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Need Help Completing Loft - Surfboard Fin...

larry_haweslarry_hawes Member Posts: 276 PRO
edited April 2018 in Drawings
I found a STEP file of a surfboard fin, imported in to OS and have a decent strategy to recreate it using the loft feature but can't quite find a way to complete the last part of the loft creating the end of the fin. I can see an additional 4 features in the STEP solid but was wondering if there was a way to recreate the end of the fin using a less complicated and more flexible method.

Thanks in advance

https://cad.onshape.com/documents/1ae2fdd02fb6c30fbd6639d5/w/cc3c6e812bfc0585f7d49753/e/6b3e0319577f61bb3f00eefe

Best Answers

  • larry_haweslarry_hawes Posts: 276 PRO
    Accepted Answer
    Thank you Billy that gives me a pretty intensive homework assignment. Curious about your first sentence, "Vertex matching is a pro/e thing, you can turn it off here." Not sure what pro/e is nor did I see where one might turn it off. Thank you again very much for taking the time to reply.

Answers

  • larry_haweslarry_hawes Member Posts: 276 PRO
    Or perhaps an completely different approach?
  • larry_haweslarry_hawes Member Posts: 276 PRO
    NeilCooke said:
    Hi @larry_hawes - when sharing a public doc, don't use the "link" option in the share dialog - that creates a view-only non-copyable doc - just make it public then share the URL from the browser bar.

    Anyway, loft to point like Owen says or try fill surface with guide curves/vertices.

    Thanks Neil, 

    Can't find a difference in the links whether copying from the dbx or the URL - the links look the same.
  • larry_haweslarry_hawes Member Posts: 276 PRO
    edited April 2018
    I thought lofts needed to share the same number of vertices? How would one loft from a single vertex to a profile with 4 vertices? I'll experiment but have been trying different methods for a long time and I think the techniques described are a bit over my pay grade but thanks for the replies.
  • larry_haweslarry_hawes Member Posts: 276 PRO
    Accepted Answer
    Thank you Billy that gives me a pretty intensive homework assignment. Curious about your first sentence, "Vertex matching is a pro/e thing, you can turn it off here." Not sure what pro/e is nor did I see where one might turn it off. Thank you again very much for taking the time to reply.
  • billy2billy2 Member, OS Professional, Mentor, Developers Posts: 1,190 PRO
    edited April 2018
    pro/e is an old CAD system that required you to match the vertices. Modern CAD doesn't really require this any longer. 

    As a surface is created, keeping it flowing properly and preventing it from bunching up is important and sometimes matching the vertices helps. In your case, your surfaces flow nicely and shouldn't need vertex mapping.

    Another thing, as possibly a tip, your primary surfaces that you have defined, can be trimmed back. Then, you can add transition surfaces to connect everything together. This is a standard manifold technique used a lot, at least by me.

    So trim your fin back a little bit:


    And then add a transition surface between your primary surfaces:


    So why would you want this? Because your primary surfaces flow nicely without much curvature. Then, upon transitioning to the other side, you might want tighter curvature. It's hard to control a free flowing surface with tight curvature at it's ends. This is why we have patches and break the manifold into surface patches. Each patch has it's own control.

    Unless you want the razor's edge to slice through the water.

    This is the bases of surface modeling. Think about the primary surfaces and then the transition surfaces that'll tie it all into a manifold.

    You in San Diego?




  • larry_haweslarry_hawes Member Posts: 276 PRO
    You in San Diego?
    Thanks again for your help. Not sure if I'll actually begin designing fins but the exercise stretches my OS skills to their max and I have a couple ideas I might 3D print.

    Yeah I live in North County, Vista to be exact. You?
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