I've been modeling some robotic systems with a number of parts, and assemblies. I'm using flexible assemblies to allow motion of subsystems. I am modeling a series of motions driven by motors whose motion functions are defined by segments. When playing back an animation everything seems fine.  When it recalculates things get whonky:it seems that the constraints get confused.  Or, If i try to just save the animation without recalculating, things show up fine, but when it saves the animation the parts start to dance around. I'm trying to render the files. So i've tried rendering as frames, but the later frames get all messed up as well. Everything was working fine until it seems I reached a limit of about 12 different segmented motions, from this point on it seems the complexity starts confusing things. i'm not switching over to trying to do the animation in Blender, but that's really a pain to use as well, partcularly for someone used to working with a feature heirarchy/history - also it's not really helpful since anytime i change my models i'll have to rexport and rebuild the animations all over again - not so helpful.

the behavior seems somewhat similar to this posting: https://forum.solidworks.com/message/266718#266718

any ideas?  I'm assuming it has something to do with the flexible assemblies. but rebuilding the system based on how to animate it does not make sense; i prefer my assemblies to be driven off of how they are to be assembled and operating.

thanks for any ideas.

(Win8, SW2013 SP3, running on an i7-4820K, 32gb ram, nvidia quadro k4000. I also tried on my laptop w530, win8.1, SW2013 SP0, i7-3840QM 24gb ram, quadro K1000M)