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I've been using thicker tops and lighter bracing on my tops over the last year or so... I'm really happy with the results. The guitars are sounding better than ever and the thicker tops are less prone to deformation. I've gone as high as .145 in the center with a little ramping down to the rim... to maybe .120.   Most end up around .130 with no ramping.

My thinking is... I want a more woody sound, so... why not use more wood?

And... if the unbraced top plate has a big, resonant, pleasing tap tone when it's at .140... how can I expect to improve it by taking it to .100 ?

long

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"No man ever steps in the same river twice, for it's not the same river and he's not the same man.” -Heraclitus of Ephesus

That's more or less what happened with my current project, Hesh. All
that sanding, trying to clean up purfling and rosettes before I knew about
scraping, etc. I'm not intentionally ultra-thin at all, but right now it's an
exercise in getting the instrument done and applying knew knowledge to
my next.

ok, since we are talking about tops and bracing, I assume that everyone is talking about some flavor of spruce for the bracing.

I have heard of people using mahogany for bracing and have actually seen WRC used to brace tops. How does this affect the tone and volume? I havent got brave enough to try it yet, but perhaps some day I will.

 

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Reguards,

Ken H

Hesh,

The thinnest top on a old Martin I've ever seen was Adirondack and at about .090 to .095. Nothing close to .065.

Lance

mccollumguitars.com

sorry but thats nuts!
That's what I was trying to say(without actually saying it),

...tell it like it is...or change your handle to "happy".

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David White, Toronto

"All my favourite singers can't sing."

Mario:
Ever hear of 'reverse graduation'? Over the last ten years or so a couple of people have been measuring the grads on every old violin they can get their hands on, and that's been a lot! Many of the 'best' ones starting with late Nicolo Amatis, and especially Strads, are _thinner_ in the middle. Most of the top is about 2.6-3mm, and it's about .25mm thinner along the center line for maybe a third to a half the length. I've made several fiddles and a couple of archtop guitars this way, and they've been the best yet. It's roughly analogous to 'scalloped' bracing in some ways.

I've been testing the properties of all of my wood for a few years now, and using that datys to figure out how to thickness them. I assume that the critical thing for resisting top deformation under the string load is the lengthwise stiffness. Ignoring the contribution of croswise bending (for simplicity) the lengthwise stiffness of the top (without bracing) will be proportional to the Young's modulus (E) and the cube of the thickness. If I have a top that I know as strong enough, and I also know the E value, I can multiply that by the cube of the thickness to get an 'index number'. If this number is then divided by the E value of the top I want to use, the result is the cubeof the thickness that will be required to have the same bending stiffness. One thing you will find if you do this is that the denser the top is the heavier it will tend to turn out, since the lengthwise E value tends to 'track' the density pretty closely.   

Al, that was one of the things we learned in Michael Darnton's violin course. If i remember correctly, Strad's graduations are pretty even throughout the plate. In any even, that is how i craved my first, and dang, it is one fine fiddle!

 But when I tried that with a mandolin, it gained volume, but became thin, nasely and otherwise too bright. Yuck. No tone. No warmth. Scrapped it. I may revisit the idea again, but not any time soon.