Small version of Robothut's Rocking body drone

thingiverse

Note: User Jcarr101 notified me that three STL files were scaled incorrectly. The updated files, leg_pivot_X2 , crank_X2 , and main_back_pin, were uploaded on September 12, 2019. I apologize for any inconvenience this may have caused. This project is a smaller version of Robothuts Rocking Body Walking Robot Drone #5. It's driven by an N20 gear motor and powered by two CR2032 cells wired in series. The toy measures approximately 75 MM tall x 90 MM wide or 3 inches x 3.5 inches x 1.75 inches. I designed this robot from scratch using Fusion 360, incorporating a built-in battery box for the coin cells. You can view a YouTube video of the robot in action at https://youtu.be/hNSt9VCsHqQ. To build this robot, you'll need the following parts: * M2 x 8 self-tapping screws - six pieces for mounting leg-pins to cranks and front plate * M3 x 8 self-tapping screws - two pieces for motor clamp * M3 washers - six pieces * 22 gauge solid hook-up wire for battery contacts * Small flexible stranded wire Additionally, you'll need the following metal rods: * 3.125 MM x 42 MM brass rod * 3.125 MM x 14.5 MM brass rod You can use either a tea light or dual CR2032 battery box as the switch. I used 1/8 inch or 3.125 MM brass rod for the shafts, but 3MM would also work. The switch I used came from a CR2032 battery box, but you can find a similar switch in a tea light. The switch sets in a pocket and is held in place by the front panel, which is screwed on with M2 x 8 screws. The back panel is glued to the main body, and you can use the back pin to help align it. The contacts for the coin cell holders are made from solid 22 gauge hook-up wire. I've included a jig for forming the shorter wires. The two short inner contacts are held in place by the motor clamp screws and washers. When building the gear train, make sure everything moves freely. This motor battery combination doesn't have a lot of power to overcome misalignment or tight spots. The 3MM washers on the main shaft act as spacers and bearings. The motor is held down by the clamp and can be adjusted up and down, which affects how freely the gears run. There's a 3 MM washer between the motor and its bevel gear, acting as kind of a bearing. The top gear/cam combo has a 3.125 X 14.5 MM brass shaft pressed into it. Make sure this isn't longer since you have to flex the frame to insert this part. I drill out the cranks with an 1/8 inch drill, making sure to drill the hole straight and at low RPM. I made them small in case someone wants to use 3MM shafting. With 3D printing, small accurate holes are always a problem. The legs are glued to the frame, and the top gear/cam is timed to the main shaft so that when a pin is all the way down, the body is pushed to the opposite side. This toy can be printed and built in a day. You just have to check that the parts move freely at each step of the build. Some soldering is required to hook the motor to the switch and batteries. A partial front plate is included so you can see the internals working. Good luck, Rick