I've seen 2 types posted on this forum. One was like what you described. A block mounted on the tool posts with a drill chuck, bearings, & a shaft so you could attach a cordless drill to power it. The other one was using a chuck & motor salavaged from a cordless drill mounted in a housing to the tool post wired up to a power source. I have no idea where those posts are though, it was a while back when I saw them.