Step One: Make magnetically coupled component for a gravity-driven device
First of all, put two motors in the chassis motor seats separately, fix them with 502 glue, and then solder the motor wires.
Squeeze glass adhesive on the printed BB-8 hubs to make the wheels and reshape the glass adhesive properly. Put the wheels at a ventilated place for one hour to dry the glass adhesive. Of course, if you don’t want to wait you can also use air blower to dry the glass adhesive for ten minutes.
Stick the main drive gears on the hubs, insert optical axis bonding to prevent shaft holes misalignment.
Inset the printed pinions on the two motor shaft separately and fix them with glue.
Insert the optical axis of 4mm diameter into the center of the chassis, and then insert runner, washer and a chock made of the sheath of a pen.
Install the motor cover and run the electrical conductor through the cover. Fix them with screws.
Install Nylon stud, battery and Romeo BLE mini controller accordingly. Fix the battery by applying small amount of hot glue at its bottom.
Install synchronous wheel bracket and fix it with 1x10 screws. Insert the synchronous axle with 3x30 screws and fix it with 502 glue. Use USB cable to connect Romeo BLE mini control board and computer, upload BB-8 control program code. 【The code was already put at the end of this article, you can download if you may like】
Connect and weld the wiring of the switch, microUSB and boost module according to the circuit diagram. Install all of them at battery level and fix them with hot glue. Connect the motor leads to MA1、MA2、MB1、MB2 ports on the Romeo BLE mini control board separately. The outlet terminals of the boost module connect to the positive and negative electrodes of the VIN terminal.
Use a neodymium magnet to attach the S-pole and N-pole magnets onto the magnetic receiver with hot glue, install them into the top bracket with 502 glue .