Inducing an arched back

[Lawrence]

Builder Folk,

I'm about to start building an arched top and back mandolin, A-style, with a bent rosewood back. I've carved a few backs, but not bent any. Any words of wisdom? To approximate the same degree of bent-ness as a typical carved back, is it necessary to steam it, clamp it in a mold, etc? Alternatively, how much arch might I expect to get just by thinning the plate and gluing it to curved bracing, without heat?

Thanks a million,
-Lawrence

[Michael Lewis]

I think in this case you would be best off using a cylindrical section sort of like the Vega cylinder back. It is much easier to do than make a dome, imparts much less stress, and stiffens the back about as much. If you have to make a dome you will need to make a form to shape it on, and do some fancy joinery. In this case it might be easier to carve the shape.

[Dave Cohen]

There was an article in American Lutherie a while back on building an Irish bouzouki. The builder had pressed the top into an arch (& maybe the back also?). He described in detail how he pressed the arch, as well as how he joind the two halves. You should go to the GAL website and look up that article before you give up on a pressed arch. ...Or, for that matter, before you decide how you are going to build your mandolin.