Arm Rig, Need help with b-bone segments

Hello, I am nearly finished with my first character rig but the arm gets a nasty twist in it when the upper arm bone is rotated on its y axis.


I know I can use bone segments to remedy this but I only want them to smooth out the y rotation, not x and z. I looked at this tutorial but it has nothing on the actual setup of the bone segments.
http://wiki.blender.org/index.php/Doc:2.4/Tutorials/Animation/Armatures/BSoD/Arm_Rigs
Any help?

If you locking the IK bones, you may still get a problem with B-Bone segments.
In the Deform panel, try settings the the Ease Out to 0.


Im not sure if that will solve youre deformation problem, but it should make B-Bones lock correctly.

Thanks, that worked. However, how did you get the bone farma and farmb to both follow ik while allowing farmb to rotate on it’s own y axis to provide the twist in the arm? On my mesh when I added farma and extended the IK chain length to it, it rotates on the y axis while farmb doesn’t.

Ive attach the arm rig. Its a test rig.

From that example I added b-bone segments to farmb.

I didnt use the pole target, because with a pole target, IK locking doesnt work on the last bone in the chain, farma.

Instead after you position the IK bone, you can rotate farmb in the 3d view, or try using different bone constraints.

Attachments

Arm_multi_bone.blend (465 KB)

Ok, thanks for the example. I got it working.