Thanks Zoners for all the help.
I have purchased a bunch of items from E-bay just for the sake of checking out linear stuff.I need it in my hands to better understand it.
Question#1 just got ballscrew 20mm dia.5mmlead 220 long , it turns silky smooth.I thought from what I read on the zone it would be stiffer.Also the smaller bearing end has play. Is this normal?
Question #2 Have 2 rails&4 blocks THK HRW21.From the thk site[ All moment loads handled by single rail]. What does this mean?Are these rails a good choice for a heavy duty Z axis?
Question#3 After looking at belt drive in detail , R&P looks like a better choice.Is it less costly and simpler to implement?The belt drive seems to require huge gear reductions.
Answers Yes I have the CNC bug with side effects of E-Bayitus.Does anybody know the cure?Got to go check E-bay, bye Larry