Learn how to use the IK function to rig a series of scissor arms inside a machine.

Summary:

• Create pairs of joints using the Point Snap option to ensure that the joints are centered at the axes of the levers.
• Create controllers (Locators) at the center hinge of all the scissor levers. Use Point Snap to center.
• Group the controllers (⌘+G) and use center the pivot point (Modify>Center Pivot)
• Rename all joint chains as desired (xLeverJoint#_#)
• Create the IK Handles for each joint chain (Skeleton>Create IK Handle)
• Parent the root joints to their respective Locator controllers (Constrain>Parent)
• Parent the IK Handles to their respective Locator controllers (Constrain>Parent)
• Parent the scissor arm polygon objects to their respective joint using the Outliner (Middle-mouse click and drag)
• Use the ScaleX attribute of the controller group to control all the scissor arms.

Resources:

• FK and IK Explained – Which One to Use and When? by Miloš Černý
• Inverse Kinematics (IK) by Autodesk