Official Luthiers Forum!

Hi guys,

Hope you all had a great week.

I started to try and voice my top. I think I have decent tone and a little
resonation coming through, but think there's more. I was wondering how
short can I go on my X braces and tone bars without losing structure.

Thanks in advance for your help and wisdom.

Ross

That is dependent on if scalloped, the thickness of the brace, the thickness of the top but as a general rule I never scallop deeper than the width of the brace. From your post I am not sure you are scalloping or just tapering. there is two ways to remove material from the brace, well three really. Side taper, lateral taper and scallop.

And you can thin the top in areas as well you knowMichaelP38849.7185300926

Thanks Michael. I'm doing parabolic bracing not scalloped. Sorry I forgot to
mention that. So if parabolic what is the shortest you think I could go
without compromising structure. Thanks again.

Ross

Tod is dead on here. To give a min is not the right way to look at it. Each set of braces are different in stiffness. It is not quite the same as working with steel where there is a known section modulus. I would go at taking from the side and not the height and stop as soon as you like the fundamentals. You have to keep in mind that the free top will respond much different than as an attached diaphragm.

Based ont MichaelP's post...

I agree the free top will act differently once attached...However...has anyone come up with a means of temporarily attaching the top to a finished boat (back and Rim glued up)???

If so...please post...I was thinking of spool clamps during a dry fit of the top to the "boat"...

furthermore is it really worth the work???? (mounting and unmounting the top during voicing).

Thanks for any responses.
JP

Thanks for the info guys. Sorry I haven't responded sooner. Been quite
busy, but nonetheless really appreciate ya'lls input. Makes perfect sense
what you guys said.

I'm sure there are a number of ways to go about it but I was just
wondering if there are any ideas to get more resonance from my top. It's
an Adi top btw and it's quite stiff. I even went a bit thinner on it because
of the stiffness. I'm pretty pleased with the tone, but want a bit more
resonance without going to skimpy on the braces and sacrificing
structure.

Any more ideas would be much appreciated.

Thanks guys,

Ross

You forgot the shape and how that can effect the strength and stiffness. I am awed that sometimes you can make smoething stiffer in one direction when shaping.
   Triangular shaped bracing will have different properties than rectangular .
john hall
blues creek guitars.
PS rememeber you want balance. Too loose and you will loose headroom.

Brian Burn's site has an article on attaching a free top to a dummy guitar to perform voicing tests.

John, thanks for answering. I'm doing triangular brace shapes. I'm
assuming that's what you needed to know.