This 3D Printed Walking Robot is just the thing to keep watch over your desktop. I tried to keep it as simple as possible with a minimum of parts. If you have any questions on the build, just ask.
What you'll need:
1 Tamiya 3-Speed Crank Axle Gearbox Pololu Robotics and Electronics. You also may be able to find these in toy stores and hobby shops.
1 Rocker Switch: 3-Pin, SPDT Pololu Robotics and Electronics.
1 2-AA Battery Holder Pololu Robotics and Electronics.
2 4-40 X 1/2 inch screws
2 4-40 Nylon locking nuts
4 #4 flat washers
A hobby shop might be the best place to find the smaller size screws and nuts although they could be more expensive.
2 10-24 x 1 inch machine screws Home Depot
2 10-24 hex nuts Home Depot
2 10-24 locking nuts Home Depot
4 #10 flat washers Home Depot
If your area has a better resource for hardware, go for it. Sometimes the large home stores charge ridiculous prices for small quantities. I list Home Depot because I know they usually stock these.
Double sided tape , Super Glue, hot glue gun or whatever to attach the battery holder to the platform.
3D Printed Parts:
This file contains all the printed parts you'll need. It consists of the platform and both legs. As laid out it will fit on a 120 mm x 140 mm printer bed. I printed in ABS using a .35 mm nozzle and a layer height of .2540. My infill is set to .4. The switch mount has a pretty healthy bridge, so I printed using supports.
The thin feet are fragile due to their orientation. They hold up fine for walking but try not to stress them too much.
For more info on 3D Printing, visit my site at www.teachme3dprinting.com
Step 1: Cut the axle to length
Find the long hex shaft in the hardware bag. You'll want to cut this shaft at 2 and 1/16 inches. I used a Dremel with an abrasive cut off wheel. A hack saw would work also. USE EYE PROTECTION ! File off any sharp edges or burrs.
Step 2: Assemble the gearbox
Assemble the gearbox with the LOW SPEED option. The video shows the assembly. When finished make sure both shafts are centered in the gearbox.and be sure you can access the setscrew through the gearbox window.
Step 3: Attach the gearbox
Using the supplied machine screws and nuts, attach the gearbox to the underside of the printed body. The screw heads fit in the recesses of the top side.
Step 4: Leg assembly
We want to use the hole closest to the collar of the crank arm. Although it's not necessary to cut down the arm, it does make for a cleaner installation. You want the screw head on the same side as the collar. Place a washer on either side of the leg and fasten with the locking nut. Tighten enough so the crank arm rotates smoothly without being too loose. You'll need a wrench or pliers for this.
Step 5: Leg Supports and Battery
Place the 10-24 screws and nuts as shown on the body. You want the nuts tight (don't crush the plastic).
Install the battery holder with the double sided tape.
Step 6: Wiring
Feed the red wire from the battery holder through the square hole. Leave about an inch and cut off the rest. Save this small piece. Strip off about 1/4 inch of the insulation from the battery wire and solder to the terminal opposite of the '0' on the front of the switch.
Strip 1/4 inch from the small piece you just cut and solder to the center switch terminal.
USE A LOW WATTAGE SOLDERING IRON. THESE SWITCHES CAN'T TAKE TOO MUCH HEAT. WORK QUICKLY.
Feed the wires back through and press the switch into place. Solder the wires to the motor terminals. The red wire goes on the bottom terminal as in the photo.
Step 7: Attaching the Legs
Insure the 10-24 nut is tight on the screw. Put a #10 flat washer on one of the screws.Next place the leg slot over the screw. Make sure the crank collar fits over the axle at the same time. Place another washer over the screw and finish with a locking nut. To make things easier, run a screw through the locking nut a few times to loosen it up a bit before you install it. This way as you tighten the nut, you won't loosen the screw. Make sure the leg can still move freely without binding. This screw is only meant as a guide.
The crank arms must be in opposite directions, one leg crank facing forward and the other facing back. Tighten the set screw on the flat of the axle.
When you're satisfied everything lines up properly, tighten up the axle setscrew.
Step 8: Finished
Congrats! You're done. Install 2 AA batteries in the holder and go for a test ride.