360 degree Spiral (helix) with tangent end points

Comments

• MichaelPascoe Member Posts: 2,536 PRO

  September 15 edited September 15

  There is not a default way to do this with the helix feature yet.

  You can however, do it with custom features like Parametric Curve by @mahir.

  Or here is a default workflow without any custom features at all:

  Adjust the start and end tangency of the spline within Sketch - Helix profile. This will control the helix path. In the example, it is set to be tangent for both the OD and the ID.

  https://cad.onshape.com/documents/cc91f79bfd12172c026d3af9/w/4fd26f7d83b5099a4778600e/e/3e5558e5af4…

  

  
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  1
• Matt_Shields Member, Onshape Employees Posts: 735 EDU

  September 15

  I like the Parametric Curve approach.

  

  2
• GregBrown Member, Onshape Employees, csevp, pcbaevp Posts: 347

  September 15 edited September 15

  For fun: [Edit] 2 native features can do it! Adjust the approximation to taste.

  https://cad.onshape.com/documents/ae804e4d73d5db653040c651/w/62d8bc92dcecd2895263cb0a/e/94411e37f517998d7c30163e

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• MichaelPascoe Member Posts: 2,536 PRO

  September 15 edited September 15

  Nice! I didn't know we had that tool. 🤯
  Curvature is a bit off on that approach though. Not that most even notice good curvature. (Shift + C) for users who don't know that yet.

  https://forum.onshape.com/discussion/comment/121190#Comment_121190

  
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  0
• GregBrown Member, Onshape Employees, csevp, pcbaevp Posts: 347

  September 15

  https://forum.onshape.com/discussion/comment/121192#Comment_121192

  Goal was tangency - which was achieved :)

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• SkiBoy22 Member Posts: 6 ✭

  September 15

  Thanks Everyone!

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• Matt_Shields Member, Onshape Employees Posts: 735 EDU

  1:40PM edited 1:46PM

  And for more fun, I was able to match the parametric curve with a 5th degree Bezier. Tangency ensured with vertical Bezier control lines.

  

  Btw, here are my parametric curve equations.

  

  Or

  ((25+37.5/PI^2*#t^2-12.5/PI^3*#t^3)*cos(#t*rad))*mm
  ((25+37.5/PI^2*#t^2-12.5/PI^3*#t^3)*sin(#t*rad))*mm
  r1=25 and r2=75 and 0<t<2PI
  

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• SkiBoy22 Member Posts: 6 ✭

  4:01PM

  https://forum.onshape.com/discussion/comment/121180#Comment_121180

  What is the equation you used to create this? And what is this spiral type called?

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• Matt_Shields Member, Onshape Employees Posts: 735 EDU

  4:52PM

  Expressed parametrically, the general equation of a spiral is

  

  I don't think it has a particular name, but logarithmic spirals and archimedean spirals are versions of this general equation. Adding some unique boundary conditions can get you where you need to go.

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• SkiBoy22 Member Posts: 6 ✭

  5:45PM

  Thanks!!

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