"filleting" the "corner" of a surface (first "non-trivial" surfacing in onshape)

Comments

• MDesign Member Posts: 591 ✭✭✭

  February 24

  

  Simple variable fillet work for you?

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• MDesign Member Posts: 591 ✭✭✭

  February 24

  

  Or split your loft face with your bridging curve. delete the little face making the corner and redifine the sweep path to include the new edge of the loft.

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• jelte_steur814 Member Posts: 318 PRO

  February 24 edited February 24

  this is your seat with 'tangent edges removed'

  

  do you see how some of the rounded edge is still a black line along the length of the seat? meaning it's not tangent in those area's.

  probably not what you want. I think the sweep approach is not the best way to go if surface quality matters.

  moveover there are some 'semi' fillets here in this area which are the result of the isoclines in the loft that are a rather arbitrary result of the 2nd and 3rd guide which will be difficult to control or get right.
  I'd suggest a different approach:

  1. create overbuilt surfaces for the back, seat, and side,
  2. create an overbuilt contour surface to cut with
  3. create a bunch of face fillets to transition between these.

  you can add more and more control and precision to the design by tuning the first surfaces.
  this approach will result in cleaner surfaces and an easier to edit result, especially using the new 'edit curves' feature on a few strategic curves.

  especially the side surface shape will have a big impact..

  https://cad.onshape.com/documents/ce2f1d9affb355246c852948/w/6f1bf4725859cd6fafad3757/e/127dade981c433389c9940e4?renderMode=0&tangentEdgeStyle=2&uiState=67bc493aa92568487a5b4f08

  you'll get something like this.

  

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• kyle_altendorf Member Posts: 36 ✭

  February 24

  @MDesign, your first attempt I had already done but I did indeed want to eliminate the corner on the first surface, not just that edge on the round over. So, your second effort looks like what I wanted. I know I tried exactly that and… I guess I gave up much too quickly. I got it working now. Thanks for pushing me back to that.

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• kyle_altendorf Member Posts: 36 ✭

  February 24

  @jelte_steur814, thank you for the detailed response and example. I was aware that the quickly hacked up example had poor (just terrible :]) surface properties. I was specifically going a 'non-planar' direction with this experiment. I can see how the planes and overbuilt surfaces offer a few distinct benefits and appreciate you bringing that to my attention.

  As I created the roundover I did notice I was not specifying constraints to the surface and knew that wouldn't be good. That was another point I was intending to explore. I just redid that roundover sketch with an intersection of the seat surface, instead of using the 'center edge' at first. The lack of tangency (let alone any higher continuity) is still present on the sides. Locking the sweep profile to the face of the initial loft seems to have addressed the tangency at least, but I know that's a bare minimum requirement in surfacing. When thickened, some tangency issues remain on the added face. You're concerns about the stability of my initial approach remain valid. :]

  

  

  Thanks again for presenting the alternative approach.

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• kyle_altendorf Member Posts: 36 ✭

  February 24

  https://cad.onshape.com/documents/5a38fb744042fa8c2982151a/w/c2e66a2445f0668f88188944/e/e61578f4c763bc663c1070c6?renderMode=0&tangentEdgeStyle=2&uiState=67bc79c17709ad15ce6b358c here's my adjusted model, for the record

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• MDesign Member Posts: 591 ✭✭✭

  February 24

  https://forum.onshape.com/discussion/comment/114361#Comment_114361

  awesome glad you got it. I always go for simple then progress. Never know the knowledge base of the inquirer.

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• kyle_altendorf Member Posts: 36 ✭

  February 27

  When splitting based on the bridging curve, the curve must be projected onto the surface. I selected normal to target, but I think this concern will apply regardless. Doesn't this allow for the curvature "cleanliness" of the bridging curve to get "damaged" as it is projected onto the surface? In this exact context the bridging curve is only minimally away from the surface so it could be argued that the effect would be negligible, but I'm also trying to make sure I understand "correct" surfacing.

  This may just be another point in favor of @jelte_steur814's concerns about this approach.

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• MDesign Member Posts: 591 ✭✭✭

  February 27 edited February 27

  If your worried about surface quality. you might think of the sweep as an intermediate step to the final product. use the sweep to build the edges of the the next surface. once that surface is built delete the sweep and apply a proper blended,tangent surface. That just one way to look at it or attack it. if the adjactent surfaces are known or built seperately you wouldn't use a sweep in that manner and opt for some other surfacing tool like lofts, of boundary or others.

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• jelte_steur814 Member Posts: 318 PRO

  February 28

  Hi kyle,

  try both and evaluate the curves using the curvature combs.

  you'll learn that projections will indeed mess up the input for the next surface. I expect the combs will look a lot less clean. that's why projections in general are to be avoided.

  be aware that the quality of your surface is very much dependent on the quality of the edges/curves it's made with.

  so garbage curvature edges in, garbage surfaces out.

  A fillet corner for surfaces feature would be a very nice addition here for Onshape. but i don't think the required operations are there yet to featurescript something for that… (I'll think about it though)

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