I 'm watching this with interest please keep those pictures coming.
These links may be of interest,showing the implementation of similar spindle idea and interesting atc.
CONVERSION: X3 mill with rails, ATC, new motor
Build Log: Servo Drive and VFD with vector control
I have considered this idea myself and seen it used but not at the power level you are thinking.I note he rewinds the motor
probably to allow higher input voltage for greater efficency,as the app doesnt limit you to batteries.This would reduce current draw to.
Possible issues include the lack of high speed cooling air,motor not designed for continuous operation,noise,torque ripple
at low speeds,controllers not designed for this app,a bit of maths for 3 server power supplys : 3 x 82 x 12 = 3kw or the maximum motor power.
Also start up is a problem.The cold motor winding are probably at 1/10th of there working resisistance. So massive
inrush current x10 normal at least.Not sure how these problems are overcome,soft starting maybe.
How much power do you need for what you want to machine? Maybe thats the what you need to know first(from an
online calculator) then work back to motor and ps requirements.
For eg portal mills the bridge and legs are cast as one piece.Alignment is by 3 screws placed at the outer edges
of the legs(forming a triangle).As long as your centre of mass falls within the triangle you can adjust for alignment;
in both axis .Grout or epoxy contained by an o-ring secures the position.Alignment finishing before setting.
This method would seem to provide considerable leeway in parts precision,less being preferred of course.
I havent investigated it but loctite but may have a product for this app suitable for steel.Machined surfaces
are probably the ideal of course,but without machine tools its the method I would use.