Cutting rib radii

[Richard Brekne]

Ribs are bendable enough that you can bend them to the exact radii you 
want, clamp them in place and remove material from the concave side so 
as to make that side flat. Unclamping will then leave that flattened 
convex line at exactly the radii you want. You can put in some fairly 
complex curves this way as well as long as your bends are not over too 
short a span to hold adequately.

Cheers
RicB