New Joint Overriding Existing Sub Assembly Component Joint

[jonathanBUCVS]

I am confused why some joints seem to pull other joints apart. If I have a fully constrained sub assembly (imported into another part as a component, and try to join one separate body to it, sometimes part of the subassembly will fly off instead of the unconstrained body joining the fixed assembly. What am I missing in my order of operations?

Some further details: 

I have an assembly with a few vises mounted to a fixture. I have constrained the jaws so the openings are adjustable with a joint, so I cannot set this as a rigid body. My intension is to "insert as component" this assembly into the design space, stack a bunch of parts on it, then do the CAM work. This vise assembly is for several parts, of several sizes, so when I import the vise assembly, I am breaking the link so I can adjust the jaws for each instance. 

[jhackney1972]

Please attach your model so the Forum users can help you out.  If you do not know how to attach your Fusion 360 model follow these easy steps. Open the model in Fusion 360, select the File menu, then Export and save as a F3D or F3Z file to your hard drive. Then use the Attachments section of a forum post to attach it.

[jeff_strater]

without the model, it is hard to tell.  However, a couple of possibilities:

1. The break link is causing some joints to be modified.  This would be a bug.  You say "I am breaking the link so I can adjust the jaws for each instance".  What adjustment are you making?  If you are changing the joint limits, then yes, you would need to break link to do that.  However, if you are just adjusting the position of components, say, for a slider joint that moves the vise jaws, then you do not need to break link to do that.  Each sub-assembly instance can have a different position from other instance.
2. Are you using Ground in your sub-assembly?  Ground does not come across when a sub-assembly is inserted.
3. If the joints are applied to the the sub-assembly, and not the part-level components, things can still be free to move

[jonathanBUCVS]

1. I am adjusting the opening of the vise, I have the drive link set to the vise opening value, so if it set it to 0 its all the way closed 6in gives me a 6in opening, etc. I did not realize I could drive the joint without breaking the link, thank you. (With the assembly linked, I did not have any issues with components moving)

2. I did not use ground in the sub assembly. I joined the vise assembly to the origin when I imported it. Other than known position, is there any difference between grounding a component and making a joint to the origin? 

3. A bit confused on this one. The joint that moved was between two components in the vise assembly. For simplicity, I have 3 components in the vise assembly, all 3 are separate components, none were created in the vise assembly: fixture plate, zero point base, vise. All of the joints for the vise jaws are in the vise. All of the joints between the three components are in the vise assembly (main part of the tree). The part which moved was the vise away from the zero point base. 

Ill add a 4th question here, to which I suspect the answer is no. Can I adjust the hierarchy of, or move the tree location of, the slider joints so they are not buried so far down in the tree? I tried redefining the joint when the full assembly was selected, not just the vise component, but it still put the joint in "main" joint folder. 

[jhackney1972]

You still did not attach your model.  The Forum users do not have a model to match yours and can not possibly duplicate it exactly, even if they want to.  You will get a quicker and more accurate answer if you attach your model.  The instructions on how to do it have been given.  Please attach your model.

[jeff_strater]

I'm not sure I can answer all your questions without more info, including the model, as @jhackney1972 mentioned, but I can try to comment on some of them.

1. I am adjusting the opening of the vise, I have the drive link set to the vise opening value, so if it set it to 0 its all the way closed 6in gives me a 6in opening, etc. I did not realize I could drive the joint without breaking the link, thank you. (With the assembly linked, I did not have any issues with components moving)

OK, that's good, I think.  If you can get away without breaking the link, that is preferable.

2. I did not use ground in the sub assembly. I joined the vise assembly to the origin when I imported it. Other than known position, is there any difference between grounding a component and making a joint to the origin? 

A Rigid joint to the origin is, in some ways, better than a ground, in that, it will act to keep the sub-assembly rigid when inserted into another design.  But, yes, it is functionally equivalent to ground in the design where it is applied.

3. A bit confused on this one. The joint that moved was between two components in the vise assembly. For simplicity, I have 3 components in the vise assembly, all 3 are separate components, none were created in the vise assembly: fixture plate, zero point base, vise. All of the joints for the vise jaws are in the vise. All of the joints between the three components are in the vise assembly (main part of the tree). The part which moved was the vise away from the zero point base. 

Yeah, that one is hard to explain without an example.  A short version is:  If you apply a Rigid joint to a sub-assembly by selecting the sub-assembly from the browser, that joint will not apply to the children of the sub-assembly, which are still free to move.  Let's ignore that, unless we find out it is the source of your problems.

Ill add a 4th question here, to which I suspect the answer is no. Can I adjust the hierarchy of, or move the tree location of, the slider joints so they are not buried so far down in the tree? I tried redefining the joint when the full assembly was selected, not just the vise component, but it still put the joint in "main" joint folder. 

Your suspicion is correct.  You cannot move a joint's ownership.