A great post from Suchan Raj Bajracharya (@tweetBoucha) with an overview of how he sets up a twist joint set up, typically used when rigging a forearm. Suchan Raj Bajracharya demonstrates two methods for keeping the set up away from using rotational constraints or connections. Check out the post Maya Twist Joint Setup Overview over at SRB’s Blog here. Also, be sure to check out Suchan’s Sinka Rig!
From Suchan Raj’s Post: “I have seen people and previously me myself using twist joint setup (usually while rigging forearm twist) using the good old rotational weighted constraints or direct rotational connection with offset values to give even twisting. It works great for straight aligned joint rotated or twisted in just single direction for example rotate X, but once you start rotating in all direction which we all tend to, some thing weird happens, something not so good that is known as flipping. This flipping behavior is the result of GIMBAL LOCK! Well then, that is a major issue.”