I acquired the following parts for this mechanism:
• One 3.7vdc 100ma Lithium Battery (https://www.adafruit.com/product/1570).
• One JST PH 2-Pin Cable (https://www.adafruit.com/product/3814).
• One N20 6VDC 150RPM gear motor (on line).
• Three R19 O-Rings (23.5mm I.D., 3.5mm section, local hardware store).
You will also need a suitable battery charger.
I 3D printed the following parts in PLA at .15mm layer height with 20% infill and no supports:
• Two "Axle, Wheel, Front.stl".
• One "Axle, Wheel, Right Rear.stl".
• One "Axle, Wheel, Rotate.stl".
• One "Axle, Yoke.stl".
• One "Gear, Crown, Axle (1.5m12t).stl".
• One "Gear, Motor (2.2m10t).stl".
• Two "Wheel, Front.stl".
• One "Wheel, Left Rear.stl".
• One "Wheel, Right Rear.stl".
• One "Wheel, Rotate (1.5m12t).stl".
• One "Yoke.stl".
Prior to assembly, test fit and trim, file, drill, sand, etc. all parts as necessary for smooth movement of moving surfaces, and tight fit for non moving surfaces. Depending on you printer, your printer settings and the colors you chose, more or less trimming, filing and/or sanding may be required. Carefully file all edges that contacted the build plate to make absolutely certain that all build plate "ooze" is removed and that all edges are smooth. I used small jewelers files and plenty of patience to perform this step.
This mechanism also uses threaded assembly, so I used a tap and die set (6mm by 1) for thread cleaning.
To assemble the mechanism, I performed the following steps:
• Slipped an o-ring onto "Wheel, Left Rear.stl", "Wheel, Right Rear.stl" and "Wheel, Rotate (1.5m12t).stl".
• Positioned the rotate wheel assembly in "Chassis.stl" then secured in place with "Axle, Wheel, Rotate.stl" making sure it rotated freely.
• Soldered the JST connector to the motor such that with power applied, the motor rotates clockwise when viewed from the motor shaft end.
• Pressed the motor assembly into the motor housing in the chassis assembly such that the motor was flush with the motor housing left end.
• Pressed "Gear, Motor (2.2m10t).stl" onto the motor shaft.
• Positioned "Gear, Crown, Axle (1.5m12t).stl" in the base assembly then secured in place by press fitting "Wheel, Left Rear.stl" into the gear, then carefully aligned the motor gear with the wheel gear.
• Secured "Wheel, Right Rear.stl" onto the chassis assembly using "Axle, Wheel, Right Rear.stl".
• Secured one "Wheel, Front.stl" to "Yoke.stl" using one "Axle, Wheel, Front.stl", then repeated the process with the remaining front wheel and axle.
• Secured the yoke assembly to the front of the chassis assembly using "Axle, Yoke.stl".
• Secured the LiPo battery to the chassis using double sided tape.
To test the mechanism, I placed it on an 8 1/2" by 11" by 1/2" thick piece of MDF, connected the battery to the motor, and off it went!
And that's how I 3D printed and assembled "No Fall" Toy Mechanism.
I hope you enjoy it!