Ask Aaron!
Q & A about Combat Robotics

Aaron Joerger at Robotica 1My son and team member Aaron Joerger (age 13) is a bit jealous about all the mail that I receive asking about the design and operation of combat robots (send those questions to: He asked for his own question and answer page here at the Run Amok website.

Do you have any questions you'd like to address to Aaron? Write your question below -- include an e-mail address if you would like a direct response.


Your questions and Aaron's answers will be posted below -- most recent ones first.

Q: Can you control robots to walk and talk? I like your website.

A: All of our robots have wheels and are built to fight other robots. Wheeled robots are faster, easier to build, and harder to beat up. Walking robots are cool, but I don't have any experience building them. Take a look at: Robo-One for some cool walking 'bots.

Q: Is hot glue good for building robots?

Technical question - Mark J. here: Lots of different fastening techniques go into a robot depending on what has to be fastened and the stresses involved. We usually hold down our radio receiver with Velcro, 'cause it's easy to remove and replace and the reciever weighs very little -- but I wouldn't use Velcro to hold the motors in place!

Hot glue could be used to hold small wires out of the way, or for other low-stress applications. Some antweight 'bots use types of glue to bond their chassis together -- rubberized cyanoacrylate or epoxy plus a wrapping of high-strength thread works well for graphite rods. I wouldn't care to try it in larger robots.

Q: Dude cool! I have a battle bot and it is so crappy... How did you do it??? How much money did it take???

A: I try to keep my 'bots simple and not try too much new on a new design. I also learn from the designs of other builders.

How much money does it take? All you have.

Q: Please, can you send me some instructions on how to build a robot just like yours?

A: There are lots of books in your local library that can help you design and build your own robot -- no need to copy mine! See the links in the last post on this page, too.

I wrote a free-verse poem for my English class today:


not like tv, being there
seeing all of it,
even behind the scenes

the pits, machines laid out
on tables, waiting to be fixed again
for battle

crowds in stands, shouting
screaming, chanting, stomping
wanting mayhem

smoke and ozone
oil and graphite
metal dust, robots fighting

Q: I'm trying to build a combat robot with an R/C car for maybe beetle or feather weight. On a modest budget, can this become a competitive robot?

A: We've built several successful Antweight competitors out of R/C toys. Our current Beetleweight is based on an RC toy (with quite a few modifications) and it has done very well. A Featherweight? Probably not.

Q: How many robots do you have? (beanodandy)

A: I count six competition robots in all:

  • Rat Amok - antweight combat - retired, but operational;
  • Mini Maxbot - antweight combat - operational;
  • Mini Maxbot 2 - Antbotica competitor - operational;
  • Zpatula - beetleweight combat - operational;
  • Run Amok/Run Away - Heavyweight combat - retired, but operational;
  • The Gap - Robot Wars heavyweight - operational.
We also have a few non-competition 'bots around, but they don't get named.
Q: Do you have any robots representing the human body? (Adam D.)

A: All of my 'bots are built for combat or head-to-head competition. No humanoid 'bots -- but I think that 'bots like Robo-One are really cool!

Mark J. here: Team Run Amok is back from the Robot Fighting League national championships in San Francisco. Aaron drove his beetleweight to third place overall! His loss in the semi-final was not a fault in his driving, but in an electronics failure in the 'bot. Nice job, Aaron!
Q: Aaron, what is a 4-bar lifter? (Jake)

A: Mark J. here: Technical question time!

A 4-bar mechanism is a simple arrangement of four mechanical links (like rods or beams) with pivot connectors on each end linking them together into a roughly rectangular shape. By careful selection of the relative lengths of the links used, you can create complex movement arcs and gain torque or speed without gear reduction. An example of a 4-bar mechanism can be seen at

Robots sometimes use 4-bar mechanisms to control and position lifter arms efficiently and allow them to scoop in a sweeping upward and outward arc rather than a simple single-pivot backward rotation. Aaron's beetleweight uses a 4-bar mechanism in its electric lifter.

Q: Aaron, what is Mini Max Bot made of? (Anon)

A: Mini Max Bot started out as an R/C skateboard toy. It's whole structure is some kind of plastic. Thin slices of automotive radiator hose are used as tires.

Q: Does you beetle use a 4-bar lifter? What are the drive motors in your beetle? What state do u live in? (Alex U., Pittsburgh, PA)

A: Yep, Zpatula has a lifter with a 4-bar linkage. Zpatula's drive motors are 6 volt Mabuchi 130s -- a Mabuchi 180 powers the lifter. We live in Oregon.

Q: Don't you think 130s are a bit small for a beetle? I use 300s in my ant. (Alex U., Pittsburgh, PA)

A: Mark J. here: Let me take this one, Aaron.

The maximum amount of drive power you can effectively use in a 'bot is limited by the weight on the drive wheels and the grip of the tires. Additional torque just spins your wheels. You can 'gear up' to trade torque for speed -- but how much speed can you effectively use in a 5 or 6 foot square ant/beetle arena?

Zpatula is 6-wheel drive and can easily spin it's wheels to avoid motor-destroying stall. The twin, mildly over-volted 130 motors give good controllable speed and deliver about 4 watts of power per pound of robot -- just about the same ratio as our Robotica winning heavyweight 'Run Amok'.

People often believe that Team Run Amok's 'bots are underpowered, but we have championships from half the events we've entered. Not many teams can match that record.

Q: Were do you get your parts? (Anon)

A: My dad get parts from a lot of places, and we make some of our own. Places you might try:

Team Delta
Robot Marketplace

Q: Do you do stuff beside fighting robots? (Anon)

A: Sure! I play soccer and streetball, I have a weekly Yu-Gi-Oh tournament, and I'm a counselor-in-training at the YMCA camp.

Q: What was your best robot competition? (Joey)

A: I won my first competition driving my own robot last month at daVinci Days. My beetleweight "Zpatula" fought in a round-robin tournament against all the other robots. I won all but one fight and took the championship.

Q: Is it really fun to beat up other robots / watch your dad beat up robots? (Tyler)

A: Being at a robot competition is great! Competing is really intense. I like out driving and outlasting the other robots, but I don't really like to break stuff. I want to leave 'em pretty, but beaten.

Q: If one of your robots was for sale, which robot would it be? (Joey)

A: By the time we're thru with a robot it's either a champion or a pile of scrap. We don't sell our champions, and nobody would want the pile of scrap.

Mark J. here: I wanted to take a second and congratulate Aaron for his great robot driving at the da Vinci Days robot competition (July 17th & 18th). Aaron won the first ever Antbotica competition with his veteran robot 'Mini Max Bot' and came back the next day to win the beetleweight combat competition with his new robot 'Zpatula'! He has qualified for the Robot Fighting League national championships in San Francisco in October. Great work, Aaron!
Q: Which 'bot was your favorite (other then your dad's) in the first season of Robotica? (Jonathan R.-New Castle, PA)

A: We made lots of friends at Robotica and I don't want to pick out just one 'bot as my favorite. I really liked JuggerBot, Jawbreaker, and Kritical Mass. My dad says he liked Pandora for the cool way the builder used the parts he had available.

Q: Where can I get a cheap combat robot kit? (Anon)

A: The only combat robot kit I know of is an antweight, and it isn't 'cheap'. Scroll down a little and read about 'converting an R/C toy' -- that's more fun than a kit and you'll learn more.

Also, take a look at this page on How to Convert a BattleBots Toy into an antweight combat 'bot.

Q: Where can I buy giant combat robots? (Anon)

A: You can keep an eye on EBay. Some builders will sell their old 'bots there to get money to build a new 'bot. It's more fun to build your own!

Q: Do you have any ant weights? (Alex Udanis)

A: Yep. See 'DaVinci Days' antweight tournament.

Da Vinci Days Beetleweight Champion - Zpatula Q: I like Run Amok,& other robots, but R/C Toys are really great. I have toy converted into IMMORTAL WHEEL, and I like battle robots. Have you any r/c toys? If you have it, you`ll be happy. (Anon - Poland)

A: R/C toys are great! I have a few R/C toys and I play with them a lot. I'd like to see a picture of your Immortal Wheel -- cool name. I converted one of my toys into a beetleweight combat robot for a competition this summer (picture at right). It did great!

Q: Can you please tell me how to make a battlebot? Because I can't find any websites that show me what to do to make a battlebot. (Kelvin - Queensland, Australia)

A: There are lots of good books on how to build a combat robot, but it's too big a topic for me to talk about here. Check my dad's web page for some of the books, and check with your local library.

You can also get a quick lesson in robot building at Click on "Build a Robot".

Q: What lightweight and strong metal would you recommend to use in an antweight robot, which has to weigh a maximum of 150g? (Rachel Mumby)

A: Wow -- that's really light! In the U.S. we get a full pound for antweights - 454 grams.

I live near some places that build parts for airplanes and I can get scrap pieces of thin titanium that are great for robots. Titanium is light and very tough, but it's usually expensive and hard to find.

You might want to consider thin carbon composite material instead of metal. marketplace sells small sheets of it. It's very stiff and strong.

Some types of plastic make good armor for light robots, too. Polypropylene is used for kitchen storage containers and is very thin, light, and tough.

Q: Hi! How do you actually convert an old r/c toy in to a robot? (Anon)

A: It's a little like making a statue of an elephant: you start with a big chunk of rock and carve away everything that doesn't look like an elephant.

Seriously -- there are all types of R/C toys. Some have steerable front wheels and some steer by making the wheels on one side turn the opposite direction from the other side. That later type is more maneuverable and might make a better robot, but either type will work. Just start taking off things that don't look like they belong on a robot -- the body, bumpers, wings, roll bars, whatever. Get it stripped down.

The next step is to weigh the stripped-down toy to see how much armor and weapon weight you can add without going over the maximum weight for the class of robot you want. Toys make good 1-pound and 3-pound weight class robots, and larger ones can fight in the 12-pound class. Bolt on your armor to protect the wheels and other delicate stuff. Plastic that won't crack is good, or fairly thin metal. Bolt on a wedge or a couple of spikes and you're a roboteer! You'll learn a lot from the things that go wrong with your first 'bot, and you'll have fun. Be careful with anything sharp, and don't attack your cat/dog/hamster!

Q: You can enter Mini Amok in the FRA world championships featherweight division. Is he within the weight limit (1kg-12kg)? (A.J Hamilton)

A: Mini Amok weighs in at about 2kg, so technically it would qualify. It would take a little work to 'harden' Mini Amok up to battle standards. I think I'd rather keep it as a pit toy.

I'm building a new 'beetleweight' robot named 'Zpatula'. Six wheel drive with an electric lifter (picture posted above - scroll up). At 3 pounds, it'll still be too light to be competitive in the 12 kilo class.

We also have a 12 pound class robot named 'Nasty Glass of Water'. It's built to pick up other robots and use them as weapons! My dad told me once why it has that funny name, but I don't remember. It doesn't show up on our website because it keeps changing all the time. But it could pick up another 'bot and still be too light to be competitive. We like heavyweights!

Q: I want to make my own robot. Were can I do this?

A: Try visiting for tips on big robots. For ideas on smaller (antweight) robots, try

Earlier questions and answers: the Ask Aaron Archive

Run Amok Combat Robotics homepage