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Why do people fear splines?

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Comments

  • kevin_quigleykevin_quigley Member Posts: 306 ✭✭✭
    Splines. Yes. Used every job, every day. In SolidWorks style splines has replaced node based splines (but of course you can show the control cage for a node spline in SolidWorks and edit a node spline using the cage...you just can't dimension to the cage).

    but the real skill is in 3D splines and this is where we default to Rhino or Ashlar-Vellum Cobalt or Shark FX. Few heavy duty MCAD systems have splines anywhere near as good as those three. Then there is Alias of course...

    two point splines or conic curves are great but they cannot deal with every form, and in my experience building up a complex profile from multiple splines by using contrainted joints is a recipe for downstream failure and poor quality surfaces....top tip...keep your surface drive curves single!
  • billy2billy2 Member, OS Professional, Mentor, Developers, User Group Leader Posts: 2,009 PRO
    Using splines Tip#2

    When you offset a line, you get a line:


    When you offset an arc, you get an arc:


    When you offset a spline, you get a spline (kinda):


    When you offset an ellipse, you get ?



    https://youtu.be/TyRXzYpkYx0


  • mark_biasottimark_biasotti Member Posts: 123 ✭✭✭
    "Surfaces are only as good as the curves that create them."
  • billy2billy2 Member, OS Professional, Mentor, Developers, User Group Leader Posts: 2,009 PRO
    edited January 2016
    Frank Gehry's Bridge: an example of splines





    There's a million screws and they missed one. Probably needed a better cad system to get the holes to line up correctly:



  • michael_stallsmichael_stalls Member Posts: 59 PRO
    Im not afraid of splines! this is the baseline configuration/onshape trial run i did for a custom aerobatic aircraft we are designing for a client. the fuselage is lofted from spline crossections. A tedious process but it produced good results



    the nose cowl was particularly complex.It was made from 10 spline cross sections

    As can be seen i cant seem to use the shell feature on the nose cowl.
    the model itself is huge and bit messy. hopefully ill be able simplify the next version


  • mark_hubrichmark_hubrich Member Posts: 2
    I couldn't have done this job without splines :) I like them. Especially nice when you utilize digital fabrication and don't require dimensions for some poor fabricator to try to layout. Let the machines do all that time consuming work :wink: 


  • jlieberjlieber Onshape Employees Posts: 4
    That is pretty awesome, thank you for sharing this!!
    Johnathen Lieber
    Team Member
    Onshape, Inc.
  • billy2billy2 Member, OS Professional, Mentor, Developers, User Group Leader Posts: 2,009 PRO
    So I submitted a fix-it ticket for my approximated ellipse and it didn't go well. Turns out we couldn't duplicate the issue. Turns out creating the geometry at the origin seems to trigger something on my computer. Everywhere else it's fine, only on mine was the origin special.

    4 mirrored splines in 4 different quadrants (forget the center one):

  • billy2billy2 Member, OS Professional, Mentor, Developers, User Group Leader Posts: 2,009 PRO
    Love the examples, thanks for sharing....
  • mark_hubrichmark_hubrich Member Posts: 2
    billy said:
    Frank Gehry's Bridge: an example of splines





    There's a million screws and they missed one. Probably needed a better cad system to get the holes to line up correctly:



    They missed one screw only or one at each panel? Do you know what was used to model this? It probably wasn't Tekla or SDS2. I have had great success using D-Loft for Rhino. This project you show is only a mile south of mine :)
  • DriesVDriesV Member, Developers Posts: 43 ✭✭
    billy said:
    Frank Gehry's Bridge: an example of splines
    ...
    They missed one screw only or one at each panel? Do you know what was used to model this? It probably wasn't Tekla or SDS2. I have had great success using D-Loft for Rhino. This project you show is only a mile south of mine :)
    Frank Gehry... so there's probably some CATIA involved. :-)

    Dries
    Product Specialist at Luxion (makers of KeyShot)
    www.keyshot.com
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