How to get elbow IK constraints to work properly? So far I have 4 IKs on my rig: 2 arm and 2 elbow. The arm IKs work fine but the eblow IKs are wonky. When translated, the elbow IK is hinged by the arm IK. If I set the elbow IK to chain length > 0, they simply stop working entirely. Any idea what I am doing wrong?

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If you set the bicept Ik chain to one, it works pretty well, but generally this kind of rig is constructed with only one IK: the forearm pointing to the arm IK, then you can use the elbow IK bone as the pole target of the single IK constraint.
Don't forget to set the right pole angle (in my example 180 degrees).