I've read a lot of posts that describe the Sherline CNC drivers/stepper as. Usually the coupler will slip before any real damage or the stepper will just stall. ATTENTION: This new high-torque stepper motor requires a special CNC coupling (P/N 671052, sold separately). Please see link below for details.
The Sherline CNC Rotary Table ControllerInstalling on other rotary tablesWe have created a modified version of the Sherline CNC Rotary Table Controller to allow it to drive other rotary tables with gear ratios of 40:1 or 90:1. Other ratios may be available on request. If you already have a rotary table and wish to utilize our controller, send us an email. You will need to use the Sherline 23 frame stepper motor with 1/4' shaft and 120 oz/in of torque. We also need to know the worm gear ratio of your table.The following photographs show the installation of our controller on an import six inch rotary table as performed by Larry Thompson in Glen Ellyn, Illinois.Shown at right is the six inch rotary table mounted at right angles to the top of Larry's milling table. The Sherline stepper motor is attached with a simple homemade mount made from a length of tubing and two aluminum end plates.
One plate bolts to existing holes in the rotary table housing, the other plate holds the 23 frame stepper motor. Larry fabricated his own shaft coupler to join the 1/4' motor shaft to the 8mm shaft on the table.Shown below is a closeup of the motor mount.