1Frame Assembly
2Underside Assembly
3Z Axis Assembly
4Build Plate Assembly
5Heat Bed Assembly
6Install & Level X Axis
7Extruder Assembly
8Mount X Drive Assembly
9X Axis Wiring
10PSU Wiring
11MKS-Gen Board/Test Printer
12Complete Control Box
Install & Level X Axis
 Printed Parts Display 

120x20x300mm Extrusion
2Fixed Mini Wheel Packs
1Adjustable Mini Wheel Pack
2M5 x 10mm Screws
4M5 Slide Nuts
2M5 Nuts

6-1 Prep X Carriage
Press M5 metal nuts into the recesses in the center of X Carriage.

6-2 Assemble X Carriage
The top two wheels use M5x30mm screws and standard 5mmID spacers. The bottom wheel uses an M5x30mm screw and an eccentric spacer. Rotate the eccentric so that it's hole will be farthest away from the center of the carriage. Press fit the eccentric's lip into the X Carriage with the screw and lock nut.

6-3 Position X Carriage On X Rail
Slide the X Carriage onto the 300mm X Rail. Be careful to not gouge the wheels while pushing past the end of the rail. Do not adjust wheel tension yet. Slip four slide nuts into the slot opposite the X Carriage.

6-4 Mount X Carriage
Mount the 300mm X Rail to the two glide bodies using M5x10mm screws. Position the X rail equally left to right and tighten the mount screws just snuggly.

6-5 Mount X Leveling Jig
Using the two slide nuts in the X rail and two M5x10mm screws, mount the silver leveling jig to the X rail. Be sure the lip on the front side of the jig is up flush with the bottom of the rail.

6-6 Level X Axis
Slightly loosen the two screws on the glide bodies holding the X rail so the rail is free to align with the body as adjustment is made. Move the bed so the center is under the jig. Place a piece of printer paper on the bed. Lower the X axis until one side touches the paper. Adjust height so that side of the paper slides under the jig with a slight drag.

Go to the other side's Z screw pulley and loosen the pulley's set screws. Holding the opposite Z screw's acorn nut with fingers to keep it from turning, use fingers to rotate this Z screw until the paper has the same drag when moved. You may then need to slightly adjust both screws to get uniform drag on the paper under the jig. Once that is achieved, check that the two lock nuts on the Z screw with the loose pulley is down against the upper bearing and the pulley is tight up against the bottom bearing - then tighten the pulley's set screws.

Spend time getting this leveling correct, this is the only time you will ever need to level the printer. Raise the X axis and remove the leveling jig. The X axis is now permanently square with the Y axis and level with the bed.