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Start of sweep along helix

gauthier_östervallgauthier_östervall Member Posts: 99 ✭✭
edited June 2021 in Community Support
I have a rectangle in a sketch, and an helix to sweep along.

When the helix has three rotations, it works as I expect:

You can see the sketch, and that the part starts there and goes on following the helix.

If I modify the helix to make four turns, the start position of the part is *above* the sketch:


What is going on? How can I keep in control of the sweep's start position?

Here is the model: https://cad.onshape.com/documents/67fb028a75ce82f860b6a0af/w/67a2efe8ba077c46e15dd6af/e/3523f2ce85349cc194eefe20
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Best Answer

  • steve_shubinsteve_shubin Member Posts: 1,066 ✭✭✭✭
    edited June 2021 Answer ✓
    @gauthier_östervall

    I guess the reasoning is —

    A profile does not have to be placed at one of the ends of the path. It can be anywhere along a sweep. 

    Apparently, the program keeps it simple in making the sweep according to the closest part of the profile to the path



Answers

  • Jenny_JohnsonJenny_Johnson Member, Onshape Employees Posts: 9
    Interesting - I tried to constrain it a few different ways with no luck - seems to not like a cylinder height below 28.25mm....  can you change the helix and path to actually touch - that will typically perform better
    Jenny E Johnson
    Principal Technical Services Engineer, Onshape
    jjohnson@ptc.com
  • gauthier_östervallgauthier_östervall Member Posts: 99 ✭✭
    With the face not touching (I guess you meant the *face* and the path), but connected to the path with a line, the sweep starts to behave.

    Weird...
  • steve_shubinsteve_shubin Member Posts: 1,066 ✭✭✭✭
    @gauthier_östervall

    Is this the way you were hoping it would work ?

    Because if I’m understanding you, it seems like it’s working OK on my mobile iPhone app




  • gauthier_östervallgauthier_östervall Member Posts: 99 ✭✭
    @steve_shubin Sorry, I modified the hole profile to test Jenny's suggestion. Document now showing the defect again.
  • steve_shubinsteve_shubin Member Posts: 1,066 ✭✭✭✭
    edited June 2021
    See below


  • gauthier_östervallgauthier_östervall Member Posts: 99 ✭✭
    @steve_shubin Sorry, I don't get it. The unexpected move of the start does not change shape the part, only it's placement. If it isn't self-intersecting by moving it one turn up, it wouldn't be either if starting at the right place?
  • steve_shubinsteve_shubin Member Posts: 1,066 ✭✭✭✭
    @gauthier_östervall

    looks like it has to do with what part of the profile is closest to any part of the helix




  • gauthier_östervallgauthier_östervall Member Posts: 99 ✭✭
    Yeah, I think you got it! This is not the behavior I expect.
  • steve_shubinsteve_shubin Member Posts: 1,066 ✭✭✭✭
    edited June 2021 Answer ✓
    @gauthier_östervall

    I guess the reasoning is —

    A profile does not have to be placed at one of the ends of the path. It can be anywhere along a sweep. 

    Apparently, the program keeps it simple in making the sweep according to the closest part of the profile to the path



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