SOLVED: pattern on a curve is rotating the wrong way and not following the curve

Lyle_Walsh

https://cad.onshape.com/documents/856ebdce6c4cedced2e02bde/w/2ff1b4330205e9e8369a0db2/e/4112ec896ffb333da1e0df82

I am back to working on a tubing support and once again having a lot of trouble patterning cutouts along the curve.  THe curve generates the loft very well but pattern on a curve seems to be rotating thepattern objects the opposite direction of the curve.  any ideas (the triangles will be cutout of the extrusion to decrease mass and improve the look)

konstantin_shiriazdanov

Curve pattern in oshape internally relies on the orientation of the transforms given by the sweep feature (which is very unintuitive compared to other kind of patterns where transform are calculated explisitly and If I designed curve pattern by myself I would use transform calculated from line to line transform interpolating function along the path ). So the case is not in the patterned object itself, but in the transforms. You may sweep some little test line along your path to see if the orientation of the swept surface significanly differs from the orientation of the lofted shape - if so built in Curve pattern doesn't help you much, since then you would need orientation by the reference surface.

@mahir given us Curve pattern normal feature, which seems to solve your problem.

https://cad.onshape.com/documents/96e5021433cc72b39f7e9922/w/cb6fe0e294d20a1353709ab3/e/0f26cf91fbbd3eef9598ac32

konstantin_shiriazdanov

Lyle_Walsh said:

just curious, I fail to see any use in the pattern on a curve that doesn't follow the normal other than when you use preserve orientation

ordinary curve patterns basically work as expected for flat curves, but I agree that for spatial curves you usually would like to give some additional info about how to define transforms

Lyle_Walsh

Note to anyone following this: the duplication has some difficulty following tight curves, works great on gentler curves and decided to make the cutouts circular rather than alternating triangles.  You can put more along the outside of a curve and fewer on the inside to make spacing nicer

Lyle_Walsh

No comments so bug report submitted
another test object
https://cad.onshape.com/documents/23db209e500aea45f2f47e9a/w/1483019ce643f64de3b0a682/e/2ad31e985ee4cba6af816289

konstantin_shiriazdanov

Curve pattern in oshape internally relies on the orientation of the transforms given by the sweep feature (which is very unintuitive compared to other kind of patterns where transform are calculated explisitly and If I designed curve pattern by myself I would use transform calculated from line to line transform interpolating function along the path ). So the case is not in the patterned object itself, but in the transforms. You may sweep some little test line along your path to see if the orientation of the swept surface significanly differs from the orientation of the lofted shape - if so built in Curve pattern doesn't help you much, since then you would need orientation by the reference surface.

@mahir given us Curve pattern normal feature, which seems to solve your problem.

https://cad.onshape.com/documents/96e5021433cc72b39f7e9922/w/cb6fe0e294d20a1353709ab3/e/0f26cf91fbbd3eef9598ac32

Lyle_Walsh

just curious, I fail to see any use in the pattern on a curve that doesn't follow the normal other than when you use preserve orientation

konstantin_shiriazdanov

Lyle_Walsh said:

just curious, I fail to see any use in the pattern on a curve that doesn't follow the normal other than when you use preserve orientation

ordinary curve patterns basically work as expected for flat curves, but I agree that for spatial curves you usually would like to give some additional info about how to define transforms

Lyle_Walsh

Note to anyone following this: the duplication has some difficulty following tight curves, works great on gentler curves and decided to make the cutouts circular rather than alternating triangles.  You can put more along the outside of a curve and fewer on the inside to make spacing nicer

Lyle_Walsh

john_mcclary

I've had similar problems with swept or loft curves, according to support it is a tolerance issue. 
the work around they suggested I have been using for a while now and have had fewer problems.

Start with a cylinder surface, then make your sweep, now use the sweep to split the cylinder surface. It seems to "cleanse" the edge and normalize it.