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I was thinking it would be cool to have a single bone control both the arm's direction and the rotation of the wrist like so:

demonstrating control bone that controls position and rotation.

The issue is that the control bone cannot follow the direction of the arm so the rotation of the wrist is influenced by the local rotation of control bone (which remains static). so a twisting motion of the control bone must be made in local space even when it is not aligned with the wrist which makes this confusing to work with:

demonstrating local rotation of control bone not following forearm direction

Parenting the free floating control bone to the forearm bone isn't an option: seizure arm

The only way to do this, that I can think of, is to unparent the entire hand so that only the control bone can rotate it. The issue with that is that I'd need to adjust the rotation of the hand every single time I move the arm rather than the hand staying in a neutral position.

I tried messing with the copy rotation constraint on the control bone to copy the rotation of the forearm, but I can't get it to work right. Anyone know if this is possible or am I forced to use another bone specifically for rotating the wrist.

ty.

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In my example, there are three bones in the same location and with the same orientation: A Blue "IK Controller", a tiny Green "ChildOfForearm" and a big red "Hand".

Hand is child of IK Controller, ChildOfForearm is child of forearm, IK controller is child of Root (or Hips, or Shoulder, as you prefer).

The IK Chain is targeted to the IK Controller bone.

IK Controller has a copy rot bone constraint with theese settings:

enter image description here

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  • $\begingroup$ So there's one small issue with this after trying it out: since the hand is parented to the IK bone I'll need to take care to not stretch the hand away from the arm whenever I move the hand, this is fiddly. Maybe there's a way to keep the hand parented to the forearm? Another quirk is that clearing the position of the IK bone does not reset the position of the arm (but clearing the rotation afterward fixes this so it's not that big of an issue). $\endgroup$
    – DED
    Commented Sep 11 at 8:40
  • $\begingroup$ Parenting the hand to the forearm and having the hand copy the rotation of the IK control with default settings seems to work well enough to resolve this issue. $\endgroup$
    – DED
    Commented Sep 11 at 8:50

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