Universal Robots UR5 Service Manual page 46

Base zero position is aligned so that the
output flange is offset 180 degrees from the
cable at the back of the robot base.
Wrist 2:
Wrist 2 zero position is aligned similar to
Base joint, with tool flange parallel with wrist
1 output flange.
10. Select Calibration tab and press Zero current joint position to calibrate the joint.
UR5
5. Service and Replacement of parts
Shoulder, Elbow and Wrist 1 zero output flange
vertically aligned (assuming Base is
horizontal). Make sure that base of robot is
horizontal, use spirit level to align joints.
Wrist 3:
Wrist 3 zero position is aligned so tool
connector is pointing upward. Mount two bolts
in tool holes and use spirit level to align joint.
40 Service Manual