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I have a simple bone system:

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I only need to lock the rotation of the "shoulder" bone along the Z axis (Y in bone local space), I lock the rotation in the "inverse kinematics" menu and everything works fine.

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Until I add the "Elbow.control" bone as a pole target. Then the lock stops working.

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How to block the rotation of the bone along the z (y) axis?

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2 Answers 2

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Duplicate Shoulder bone and add Stretch to or Track to constraint with target to Forearm. This type of twist is widely used in rigs.

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You might wonder why you would use Stretch to? But it is actually used in Rigify rig and allows stretching arms and legs if it necessary:

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  • $\begingroup$ So simple. Thank you. $\endgroup$
    – arachnoden
    Commented Jul 28, 2022 at 1:08
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In this case, the bone rotation lock is overridden by the rotation of the pole target. This is a well-known problem, it can't be solved because of the logical conflict of the task.
Specifically in this case, we tell blender not to rotate the bone on the the Z axis (Y in bone local space), and the pole target has full control over every bone rotation of the entire IK constraint chain, so it will override the IK locks.

Visit links with similar questions:
Inverse Kinematics locks ignored
Adding a pole target causes bones to ignore their IK constraints

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