A Pin constraint links two rigid bodies at a specified position. It works as if the two objects are connected by a metal pin with a ball joint between its ends. You can use a Pin constraint to create effects such as a link in a chain or a robotic arm. You can pin together two active rigid bodies or an active and a passive rigid body

To create a Pin constraint

1. Select the two rigid bodies you want to constrain.
2. Select Soft/Rigid Bodies > Create Pin Constraint > to display the options window.
3. For the Constraint Type, select Pin.
4. If you want the rigid bodies to penetrate each other rather than collide upon contact, turn on Interpenetrate.

   If you turn on Interpenetrate, animation playback is faster.

5. If you want to specify the constraint’s initial position, turn on Set Initial Position and enter X, Y, and Z values for the position.

   If you don’t turn on Set Initial Position, a Pin constraint is created at the midpoint between the two rigid bodies. It extends from one rigid body’s center of mass to the other’s center of mass.

6. Click Create in the Constraint Options window.

   To alter the constraint after creation, see Edit constraints.