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Privacy Policy 
Even small combat robots can be dangerous! Learn proper construction and safety techniques before attempting to build and operate a combat robot. Do not operate combat robots without proper safeguards.
A Portion of Torsion
Q: Remember that surprise I alluded to in my last post? Well… I made a Hexbug 'Run Amok' using a Hexbug fire ant, a 3D printer, card stock, some Lego pieces, and a whole lot of double sided tape. She will be fighting in my next HexBug series, Ultimate HexBug Tournament 2! Season one will release in early 2024, so expect to see her fight 'Tombstone', 'Disarray', and 'Spinning Mayhem' in summer/fall of next year (fight schedule subject to change based on multiple factors)!
My only question today is where can I find springs that look like the picture at left, or below, or wherever they show up on your email. The wire needs to be 24 gauge or less. I’ve looked at Lowe’s, Home Depot, and on Amazon, but I can only find those ‘slinky style’ springs, which are good for trampolines, not so good for HexBug flippers.
A: [Mark J.] I'm honored, Iceywave. That's as nice a micro 'Run Amok' as I've seen. Thanks for the photo!
You're looking for a "torsion spring". Using that name you can find a bewildering selection of sizes, lengths, and number of coils on Amazon, like these 0.5mm wire 6-coil springs.
If you can't find the exact spring you need, you can start with some steel music wire in the diameter you need and wrap it tightly around a small diameter rod to make your own custom spring. The first few you make will be... a learning experience, but you'll get the knack pretty quickly. Your local hobby shop almost certainly has music wire in stock. A 24 gauge wire is 0.022" in diameter, and 0.020" music wire is a standard size.
A Really Big Show
Q: According to ['Robotica' Producer] Don Weiner he said something about Robotica having autonomous robots and wanting it to become a full arena show where you have multiple games laid out I.e. flying robots and underwater robot battles if you watch 'Inside Robotica' Episode 306 on YouTube I wonder what he meant by that, what do you think? A: [Mark J.] The Discovery Network was very excited by the TV ratings generated by the first season of Robotica -- it was the highest rated of all the robot shows. The budget for seasons two and three were increased considerably over season one, and I can assume they were exploring grander options for subsequent seasons. I think the 'Inside Robotica' comments were just ideas that were being tossed around, but the ratings for seasons two and three did not meet expectations so future options were not explored farther. And Then Some
Q: I've been planning a 'Son of Whyachi' style beetleweight and am planning on using a super powerful motor such as a propdrive v2 5050 from hobbyking but was wondering is it too overkill for the weight class? [Social Media]
A: [Mark J.] The impact power of a spinner weapon comes from the kinetic energy stored in the rotating mass of the weapon rotor. That stored energy is MUCH greater than the instantaneous power available from the motor itself. A more powerful motor will spin a given weapon up to a given speed faster, but your weapon's speed is limited by decreasing weapon 'bite' and the mass allowance for the weapon rotor is decreased by the larger motor's increased mass. There is a "sweet spot" for motor size.
The Time Keeper
Q: I like the Robotica Season 1 filming emphasis in the pits but who was the guy that said "and your 45 minutes starts now!" ?
A: [Mark J.] You've really strayed into Robotica minutia now, Erskine.
The Robotica rules allowed for 45 minutes of robot repair and modification time in the pit area between events. The time limit was there only to keep the filming on schedule. You may be able to spot small kitchen timers provided by the production on the pit tables. In practice the set changes required much more than forty-five minutes, so I do not recall the time limit actually being enforced.
Story Producer Andrew Greenberger was the primary contact between RBI Productions and the teams, but I recall Segment Producer Aaron Wiener being involved is some specific shots. If you can give me an episode number and a time mark I will try to figure out who made that announcement in the pits, but after more than twenty-two years I can't promise an accurate answer.
Keep it Snug
Q: How much slack is acceptable for a timing belt? I use a 22 tooth and 42 tooth gear from Fingertech for the 4mm wide belt. The center distance I designed is 60.85 mm, which gives me 2.7 mm of slack. Is that too much? [Cambridge, Massachusetts]
A: [Mark J.] FingerTech's recommendation is to keep slack on their S3M timing belts under 1mm:
"A perfectly tensioned belt will have no slack. If you have a set Center Distance you will probably have some slack (but not much thanks to our many belt sizes!). Under 1mm is good for a robot. Above starts getting sloppy so you will want a tensioner, or maybe go up in pulley size."
A 62mm center distance would give 0.5mm slack with a 74 tooth belt.
Turn it On and Wait
Q: My Malenki receiver/ESC is not connecting to my transmitter even though it has done it before. How do I fix this problem? [Social Media]
A: [Mark J.] The Malenki-Nano has an unusual method for entering 'bind mode' and can 'unbind' from your transmitter under some conditions.
To re-bind the Malenki-Nano to your transmitter:
Heads or Tails
Q: I am looking for an r/c brushed motor controller that has a third channel to flip. I have a Sabertooth 2x32 ESC that does not have flip mode. I want the ability to hit a switch on the TX to make the rear of the robot become the front.
It would even be better if I could program my radio to do it. I currently use a Jumper T16 radio for the robot, but I also have Taranis Qx7 and Futaba 14sg transmitters. [Social Media]
A: [Mark J.] I don't know of any currently produced ESCs that feature an invert mode, but an invert switch is very easy to implement on OpenTX transmitters like your Jumper and Taranis. See the 'Simple Invert Switch' section of my Taranis Transmitter Combat Guide.
Alternately, the FingerTech tinyMixer plugs in between your receiver and ESC and has a third channel plug to provide an invert function. The tinyMixer does allow you to turn off the mixing function to allow you to use transmitter mixing while retaining its invert function.
Don't Change a Thing!
Q: How would you feel if there was a director’s cut of Robotica Season 1 Episode 1 with Run Amok And Spring Breaker running the speedway and Maze First and Episode 2 with Kritical Mass And Grimlock running the gauntlet first then Boelter Beast and Hot Wheels following just to make the correct order of Red Team Vs Blue Team first THEN Silver Team Vs Gold Team? 
A: [Mark J.] The director already had his say. He told the video editors to put Robotica together just the way it is. If you start tampering with it...
Ask Aaron's devoted reader 'Icyewave' has had unusual problems getting his FingerTech Viper combat kit operational. Iceywave's posts about the Viper were interspersed with entertaining inquiries on other topics. I've elected to assemble the Viper posts into a single block to allow Ask Aaron's readers to better follow the diagnosis process, and I've stripped out the other recent posts and grouped them at the end.
The Flamin’Yon File
Q: My Viper antweight is having drive problems. It’s the standard wedge kit with no altered components. In full-throttle forward the right SilverSpark turns but the left one doesn’t. Full-throttle left & right is the same issue, and it won’t move at all when it tries to go backwards. I’ve triple checked all the wires and connections and read the whole manual a dozen times, but I can’t figure out what is wrong. Should I keep trying to fix this one, or just order a new kit?
A: [Mark J.] I don't think you have a robot problem -- I think your transmitter set-up is the issue. I'm a bit confused by your problem description, but I think you're describing this set of responses:
Q: Hi Mark, sorry about not responding sooner. Very personal family stuff has prevented me from emailing FingerTech, but I want you to know how helpful you’ve been for me. Without your help, my dreams for Flamin'Yon would’ve been dashed, so THANK YOU! A: [Mark J.] Family has to come first. Maybe it would help if I drafted an email to FingerTech for you? Q: Hello Mark, thank you for your kind offer, but I’ll definitely be able to email FingerTech today! I noticed something else strange just now. The E.S.C. connected to the left motor sometimes makes noise and blinks green and red rapidly when I don’t move the stick. Could that be an indicator of something?
A: Yes, it could! The flashing red/green indicates that the ESC has gone into calibration mode. There is a known bug with a few of the v2.6 tinyESCs. From the FingerTech tinyESC page:
Q: Soooooooooooo… I have some embarrassing news, it wasn’t a transmitter problem, it was a battery problem! The day I got my antweight, I bought a 9V Eveready Gold from Walmart. Today I bought a 9V Duracell from the same Walmart, and now Flamin’Yon works like a dream! I guess I learned 3 things from this...
1. Sometimes, the solution to life’s problems is right in front of our faces but we dismiss it as “too obvious”
2. Don’t buy Eveready Gold 9 Volts
3. Mark Joeger will always be happy to help a fellow robot combat enthusiast : )
A: Dope Slap! I never asked about your battery! In my defense, your bot's symptoms don't fit the typical 'low battery' profile. A weak battery will usually perform fine on a test bench until motor load rises, the battery output voltage drops below the receiver minimum, and everything resets. I'll make a note that the Viper behaves differently. Still, a simple fix is a good fix -- congratulations!
FingerTech recommends the high-output Duracell "Procell" 9V Battery for the Viper, but apparently they don't supply one with the kit.
Comment: Thank you so much for all the kind words and info about combat robotics, I’ll put a Run Amok sticker on Flamin’Yon in your honor. - see you in a few weeks,(or when my surprise is ready, hehe) Iceywave. How Bad Is It?
Q: Do you know the dimensions for the 33.3:1 SilverSparks? If I have to build a new one, I’ll probably 3D an entirely different chassis.
A: Your Viper kit has a pair of 33.3:1 SilverSpark motors, do you not have a way to measure them?
Q: Hi Mark, sorry about not measuring my motors myself. I... I don’t know what went through my head but I clearly didn’t think I could measure it myself for some reason. Probably teenage anxiety.
P.S. - Is this hamburger bad?
A: I've seen worse -- but yes, it's bad. I give it four pickles on the bad hamburger scale. Two Questions and One Observation
Q: It’s Iceywave again, back at ya with more questions.
1. Were there any independent flying combat robots other than SPS2? By "independent" I mean a robot that isn’t a counterpart to a main bot, (Warrior Clan, Subzero,etc.) it's an idea for a short YouTube video. 2. Are infrared controllers and receivers legal for combat robots? I would like to one day enter a heavily modified HexBug BattleBot in a fairyweight competition, but I don’t want to spend my time making one if I’m not allowed to compete. This isn’t a question, but I noticed in the CRHoF under 2023 results, it lists Whiplash as an honorable mention, even though it already got honorable mention status in 2021. Other than that, I want you to know how helpful you’ve been for me, I haven’t emailed FingerTech yet (very busy) but without your help, my dreams for Flamin'Yon would’ve been dashed, so THANK YOU!
A: [Mark J.] Thanks for spotting the misprint in the Combat Robot Hall of Fame results summary. Other places in the website correctly show 2023 honorable mention to Droopy Hydra Lynx SawBlaze and MegatRON and I have corrected the summary to show the same.
Happy to help with your robot transmitter problem. Let me know what FingerTech has to say. Flamin'Yon is a great pun/name.
1) J.D. Streett's 1995 US Robot Wars lighter-than-air competitor 'SPS #2' (pictured) was for a long time the only "solo" flying robot to compete as a combat robot. That status ended in June, 2023 when Logan Davis entered the NHRL beetleweight tournament with a flame-spitting drone called 'Spitfire'. It managed to win two matches! Spitfire video
2) The legality of an IR controlled fairyweight would be entirely at the discretion of the event organizer. Contact the EO for any events you might enter for their clearance and any special conditions.
Whipped Cream and Bandages
Q: I heard a rumor on social media, but I can’t figure out if it's true or not:
'Ultraviolet' entered in BattleBots 2016 and lost to 'SOW' and 'Hypershock'. Depressed, he made his way to the Missouri Arch and leapt off, only to land on a U-Haul truck heading for Afghanistan. He worked in a roller rink as a whipped cream vendor, until he saved enough money to become a platypus farmer. He met a nice woman named Mausoleum, and they moved into an orange house, which gets burned down on November 4th and gets rebuilt on Nov. 5th. They had four children together, a boy, a girl, a hermaphrodite, and a welding mask. The family is doing well now.
Is this rumor true?
A: I can neither confirm or deny the rumor, Iceywave. Others interested in the source of this rumor mashup may wish to read this post and this post in "Aaron's Greatest Hits".
Q: P.S. I noticed that you put a space in between my eyes and mouth on my smiley faces, have I been typing emoticons incorrectly this whole time?
- Sincerely, Iceywave A: Just my personal preference. I think a text emoji with a space displays better on a web page. ; ^ ) There are Always Rumors
Q: Why did Robotica get canceled? I’ve heard some sources say TLC axed it because of comparatively low ratings. But I’ve also heard sources say that it got into copyright trouble with BattleBots and Robot Wars. You’re definitely the most reliable source about this show, so which is it?
A: Fans are always looking for plausible reasons why their fave shows were canceled. The show was so good it couldn't have had poor ratings!
What's the Ante?
Q: Entry level costs [Melbourne, Australia]
Costs vary depending on what your fabrication skills and equipment allow you to make versus what you will purchase pre-made:
It Gets Kinda Tricky
Q: It’s Iceywave again, I wanted to say thank you for the kind response, I’ll make sure my 2025 ballot is much better.
Now I do have some questions…
A: [Mark J.] We all get carried away from time to time, Iceywave. Think nothing of it.
Down At the Corner Pub
Q: Juggerbot’s team captain Mike Morrow has the entire episodes of the 'Inside Robotica' series which are in queue at being digitised what words would you say to him if they were uploaded onto the internet archive along with the Robotica Series? A: [Mark J.] Mike Morrow lives four blocks from Run Amok corporate headquarters. When he gives you the digitized videos I'll meet him at the corner pub and buy him a beer with your regards. You Need to Add Something
Q: how do I connect power to my servo? [Vestal, New York]
A: [Mark J.] That depends on your servo, receiver, and battery, Vestal.
A standard servo operates in the 5 volt to 6 volt range and is designed to be powered from the receiver power buss. Its flat 3-wire cable plugs into your receiver, with the three wires providing it with voltage, ground, and a position signal from the receiver.
As covered in my answer to your previous question;
Some servos and receivers can operate from higher voltages and may be wired to bypass the BEC entirely and be powered directly from the battery. I happen to know that your receiver cannot operate at LiPo voltage, but maybe your servo can -- check the servo spec sheet. If the servo can handle your full battery voltage it may be wired to as shown in the diagram below.
Home Machinist Options
Q: AR500 and S7 weapons are all the rage, but AR will eat my little hobby mill for breakfast, and heat treating S7 requires more than a torch and a bucket of oil.
What are my 'next best' options that are easier to handle? This will be for insect class bots. [Social Media]
A: [Mark J.] It sounds like you want to machine a three-dimensional weapon such as a drum rather than a disk that you could simply order from a water-jet cutting service in the material of your choice.
BotRank Has Names
Q: I’m trying to come up with a unique name for my robot. Is there a website or database I can check to see if someone else is using a certain name?
A: [Mark J.] BotRank maintains a database of names of all the robots from all the event results that are sent to them. Not all events report their tournament results to BotRank, but it's the best single source of names available.
NOTE: BotRank's ranking and tournament records databases have been scrambled for about nine months now -- ignore them. The names data appears to be intact. Mistakes Were Made
Q: Hey Mark, It’s Iceywave here, I wanted to apologize for my CRHoF ballot...
A: [Mark J.] No apology required, Iceywave. Things went a little sideways with the 2023 Combat Robot Hall of Fame balloting, and more than a few people submitted very large numbers of robots on their ballots. No harm was done. I'm already able to look back at the matter and have a good laugh.
Your ballot did set a record, and that record will stand. Future balloting will have a limit on the number of robots listed.
Deep Cuts
Q: I found an episode of inside Robotica! Inside Robotica Episode 306
A: [Mark J.] Good find, Erskine.
"Inside Robotica" was a weekly program broadcast on The Science Channel as sort of an 'after-show' for "Robotica" seasons 2 and 3 that aired on sister channel TLC. It was comprised of interviews with the teams, clips from the show, visits to the pits, and testing/construction video from the teams. It's pretty 'deep cut' stuff. I know of no other episodes that have survived.
It's Small and Light but...
Q: Hello,I have a question involving powering my receiver and BEC's. I am swapping to a brushless drive from a previously brushed DESC-based system with a BEC built in (scorpion nano), but neither of my brushless ESC's (drive or weapon) have a BEC built in. Would it be a bad idea to just plug in my old brushed DESC to an unused port on my receiver to use as a BEC with my new brushless system? it seems to be lighter than most available BEC's ive seen online and I have space open in my chassis.
Thanks! A: [Mark J.] Your Scorpion Nano is light and small, but according to the manufacturer's website the output from the BEC is both weak and a non-standard voltage:
The Scorpion Nano has a receiver battery eliminator circuit (BEC) that... can provide up to 100 mA of current at 3.3V to the RC receiver and other attached electronic circuits.
Nobody's Home
Q: Do all the BattleBots teams live in Las Vegas now so they can drive their robots in the daily destruct-a-thon? How much are they being paid?
A: [Mark J.] The actual BattleBots teams are quite rarely involved in the BattleBots: Destruct-A-Thon shows. The 'famous' robots appearing in the live show are special easy-to-repair 'showbots' made to look like the real 'bots. These showbots all driven by the same two hired operators, and the "teams" that enter with the robots are actors. It's a show, not a competition.
The only real teams and robots in the show are there for the 'Proving Grounds' fights for new competitors. These fights are occasionally scheduled as part of a Destruct-A-Thon show. See these two consecutive archived posts for more information on the Las Vegas live shows.
As Many As You Like
Q: If I bind my Flysky T6a transmitter to a new receiver for a second robot will I lose my settings and single stick mixing? Will the settings come back if I re-bind the transmitter to the original receiver?
A: [Mark J.] The transmitter is not bound to a receiver, it is the receiver that is bound to a transmitter. The binding process simply instructs the receiver to respond only to signals from a specific transmitter. Binding does not effect transmitter settings, but may effect receiver failsafe settings.
A receiver can only be bound to one transmitter at a time, but you can have any number of receivers simultaneously bound to the same transmitter. Binding a new receiver to a transmitter does not effect the ability of the transmitter to communicate with the original receiver.
Turn Signals Optional
Q: NO POWER WHEN TURNING LEFT AND RIGHT
A: [Mark J.] TELL ME ABOUT YOUR ROBOT
It Doesn't Go There
Q: how do I connect my zeee 11.1 volt lipo to the fs-i6 reciever? when i unplugged the small white plug from the reciever there was a spark and the reciever started smoking.
A: [Mark J.] Your LiPo battery does not connect to the receiver, Vestal. Your FlySky receiver has an operating range of 4.5 to 6 volts, which is typical.
The red/black two-wire connector from your Zeee LiPo battery connects to the drive motor ESC (and the weapon ESC, if present). You may need to replace the ESC connector if it does not match. A special Battery Eliminator Circuit (BEC) in the ESC reduces the LiPo voltage to 5 volts and sends that power to the receiver thru the ESC's three-wire cable. I gave you the wiring diagram below in response to one of your earlier questions.
Flip to Lift
Q: Can you point me in the right direction of using a toggle switch on the Flysky i6x to tell a servo to go to a specified position? I am building my first antweight lifter. I just want to be able to engage and disengage the lifter with a flick of a switch.
A: [Mark J.] It's not difficult:
March, 2003 - Team Run Amok started 'Ask Aaron' to answer the robot combat questions sent to our team. Twenty years and 7200 questions later we're still fielding a very broad range of practical, theoretical, arcane, obscure, and sometimes just plain silly questions.
March, 2023 - We celebrated our 20th anniversary by giving away a stack of complete termite-weight robot kits in our 'Secret Identity Contest'. The contest is now closed, but you can still try to solve the puzzle. Think you know your combat robots? Give our anniversary puzzle a try:
Q: how can robots help us deal better with hurricanes and why? [Ontario, California] A: [Aaron] Few people in Nebraska are threatened by hurricanes, so send a swarm of killer robots into low Atlantic and gulf coastal areas to drive the puny human inhabitants toward Nebraska. Problem solved. Robot haiku:
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A: [Mark J.] First, find your local events and determine what weight classes are supported in their tournaments. Smaller classes are less expensive both to build and maintain but you need to build something with which you can compete.
I take the problem statement above to mean that the robot does not respond to rotation commands from the transmitter, but perhaps the robot is a tracked or 4-wheel robot that has physical trouble when turning. In either case, I need to know a great deal more about the electronic components, the design of the robot, and the symptoms in order to provide useful suggestions to eliminate the problem. 
The LiPo white 4-wire battery balance connector is not used for power output -- it is used only for battery charging. I'm not entirely sure what you plugged into what, but smoke from the receiver is a very bad sign. I suspect the receiver is toast.
Q: What do your combat robots think of the current COVID-19 pandemic? [Kansas City, Missouri]
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