IK Arm Rigging with more than 3 bones I have an exported model from 3ds Max, it was rigged with CAT.
The main problem is that the CAT skeleton has lower arm roll bones that linked consistently (UpperArm -> LowerArm -> LowerArmRoll -> Hand).



So, i don't understand how to make IK rig properly, because that hierarchy obviously screws up IK solving.

Any thoughts? I'd appreciate any help.
So if you're trying to limit the rotation between the 2 lowerarm bones, what you're looking for is probably the IK Limits: In Pose mode, select the bone you want to constrain, go in the Properties panel &gt; Bone &gt; Inverse Kinematics (this menu appears as soon as the bone is influenced by an IK), then limit on the axis you want, in that case X and Z.
As you mentioned, in 2.8 you can simply click on the Lock IK option (top of the same menu).