the Z axis is based on a MGN12 linear rail and and SFU 1204. both of these parts are extremely stiff and the cheap version of the SFU1204 are note exactly straight. The movement of the SFU1204 with a fix mount to the rail will generate bendings and torsion of the frame and generate Z wobble lines on the prints.
The Z anti wobble coupler designed for the Alpha printer will try to allow a perfect movement without having any transfer of forces to the frame or the bed. The design is based on three parts lying on each other 6mm steel balls with magnets.
This system will allow movement in perpendicular movement allowing any misalignment between the SF1204 and the linear axis allowing a perfect linear movement.
Looking on the internet for possible improvement I discovered that someone had the same idea. MirageC developing the Hevort printer did pretty much the same design and the base printer design is almost identical. How to person can come to the same design ! The wobbler design of MirageC can be found here.
The Z axis design is almost completed and will be published soon !