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Undesired sweep results
robert_scott_jr_
Member Posts: 698 ✭✭✭
Hello All. My goal is to make a muti-sided lighting fixture for the underside of a stair landing. The landing floor joists are exposed, and I want to have the joints of the side pieces of the fixture's surrounding wall to meet at the joists' centers (line midway down the edge of the joists); Any angle between two joists is not the same as any other pair. There is no symmetry so each piece of the surrounding wall will be unique.
The problem I'm having is getting correctly formed pieces using a sweep. Each end face of a piece, where meeting another piece, should have the same angle so the resulting joint is aligned to the centerline of its respective joist. It's not happening with a sweep. I've tried repositioning the sweep profile to the endpoint of the sweep path in an attempt to figure out why I'm not getting the expected results, but the sweep always had similar results.
I did finally get properly formed pieces using multiple extrudes in different part studio, but I'd like to why I'd didn't get the desired results with a sweep. Please take a look. - Scotty
Comments
I think it's just a geometry thing: the sweep corner is only going to line up with the joist if the joist bisects the sweep path corner angle. The sweep will create equal angles on around the corner of the path:
You could force the path to have equal angles at each joist but then you wouldn't control the resulting overall with and length of the shape and the vertices of the pieces wouldn't fall on a circle anymore…
I should also add that the way you have drawn it with the extrudes isn't correct: your molding profile has different thicknesses on the different segments!
Basically what you are trying to achieve is impossible: the profile of each segment is only going to match properly if you use the sweep method!
Thanks for the response, Eric. I now see the non-alignment of the joist centerline and a virtual centerline of the sweep path's angle at the place where the angled faces meet the joist.
I think I can live with the sweep results since all but two of the exterior angles are very close to, if not dead on and the two that are off a wee bit I don't think would be of any matter considering the view would be from below and visually catching that they are not precisely centered may be difficult considering the non-symmetry of the joint in relationship to the joist. Also, the interior corners cannot be seen once the 'roof' to hold the small globes is in place so that can be ignored. The primary reason for posting my dilemma was to discover why the sweep didn't do what I expected.
I didn't notice the differences in piece thicknesses with the extrude method. Glad you caught that.