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Challenges with Origins, Mate Connectors, and Imported Assemblies

S1monS1mon Member Posts: 1,062 PRO
If I import an assembly (call it 'A'), and its origin is not located on a part feature, but yet I want to use the origin as a mate reference in another assembly (call it 'B'), what is the best way to do this?
(this happens to be a PCBA that I can't share)

  1. Import a STEP from Allegro for a PCBA
  2. fix one part in assembly A (a connector or some other unlikely to change part)
  3. group all the parts in assembly A
  4. add a mate connector (call it 'C') at the origin of A
  5. create a mate connector in B (call it 'D')
  6. insert A into B and use a fasten mate between 'C' and 'D'
  7. drag parts of A around in B
  8. C and D stay locked together, but because the fix from #1 goes away in B, C just floats relative to the parts from A
It seems like there's probably a better way to do step #3 so that the mate connector is tied to the parts, but since there's no feature at the origin, it's awkward. I can create a mate connector which is manually offset from some part feature, but if there's a good chance it won't be a round number, and then I can't be sure that my assembly positions will match the other CAD system. This seems like madness when all I want is a reference at 0,0,0 that doesn't float around.

I'm slowing wrapping my head around how the mates in Onshape work but decades of Pro/E and Solidworks are making this confusing. Especially since so many things that I work on are assembled and don't have a lot of motion. I'm used to dropping in an assembly at a default position and having it not move.


  • sebastien_fryssebastien_frys Member Posts: 3 PRO
    Hi Simon,
    I have a very similar issue.
    Did you find a solution?
  • S1monS1mon Member Posts: 1,062 PRO
    I can't remember exactly how I ended up dealing with this. I think I might have manually created a mate connector in a part studio using offsets to put the MC out in space at the 0,0,0. I don't remember there being a great solution.
  • romeograhamromeograham Member, Simulation EVP Posts: 614 PRO
    edited April 8
    I use this Custom FeatureScript "Mate Connector at Origin" (by @Jake_Rosenfeld at Onshape) for this: https://cad.onshape.com/documents/7a2aca223858e21747087f1c/v/d06b9de45deb6bba4211204a/e/36a983633c3f3c601fd50add

    It creates Mate Connectors (one for each part you select) at the Origin, with Z aligned with Z.

    Great for positioning parts later in the assembly.

    Though - you'd need to ensure that your original import put all the bodies in their correct positions in the Part Studio (rather than putting them all at the origin).

  • S1monS1mon Member Posts: 1,062 PRO

    I remember reading about this FeatureScript before. Now I've added it to our toolbar.

    (BTW. Your link has an enterprise account in the URL.)
  • romeograhamromeograham Member, Simulation EVP Posts: 614 PRO
    Thanks @S1mon - interesting - that's the original FS that I linked to...not an internal copy or anything. I think it builds the URL that way because I'm logged into my Enterprise account - not to cad.onshape.com.
    I'm guessing that when you click that link above, the URL that you go to is either cad.onshape, or your enterprise account. Is that the case?
  • S1monS1mon Member Posts: 1,062 PRO
    When I click that link, I get an error because I don't have permission to log into your enterprise. If I edit it to replace "jps" with "cad" then it works.
  • romeograhamromeograham Member, Simulation EVP Posts: 614 PRO
    OK - thanks. I edited the URL to fix that for others. Haven't run into this before when I paste URLs.
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