Chinese Ballscrew nut play

[Fancy]

I bought some balls and for more than 4 hours i was unpacking and repacking the ball nut but non gave me smooth motion & a tight fit so at the end i gave up and put the original balls back and will install the ball screw as it is since most play is in the 400mm Ball screw intended for Z axis & gonna change it at a later time for another one. I guess that's what you get buying cheap Chinese screws :(

[magicniner]

I bought some balls

If you don't tell us what you bought and exactly what you did it's pointless mentioning it at all!
Did you alternate new size with Under-Size when re packing?

[Fancy]

The sizes i found were 3.12, 3.14mm and 3.16mm and the ones that were packed in the screw were 3.10mm. i tried each by them selves @ 3.12mm there was wiggling so i increased the ball size the wiggle decreased but the at some points along the screw it got harder to turn then i tried alternating with 3.10 but no luck 3.12 & 3.10 wiggles & 3.14,3.16 with 3.10 wiggles and get harder to rotate at some points along the screw.

[m_c]

It sounds like you've got cheap rolled ballscrews, which as you've discovered, are not great for accuracy.

The only thing you could do (other than buy a new screw), is put the bigger balls in, and hope they wear/burnish in the tight spots on the screw, but you do risk damaging things if thing are too tight. If you do try this approach, I'd make sure things are kept very lubricated to help flush any debris out, until you are happy things have bedded in nicely.