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Surfacing Nightmare- Can't get these corners
heep_xj
Member Posts: 11 ✭
Been fussing around with this for a few hours. It doesn't like me filling in the corners for some reason. Any suggestions? I know, the amount of features is ridiculous. I've been trying to brute-force my way through this thing and got hung up here.
https://cad.onshape.com/documents/eda53b20ad6113d837b8b3f1/w/95c9da31a1b3d4ca774ec8c0/e/89e4e99b8f5ba06959d52de9?renderMode=0&uiState=68b91422fa54d3eb0fd92036
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Right now this is view only, so I can only investigate so much…
That said, I would avoid loft, and avoid lofting so much in one feature. I would recommend constructing the cleanest, most simple curves you can for each of the sides of that shape, and then build the corners from that. Right now you're getting a surface which is way too dense and not great quality.
While Onshape doesn't have all the same tools, this series of tutorials on surfacing with Alias might help you with how to break things up and use better techniques:
https://www.autodesk.com/campaigns/alias-automotive-tutorials
https://help.autodesk.com/view/ALIAS/2025/ENU/?guid=GUID-21501AEB-9E7A-4F9F-A0B3-0A4B3431B9BD
One of the most important things in this case, would be to "build to theoretical edges"
These videos from Onshape's @GregBrown goes into some of the newer curve features and techniques for dealing with scan data:
Simon Gatrall | Staff Mechanical Engineer | Carbon, Inc.
Great! Thank you. This probably explains my issues with thickening this now that the corners are solved. I'll have to take a look at those.
EDIT: this advice is more general, as many of the techniques I used at Honda were done with custom software, and don't work in Onshape. So different approaches may be needed.
one of the other most important things to keep in mind (besides breaking down shapes like that into slabs and corners) is that, ideally, the surfaces should either be made out of as few boundary curves as possible in order to have good surface quality and highlights/reflections (as can be seen with zebra analysis).
- one edge would just be a straight extrude
- two edges would be a blended corner, but now that you have two curves on opposite ends of the surface, you need to try and ensure that they are related to each other, as in they have the same DNA. if the two curves have very different shapes and construction, it could cause issues in the surface shape and quality.
- three curves would be a bi-rail surface, but unfortunately i don't think Onshape has these.
- four curves is available, but again, you should try to make sure that the opposite curves are related as closely as possible.
the corners of your "i solved it" tab are made from curves that are very different. rounded in the back, and sharp in the front (with extended straits at each end) It may be easier if you try to blend the two slabs and just let that blended surface cut through the front and back to create natural corners. if you want, you can make tapered lines to blend from, so it gets tighter in the front corner. but just let the blend cut through the front face.