"DoN. Nichols" wrote in message
...
On 2012-10-10, Paul C. Schiller wrote:

Hmm ... it might be a removable T-slotted plate with the chucks
bolted in place from the back.

Or -- it might be a flat backplate attached to two T-nuts (they
both seem to be centered over slots), and the chuck then bolted down
to
the plates using through screws accessible from the front, as is
common
for adjust-tru style chucks.

Enjoy,
DoN.

If you want to be clever and mysterious you could thread a
center-drilled plug with the spindle thread and drop it over a tee
slot bolt. It might shift under a heavy cut.