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Old 10-09-2011, 08:41 PM
fulfillingsoul fulfillingsoul is offline
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Quote:
Originally Posted by Tim McKnight View Post
Bruce,
I thickness each back to a desired stiffness and not to a given thickness dimension. I measure how much the top (and back) bow or "deflect" under a standard weight. This measured deflection of each piece of wood tells me exactly how stiff the top or back is. I keep running the top & back through my thickness sander, gradually removing a few thousandths of wood per pass and then repeating the deflection measurement until it bows or deflects a certain distance. This way all of my backs and tops are thicknessed to a desired stiffness regardless of the thickness. I have built with extremely stiff tops that measured -.080" and I have also used "floppy" tops that were +.140" thick yet both had the same stiffness measured on my deflection board. This just proves how much natural inherent variation there is in wood.

"Tim don't you ever get tired of sanding?" Yes, I do Bruce and I often ask myself why in the world do I sand the interior parts of the guitar that no one will likely ever see or touch. The only logical answer I can muster is "because its the way I am wired".

The two carbon tubes are braces that take the rotational torque load off of the neck block. As the strings exert pull on the neck the resulting force is trying to rotate the neck block and entire upper bout end of the guitar in an effort to make to collapse the top into the sound hole. This force will eventually allow guitars, without supports like these, to deform which results in a need for a neck reset. The carbon tubes transfer this rotational force to the waist which is the stiffest point on the guitar. It is highly unlikely that guitars with this truss brace design will ever need a neck reset. It makes the upper bout system extremely rigid without negatively influencing the movement of the soundboard.
Hi are the carbon tubes installed solely for structural reasons, any effect on tone at all?

Is it necessary because soundboards of guitars by custom luthiers are thinner or braced more lightly, compared to the usual factory production guitars? Thanks!
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