Monty
Well-Known Member
I said I would do this a while back and got distracted. Anyway, here is my method for creating surfaces for sheet metal fabrication in Rhino. I don't count on this being accurate enough for matched hole type construction. Therefore, I only lay out the rivet pattern on the outer sheet. It is easy to put a couple holes on the centerline fore and aft to get the parts aligned. Then you can proceed to match drill and cleco all the way along the rivet line.
I'm using a generic tailcone here to get the point across. First you start with a profile view. I am so used to working in 3D that I don't bother with the planform view. I just work out from the side view. Then I used the ellipse command to make the top of the tailcone. Trim to the centerline. Then I used the conic tangent at both ends command to create the bottom curves. Mirror them and join them.
Now the fun part. Use the sweep two rails command. Select the two half ellipse curves as guide curves. Select the three lines as cross section curves. When the sweep two curves dialog pops up, select the simple sweep box. Repeat for the bottom conic curves. You should get something like this:
I'm using a generic tailcone here to get the point across. First you start with a profile view. I am so used to working in 3D that I don't bother with the planform view. I just work out from the side view. Then I used the ellipse command to make the top of the tailcone. Trim to the centerline. Then I used the conic tangent at both ends command to create the bottom curves. Mirror them and join them.
Now the fun part. Use the sweep two rails command. Select the two half ellipse curves as guide curves. Select the three lines as cross section curves. When the sweep two curves dialog pops up, select the simple sweep box. Repeat for the bottom conic curves. You should get something like this: