Stages and rotary tables

1. Stages and rotary tables

2. Linear stages • Examine various types • Note key components • Measure pitch and yaw with PSM • How to avoid damage to stages • How to fix if damaged

3. Types of linear stages • Recirculating ball on ground rod • Dovetail slide • Ball in V groove or pair of cylinders • Sliding wedge • Scissor jack • Flexure

4. Types of nuts or actuators • Recirculating ball • Pre-loaded nuts and thrust bearings • Micrometer and spring • Fine pitched screw, brass nut and grease • Plain nut of plastic material • Servo or picometer

5. Tilt stages • Gimbel type pivots • Corner pivot • 2 or 3 degree of freedom • Goniometer stage – virtual pivot • Preload – spring or magnet

6. Rotary stages • Air bearing (or oil hydrostatic) • Rotary linear motor plus encoder disk • Ball or crossed roller • Solid mechanical and grease • Worm gear driven • Encoder is the worm drive

7. Avoid damaging stages • Shock like dropping, removing actuator • Screws that are too long when mounting • Jamming into stop at end of travel • Trying to move when stage is locked • Loads & moments that are too large • Contamination, rust & no lubrication • Leaving springs in stretched position

8. Fixing stages • Loosen gibs – screws along way • Retighten to get uniform feel over travel • Keep ways and screws clean • Lubricate ways and screws • Use spanner to rotate micrometers • Don’t loosen too much & loose balls

9. For the lab • Stages are labeled • Identify and note details of main components • Move stages and feel stiffness of adjuster • Note backlash or lost motion on each • Note how gibs are adjusted • Note center or rotation for tilt stages • Figure out scale reading on large rotary table • Note how hexipod works