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I am making a steam shovel model and trying to do a simple rig with no bones. I threw on a pivot constraint so that I could move the main arm and still have it rotate around an axis. It works great, but now when I try to move the whole machine (ie. turn it on the z-axis), it goes kind of crazy. Here are some pictures to show what I mean: 12

Note that I have "Always" selected for the "Pivot When:" option. I tried changing this to just the Y-axis to no avail, so that is not the answer. For those curious, here is the .blend file

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  • $\begingroup$ Is it possible that you are rotating in World space instead of Local space? Your blend file does not seem to be available any more. $\endgroup$
    – Dan
    Commented Oct 29, 2016 at 19:14

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It is a Loop Dependency. You can't make a children object parent father of is father. A constraint look like a parent in Blender, so you have to make some parents organization in your file.

Arm Rotation is Father of Shovel.
But, Arm Rotation is in the Pivot constraint of Shovel, so, it's child of Shovel.

This parenting are avoid, you have to use bones and armature to simplify.

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  • $\begingroup$ I'm sorry. Could you elaborate? I don't see where the loop exists. Both the object and the pivot point are children of the same object. $\endgroup$
    – jemtan990
    Commented Sep 15, 2014 at 17:54
  • $\begingroup$ Arm Rotation is Father of Shovel. But, Arm Rotation is in the Pivot costraint of Shovel, so, it's child of Shovel. This parenting are avoid, you have to use bones and armature to simplify. $\endgroup$
    – Alfonso Annarumma
    Commented Sep 15, 2014 at 18:17
  • $\begingroup$ I see what you mean, though I still don't completely understand why it was impossible. Either way, I started to make an armature, but the pivot constraint does not want to behave with bones. Is there another way I can achieve what I'm trying to do here? $\endgroup$
    – jemtan990
    Commented Sep 17, 2014 at 5:56
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I had this issue and corrected the parenting chain but the issue was still not fixed. So I just randomly just tried to correct the bone roll and it worked as I had hoped. Seems like there is an issue when the bone roll of the 'target pivot point bone' and the bone that has the pivot constraint have different rolls. I don't know the underlying concept but it worked so 🤷.

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