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Anyone else have assembly rebuild issues in 2018 when you have flexible sub-assemblies.

Question asked by Dennis Parr on Aug 2, 2018

I've turned in files to my VAR on this. I have assemblies that I have sub-assemblies in them which are flexible. Example, a pneumatic cylinder. The rod is allowed to be free to move in the cylinder assembly so I can fix the body and attached the rod to the part it will move in the assembly lie in a punch die with the cylinder fixed to the top plate and the rod to the punch which is stroked down to punch the part. I set the punch in a configuration I call "load part" and then put the punch in a configuration using constraints that puts it through the part and call that configuration "punch part". For these two configurations to work the cylinder must be flexible. The problem is I can go between the two configurations and get ZERO constraint errors. Add a part (example, a fastener) which is being placed on a part that is not a moving part, isn't attached to a moving part, is being placed on parts that have all degrees of freedom locked down. When I place the face mate, then the axial align, suddenly the new part gets a constraint error. I suppress ANY constraint in the model and unsuppress it and everything is fixed. No more constraint errors. Save, close the assembly. Open it up a couple days later to add some more parts or to put the punch die onto a frame / table and it is fine. I place another part on the frame / table, no constraints related to the die assembly I just put on the table and the die assembly (which has the flexible cylinder in it) suddenly has failed constraints. Open the assembly.... no failed (or conflicting) constraints. Save and go back to my top level and magically the constraints are all fixed. But, when I place more parts (wheels on my table, etc.) I get error messages and failed (or conflicting) constraints. I've gotten so tired of always having to close dialog boxes for the error messages I just turned this error message off. I get failed or conflicting constraints I ignore them, place more parts and as I place them the failed/conflicting constraints fix themselves, then new ones pop up. When I sent a sample assembly to the VAR, they sent it to Solidworks who's response was "the user has the error message turned off". I KNOW THAT!. I'm getting a false negative. Solidworks is showing constraints in sub assemblies as being failed or conflicting when they're not. If I change the flexible assembly to be rigid, then the constraints that fail or conflict show up. I suppress them and everything is fine. Put everything back so my flexible assembly can be flexible and the false negatives start up again.


I just want to check if anyone else is having this problem with flexible assemblies. Solidworks telling me I turned the error message off is the dumbest answer they've given me yet for a problem (been a user since 1999). This same problem existed in 2015. The constraint in the sub assembly that is suppressed to allow the assembly to be flexible is included in the rebuild as if the constraint isn't suppress. Example, a pneumatic cylinder the rod is mated to the bottom of the bore of the cylinder to fix the rod in the full retract position. Then you suppress it so the assembly can be made flexible. The suppressed constraint gets included in the math for the rebuild, causes the error, but then is ignored and everything works like it should except the parts still show with the failed or conflicting constraint color. A constraint that is NOT suppress shows as having failed or is conflicting even though it isn't. Suppress ANY constraint and unsuppress and the rebuild is done right this time. Everything is fine until you put a new part in. They had to fix the problem with a service pack back in 2015. However, if I'm the only user seeing this I know I can't expect to see a service pack coming anytime soon. If anyone else if having this same issue, please report it to your VAR. If enough of us are having the same problem we can force Solidworks to fix it in a service pack.... or at least on the next release.


Thank you everyone for letting me vent a little here.