Have you ever wanted to have an RC tank? This one is almost fully 3D printed, so if you have access to a 3D printer, you can build it! It is very easy to construct and once it is running, it is awesome! Please vote in the 3D printing contest!
Step 1: The Parts
First, you'll need the parts. You will need:
94 tread segments: http://www.thingiverse.com/thing:1596549
4 drive sprockets: http://www.thingiverse.com/thing:1596550
4 sprockets: http://www.thingiverse.com/thing:1596108
2 brackets: http://www.thingiverse.com/thing:1596552
2 base pieces: http://www.thingiverse.com/thing:1596555 and http://www.thingiverse.com/thing:1596553
a plastic container
around 10 jumbo Popsicle sticks
4 motors (I used the ones from RC Thunder Tumblers)
A transmitter and receiver (2 channel): http://www.hobbyking.com/hobbyking/store/__8338__Hobby_King_2_4Ghz_4Ch_Tx_Rx_V2_Mode_2_.html
2 brushed motor ESCs: http://www.amazon.com/Hobbypower-Brushed-Motor-Speed-Controller/dp/B00DU49XL0?ie=UTF8&keywords=brushed%20esc&qid=1464570784&ref_=sr_1_11&sr=8-11
A lipo battery, 2-3S: http://www.hobbyking.com/hobbyking/store/__9272__Turnigy_1300mAh_3S_20C_Lipo_Pack.html
A few pushrods: http://www.hobbyking.com/hobbyking/store/%5F%5F65717%5F%5FMetal%5FPush%5FRods%5FM2%5F2xL300%5F10pcs%5Fset%5FUS%5FWarehouse%5F.html
Some music wire: http://www.amazon.com/Carbon-Smooth-Diameter-Precision-Tolerance/dp/B002M3JQGC?ie=UTF8&keywords=high%20carbon%20steel%20wire%20%232B%20.055&qid=1464615056&ref_=sr_1_2&sr=8-2
A couple small pieces of plastic
A couple small wooden blocks
You will also need:
A hot glue gun
2 pairs of pliers
A soldering iron
Some heat shrink
Connectors for your escs
Step 2: Assemble the Treads
Once you have printed the treads, make 2 sets of 47 by putting the ends together and locking them with a small section of music wire through all 4 holes. Then, bend each end of the wire to lock it in place. Do this for all 47 pieces, then connect the end of the tread by taking another piece of wire with 1 end slightly bent. Your treads are now assembled.
Step 3: Assemble the Brackets
First, you will need to pull out the sagging filament from the sprocket wells on the base pieces and the brackets and clip off the outer supports as shown, so that the hole in the middle has about half a centimeter of space around it. Then, fill the space with glue. You will also need to clip a slot on the upper wells for the motor shaft to go. Then, screw the wooden block to the bottom of the base piece with the given screw holes and glue sections of pushrods into the bottom holes of the bases. After that, Glue the drive sprockets to the motors and slide them into the top wheel wells, elevating them off the piece with Popsicle sticks. Then, screw them in place, making sure there is little friction between the drive sprockets and the well. Then, slide the regular sprockets onto the lower pushrods. After that, slide the bracket on and screw it on at the bottom. After that, measure the distance between the holes on top to drill holes in the plastic, trim it to fit, and then screw it on. Your brackets are now assembled.
Step 4: Assemble the Body
Now it's time to assemble the parts and put the tank together. The first step of this process is to attach both base pieces together using the given screw hole in the middle. Make sure you tighten this screw enough, and if the pieces are a bit loose, it's ok. After this, wrap the treads around the brackets and secure them with the slightly bent pin. After you have the body assembled, drill two holes on either side of the plastic container and put Velcro on both the plastic container and one side of the base so that you can secure the container on the base. Then, if either of the treads is not tight, you can remove a tread piece or use bungee cords to hook onto holes drilled into the base, tightening the tread as shown.
Step 5: Assemble the Electronics
First, you will need to hook up the each side's motors in series, but make sure they are spinning the same way. To do this, test the polarity of each motor with a 9 volt battery to figure out which pole is which. MAKE SURE YOU HAVE HEAT SHRINK ON ALL WIRE BEFORE YOU SOLDER. Then solder the positive of one motor to the positive of a female JST plug and the negative of the other motor to the negative of the JST plug. Then, solder the other two poles to each other with some wire. Do this on the other side and shrink the heat shrink. Then, make a power splitter by soldering all the positives of one female JST plug and one male JST plug together and soldering all the negatives together. After that, connect the power splitter to the ESCs and plug the receiver wires into the throttle and elevator channels of your receiver (make sure one of the red wires is cut and the switches are ON). Then, put everything into the container and plug in the motors through the holes in the container. Your tank is now finished.
Step 6: Driving Tips
To start the system, turn on your transmitter and plug your battery into the splitter (I had to make an adapter for my battery). The ESCs should light up and the tracks should move if you push up on the sticks. The tracks should move easily, but DO NOT GO FULL THROTTLE IF THE TRACKS DON'T MOVE. This could cause a motor burnout and the motor brushes will melt, which I have been having problems with if too much torque is applied on the tracks. If anyone knows how to help, I would appreciate a comment.
Step 7: Conclusion
I would love to see a modification on this design. I have been pondering a turret or perhaps a robotic arm, but please take this and run with it. If you have any questions or suggestions, please leave a comment and PLEASE VOTE FOR THIS IN THE 3D PRINTING CONTEST. Thanks and happy driving!