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Bike Head Tube Organic Shape
marcel_graber
Member Posts: 4 ✭
in Drawings
Hi all,
I'm in the design of a bicycle frame with 3d printed lugs and carbon tubes. But I'm still struggeling with a clean organic shape for the lugs. As an example, I made a simplified lug. Can you help me in how to do it the "clever" way in OnShape? As you see on the picture, I do not get a smooth transition between the loft of the tubes and the "filet" between these lofts.
https://cad.onshape.com/documents/3962d9bf5086bf7cc2562aaa
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marcel_graber - You might try working with the variable fillet option inside the fillet command - there is a bit of a learning curve involved. I've found that getting a perfectly flowing organic shape can be quite challenging.
Thanks @rick_randall
I tried the whole day… the problem with the fillet is, that it brakes, when I change the base geometry (which happens often, because of the different frame sizes) I tried another approach with bridging-curves and fills. Looks better now, but still not perfect.
These kinds of joints are extremely challenging with any NURBS based modeling tool. NURBS are by definition 4 sided surfaces, but there's no simple way to break up this transition without 5 or 6 sided surfaces. Even then, those surfaces don't necessarily have a natural order of which one(s) should be first and influence the following ones (beyond perhaps the tubes being fundamental). Even with something like XNURBS, which is like Parasolid's fill surface on steroids, it's going to be a lot of very careful tweaking to get anything decent.
Simon Gatrall | Product Development Specialist | Open For Work
I know Onshape's surface modeling tools are up to the task. I hope one of the community surfacing experts will chime in with a proper solution, but here are a couple of tips in the meantime: