Cebulatron robot arm first axis - base joint

This actuator is first axis for 6-axis robot arm but it can be used as rotary table and in many other applications where you need a rotational move. To drive I used one Nema 23 stepper motor, but it is possible to use two Nema 23 and two Nema 17 or any combination depending on the needed torque. The gear ratio is 1:7 (motor gear has 15 teeth and big spur gear has 105 teeth). The hole in motor gear need to be drilled to press the gear on the motor shaft.

BOM:
12x M4x50 DIN 912 hexagon socket head cap screws
6x M4x45 DIN 912 hexagon socket head cap screws (it might be necessary to shorten them a bit)
2x M4x15 DIN 912 hexagon socket head cap screws for mounting motor (1x Nema23)
20x M4 nuts
2x 6012 Ball bearings
Nema 23 or Nema 17 stepper motor
4x M6 DIN 912 hexagon socket head cap screws for mounting full assembly to the ground
RAMPS 1.4 or another board to control the motor(s)