semi-freeform 3d shapes?

david_rysdam

I'm making a kinetic sculpture. It's going to have golf balls rolling down tubes made of welded-together wire. I was having some difficulty figuring out how to make the routes, but I think I've mostly got it licked. However, I'm not sure how to join sections that meet at arbitrary solid angles.  To see what I mean, I've constructed a test version.  (For the sake of discussion, call the 4 vertical bars the "feed tube" and the spiral bars the "descender".) 

How do I attach the exit of the feed tube with the top of the descender? "Loft" is just going to do shortest path thing, which won't leave room for the balls. I could sweep a sketch, but I'd have to define a new plane for each bar probably. Or maybe I could make a spiral with a tighter radius and lower pitch that would connect the two, but that's going to be a huge hassle. 

Basically, I think I want a 3D spline...

(Incidentally, is there some easy button or something to include screenshots of a document here in the forum? Other than manually taking a screenshot and uploading it, I mean.)

david_rysdam

I thought I'd be clever and change the circular spiral into a square spiral, which would make all the corners square. I now realize how stupid that was, since it does nothing to help the "solid angle" problem and multiples the number of intersections by a jillion. It also brings up how difficult all this is going to be to fabricate in the limited time I have available.

I think the main conclusion for my use of OnShape is that it needs a way to connect points that is simpler than

1) figure out a way to construct a plane containing and/or perpendicular to those points.
2) make sketch(es)
3) extrude/sweep

joris_kofman

for me this is where the 3d sketching tools in other programs really come in. You want to make extrudes/sweeps along paths in 3d, you want to be able to make sketches perpendicular to arbitrary points along those curves.