This  machine mounted microscope is good for doing  small radius.  Easy to mount 

The Combination of the Digital read out for accurate positioning, combined with being able to see what your are doing is a game changer.

Easy set up. 

A substantial  improvement over the traditional radius attachment. The  CM O3P is a honed fit spindle with Bushplate and thrust bearing pivot cap it is not an air spindle. On a DRO Base the X&Y axis dovetail ways on the machine base are lapped, improving table movements .