Mahogany Back

[ScottC.]

Hello, I am making 2 steel string J45 Dreadnoughts using mahogany backs. Using the tapping method and formulae, I came up with 3.5 on one back and 3.75 on another, does this sound close to any you guys have done? I know all pieces are different, but this seemed a little thick, but it could be that they are mahogany and not EIR.
Thanks Scott C.

[Trevor Gore]

Sounds real thick to me, too.

If the numbers are right, you'd probably be able to feel that the wood was comparatively floppy.

As usual, check everything. If it still seems sus, try a different method and see if you come up with the same number. For example, it's pretty easy to check Elong with a beam deflection method. It's in the book. The numbers generally agree pretty closely (i.e. better than 5%).

If you come out with a low mass back even at 3+mm thick, you're probably good to go, otherwise think again.

As a point of reference, the meranti I used recently on the Shed guitar came out in the mid 2's and I'd expect the mahogany to be somewhere in that ball park, for an "average" piece.

[ScottC.]

Thanks, It feels pretty rigid, I'll double check everything.
Scott C.

Sounds real thick to me, too.

If the numbers are right, you'd probably be able to feel that the wood was comparatively floppy.

As usual, check everything. If it still seems sus, try a different method and see if you come up with the same number. For example, it's pretty easy to check Elong with a beam deflection method. It's in the book. The numbers generally agree pretty closely (i.e. better than 5%).

If you come out with a low mass back even at 3+mm thick, you're probably good to go, otherwise think again.

As a point of reference, the meranti I used recently on the Shed guitar came out in the mid 2's and I'd expect the mahogany to be somewhere in that ball park, for an "average" piece.