Hi!
So as my title suggests, my goal is to be able to move the whole arm while translating the wrist. Just like you can in IK, but where it still moves with spine, and I can still rotate the fore / upper arm. This was a function I could do with the 3ds CAT rig. I don’t need a full IK setup.
Hope this makes sense. 
Hello and welcome aboard!
What I think you are after can be done, it’s kind of hackish, but it works. Put an IK constraint on the FK hand bone. Don’t set a target for the constriant, but set the bone chain length to the number of bones to control.
Hand bone, lower arm bone, upper arm bone = chain length of 3.
There is an option somewhere, (don’t ask me where) for an ‘Auto IK’ while in pose mode.
Randy
You guys are absolute chads! Thank you so much!
I cannot believe how easy it was. XD
