Here shown a cnc retrofit of an old manual mill 1/3 of size than mine.
He used cheap rolled chinese c7 ballscrews 2505 for x/z and 1605 for y
reduction 1:2 with htd5m pulleys-belts 750w cheap chinese servos with 2500lines rotary encoders
(i have those in 1.8kw version) and 2 nitrogen gas springs as counterweight for knee.
Very nice retrofit with cheap ballscrews-servos

https://youtube.com/watch?v=DxrFXhX9NjM