A rotary table is designed to be used in conjunction with vertical mills. When a rotary table is put on a vertical mill what you create is a machine that is theoretically capable of reproducing itself.
A standard milling machine set-up usually involves aligning the work with the table and then with the spindle. The table can be accurately moved with the hand wheels making this a simple operation for most. Aligning a part on a rotary table however can be difficult because the work has to be clamped into position. This is not always easy when you are working alone.
Most experts suggest that you start by doing the rotary table work first which can eliminate the need for precision aligning. Aligning the milling spindle with the rotary table can be done by indicating the hole in the center of the rotary table. You then need to spot drill the center on the work you wish to have line up with the rotary table. Finally put a pointer in the spindle that is accurate. After doing this set the work under the spindle and lower the head until it engages with the center mark at this point clamp the part down. And there you have it, locked and ready to work with.