How deeply can you radius a back?

[Bruce Sexauer]

What Fred said: two sentences, two thoughts.

[JDaniel]

Originally Posted by Quickstep192

...A curiosity question as much as anything.

How much can you practically radius a back?

A 15’ radius is about the deepest dish I’ve seen.
I assume there’s a practical limit. Is 15’ about it?

The limits are the capability of your material. The back is usually a compound radius - front to back and side to side. Ultimately wood will only bend so much, but synthetic materials, of course, can do more. I do a standard Martin-like radius and often think about doing a more Tielke-like radius back. And I also do more extreme shapes like this:http://img.gg/RN6CKX0

[printer2]

Just a thought. Do we really need a radius on the back, top to bottom? If the quartered wood shrinks mainly across the width of the back could we get away with mainly adding an arc across the width?

[yellowesty]

Some builders use a cylindrical form to add strength to the back (and even the soundboard). The use of a spherical shape (via, for example, a radius dish) is convenient for the builder -- there's no "center" or alignment issues and braces can be affixed in any direction and still conform to the intended shape.