Hi, I have been trying to decide which ball screws would be good for machine that is 1500 x 1500. I am finding for diameter I can get 16,20,25 mm in overall length of 1500mm. How big of a diameter is enough for that length? Is 16 ok or should I get 20? Also what pitch is good? I see I can get 5 or 10 mm. I read people using 5 then other people say 5 is too fine and the movement would be too slow.