Sherline's CNC driver box comes equipped with an A-axis output cable ready to drive a 4th rotary axis. The 8730 rotary table is all you need to turn your Sherline CNC mill into a 4-axis machine. Just plug the "A" cable from the external 8760 driver box or the built-in driver box in your Sherline computer into the matching plug on the stepper motor. The EMC software is already set up to handle G-code for the A-axis, and numbers entered after the letter "A" in your code are interpreted in degrees.
The same end result can be obtained by ordering a 3700-CNC rotary table and a 67127 stepper motor and attaching the motor, but this single part number does the same thing, making it easier to order and saving you the trouble of installing the motor on the rotary table.