Hey Bob, hey Jim @Webb , hey all,
I already mentioned the link to the Mafell FM above with the hint that’s not a spindle but a milling motor, i.e. not an 3-phase Asynchronous (brushless) Motor but a Universal motor with carbon-brush commutators. As @ben pointed out here, it is available only for a 43 mm Euro mount which the Onefinity does not offer, or with this tool changing mechanism that would require a custom Milling Motor Mount either.
Yes I know this Marius’ video, this is very cool, he builds it out of plywood, you got to see it:
Engineering an Automatic CNC Dust-Shoe