After having tested different solutions to remove the wobble from the Z axis of my "geetech prusia i3", without a total satisfaction, I designed this piece.
It allows complete decoupling of the "XY" movements of the Z-axis screw relative to the X-axis carriage.
An axial ball thrust bearing is used to support this carriage with minimum friction.
THE TOP DISK OF THIS BEARING IS MOUNTED WITH ITS FLAT FACE DOWN (IN CONTACT WITH THE BALLS SO AS TO HAVE NO FRICTION AND A DEGREE OF FREEDOM IN XY). THE CENTRAL HOLE IS ENLARGED TO 9MM SO AS TO NEVER RUB ON THE SCREW OF THE Z AXIS.
The result is that the X carriage is placed on two discs floating on balls. So a freedom in XY and no rubbings.
V2: addition of a piece to hold the top plate of the bearing in place relative to the carriage "X".
The bearing is of type F8-16M.
The picture of the pieces shows, the left the printing before modification, then some others modifications, and on the right the current result.
V2: one piece is needed at the top of the "Z" screw to have a two "fixing" points. For example, a simple PLA diameter reducer with some play.