This pic is of a Tasmanian Blackwood top which was amazingly stiff - it's around 1.5 mm and I could have gone thinner. Instead I'm using minimal bracing and bridge patch (this design is narrow bodied with a thin waist, so the top bout doesn't need a brace).



I own a 1920s Kumalae in koa whose top is only 1.3 mm or so, but its bracing is far beefier (no bridge patch though).

Lots of ways of doing this, but for a soprano I always say make it as light as you dare, take a deep breath, and then make it lighter.