Ok, so I want to fit a 100mm 4-jaw (as used on minilathes, 20mm central bore) with mounting holes in the back, to a SOBA 4" rotary table with 3 x 120degree t-slots and an MT2 central taper.

One option would be a backplate screwed to a MT2 arbor. I suppose with the table horizontal this wouldnt need a retaining bolt on the rear of the table (otherwise that would prevent the table being bolted down to the milling table without some spacers in between), but might need one when the table was vertical?

I looked at the way RDGTools/Chronos do it but they fit a 80mm chuck to a 100mm plate and therefore there is room to have bolts round the outside, or they use a front-mounting chuck and I want to use what I already have..

Thoughts?