We want the elbow to maintain its volume, and the inside crease should maintain its position half-way in-between the two arms joints. ![[ModelJointsBoundBent.png]] The Y rotation (RY) of the driver joint is connected to a multiply/divide node, set to Divide, where the Input2Y is -2, so that the rotation is cut in half. The raw value is piped to the inside deformation joint RY, and the elbow joint RY is connected through a Negate node, which flips the sign. ![[NodeEditro_Multiply.png]] The elbow deformations joint (Joint9 and joint11) have their SX (scale X) driven by the RY (rotation Y) of the elbow joint. You can use Set Drive Key to set this up, then edit the tangents of the animation curves to change the performance. Here is the Maya file for demonstration ( change the extension to **.ma** to open in Maya ) [[MetaArmBones]]