From the rotary table Operating Instructions: "The center sleeve has been ground to a Morse Taper (#2). Centers with a Morse Taper shank can be mounted to the rotary table for precision centering and measuring operations." How to secure the "centers" is left to the user. As seen in these photos this is not straight forward without mounting the rotary table above the mill table, on say 1-2-3 blocks. This does not seem ideal.

Bolt that will not workBolt that will not work - view 2 

Note that the flange head bolt, or a bolt with a washer, would keep the rotary table from siting flat on the mill table.

A normal hex head bolt fits to closely to be tightened. The cap head on a 3/8" -16 bolt can be flush and tightened with an Allen wrench. but needs an adapter to tighten agents. The cap head bolt I found at the hardware store is chromed.

Bolt that will not work, close up Different bolt that will not work Cap bolt will do the job 

All this to hold a collet snug, to hold a pin, to center parts/jigs on the table.

Collet that the blot holds tight Diagram of need coller

In the drawing of the adapter, the pocket on the left is a recess for the bolt cap head. The smaller recess on the right is to clear the end of the collet.

The brass adapter works at planned. There are a couple of "as built" dimensions, but it works. Maybe someday I will make a cleaner one.

Close-up collet holder Close up of reason for collet