Hey all, sorry I didn't reply sooner, been busy and not paying attention... Ward the turbocad functions took a little bit of fiddling to fine tune. I start with surface deform which has elasticity stretch and bend inputs so you can develop the curve or "arch" . I start with a full 17" top profile and reduce it in scale to allow for a 1/2 " perimiter "flat" Next experiment with surface deform settings until I get a curve resembling the arch I'm looking for. Turbocad has a drafting pallet which creates sections of the solid for verification. After I have the curve I want I go back in and fine tune the shape using deform to point. Again there are elasticity, stretch and bend settings to fine tune but this function allows fixed control points and isolated surface modeling for small adjustments. I have worked up several guitar tops based on an archtop I own, two sets of plans I bought, and my own sense of "curves". The turbocad settings are very intuitive, the more you play with it the better it gets... Using the turbocad language to interpret your curve it looks like you have a very rigid surface, (no elasticity), deform to point in the center of the lower bout and no tangent edge relationship (flat or recurve) Instead of an arch you have a cone... You need to relax or inflate the surface so it arches tangent to the control point and recurves tangent to the edge. I cant really read the control functions in the screen shot but it looks like you have the menu options to do these things. Just experiment and compare you'll get there. Buy Benedetto's book its well worth the $$ and there is a set of full size templates you can take control points from. I'll keep watching, just post back if you have any other questions. Good luck
garry, I'm not really sure on the hours, I worked part time little bits here and there (some bigger) over about 4 months. Lots of r+d time... I'm building two more right now and keeping track of the hard hours so I have a baseline. I use turbocad and bobcad back and forth, both have their proprietary version of cad file but import export pretty cleanly with dxf. bobcad generates the toolpath files as .tap. I use a shopbot cnc with a 3hp columbo dc controlled spindle, 4'x8' table 8"z axis. Shopbot has a very user friendly program and converts .tap (generic g code) to their.sbp proprietary controller language. I have been using this setup for about 6 years now, (various upgrades) and no real problems.
B.M. Chair?
Good Luck, I'll keep checking back. thanks for looking, dkw