Official Luthiers Forum!

[QUOTE=JohnAbercrombie]
Your use of the term 'parabolic brace' is not the same as many folks seem to use, and may cause some confusion. (It always seems to, for me!). Most of the time when you see 'parabolic bracing' referred to, people seem to mean braces which have smoothly curved upper surfaces, with the deepest part of the brace being somewhere in the central region. Other top profiles are 'scalloped' and 'straight' which you see from time to time on transverse braces and braces in factory guitars.
[/QUOTE]

Thanks John, that’s what I thought.

By parabolic I actually meant the rounded braces that you describe which I realise can also be subsequently scalloped, but I meant them as separate to scalloped ones. I probably wasn’t clear enough, I’ll use my newbie status like a shield here

Of course, this begs the obvious question – has anyone tried radiussing *both sides* of the braces and therefore started with a uniform stiffness then worked from that?

I’m a beginner, so I’ve been paying close attention to what’s being said in this thread. There has
been a lot of good information given here, by a lot of good people/guitar builders.

For me, the most important lessons here, are, as Mario said “Learn to Learn”, and “Intuition”.

As I see it, these two concepts are the most important to understand.

In the beginning, most of what I learned about guitar building, was through the internet, and most
of that has been right here at the OLF. (Many thanks to All) However, I learned much more,
through the actual process of building a guitar. Hence the saying, “Experience is the best teacher”.

“The cube rule” is a fine tool, but IMHO, not a good means for defining any particular sound you
are trying to achieve from any particular instrument. Math is a necessity in guitar building, and
accurate measurements are imperative. But, getting a “feel” for what you’re doing, has got to be
one of the most important aspects of guitar building. Also, recording data, or keeping track of the
specs to your design would be essential to predicting (as much as one could) the sound for your
next build. But, even that could only be used as a guide line, and not a means of exact replication.

In a nut shell, seems to me, its all about the doing! The more you do it, the better you get at it!

Anyway, that’s my take on it!

Robert

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Everything has beauty, But, not everyone see's it!

[QUOTE=robertD]
“The cube rule” is a fine tool, but IMHO, not a good means for defining any particular sound you
are trying to achieve from any particular instrument.
Robert[/QUOTE]

Exactly! As a rule of thumb, the cube rule only tells you to trim the height to reduce stiffness and trim from the sides to reduce weight. As to where on the braces to reduce stiffness or weight or both or by how much and why to reduce it, that's the $64,000 question.

To know that you have to have some way of evaluating the top. That may be tapping the top, Chladni patterns, smell, dowsing rods, psychic consultations or any other method that matches your idea of how to correlate the behavior of the top to the sound you are trying get.

I don't know of any way to draw that correlation without building a bunch of instruments. There's no free ride.