Battle Bot (Little Mac)

Little Mac is my 3 pound battle bot that I will hopefully compete with later this year.

3 pounds is the Beetleweight class. The frame of my bot is a 2009 Mac Mini.

This page will be updated later with more information. For now, enjoy some pictures! 🙂

Highlights of Utah Bot Brawl 2020

Video Tour

Unopened Mac Mini

This is a 6.5 inch square

Custom 3D printed gears

Custom 3D printed gears and wheel hubs

1/4 inch thick HDPE plastic frame

Weapon is made from a rubber roller from a copier and square steel

Test fitting some parts in the frame

“Robot Salad” Weighing all the parts was a regular occurrence

Some of the tools I used. Drill, jigsaw, and rotary tool. All from Harbor Freight

Battle hardening the gearmotors with Loctite on all internal screws.


More test fitting of parts.

Designed a power “switch”. You unscrew the screw to turn the bot off.


Testing some of my code with the hardware. Remote Control -> Arduino Nano -> H Bridge Motor Driver -> Motor

New weapon motor. Extended the shaft of a printer motor.

Testing the weapon drive system

Another view of the weapon drive

Full schematic of the bot. Some resistor values have been changed

Modified R/C receiver. The connector has been moved to the other side so the receiver can fit in a tighter spot.

My interface board before the Arduino is installed. Has a 5V regulator and MOSFET for driving the weapon motor. This board connects between the H-Bridge board and the Arduino.


Completed circuitry

Completed circuitry. The LED is for status, the 3 pin connector goes to the R/C receiver

Battle hardening the circuitry with hot glue to prevent loose connections

Foam holding the circuitry in place. Beginning install of the wiring and motors. Hot glue to keep wiring from vibrating loose.


Top view of the completed internals. Only thing not in the picture is the Velcro that will hold the top plate on.


More completed views

2 red LEDs for indicating power, blue LED indicates good connection to remote

Side view of weapon spinning

Top of bot

Bottom of bot


Side view of weapon drive

Back of bot. The spikes are good as weapons and for preventing the bot from getting stuck on one side. The larger hole is where you use a screwdriver to turn the bot on/off.

Front of bot, with weapon

Just below the weight limit!

Completed bot! Ready for some practice driving!


2 thoughts on “Battle Bot (Little Mac)

  1. What is the Arduino, electronic blueprint, I’m actively trying to build this in my engineering class and am kind of stuck on this aspect. Is there any way I could get the STL files for all the custom-made pieces?

    1. Hello, thanks for your interest in my bot!

      This battlebot was basically all handmade to fit inside an old mac-mini. The only CAD created parts are the orange gears. Everything else was hand measured and cut with a rotary tool.

      Not sure what your objective with the project is, but since the gears are custom made for the exact junk motors I had, I would just create your own.
      Add a gear model into Fusion360 from McMasterCarr, then do a few edits to customize it. Lots of tutorials online.
      Overall, this bot was fun to build, but it’s not very competitive with the weapon shown. Mostly a driving brick.

      Same with the circuitry and code, I built it more as a learning experience, so it’s not optimized much. You can use an off the shelf Malenki Nano HV to replace all the circuitry and code.
      The electrical schematic is already on the page if you wanted to see what I designed though.
      Arduino code is basic R/C input translating to an output. Only special part is the library for reading the iBUS protocol from the FlySky receiver, which you don’t need unless you’re using a FlySky R/C system.
      Here’s a popular version:

      In closing, have fun building and learning, but know that this bot is not the best if you’re looking for a download and assemble project. There are plenty of other battlebots online that you can 3D print and build.

Leave a Reply

Your email address will not be published. Required fields are marked *