The video instructions are pretty bad, from an assembly perspective. Build the Z-axis plate complete first, including alloy spacers, Z-axis anti-backlash nut and screw and wheels all installed, but without the top and bottom plates or moving extrusion. When assembling the X-axis, START with the lower wheels - the ones with the eccentrics. Push the four screws through the plate and put the plate down on the bench, then it's just a matter of dropping the components in the right order onto the screws, unlike the ham-fisted, two-thumbed aberration that is the assembly video. Drop the eccentric or spacer, washer, wheel, washer, spacer, two washers, wheel and eccentric onto each respective screw, then put the front plate, complete with installed z-axis screw, wheels, etc. onto the screws and nip up with the nuts. Then you can stand the assembly on its side and tighten up to the stage at which you want to adjust the eccentrics. No faffing around balancing holding the plate, juggling the screws and trying to jam everything in between the plates like was shown in the video. Should be a piece of piss.
The next step is to mount the top plate and the stepper. Assemble the plate, screws, spacers, coupling and stepper in one go, then mount to the top of the extrusion and screw down tightly. Add the bearing and locking collar to the threaded rod and adjust the threaded rod until it engages correctly with the coupling. Fit the bearing to the base of the plate and snug the locking collar in place. Rotate the rod to ensure free movement and if you are happy, lock the grub screws for the flexible coupling and the locking collar down tight (I put a little dab of Loctite on them - you are never taking them apart unless you are replacing the stepper, anyway). Fit the lower collar, bearing and plate and lock in place. Check for free operation.
