Sliding Joint, Why is everything moving? Screencast Inside

[Anonymous]

Here is my screencast: http://autode.sk/1UeWEEo

Thanks in advance!

[Anonymous · Accepted solution]

Hi there, it looks like the probable culprit is that you need to also ground the subcomponent(s) in your parent component, I think one of the subcomponents was the rail.  If you still have trouble with it you can also export the file as a .f3d and upload it to this thread or google drive if too large.

Good luck!

Jesse

[innovatenate]

You've grounded the component group (Gantry Rail Top). This means the origins for the Grantry Rail Top will stay put with relation to the top-level's orgin. However, the components and sub-component groups located within Grantry Rail Top are free to move with relation to the origins of the Gantry Rail component group. To remedy the situation, try using the Rigid Group command to "weld" all of the components together, or ground the individual components.

I hope that helps. Let me know if you have any questions.

Thanks,

[Anonymous]

Grounding the individual components did the trick, I thought grounding the group imposed grounding on the other components as well.

Thanks for your help!

[Anonymous]

Something that I noticed after grounding the components, I saw that the aluminum bar underneath the rails was still a body. I converted them into components and this broke the slide joint (the assembly wouldn't sit still, like before). Is this a glitch or bug?

[Anonymous]

Great to hear!  It's interesting, grounding a component essentially grounds its coordinate system.  For clarity you can turn on the visibility of the component coordinate system (referred to as the Origin).  So if you try to perform a Component Move operation on a grounded component, it will not work.  Yet objects that use that coordinate system (being "in" the component) can still move within the system, such as bodies (like with Body Move operation) and subcomponents (such movement is necessary for subcomponents to have a movable joint with the parent component, and you can turn on Origin visibility of subcomponents and watch their Origin move with joint movement...it's a little confusing, but grounding the parent component tells bodies in the parent they cannot move for a joint, it must be a body in another coordinate system, such as a subcomponent, that moves for a joint).

Eh, I'm not sure why I looked into this so much just now, it's really not necessary to know all these little details 😉

Jesse

[Anonymous]

Hmm, regarding your latest question, not exactly sure, and I haven't worked with large assemblies much myself yet, but for one thing it's not necessary to always make everything a separate component or subcomponent, just being a body somewhere can be fine I think.  Of course to make a joint, it must be between a component and another component or subcomponent.  And organizing things into relevant components and subcomponents obviously helps tidy things up.  I suppose it may make sense since that rail and bottom aluminum piece is one unit, to have those bodies all be in the same component or subcomponent.  But I think as you found, moving a body into a different component, will likely cause an existing joint to loose references, so they will need to be edited or redone possibly with a renovation like that. 

Hope that helps a little 😉

Jesse