Large Assembly losing constraints, temporarily.

[Ken226]

I've been having this issue alot lately with an assembly.

I click on a face or edge, and the assembly comes apart, leaving various parts and moving other parts.

The constraints in the design tree all show to be active and good, with no errors.

If I save the file, the close it and reopen, it opens with the parts all scattered at first, then after a couple seconds they all snap back together in their appropriate locations according to the constraints. After this, I'm good for awhile, but it always happens again.

Anyone else had this happen?

 

[HaroldL]

Haven't seen this kind of thing but reminds me of the Minimum Motion toggle. Do you have it activated or not? I always leave it selected on my system:

 

[Ken226]

Yes, it is activated.

Next time it happens, I'll try and get some screen captures and submit a ticket.

 

[Ken226]

Ok, here is a screenshot.

Some of the parts appear to have lost their constraints, even though all of the constraints appear fine in the design explorer. Particularly around the spindle and tapered roller races, as well as the chip pan having come detached from the bed and stand. You can't see them all in the design explorer, as this thing has lots of parts. But every single constraint shows to be fine.




With the headstock casting hidden, you can see that in this case, the tapered roller bearings are no longer constrained, in addition to the stand casting and chip pan.



The gearbox, gears, linkages and the tailstock assembly seem entirely unaffected.

 

[Ken226]

So, now I hit the save buttton so i don't lose all of the edit work I just finished on the stand casting, then reopen the assembly file, and:

It opens, still in disarray for a few seonds while its processing.



It spends about 30 seconds processing, then when the status bar hits 100%, everything pops back together perfectly constrained.





BTW:

@bolsover , Your involute gear add-on rocks! As you can see, I gave it a good test run.

 

[HaroldL]

It spends about 30 seconds processing, then when the status bar hits 100%, everything pops back together perfectly constrained.

I've noticed that when I open assemblies that it takes a few seconds for Alibre to evaluate/update all the constraints. IF the constraint folder is expanded I can see all the constraints grayed out until it is done updating then they all become black/active. I haven't seen the model all exploded like your screen shots though.

 

[Ken226]

It never seems to happen on smaller assemblies. I've only noticed it when I get up to well over a hundred parts. It's easy to fix, only requiring close/reopen the assembly file, so not really a big deal. A minor annoyance at worst.

I submitted a ticket on it nonetheless.

 

[Ken226]

Just following up.

Alibre support was able to narrow this issue down to the bearing assembly files I downloaded from SKF bearings.

I originally imported the bearing .stp files, and at some point they got saved as Alibre assembly files in the same folder and with the same name as the original .stp files as well as with some empty files.

Multiple files with the same names, and the empty files were giving Alibre fits. It seems to be working well now after cleaning up the folder containing all of the bearing race, cage and rolling element files.

 

[Ken226]

This issue has been popping up again. Apparently, there are things other than multiple files types of the same name that can cause this. I just havn't figured out what they are yet

I've resorted to deleting the offending parts from the assembly, then reinserting and constraining them. It's a minor PITA on the occasion that it occurs, but it's pretty infrequent.