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Using group and sub assemblies

guy_rogelguy_rogel Member, User Group Leader Posts: 84 PRO
edited September 2020 in Using Onshape
After a very expensive mistake in a project , I have realized there is a major logic problem with sub assemblies in on shape.
When inserting a sub assembly to a top level assembly it is possible to "Group" it. But this will only lock the position of the sub assembly parts. A change in the location of one or more parts in the sub assembly tab will not reflect at the top level assembly tab.  this means there is no option to have a sub assembly linked to it's tab in the same document.  I find this to be very very trubbling. what is the point in having sub assemblies if they do not reflect correctly.
I think there must be an option (I think it should be by defult) to make sure sub assembly in  the top level will be the same as it's TAB
It cost me more then 5000 USD to find this logic issue.

UPDATE
please see my comments how this can be solved




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Comments

  • MBartlett21MBartlett21 Member, OS Professional, Developers Posts: 2,034 EDU
    :+1: Absolutely!

    This sometimes seems to happen with linear patterns of assemblies as well.
    mb - draftsman - also FS author: View FeatureScripts
    IR for AS/NZS 1100
  • lougallolougallo Member, Moderator, Onshape Employees, Developers Posts: 2,001
    @guy_rogel We will reach out. Not a place to post an issue you had here when we can look at what happened.  We will be in touch soon.
    Lou Gallo / PD/UX - Support - Community / Onshape, Inc.
  • guy_rogelguy_rogel Member, User Group Leader Posts: 84 PRO
    Not so major....

    I now use a very simple (not nice but simple) solution to my problem
    If I need to move a sub assembly which is not fully defined (for example an imported PCB ) in a top level assembly I :

    1. Group it first
    2. use mating to move it wherever needed
    3. Delete or supress the group mate to make sure any changes in the sub assembly will reflect in the top level assembly
    not the nicest solution but works
    use the group mate with care
    Guy
  • alnisalnis Member, Developers Posts: 447 EDU
    @guy_rogel if you're working with imported data, it's best to either use the "composite part" feature to create a single composite part for the whole PCB or whatever it is, or insert it into an assembly of its own, fix one part, and group all of them. This will let you drag/mate it however you want in other assemblies

    Making a composite part (good for imported stuff or things you model, "closed" makes it a single "thing" with one color for everything, not "closed" preserves colors)



    Adding the parts to a subassembly, then grouping. Be sure to fix so that they aren't moved from the default position! That will let you add stuff later by directly clicking the green checkmark to insert in a consistent location, then grouping, rather than having to mate everything individually


    Student at University of Washington | Get in touch: contact@alnis.dev | My personal site: https://alnis.dev | Currently an Onshape intern: asmidchens@onshape.com
  • guy_rogelguy_rogel Member, User Group Leader Posts: 84 PRO
    Thank you Alnis
    I will defiantly check this soon
  • MBartlett21MBartlett21 Member, OS Professional, Developers Posts: 2,034 EDU
    There is also an option when you import the part as well.
    mb - draftsman - also FS author: View FeatureScripts
    IR for AS/NZS 1100
  • john_mcclaryjohn_mcclary Member, Developers Posts: 3,890 PRO
    I agree, group mate is nice, but it ignores subassemblies and goes right into the parts within the sub assembly. Fixing them in the same place they were when the group mate was created.

    This is not intuitive for subassemblies and is always a confusing issue. I think group should throw a warning when someone selects a sub assembly. Or just prevent the ability to select sub assemblies when creating a group mate.
  • tomasz_szwarc457tomasz_szwarc457 Member Posts: 7 PRO
    @alnis
    Hi,
    I just moved to OS from other cad and the solution with "composite parts" is not really well suited for working with imported parts.
    Imagine you purchase your PCB as an single product and you need to assign an Part Number for the whole PCB (then also Vendor and Supplier PN for the BOM purposes)

    When you try to release such "composite part" in OS you're asked to apply Part Numbers to ALL items in the composite parts.
    I.E. you must assign part numbers to all bodies in composite part - an complete waste of resources.

    When I buy an complete PCB assembly from a supplier it has an SPN assigned to it and just ONE part number.
    Now - in OS - when you'll export a BOM it will turn out to be excessive complex.
  • NeilCookeNeilCooke Moderator, Onshape Employees Posts: 5,308
    @tomasz_szwarc457 try closed composite
    Senior Director, Technical Services, EMEAI
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