upper level assemblies are not updating automatically when lower level sub-assemblies are updated

steven_elliott555

I am having the same issue as this person posted in this discussion, but it is still not resolved:
https://forum.onshape.com/discussion/5120/automatic-subassembly-update-in-assembly#latest

For my example, I am working in a single document (with no links to other documents)
I have 3 levels: part, sub-assy, and main assy.

When I make a change to the part, the next level up sub-assy updates AUTOMATICALLY.
When I go to main assembly - to see those changes - the updates are NOT there.
It seems to only be forced when versions are created at all levels and then each update is pushed manually going through every level.  This is only a 3 level deep assembly example.  Imagine if it were 10 levels deep.

What are the options here?

steven_elliott555

This issue is related to the "group" function used in assemblies.  If part or sub-assy is "grouped" - it basically locks down any future correction in the sub-components from live updating.  If a group is absolutely required - the group must be suppressed and the unsuppressed in order for those sub-component corrections to push through.  Now that I am aware of this nuance - I try to avoid using the "group" feature.

NeilCooke

You should open a ticket and share your doc with support. Always works for me, but cannot tell what the issue is without seeing the doc. Can you reproduce it on a simple cube?

robert_morris

Are you using a Group mate in one of the lower assemblies?
If you are, then that could be the problem. Try to suppress the Group mates, let it update, then unsuppress them.

lana

@steven_elliott555
 This sounds like a variation of https://forum.onshape.com/discussion/8142/updating-linked-documents request. Please vote for it .
Just to understand the use case better - was this structure a result of importing an assembly into multiple documents or did you build it in Onshape? 

steven_elliott555

This issue is related to the "group" function used in assemblies.  If part or sub-assy is "grouped" - it basically locks down any future correction in the sub-components from live updating.  If a group is absolutely required - the group must be suppressed and the unsuppressed in order for those sub-component corrections to push through.  Now that I am aware of this nuance - I try to avoid using the "group" feature.

billy2

@steven_elliott555 understanding what gets inherited in higher assemblies is critical to onshape's behavior.and requires a little practice.

With onshape's assy structure, I can easily create working sub-assy's and when importing to higher assy's, the mates inherent properly. You can build a library of working sub-assy's and import them to a higher assembly making everything work easily. If in the higher assembly, you add another constraint, the top respects this and the motion is further constrained.

When showing people onshape's assemblies, I tell them it's like building things on a bench. Each sub-assy works properly (I use limits) and as I gather them into higher assemblies, it works. It's the closest thing to real life that I've seen building things up into complex automated equipment.

I haven't seen this is previous CAD and not sure 'flexible' can achieve this behavior.

Our libraries have working sub-assy's and when you import them into the higher level they work. You don't have to worry where you assemble something to show a particular machine's motion. The top level inherits proper motion from the sub-assy's and this is a top/sub assy relationship you'll have to figure out.

Onshape is different and I think it's quite good, please don't throw grouping out.

rokerson

I had a similar issue. billy2's response is insightful. OnShape only pushes changes from sub-assemblies to a higher level if they are made by a mate connector.  If you simply move something around without the positioning being defined by a mate connector, it won't be pushed to the higher level.

steven_elliott555

rokerson said:

I had a similar issue. billy2's response is insightful. OnShape only pushes changes from sub-assemblies to a higher level if they are made by a mate connector.  If you simply move something around without the positioning being defined by a mate connector, it won't be pushed to the higher level.

@rokerson

As I've used Onshape more over the past several years since I've posted this issue, I've come to understand better when to use "grouping" and when to to create mate features.  There are times and places when grouping makes more sense to use (for example - during very early stages of product development where you might just want to drop in quickly an entire part studio of parts into an assembly and just "lock it down" for the moment.)

Then as design progresses moves forward - you need to remove that "grouping" feature from the assembly and then just start adding in proper mate features.

Once you come to understand what grouping does and what it does not do - it all makes sense on when to apply it.