Make sure this section is clean of dust, it will be used as reference for the z_motor_mounts.

Slide the z_motor_mount from the top of the frame, slotting the t-nuts into the extrusion channels. Note the orientation, the hole for the Z smooth rods should be to the outside the frame

Tighten the M5x10 strongly.

Double check the orientation of your z_motor_mount or it will make the next steps impossible.