[SteinHDan]

I tried to make the swing mechanism as simple as possible. It's currently made up of one worm gear motor (20rpm, 12v, 6mm axle), a steel rigid flange coupling (6mm axle, M3 holes). The motor and the coupling is the same type as used for the wheels, except that the RPM is 20 for this motor.

The motor drives a 40mm long 6mm diameter steel axle through a 6mm coupling. The axle has one flat side grinded 1mm down. A hole-type slip ring (7mm hole, 6 wires) is put on the axle and allows the unlimited turning of the excavator house on the undercarriage:






Drill a hole in the bottom center and expand it to 10mm. Use the flange coupling as a template to drill the small holes:




Remove plastic to make the floor inside flat:




Attach the flange coupling to the axle with the two set screws:




Insert the axle and coupling from the bottom:




Attach with four M3x8mm screws and locking nuts:








Add the slip ring. In the undercarriage I made Dupont connectors on both the motors (male) and the slip ring (female):






3D print a template to drill the holes in the house floor:








3D print a 6mm spacer to get the motor in position at the right height:




Fix in place with four M3x10mm bolts: