constraining sub-assemblies in an assembly

[astronomer]

Greetings,

I created a sub-assembly with constraints among the parts. When I build an assembly using a set of these sub-assemblies and set constraints among the sub-assemblies, the update command doesn't seem to have any effect on the parts in the sub-assemblies. I wonder why?

For example: The sub-assembly is a ball joint rod end. A constraint is defined to allow the ball to rotate freely in the socket. When I put two rod ends in an assembly and define constraints which require the balls to rotate to a particular position and hit update, I usually get warnings that my assembly is inconsistent or over constrained etc. Apparently, the constraint that the balls can be freely rotated is not recognized when the assembly is updated.
How do I fix this?

Thanks.

 

[mymylepire]

Hi astronomer,
you can use Analyze-constraint to understand better what is going on with the constraints.
I see what you try to do is to modify the sub-assembly in an higher assembly. Maybe to make this sub-assembly flexible in your assembly will solve it. Look the help for more info.
Myriam

 

[astronomer]

Thanks Myriam.

Making the sub-assemblies flexible is something I'll look into. Naively I thought a higher order assembly would know by default about constraints set in a sub-assembly and update would act on those constraints.

Laszlo

 

[MarkAF]

Something additional to try would be to check your update options. Under Tools > Options > Mechanical Design > Assembly Design, "Update propogation depth" can be set to the active level, or all the levels. (This is a separate issue from the flexible/rigid assembly, and I agree with Myriam that setting your subassembly flexible is necessary)

As an aside, I have found that "all the levels" actually means all children levels. If you have a sub-product active and update, that sub-product (and any of its sub-products) will update, but the top level product will not.

Cheers,
Mark

 

[astronomer]

Thanks Mark!

The update option was set to "All levels".
Making the sub-assemblies flexible made the difference. I'm on the right track now but still have issues to sort out.

Laszlo