spring_rabbit

*Pictured: the original GIANT ENEMY CRAB and work in progress JACKALOPE *

I will be linking parts I use as examples. They are not necessarily recommendations for parts or suppliers, I just want you to see what I'm talking about.

Hey sickos, spring_rabbit here, that weirdo who keeps posting about BattleBots. I thought this com could use some more long content, so I'm going to do a build blog of my next combat robot project here. In this post I will be introducing the GIANT ENEMY CRAB 2 project and talking a lil bit about the electronic components I will be using, and I will document future work on the robot as well to keep track of its progress.

PART 1: INTRODUCTION

In the winter of 2021 I finished building my first fully-functional combat robot, GIANT ENEMY CRAB. GEC is a 4 wheel drive robot with a horizontal spinning hammer up front, driven by a drone motor inside the chassis. It weighs just under 1 pound and uses simple 3d printed materials to comply with my local league's "Plastic Antweight" division. The chassis and weapon are made of PETG (one of the few materials allowed in the Plastic Antweight class), the tires are cheap foam wheels I found online, and it uses a hair tie for a weapon pulley belt. It's bulky, ugly, the wiring job sucks, and while the hammer could easily break your finger once spun up, it doesn't do a ton against similar opponents. But it was my first robot and that is something special.

Since last winter though, I've learned a lot. My other antweight JACKALOPE is coming along nicely and a quick glance shows how much more compact and efficient I can get with my designs. So with much more experience under my belt, I'm looking to build a new version of GIANT ENEMY CRAB, using better materials and more knowledgable design to make a much more competitive bot. Unlike the original, GEC2 will be made for the standard 1lb Antweight division, allowing much more flexibility in materials I can use, including engineering filaments and laser-cut metal parts. This is at the request of its future driver, who wants to compete alongside me in the more destructive 1lb weight class.

So what will make GEC2 a proper successor to the original GEC?

• It will retain the wide 4wd horizontal spinner design.
• Same electronics (mostly), with better hardware, design, and materials.
• Angery eyes - so angery
• Crab

PART 2: ELECTRONICS

The electronics used in GEC2 will be the same as in the original GIANT ENEMY CRAB, save for some upgrades to the battery and power switch. This is because I bought multiples of each of the original components and don't want them to go to waste.

Like most small combat robots, GEC2's electric components will consist of a Battery, Brushed motors for drive, a Brushed Electronic Speed Controller (ESC) to control the drive motors, a Brushless motor for the weapon, a Brushless ESC for the weapon motor, a Receiver, and some switches and terminal blocks. Each of these parts are pretty typical for the weight class, but I will break each of them down here.

Battery - The original GEC used a 2S 300mah battery. It works, but that size of battery is more commonly used for 150g fairyweight/British antweight bots. I will be bumping it up to a 3S 450mah battery which is much more common for this weight class.

Drive Motors - Much like the original, GEC2 will be using 4 1000rpm N20 micro gearmotors to drive it. These are a little small for the weight class, but using 4 of them is enough to carry 1lb just fine.

Drive ESC - The big choice with drive ESCs is whether you want to have a separate ESC for each motor, or one that drives both of them. Dual ESCs are really convenient and cheap, but also bigger and thus a little harder to fit into your design. This is the one I use. In my experience it will run the 4 small motors just fine if I assign two motors per drive channel, and it has a similar footprint to the battery which makes designing an enclosure easier.

Weapon Motor - The weapon will be driven by a MT2204 drone motor. I don't actually like the mounting system on these and prefer a thinner shaft and top that you can screw into, but they come in sets of 4 and I've only used 2 so far. Next time I'm buying parts, it's something I will look out for.

Weapon ESC - The weapon motor will be driven by a 20A Brushless ESC. Again, these came in sets of 4 when I bought them, but unlike the motors I have no complaints. These make the motor go spinny!

Receiver - I like this receiver. I'ma be real, I don't know anything about receivers, but this one is compatible with my transmitter (controller) and has enough channels to run this bot so I see no need to change things up.

Switch/Terminal Blocks - In the original GEC I used a tiny spdt switch to power it on and off, and all of the wire connections are horrible tangles of badly-spliced wire. This time, I will be using a Fingertech switch, and terminal blocks for all 3-way connections. These are mostly for convenience sake as I don't think there is any reason I couldn't do things the old way. I just like these way more for ease of construction and repairability.

So nothing too special as far as electronics go. These are mostly just what I had on hand, and very typical of 1lb bots. Mostly the same as in the original GIANT ENEMY CRAB but with better battery, or like JACKALOPE with different drive motors. The real magic of bot building happens when you start to put a shell around it all...

NEXT: Let's open up Fusion 360 and build a first draft chassis!

update: the wiring diagram update 2: Preview for what I'm doing next

It's Robot Fighting Time!

Remote Control Robot Combat is a sport where competitors build remote control vehicles, generally with armor and weapons, which then fight against each other in a walled-off arena. It’s a competition based on good design, good construction, and good driving, with all three necessary to succeed in any given competition.

Remote control robot combat traces its lineage back to 1987's Critter Crunch, organized by the Denver Mad Scientists Society at Denver's MileHiCon, conducted on a hotel table which competitors were forbidden from damaging. This ad-hoc competition began a sport that quickly took off across the world, particularly in the Anglosphere (but not exclusively! Brazil, Russia, and China also have vibrant scenes, and India and Pakistan have begun making their way into international competitions). The sport got a big publicity boost in the 90s with the airing of Robot Wars in the UK, and later BattleBots in America, which became the two premiere televised leagues each with their own peculiarities and rule differences.

While Robot Wars has been cancelled, uncanceled, and cancelled again, BattleBots still airs a yearly competition on Discovery Channel, where teams build 250lb machines with hammers, spinning blades, flamethrowers, and other weapons to fight for the coveted Giant Nut. Gone are the hotel tables and ad-hoc rules - over the last 35 years the rules, technology, and metagame has evolved into a stiff competition where teams will put thousands of dollars and man-hours to make sparks fly in the BattleBox.

Don't have thousands of dollars or big business sponsorships that will pay for your bot? While the 250lb heavyweights suck up most of the attention, robot combat happens at many weight classes, with hobbyists also competing at the 150 gram, 1 pound, and 3 pound leagues, with the biggest "insectweight" league being Connecticut's Norwalk Havoc, where 3lb beetleweight robots fight over the course of a weekend, streamed on YouTube for all to see. There are also 12lb and 30lb leagues, but I don’t know enough about them to speak confidently.

New competitors will often start with a robot kit, such as a Fingertech Viper for the 1lb “antweight” class or a BotKits D2 for the 3lb “beetleweight” class. These come with essentially everything needed to compete minus the transmitter (controller), and you can expect to see several of them during any large open event. Of course, if you have a 3d printer and know what parts you need, it can be much cheaper to roll your own. I estimate that an average 1lb bot costs me between $100 and $200 in parts and spares, but that number can increase rapidly with different weight classes or if I get too creative with exotic materials (I love titanium!).

I could talk about robot combat all day, but instead, here are a couple classic fights from each of the major franchises, showing many of the different weapon types you might see in these competitions.

🪚 Carbide vs Eruption 🌋 (Robot Wars 2017)

🔨 Shatter vs End Game 🥝 (Battlebots 2020)

🐸 Polywog vs Silent Spring 🍃 (NHRL 2022 3lb, both drivers also pilot BattleBots heavyweights Ribbot and Sawblaze, respectively)

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