If you just rotate in one direction you do not need to worry about backlash in the A-axis.
I have built a number of Barrel CAMS -over a hundred using a simple A=axis stepper system attached to a cheap INDIAN Manufactured Rotary table. The repeatability of was very acceptable. I checked them all for a customer and the resulting Cpk was 1.87. My solution was to use the inexpensive rotary table, even though the backlash was horrible. Remember that backlash is only a problem if you are changing the A axis rotation. In my case I use an optical switch which has an accuracy of 0.01 degrees. |