A4 kirfing + elevated fretboard

[kencierp]

Just conversation, since I am clueless and have zero background in sonic engineering. I wonder why its so important to have banjo rims and drum shells as stiff/solid/rigid as possible so the skin/membrane does not loose energy transfer and get dampened. Would this not be the case with a guitar sound board as well? I believe that is the point being made in the Taylor rigid rim advertisement.

[johnnparchem]

Just conversation, since I am clueless and have zero background in sonic engineering. I wonder why its so important to have banjo rims and drum shells as stiff/solid/rigid as possible so the skin/membrane does not loose energy transfer and get dampened. Would this not be the case with a guitar sound board as well? I believe that is the point being made in the Taylor rigid rim advertisement.

Just continuing the conversation, I also have no knowledge of sonic engineering ...
I can accept the need for stiffness of the rims, I am trying to understand the incremental difference in stiffness from the various kerflings\linings once the top and back are glued on. If one considers the inlayed band on fox's kerfling as a brace and then compare its thickness to width\length of the top (also a brace once glued to the kerfling, it is hard to see the what that band is doing once the top or back is glued on. The stiffness of a brace is an exponential function with regard to height.

[kencierp]

The operative is torsion -- a rim with out top and back assembled with solid, Fox or RR kerfing is much more difficult to "twist" -- hold the rim at the tail and neck block and twist it. This added strength/feature is "not lost" when the top and back is assembled to the rim. Perhaps gluing on the top and back helps resist torsional stress too but the fact is with the said above kerfing arrangement there is much more resistance to torsion (top/back and more rigid kerfing) --- again that is the claim in the Taylor advertisement. And actually I happen to agree. As to an improvement in sound quaility -- again "I am clueless!"

[kencierp]

Rick as I mentioned I don't really do not know of, nor can I verify any acoustic benefit. Bob Taylor claims there is a benefit. I do know from working with triangular, solid and RR kerfing in my shop, that the later two produce a rim that holds its shape better and is more resistant to twisting especially during top and back assembly to rim.

As a side bar - there a story that ran through GM regarding the Oldsmobile Toronado (the first major front wheel drive pasanger car). Anyway it was few weeks before production startup -- one of the test cars at the GM proving grounds got a flat tire. So it was out on the track so they pulled the jack out of the truck proceeded raise the car -- with the rear tire about three inches off the ground "the front windshield popped clear out of the frame!!!" The twist caused by lifting the rear quarter distorted the entire body.

[Tom West]

Just to jump in and add a comment. Never used A4 linings but have converted to reverse linings. Have heard the discussion before about the added stiffness and must say that I like the added stiffness.Not going to comment on it's value re the out come of the guitar. The main thing I like about reverse lining is how it looks in the completed guitar. I can do a much better job of inletting the braces into the lining compared to traditional triangular lining.Also I find the reverse easier to make .Sorry if I hi-jacked the thread away from A4.
Tom

[deadedith]

Another benefit of the reversed rounded kerfing is that it allows for thicker bindings, which look good on some instruments. For instance, the one I am currently working on has a binding + purling depth of .140".

[dandenson]

Would having a cutaway add anything to the mix? It seems like the combination of narrower neck block, thinner than normal sides, and asymetric stress would make you want to have the rims as rigid as possible.

Has anyone ever had a problem with neck alignment changing under string tension due to the body assymetry?

Thanks,
Dan

[tippie53]

you are on the money Rick, The curvature helps to add stability to the structure .