Welcome to the Onshape forum! Ask questions and join in the discussions about everything Onshape.

First time visiting? Here are some places to start:
  1. Looking for a certain topic? Check out the categories filter or use Search (upper right).
  2. Need support? Ask a question to our Community Support category.
  3. Please submit support tickets for bugs but you can request improvements in the Product Feedback category.
  4. Be respectful, on topic and if you see a problem, Flag it.

If you would like to contact our Community Manager personally, feel free to send a private message or an email.

Options

Another Mirroring Issue

S1monS1mon Member Posts: 2,434 PRO
edited October 2021 in Product Feedback
I found another basic mirroring issue. Feature Mirroring a sketch doesn't update correctly. I've reported this as an issue to support.

If a reference for a sketch changes, it's not seen as "dirty" by the mirror, and it produces an incorrect result. I created this simple model and Loft 1 was fine. Then I moved Sketch 2 (the upper circle). Sketch 4 (side curve) updated correctly, but its mirrors fail (no longer connects to the right place on the upper circle), which causes the loft to fail because the guide curves don't connect anymore. Going in and editing Sketch 4 will fix the mirrors and the loft, so this is likely a dirtiness issue.


Tagged:

Comments

  • Options
    John_P_DesiletsJohn_P_Desilets Onshape Employees, csevp Posts: 237
    @S1mon Can you make this document public please? 
  • Options
    S1monS1mon Member Posts: 2,434 PRO
    @John_P_Desilets

    Sorry, I thought I had clicked Public, but it should be now.
  • Options
    John_P_DesiletsJohn_P_Desilets Onshape Employees, csevp Posts: 237
    Thank you @S1mon    I replaced the coincident constraint with the pierce constraint for the guide curve and that corrected the mirroring issue. I'm not sure why this does not work for the coincident constraint. Support can take a closer look from the ticket you submitted. Thank you for sharing! 

    https://cad.onshape.com/documents/42decfc43f748663ccd16459/w/da1b9ade01794d5aa16d9a3c/e/bb6df2aceaf8ad8ac3f80598


  • Options
    S1monS1mon Member Posts: 2,434 PRO
    @John_P_Desilets

    I just tried using the pierce relationship on another model (that I didn't want to make public) and at first I thought you had a good fix. Unfortunately it seems to still be a dirtiness issue. Even with the pierce relationship moving the reference will cause the mirror to fail. I've added V2 to the document with the pierce relationships. If you modify the "50" dimension back to 40, this model will be fine. If you go into sketch 4 and tweak a spline handle, it will be fine. 


  • Options
    John_P_DesiletsJohn_P_Desilets Onshape Employees, csevp Posts: 237
    edited October 2021
    @S1mon As an alternative workflow, you can create a projected curve that can be mirrored using the mirror part feature. Or, build only half of the model and mirror as a final operation. I adjusted the 50mm dimension and this workflow updates as intended for the projected curves. 

    https://cad.onshape.com/documents/35110b7fa7200960f00b3422/w/99a60bd4b6feec92f1b83c30/e/34c67fecaa503e6d03da2954




  • Options
    S1monS1mon Member Posts: 2,434 PRO
    @John_P_Desilets

    In the real non-public model that I'm working on, I just added another angled plane on the other side, and created another spline with the same constraints.

    In the public model, I've added a branch which implements your projected curve idea. This does work. I usually shy away from using projected curves because with anything other than a line, a projected curve will end up with a zillion internal points and have bad quality. In this case, it is quicker to model and rebuild with a projected curve/part mirror instead of recreating the sketch curve with the same constraints.

    I also avoid building 1/2 models for class-a surfacing because it's difficult to maintain G3 across the mirror plane in many CAD tools unless the surface is built in one piece. You generally never model the hood, windshield or roof of a car in a 1/2 and mirror it - you model the curves in a way that their CVs are all symmetric so that things are clean across the mirror plane.
Sign In or Register to comment.