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Post-Assembly Part Modifications

mark_proulxmark_proulx Member Posts: 48 ✭✭
edited February 10 in Using Onshape
I'm designing an electrical panel that consists of terminal blocks and other components mounted to DIN rails.  My initial DIN rail lengths turned out to be excessive; I want to trim them.  When I trim them in the Part Studio, all of my mate connectors and mate connections in the assembly become invalid. To make matters worse, when I split the rail, delete the unwanted portion, and insert the truncated part into the assembly, the mate connectors on the part don't load into the assembly despite being visible and seemingly legitimate in the Part Studio.

Is there a way of modifying parts after their inclusion in an assembly that doesn't sabotage the work done to that point?

I don't know if it is relevant, but the parts in the various Part Studios are .stp files imported from vendor sites. I didn't create them from scratch.

Here's the document:



  • glen_dewsburyglen_dewsbury Member Posts: 527 ✭✭✭
    when you use split part and delete the IDs of parts get changed, Try move face and see if that takes care of your issue.

  • matthew_stacymatthew_stacy Member Posts: 473 PRO
    @mark_proulx, it looks like you split your DIN rail twice:  1st to 12 inches long and then down to 8 inches long.  What is the reason for that second cut?  It might make more sense to just edit that 1st split to whatever length is required.
  • matthew_stacymatthew_stacy Member Posts: 473 PRO
    @mark_proulx, also I forgot to mention that the SPLIT tool has an option to "keep both sides" selected by default.  Deselect that and you can eliminate the subsequent DELETE PART operation.  Play with the direction arrow to choose which side of the split part to keep. 

    Only keeping one side of the split part should also address the part ID error that @glen_dewsbury described above.

  • glen_dewsburyglen_dewsbury Member Posts: 527 ✭✭✭
    Another way to do this is to predefine the splits so that part IDs don't change with length. It's a bit fiddly since you'd need to keep updating part names based on length measured in assembly and track parts already used so as not to over write.


  • mark_proulxmark_proulx Member Posts: 48 ✭✭
    @glen_dewsbury...Thank you for taking time to respond. I initially considered moving the face, but opted for the split since moving the face would have run afoul of the slots in the bottom of the channel.
  • mark_proulxmark_proulx Member Posts: 48 ✭✭
    @matthew_stacy...Thank you for taking time to respond to my question.  The stock part is six feed long. I'm laying out this panel without being certain of the final channel lengths that I'll need. The first cut took it down to 12 in. That ended up still being longer than I needed, hence the second cut to 8 in.  I will check to see whether use of the "keep both sides" (or not!) function would have prevented this problem.
  • matthew_stacymatthew_stacy Member Posts: 473 PRO
    @mark_proulx, I suggest not making a second cut.  Just edit the first cut.  That is the essence of parametric-feature-based CAD.  The length of your part is a fundamental parameter.  If 12 inches is too long, then just edit that value to 8 inches, or whatever length suits your need.  In this scenario there does not appear to be any compelling reason to create additional features.

    Also note that the SPLIT tool lets you use a mate connector rather than a plane to locate your cut.  This even further simplifies your model, making it clear and easy for others to understand your model and design intent.
  • martin_kopplowmartin_kopplow Member Posts: 222 ✭✭✭
    I have the impression that it would be a good idea to create the DIN rail as a configurable part. That way, the lenght could just be typed in as necessary, and no cuts would be made, so no ID change will occur, thus keeping the mates alive, at least those which are located on the part of the rail still existing after the edit.
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