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Trouble sweeping a thread profile over a tapered spiral for BSPT thread.

chris_dalbychris_dalby Member Posts: 13 ✭✭
I am new to Onshape and having come from TurboCad, I am finding it a steep learning curve.

I have created a tapered cylinder and then a spiral in an attempt to create a BSPT thread but I am having trouble sweeping the thread profile to "cut" the thread.
I get an error, "Sweep did not regenerate properly: could not create valid swept body, check input <-Thread profile [sketch]".

I have looked at the thread profile sketch and cannot see where the problem is.

Can anyone help?


Best Answers

  • chris_dalbychris_dalby Member Posts: 13 ✭✭
    Answer ✓
    Thanks to you both, Neil and Dave.

    This did the trick. Can fix my other drawing now :-)


  • chris_dalbychris_dalby Member Posts: 13 ✭✭
    I got tired of trying to sort that out so I changed the spiral and tapered cylinder to the thread minor dia and tried to add the sweep. Still no good but it would allow me to sweep a new part so thats the way I went.

    Not the result I wanted but time is precious.
  • bradley_saulnbradley_sauln Moderator, Onshape Employees, Developers Posts: 375
    Engineer | Adventurer | Tinkerer
    Twitter: @bradleysauln

  • chris_dalbychris_dalby Member Posts: 13 ✭✭
    I just tried it now. Great feature but it did not work. :-(  "Error regenerating". I have left the part with the TH in place if you want to take a look.
    Does it not work on revolves?
  • chris_dalbychris_dalby Member Posts: 13 ✭✭
    I found it impossible to do a tapered thread so have reluctantly gone to a parallel instead.

    Hi Chris,

    Hopefully I can help out with your thread situation! I made a quick tapered cylinder and created a thread using a Sweep. Here’s the process I used:

    1. I created a conical face by drafting an Extrude feature.

    2. I used the Helix command to create the sweep path on the face. Simply select the conical face, then set the number of revolutions, direction of the helix, etc.

    3. In order to create the profile, I created a new reference plane that’s attached to the end point of the helix and is normal to the curve. To do this, I enabled the Reference Plane command, selected the “curve point” option, and selected the endpoint of the helix as the reference point as well as the helix itself as the reference curve.

     4. Sketch the profile on this new plane. In this case I created a triangular cutout. Just be sure that your profile won’t be self-intersecting as it’s swept around the path. This will cause an error and keep it from generating. If it does this, try adjusting the width of the profile.


    5.      Enable the sweep command, set it to the “solid” option, and choose the sweep profile and the helix as the path. Click the green check and you should be good to go!

    Hopefully that works for you! The thread could be refined a lot more than what I showed here, but it should be a good starting point for what you need.

    James Jepsen
    Content Services Manager, SolidProfessor

    Interested in improving your CAD skills?
  • chris_dalbychris_dalby Member Posts: 13 ✭✭
    Than you for your response James, much appreciated.

    Your excellent tutorial is almost identical to one I have been referring to, https://forum.onshape.com/discussion/comment/4993#Comment_4993.

    Using the method you described, I have been unable to create the tapered thread on the revolve that I have in my drawing. I tried reducing the width of the thread profile to something ridiculously small just to prove it was not interfering with itself.

    I have created a copy of the problematic version if you want to take a look.

  • chris_dalbychris_dalby Member Posts: 13 ✭✭

    What am I missing?

    An example based on your very clear tutorial James.


  • chris_dalbychris_dalby Member Posts: 13 ✭✭
    Answer ✓
    Thanks to you both, Neil and Dave.

    This did the trick. Can fix my other drawing now :-)
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