Hi Charles,
...I only mention this because you asked about CNC ribs for a Pietenpol specifically.
I made a set of CNC'd plywood replacement ribs for an old Pietenpol that was damaged in a landing accident.
If it was a whole new "per the plans" wing it would have been very quick and simple to make the CAD and CAM files and cut the ribs (I've done several all CNC'd "per the plans" rib sets), but for this airplane I had to scan one of the old ribs and go from there. There's a short thread on the process here:
http://www.homebuiltairplanes.com/fo...ad.php?t=23156
IMHO you can build light, strong wings ...
very quickly using a CNC machine.
http://www.homebuiltairplanes.com/fo...ad.php?t=20101