Dragon Con 2018: Postmodern Robotics Comes Home With a Vengeance

Coming hot off my end-of-July trip to the mountain range I keep seeing next to I-81, and aiming to complete my original intended run down to Atlanta via the Blue Ridge Parkway, I decided to do Dragon Con a little differently this year.

Normally I’d be transporting down a whole production of robots from everybody and myself. Life, it seems, hits everyone eventually in the most inconvenient of ways, and a lot of my usual crew couldn’t make it (it seems startups are the robots and elaborate cosplays du jour).  And so this time, I decided early on to stop any plans for developing the next Überclocker /30-haul during the 3 or so weeks of August I had, and only bring Overhaul for display and what of Roll Cake I could get together. I wouldn’t even pack a Markforged printer this time! Imagine that.

So really this was one of the lightest loadouts I’ve done for Dragon Con, ever.  This was actually going to be different for me, and I wasn’t quite sure how to feel about it: Taking an eternity to get down there, actually maybe doing con stuff for once, and only whipping out a robot when convenient. Who the hell would ever do THAT? Go to an entire 100,000+ attendance convention to do stuff that’s not build robots!?

I did a speed-run departing Monday night before the con (Now featuring actual speed!) down to the area of Fancy Gap, VA where, the next day, I jumped onto the Blue Ridge Parkway. I was more interested in the mountainous portions in North Carolina, more so than the scenery itself, so I elected to skip the portion in Virginia as well as not run the Skyline Drive park again. There were plenty of opportunities to take Vans Next to Nature photos.

This was somewhere in Western North Carolina. Where? Hell if I know. The group of motorcyclists in this same parking area didn’t seem to know either. It seems you’re not supposed to know, or pay attention, or care at all; just disappear into the woods and assume you’ll pop out the other side at some point.

I get it. Not as much as someone who actually likes Naturing would, but I do understand.

As night descended on Tuesday, I decided to call a stopping point in Little Swaziland Switzerland, a mountain resort town. This region is very popular with motorcycle tours, as can be seen with Mikuvan’s new and temporary friends here. When you need the size of a van with the cargo capacity of a motorcycle…. Polaris Slingshot. By the way, the NC222A loop around this area is absolutely fantastic. I’m sure it gets tiring if you have to drive it every day to go to work.

I lied. While I didn’t bring along a Markforged printer, I sure as hell did bring a printer in general! I grabbed my “derpy van of 3D printers” Flashforge to make some parts for…. something, on the way down. Yes, I ran it overnight in a hotel room. I ended up having to build a pillow fort around it so I could actually sleep.

By mid-afternoon Wednesday, I’d reached the outer limits of Asheville and….. decided to tap out.

Keep in mind the Blue Ridge Parkway are all very winding, slow 2-lane roads, and that’s no way to cover distance effectively. At some point, I actually had to reach Atlanta and check into my AirCNC.

I decided to express the rest of the way after a harrowing foot-to-the-floor 55mph 4000RPM, 3rd gear climb up the side of Mount Mitchell for what felt like 10 minutes straight. If there was one moment that I was going to blow up my freshly rebuilt engine, I felt like it was going to be right there, but it would have been worth it. Worse, I was low on fuel at that point – there are no gas stations on the BRP – and feared that the straight uphill pull was going to get cut short. I basically coasted down the rest of the way into Asheville to try and conserve fuel.

From Asheville, I took I-40 west until US-74, then followed that down to US-23 – a well known historical path of mine, which I followed to basically outside my old front door…..


…step? Nah, in the intervening year, my parents sold the house. I instinctively glided into my favorite gas station from throughout high school and visits during my years at MIT, on Exit 111 on I-85, but realized I had no more business there afterwards. That was a strange moment indeed.

So, onwards we go to my aircnc house in downtown Atlanta. My local chariot was awaiting as soon as I got there! How positively quaint. There’s been a ton of fuss around Atlanta about scooter rentals lately. I mean, my whole goal of getting a place this close to the convention – right over the Downtown Connector in the “Most Boston part of Atlanta”, the Old Fourth Ward, was so I could just (as we memed it) “Millennial my way over” – whether that means rideshare app or silly scooter rental.

To be entirely based: I completely support silly scooter rentals. The only reason, in my mind, that they don’t work is because governments have outdated patchworks of laws regarding vehicular traffic that isn’t private passenger cars – our current society arguably came of age with the expansion of suburbs centered around the private car, and legislation has ossified around this concept to the point of being cancerous, just like infrastructure spending that is continually strongly biased towards private passenger car use. Much of the battle over scooter rentals is what kind of vehicle to tax, title, insure, and operate them as, and the context of legislative preference for FMVSS-certified normal people cars is unavoidable.

Fight me – I own several shitty cars and several more shitty scooters.

It would also help if people didn’t throw them in rivers.


Hi. (灬♥ω♥灬)

Who I think were the owners of this Model 3 were watching me very intently from a restaurant outdoor seat, so I didn’t get any closer. I was otherwise going to get within an inch for this photo op.

Thursday Funday is over – onto the con!

Overhaul was going to live in the Robotics track room for the whole weekend, so I did that unloading Thursday night when everyone was getting in the area, so I had backup. It would be rolled out for the Battlebots-related panels and otherwise hidden under a tablecloth. It was part of the Battlebots watch party and the “How to Get on BattleBots” Q&A session.

So, how do you get on Battlebots? Well, hell if I know. It’s clear your robot doesn’t have to be good.


That night, I finished the last print at my AirCNC house (whose host said “Would the neighbors mind if I ran a 3D printer all night?” was the weirdest request he’d gotten). And what I’ve been printing all along were in fact parts for my Overhaul cosplay.

It’s a little known fact that Haru-chan, like all good characters, has a male analogue. We actually have a rough sketch of what I call “Haru-dude” made by Cynthia (Lushanarts) from after the rework of Haru-chan:

But he’s too hot for me to pull off, so I simply used it as a design guide and changed up a few things (and also making it more realistic to put together). The “Overhaul head scythe” would obviously not be happening for Dragon Con, but I’ll consider it for something in the future.

I basically modeled and printed the whole thing on the fly, literally during the trip down and on site. I brought a handful of things I figured would be helpful, such as Velcro straps and hot glue and the like. Most parts were not actually modified from the CAD models of Overhaul parts, but made from scratch to exaggerate certain features that would appear too small if I just printed wheel_hub_assy.iam.

3D printing: Replacing the time-honored artform of hand-crafting costume pieces with on-demand kitted disposable bullshit, as-a-service, just like every good millennial trend!

So here we are.

Oddly enough, I was once again behind the camera 99% of the time and only really got this one photo taken of me (credit to Aaron Fan). Oh well, it was the prototype anyway. I actually don’t know of any full-body photos at the moment.

Besides the wrist shanks, I got a gray utility vest and added button snaps to reflect the staggered bolt pattern on the frame rails. I made two “edgelord belt chains”, one out of actual number #40H roller chain from Sadbot’s pokey stick) and one with orange wire loom wrapped around it.

I also made some cartoony wheel sprockets (which are hijacked #80 sprocket models, because again, teeth that are realistic can’t be seen in real life) to clip onto my repurposed motorcycle boots which I used for “dude-Ruby”. I had a few different shades of blue going on, which I’d like to fix for a future more proper rendition.


Saturday night robots with a few more of the crew. A couple of AirBnB houses around the area definitely suffered some robot building shenanigans. This was primarily to finish the 30lber seen on the right, but also to work on beetleweights because Sunday SUNDAY SUNDAY is the Robot Microbattles!

Likewise, after I got done working on other peoples’ robots, I put the last few solder joints in on Roll Cake, then test drove it in the hallway (“Do you mind if I test robots indoors?”). It’s quick, but controllably so, and I was fairly comfortable handling it after a few minutes. I like this new drivetrain a whole lot – the slight lag and torque ceiling of the hub motors is completely gone. It’s almost too twitchy now, and I know for a fact the drive motor size can come down to the next smaller outrunner class and be fine – this will be on the docket for a revision.

Now, back to the post title. I said there was a lot of postmodernism in the robots this year. What do I mean by that as applied to robots?

Postmodernism, broadly speaking, encompasses schools of thought which criticize traditional rationality and notions of objectiveness, calling into question the nature of what we call objective truth. In its basest form it often revolves around the ironic deconstruction and decontextualization of something in a disseminable media format, whether it be visual, text, audio, etc.. In a postmodern reading of something, then, nothing is considered “sacred” or free from reproach, and ideas are stripped down to their essence, lampooned and prodded, and then promptly bolted to the front of your robot.

Stance Stance Revolution is an instantiation of postmodernism in robot fighting: from a vertical spinner foundation, the discs are rotated to lie at angles to create an entirely new robot concept. It simultaneously derives from yet rejects the notions of the traditional vertical disc spinner, and is a complete eyesore while doing so. It raises questions at once of why the epistemological fuck would you do that and huh, I never would have thought of that. That’s kind of cool. I guess.

i am the department head of the school of postmodern robotics. don’t question me.

In short, it seemed to me like more robots than usual this year were doing away with, or severely reinterpreting “being competitive”. For instance, this….

….is quite the expression of postmodern robotics. Elements from a proven topology – a 2WD vertical “eggbeater” style drum – are seen as the foundation, but it destroys all notions of being outwardly serious and competitive by the fully functional LED-lit rubber duck mounted to it.

The duck is a liability. It’s a target for opponents. It prevents any form of operating upside down or self-righting. It might fall off and end the match right then… because all the electronics were stuffed inside it.

But it is the central statement of the bot, at the end of the day. This is truly the beauty of Postmodern Robotics.


From another branch of Postmodern Robotics, this robot is simply a knife with wheels. Why? Fuck you. It’s a knife with wheels. Are you really going to argue?


Roll Cake after the battles were all done. It gave some damage, and took some damage. But most importantly, it moved! And spun! And flipped things, mostly itself!

Full Disclosure: I actually slept through half of MicroBattles. ggwp. I showed up in time to watch a few more matches and participate in two rumbles at the end. Overall, I’m content with how the bot handled itself in the arena. One of the drive motor pinions ended up letting go and I was down one drive side for much of the first rumble, but used the gyroscopic forces of the drum to hobble around and make a few more hits.

One thing I ended up discovering was that the flipper arm wasn’t aggressive enough, due to the more conservative linkage travels I designed in. If your flywheel doesn’t slow down much per use, it’s oversized for the load power. I can probably make the linkage fan out more and trade some more efficiency points for a higher travel.

I ended up not really having time to recharge the battery for the second rumble, so it was running out of power around the middle. Overall, not a very competitive outing, but it showed me the drivetrain idea was sound now and the weapon drive system is fairly flexible in terms of actual layout. I’ll design up another version which is more Roll Cake 3.1 than 4.0 with some changes, but in the back of my mind is also a flipper-focused (non-exposed drum/flywheel) version, more like Magneato of NERC 30lb Sportsmans which Überclocker has fought a few times.

Now, we move onto Monday and the full-size Robot Battles. Remember when I said something about bad ideas just being bolted to your robot? Well some times it’s not even with threaded hardware….

That’s…. an interesting approach. Why so many ducks? Well, why not!? Better yet, they’re all squeak toys. Whenever this robot landed off the stage, it usually let out a protracted squeal sound from one OR MORE! of the ducks deflating.

It was otherwise a nondescript 4-drill-drive pusher bot. Postmodernism!

This is a robot which solely used a pool noodle for a weapon.

Appropriately named “Eyesore”, a newbie team (yay!) with a love for fluorescent paint.


nice bite force


Now we’re getting extra weird here. What do the ladybug balloons do on this robot? Nothing in particular. Yes, it fought every match with them!

There were not one, but two mildly-modified Roombas (and Roomba clones, as seen above) with things appended to them. One was in fact still “autonomous”, as autonomous as a Roomba can be, and was simply set loose on the stage.

This is a….

You know what? This isn’t even postmodernism any more. An entry with a FULLY FUNCTIONAL, ALL 3D-PRINTED tower crane on top of it? Now you could say we’re hitting on the territory of…


Get it? It’s a crane. Structures. Hhhhueuheue

This little saw-bot returns from previous years with an overpowering serving of new incongruently-themed stickers.

(Saws on an open stage?! I always take the time to explain that all freely-spinning appendages of robots are limited to 20ft per second tip speed in the Robot Battles rules, in case the message doesn’t carry through on first glance).

And finally, the robot I was helping work on, Skuld! Built by Leanne from Valkyrie, it’s a 30lber that has a very competently-powerd hammer with a 63mm-class outrunner. This thing could hit hard if it needed! It also had brushless drive with some highly geared inrunners.

That’s not a safety cover on the hammer arm end. That is the hammer arm end: One of several interchangeable plushies.



This is what the ideal robot fight looks like. You may not like it, but this is peak performance.

I don’t even know what the snout-on-a-piece-of-wood is from, but it paired with a powerful drive base is surprisingly effective.

Look! I entered a robot this year! It’s only 217 pounds overweight, no biggie.

On a last minute whim before the 12lb 30lb rumbles, we decided to heave Overhaul on stage to act as an arena hazard (it’s not running since I haven’t repaired the ESC damage from #season3 yet). It added an interesting play element: Suddenly, there was something to drive around and play hide-and-seek behind. People used Overhaul immediately to their advantage this way, skulking around looking for easy openings. Bots with giant wheels could escape by just driving up and over the forks. At one point, 3 or 4 30lbers teamed up to try and push Overhaul – they got a few inches in before the party got violent and broke out into fighting.

Probably one of the best rumbles I’ve ever witnessed come out of this event. It really makes me want to add a terrain element to the MassDestruction arena even more, in order to change up the small-bot game.

And this concludes your introductory lecture to Postmodern Robotics! I took a while to meander back north afterwards. Overall, I can say this Dragon Con was way more stress-free than any previous one. I was happy to see the competitive edge coming off of Robot Battles again, because a few years ago, when I and Jamison and many others were in (or around) colleges, we went through what I call the Tryhard Era of Robot Battles where the matches were becoming just as intense as any of the NERC parties and newbies were getting shut out or demolished. With the return of the TV shows, a lot more folks are cutting their teeth (metaphotical, drum, or otherwise) at these events, and I’ll happily step aside (or sleep through) them to let the interesting unjaded, sacrilegious designs fluorish.

On deck for the immediate arrival of fall is a lot of company-related pregaming before winter really sets in, so I’ll probably have limited content again for a little while. I’ll be slowly picking at 30haul, Overhaul, and the silly van nation in the mean time, but probably aren’t going to do any intense building until well after the new year.

Roll Cake 3: The Build!

It’s time to put a robot together! This post covers the entire fabrication of Roll Cake 3 in the week or so before Dragon Con. The goal of the bot was primarily to try and drive better with an indirect drive brushless setup and also further refine the packaging and action of the flipper linkage. Will it do anything?! Hell if I know, that’s the fun part to discover!

Even as I was finishing up the design the weeks prior, I was pregaming getting parts. Basically as soon as I determined the C2028 motor would fit in the triangle behind the wheels, I went ahead and ordered 3 more since I only had 1 to start with.

I also ordered these OMG THE MOST ADORABLE LITTLE 0.8 MODULE PINIONS EVER THAT COST WAY TOO MUCH MONEY from SDP-SI. I had to go solely by what they sold for 2mm bores in these gears. I wanted an 8-tooth gear to achieve the 8:1 reduction I wanted to get with the wheel gears, but they only sold the 8-tooth with a 3mm bore. So my drivetrain reduction is going to end up more like 10.6:1, which is fine by me – the bot will be too fast no matter what.

The problem with these tiny gears? The 2mm bores were slip-fit, not press-fit! Certainly irritating, but not the end of the world. Already noted for a revision in the future is maybe transitioning to R/C model pinions, such as R/C car transmissions. Those typically come in 3mm or 1/8″ bores.

I used Loctite 609 to stuff the pinions onto the motors in the end – I tried to silver solder one of them to little success – while I’ve managed to solder or braze pinions before, it seems that the steel they used in this motor shaft is an unusually high chromium grade which didn’t want to take with any flux I had on hand.

That was before I melted the pinion completely. Ah well.

Completed drive motors refitted with their shafts, which was a minor press fit job. I also replaced the stock stainless steel prop-saver screws with drilled-out and re-tapped #4-40 set screws. Another minor point of trouble with these motors is that due to their length and the small shaft diameter, it was hard to get these things to spin entirely true again after resintalling the shaft. A shorter motor (more pancakey) will resolve this.

I put the gearbox parts on print in Onyx as soon as I finished the bot design. The two ring gears and main cam linkage (sticking off to the left) have hoops of carbon fiber; everything else just derives strength from a bunch of perimeters. On the very left are the two connecting links between the cam link and the arm. I also made two first-pass prints of the drive wheels, seen here with O-rings.

Frame parts freshly done and needing cleaning. I’d say this is the only irritating part of doing unibody bots for me – picking the support out of difficult crevices. There’s certainly orientations that I can print in for minimal support, but they sacrifice immense strength in the part itself.  Both of these frame halves were printed in the orientation shown to give continuous loops in the XY (flat) plane.

In Roll Cakes past, I’ve actually taken to making fiber laps around the frame in this orientation, but with the more recent-ish changes to Eiger, you can change the perimeter and fill with more flexibility such that I just stack on the perimeters.

Otherwise, pull out some injection-molded part design – relatively constant wall thickness and smooth transitions if you can manage it, using ribs and cavities versus just solid massive areas, etc. However, my habit with 3D printed frames is leaving a few bulky areas up front such that they remain somewhat hollow – this acts as a very effective energy absorbing medium. For instance, basically the front inch or so if this bot is solid in the model, which means it’s perimeter plus non-solid infill in real life.


Drive motor installed with some test fitting done on the wheels here. Most of the hardware on Roll Cake 3 is specified as plastic or metal threadforming screws. If you get really fancy, people like using heat-set or tanged flanged inserts in MarkForged prints. However, I like my expediency, so some fat #10 tri-lobe threads will do to hold the wheels on.

Here’s the final drive fitup. The 0.8 Mod (32-ish DP) gears printed perfectly fine. In my experience, this is about as small as you can print reliably because the nozzle diameter still is small enough to go in and out of tooth tips profiles.


Both sides now fitted with drives. The front binding screw is shown sticking out here.

…and now joined together. Already, this thing is way more rigid than last time side to side. Hell, I might as well just ditch the flipper and make it a pure drum :v

The screw length needed to do this assembly were compromises with what I had on hand, so the bot dimensions shifted a little to accommodate them. Roll Cake is in fact not a perfect circle, but slightly squished inwards to yield the rough double-D-flat shape.

I slid in the trigger piece (which has a cutout for the servo arm) first, then I slid the servo into the DMs.

Alrighty, all the easy 3D printed stuff is assembled now. I still have to make a drum and motor, so off to Taki-chan we go!

(Also, check out the waterjet-cut feeder wedges made from leftover Hardox 450 from Overhaul!)

First order of business: separate the motor magnet ring so I can stuff it inside the drum. This can’t always happen cleanly, depending on the motor’s construction. The Donkeys have a single-piece stamped steel rotor, so I simply chucked the shaft in and very carefully parted at the outside corner where the magnet ring area joins the endcap.

With a motor that has an aluminum endcap, it’s often scarier since the parts can separate and self-destruct.  Luckily, this operation went very smoothly with higher speed and gentler feed to keep the forces on the rotor low.

Next up is to rough the drum shape. Most of this was easy, but I had to make the dual-disk shape, so I had to cut a valley in the middle. I just went with multiple staggered parting tool cuts to nearly the right shape, then very very carefully and gently made really shallow passes side to side to clean the profile up. Very gentle. These insert tools really should not be taking any side forces. To do this without wallhacking, I’d have gotten a single wider custom-ground HSS tool or something.


Then I bored the drum interior. There’s three stepped diameters – one for the ring bearing, then the magnet ring of the motor, then the “doesn’t matter” internal diameter. For the output side “bearing-stem-gear” I just did a straight drill to 12.0mm since it did not have to be that precise.

Next up: stator holder.

With the aluminum parts roughed out, I decided to make the one odd piece, which is the gear-on-a-stick that will carry the drum energy into the gearbox. This was a pretty easy turning job, but remember, it’s also the other bearing of the whole drum. The center bore, then, had to be 1. a clearance, but not by much, and 2. very clean and precise.

I actually went out and bought a 8mm-plus-0.001″ …. yes, this exists in America…. reamer to make this bore. You read that correctly – it’s a 0.3159″ reamer.

The gear gets a cylindrical boss on both ends eventually. After I finished both sides, I actually had to take a wire brush on an angle grinder to it in order to deburr the gear tooth edges – there were many little burrs and swarf hanging on which would have prevented the gear mate from working.

Parts in the midst of preparation! The stator bore has been drilled and the stem gear keyed on the top surface seen.

Throwing it together for a quick test fit! Here’s where it’s clearly visible that the stem gear skewers the cam ring gear and the cam linkage.

The next task was to drill the tooth holes in the aluminum drum body. I no longer have my old indexing head that made guest appearances in many of my undergrad builds, since I donated it to MITERS years ago. So to make sure I’m able to place the teeth 180 degrees apart, I milled a very shallow flat, then rotated it to sit on that flat, then milled another one.

This ensured I can drill and tap both sides with relatively equal precision. The teeth are just 3/8″-16 alloy cap screws, so they thread right in.

After the drum body was fully fnished, I broached it for a 3mm key – the stem gear is shown here mated to it. The magnet ring pressed into position without much trouble.

Unfortunately, I didn’t have time to make a new set of cluster gears, so I had to take them out of Roll Cake 2. Sad, since I wanted to keep that bot fully operational if I could!

The thought has crossed my mind of hiring out a whole basket of little cluster gears to be made if I’m going to keep evolving this bot.

The catch with these compound planetary cluster-fuck gears is that they have to be assembled at specific angle, or phasing, since there’s a hard relationship between the number of gears and the relative tooth counts. I scratched alignment marks into them when I first put them together for Roll Cake 1, and still use them for reference.

The gray goop I have dripped all over the assembly is liquid bike chain wax. I’ve been avoiding using petroleum-based lubricants like common greases because I don’t want to risk damaging the nylon-based Onyx material from the solvent action. Grease would also add immensely to the no-load drag of the gearbox, which is already a lot happening for a weapon drive.

The planet carrier installs easily after the gears are properly phased in place. It looks from here that there’s a ton of stuff going on, but I guarantee you this is not the case :v

As I mentioned in the design post, this carrier now has its own bearing to support itself. This is a pretty odd (but still apparently some kind of standard) 8mm bore, 14mm OD bearing – very low profile.

The drum drops into place from the front. The service order of this thing is a little suboptimal – to service the drum, I have to disconnect it from the folding linkage, but the central pivot bolt doesn’t rise up out of the body’s central cavity…. so really I have to undo the bottom linkage anchor (those three screws in a row from the CAD model) first, then remove the arm hinge. At least I made sure to make it all serviceable with at most 2 tools this time!

After the drum and arm are mounted, it was time for electrical dressup.

Along with the feeder claws, I cut another insectweight top plate set out of this piece of 1/32″ blue spring steel shim. I bought like 10 feet of this shim some time during undergrad, and have slowly been generating robots out of it since. This thing made its first appearance all the way back in 2009 with Pop Quiz’s rebuild! I’m now on the very last 8-10″ of it after Roll Cake’s parts are accounted for!

For better or worse, picking the parts out of the mother material was one of the last things I did before absconding on  3-day long slow meander down to Atlanta for Dragon Con. On the way, I hit up the Blue Ridge Parkway, like I promised myself I’d do. I only brought Roll Cake and its suite of service tools and a box of parts I think I’d need (mostly electronics), and Overhaul for display. This Dragon Con was going to be a pretty clean show instead of scrambling to take care of a few robots – the reason for this is I was pretty much solo this time, as there was a lot of bad timing involved for the various startups and schemes my friends and I are all involved in.

So what’s better than finishing your bot in the airBnB room when you got into town? Not all that much. I pre-gamed some of the electronics wiring (like battery leads and the like) before I left, so installing the two drive ESCs (AfroESC 12A) and weapon ESC (Spider ZTW 40A with SimonK) was a quick affair. I was able to drive Roll Cake around on the floor to get a gauge for its handling – which is much, MUCH improved over the hub motor drive version.

It’s very quick, but much more maneuverably so than Roll Cake 2, which tended to twitch everywhere. I swear the twitching is better than it was! At least now I could predictably send the bot places, which is an improvement over before!

The flipper geartrain was very tight, though, because I hadn’t had the chance to run it fully in up until that point. It would take several minutes of just running the drum at maximum speed and also a while of keeping the linkage engaged to wear everything in.

Here’s Roll Cake 3 fully buttoned up!

And shown with the flipper linkage at full height. In the next episode, hopefully you’ll get to hear about what it did, if anything!