Arm IK rotation woes.

http://www.glennmelenhorst.com/misc/blender/armtest.blend
Here is a test build of a character I’m working on. I need help with the IK on the arms which wigs out when I try to click on the ROT button to constrin the hand’s rotation to the target object…

Any help appreciated.

Glenn
www.glennmelenhorst.com

Instead of using the Rot option in the IK solver, put a Copy Rotation constraint on the hand bone (Bone.002.Bk_R.003 … maybe you could change your bone names to something easier to remember ? ;)) if you want to have the hand rotate with the target empty . With your current setup with the empty as the target using the Rot option with the IK will not give you good results .

Using the Rot option is usually not good in general with arm/leg (folding) rigs . It is better with spines and snake like rigs sometimes though .

You might also consider changing your IK targets to bones instead of empties too … Because right now if you hit Alt-G and clear the location the empty will snap to the 0,0,0 Global center . You could change that by parenting the empties to other empties and moving them into position, but why bother when an armature bones’ default cleared location is the same as the Rest/Edit pose ? Also with a bone you can rotate them in Edit Mode to align with the constrained bone (bones have a single fixed orientation), so if you had a bone as the target in your set up and it was aligned to the IK constrained bone it wouldn’t flip like it is now … when you turn on the Rot option in the IK it makes the whole chain try to track the rotation of the empty with unpredictable results …

What a concise, considered response. Thank you very much for your time VP, I really appreciate it.

Glenn