Table 4.5-3 Panel mass

[Edzard]

Hello Trevor,

Thanks for making these books available and taking time to answer questions about them.

I am starting to measure some tops and building up a small database like you did in table 4.5-3 "Measured elastic constants and thickness targets".

I have "implemented" the equations in Excel and they work well. For some (probably very dumb) reason I can figure out how you calculated the Panel mass (last row). Is there a fixed valuable (rosette hole etc.) you subtract from the Volume*density (per species?).

Just out of curiosity: what happens with the rejected wood. Did some of it get used by a apprentice or an other project? Therefore confirming what you had measured (not good for a master guitar)?


Thanks again,


Edzard

[Trevor Gore]

Hi Edzard,

The answer is here; basically the relevant area is the area of the guitar soundboard (no sound hole), not the the area of the unshaped plate.

I don't have much by way of reject wood. Probably the single largest cause for failure (across a number of suppliers) are cracks/splits parallel to the surface of the board, revealed when thicknessing (if not by tapping) and caused during the drying process with the re-saw sandwiching a radial crack. If it was "expensive" wood, I send photos to the supplier and usually get a credit against my next order. The remnants can be used for sound hole reinforcements, back marriage strips, etc. Bits of back wood are used in rosettes, purfling etc.. This rosette and the purfling were all made from what would normally be regarded as scrap; maple not big enough for sides or binding, but OK for purfling with the rosette tiles made from back and fretboard off cuts.

Curly purfs.jpg (103.37 KiB) Viewed 5555 times

[Edzard]

Thanks!

Somehow I missed that thread completely.


Very nice rosette BTW!


Edzard