I have a 6" Parker rotary table I would like to use for light milling and indexing work with a NEMA 23 on my mill.

Unfortunately, it didn't come with the home switch option and I'm not real inclined to drop $500+ to Parker for the add-on.

So, I would like to fab up one.

The only info I could find about the stock Parker switch was that it was "magnetic". I'm really unclear as to how a magnetic field type switch would provide repeatability commensurate with the accuracy of the device (it's supposed to be repeatable to 12 arc-seconds!), but apparently that's what they use.

After thinking on it a bit, I'm leaning towards a photointeruptor type optical switch where a beam must be broken to trigger the switch. I'm starting to think the key to repeatability with rotary type motion is that when homing, the switch must always be approached from the same direction (i.e. CW vs CCW).

What do commercial units use?
Am I better off with a different type of setup?

Any info would be appreciated!