4 inch rotary table 4th axis
I added a 4th axis to my G0704 using the same 570 in/oz stepper that is on the rest of the machine. The 4″ horizontal/vertical rotary table came from an ebay vendor but is very similar to the Little Machine Shop 1927 and Phase II 221-304. The worm is eccentrically adjustable and I have it drawn up tight to the worm wheel for effectively no backlash. The stepper is mounted with an Oldham style coupling and has plenty of power to rotate the table. Mach3 is configured in degrees for this axis. With the Mach3 kernel speed at 25 mhz, the table is limited to 720 degrees/minute.
The 4″ chuck off the Jet 9×20 lathe mounted to a Little Machine Shop 4″ rotary table adapter plate. The slots didn’t work with the table I bought so I pressed and then welded a nut into the center and turned the head down on a shoulder bolt to make a drawbar configuration. The center locating shoulder is a little undersized and a mallet can adjust the chuck to less than .002 runout.
The MT2 taper in the center of the table holds an ER-32 collet chuck during a multi-sided milling operation (despite the fact that I did not seat the 1/2″ collet correctly). The threaded end of the collet chuck is used in drawbar fashion as well.