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Sub Assembly Mates and Fixes Not Working in Upper Level Assemblies

ConradspartaConradsparta Member Posts: 3 PRO
We have had issues with slow model performance with large assemblies and part studios. We are working around this by splitting our model into multiple documents. We are frequently updating linked documents and referencing items between docs and between internal sub-assemblies. When adding sub assemblies into upper level assemblies we are finding that the model becomes unpredictably unstable. We have had parts that are fixed in the sub-asms that have had that "fix" become active in the parent when it should not be fixed in the upper level assembly causing mates to fail. We have also had mates in the sub assemblies not properly translating into the upper level assemblies leaving parts floating undefined or in an incorrect position but unable to be dragged by the cursor. We have had to use groups in the assemblies in order to keep our parts defined and in the correct position without having our mates fail and exploding the assembly. These errors are usually occurring after updating an assembly to a new version from another document.

Is anyone experiencing these inconsistencies in assemblies with mates, if so is there a workflow to increase model stability or a way to structure assemblies and mates to decrease the chances of mate error or incorrect part positions.


  • Arunabha_NagArunabha_Nag Member, Onshape Employees, Developers Posts: 8
    Hi Conradsparta,

    Fixed sub-assembly part should not become fixed in upper-level assembly when inserted. User needs to manually fix it. 
    All these issues can be document specific based how the mates are created. I would suggest reporting it to support for investigation. 

    Thank you,
  • GlenDGlenD Member, OS Professional Posts: 255 PRO
    some hints from personal experience.

    Remember to create a 'version' when changing 'linked' documents.
    Fixed is only local to the particular assembly or sub assembly and does not carry through to next level.
    Grouping seems like a nice shortcut but can cause trouble later unless it's a very simple project with very little change or functionality.
  • john_mcclaryjohn_mcclary Member, Developers Posts: 3,253 PRO
    @Arunabha_Nag Actually @Conradsparta may be onto something. I noticed that yesterday and today for the first time.

    A sub assembly was not updating, after a while I saw the FIX'ed part did indeed fix itself in both assemblies it was in.
    But not the other sub assembly (Upper Leg) which was a duplictation of (Lower Leg) with part configs changed in it only.

    So it seems random so far when it happens. I didn't think much of it until I saw this post. It seems to be a recent thing (for me at least).

    I went back through the version history to pull out when I happened today:

    I'll submit a support ticket if you like with my doc attached
  • Arunabha_NagArunabha_Nag Member, Onshape Employees, Developers Posts: 8
    john_mcclaryConradsparta ,
    We have reproduced this issue with linked-document sub-assemblies. We however could not reproduce it with same-document sub-assemblies (like the case in your image). A bug-fix is coming in the next release of Onshape that should potentially solve this issue for linked or same document sub-assemblies. If this still happens after the next release, please report it to support with the problem document. (Note: The bug-fix is not going un-fix the instances that have already become fixed in top-level. It would avoid them becoming fixed in future)
  • john_mcclaryjohn_mcclary Member, Developers Posts: 3,253 PRO
    Noted, thanks!
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