12 O’Clocker & MassDestruction 6: Where I Rebuild a Bot After the Event is Done


I feel like this website has become the Life of Charles, what with real editorials and non-stop round-the-clock van coverage and my tenuous professional aspirations… This is not the man I know. Where has he gone? *looks at own hands*

But now I’m back, with some new developments for Überclocker in preparation for Motorama coming up next week, as well as 12 O’Clocker stories to tell first. This bouncy little thing has been going to events and demos since 2013 with hardly any changes – just switching motors, basically. It’s gotten sufficiently worn down to a stub in the past few months that I decided to do a full teardown rebuild with some new parts!

To tell this story, we go back to the dark days of MassDestruction #5, like 3 months ago… Wait, CAN YOU BELIEVE THERE’S BEEN 5 OF THESE THINGS ALREADY? THAT’S MORE SEASON THAN BATTLEBOTS please take me back greg ;~;

This MassD, I took a more organizational role, helping judge and run matches. However, this didn’t prevent me from putting 12 O’Clocker (at the time, my only working bot -_-) into the arena in the somewhat informal 12lb Sportsman’s Class, where pretty neat matches like this occurred. MassDestruction has become a popular regional attraction; word has gotten out, and we pretty much filled out the Artisans’ Asylum event room to capacity. Like, look at this photo.

This is “filming a music video using the flashmob mosh pit at your post-phlegmpunk band’s free unannounced concert” level stuff. What’s better is that the builder population is getting more and more towards being newbie-dominated. This is a great problem to have.

12 O’Clocker came in 2nd place (out of like….3?) at this event, which was great, but it did take some damage. For the deterioriating ABS motor mounts that retained the lift motor finally gave out completely, wrenching the drill casing apart under its own torque:

Oooooh, that’s not good. I finished the tournament using a found drill motor given to me by an Artisans’ member, unceremoniously hot glue MIG-welded into the remaining mounting block pieces. At some point in the final against Snek Plissken, I also lost the lift motors which turned out to be one of the logic capacitors on the old RageBridge 1 units in 12 O’Clocker just breaking off the board. I also ended up demolishing another motor pinion just like at Momocon; the most recent set of motors for 12 O’Clocker came from some 12V Ryobi drill motors, and it seems like they were not up to the task of being run at ~20 volts.

Fast forward another 2 months, and MassDestruction the SIXTH! was on the horizon.  With the promise of more rematches with Alex Horne’s not-Sewer-Snake, I decided on a quick tuneup by replacing the broken ABS lift motor mounts with MarkForged Onyx prints because of course I did. New drive motors were also on the docket.

The Rage Panel slides out from the bottom, so I took the bottom plate off, which also let me do a hardware inspection on parts of the bot I rarely touch after finishing. This level of surgery was also needed to finally detach those ABS blocks.

So new drive motors were a bit of a conundrum. When 12 O’Clocker was built, it was still common to find generic cordless drill motors with 9-tooth pinion gears and 36:1 reduction (two 6:1 stages, 9 tooth sun, 18 tooth planets, and 45 tooth ring) gearboxes. Nowadays, it’s almost impossible to find these kinds of gearboxes, with 24:1 being the most common such as being found in all of the Harbor Freight 18v drills and most other rebrands. The 24:1 boxes have a 4:1 first stage using a 15 tooth pinion.

Trouble is, 12 O’Clocker was already geared to go fast, and dropping the gear ratio another 50% would have made it impractically fast and probably burnt out the motors in short order. Those Ryobi drill motors that I kept slipping the pinion on were attempts to find more 9-tooth motor pinions to fit the existing gearboxes.


After some haunting online, I found that one of my usual Amazon suspects uxcell sold 18v rated 550-sized motors with steel pinions already installed. Well imagine that, a prepared artificially flavored drill motor!  So I got a bunch to play with. They certainly look like 550-size motors and quack like them. The cans are a little thin, pretty typical of a mature Chinese genericized product… I can pick them up with a screwdriver. Every possible area of cost cutting has been well optimized!  The bronze shaft bearings obviously have no oil in them, since they are a little rattly, but a drop of motor oil in each solved that.

What I did notice was that the pinions’ press fits weren’t that tight. It was actually easy to undo them with a flat-blade screwdriver alone. To pre-emptively avoid embarrassing public gear slips, I took the pinions off and repressed them with a healthy dose of lime-flavored Loctite.

You know what – I’m just all giddy at the fact that they’re motor-shaped at all.

At some point in one of its tournaments, 12 O’Clocker either fell off a Dragon Con stage and landed on its main sprocket, or I got beaned by some flying robot, because the sprocket developed a flat spot which caused the chain tension to vary cyclically, leading to some lost chain moments.

In a moment of either desperation or brilliance, I decided to use my Harbor Freight slide hammer kit with a hook end to pull the sprocket rim back out like you would pound a very reticient dent. I bought this originally for van repair, but it looks like it works for robot dent pulling too!

Putting things back together, sans battery. The Ragebridge 1 with the missing capacitor had that repaired; the capacitor ripped out a logic power trace when it fell off, so it just turned the controller off. All the caps were securely Goop’d in place after the replacement surgery. If you’re using a Rage or a Rage 2, you should do this just in case also.

The biggest problem plaguing 12 O’Clocker was its battery, which I balanced once in 2013 and never again since. The cells had drifted far enough apart since then such that two of them flatlined at MassD #5, and I could no longer revive them. This meant I had to cut the battery open and undo the cell joints to the point where I could pull the two dead cells out and replace them with fresh cells. I closed the battery up again after this replacement (the green tape is new and covers the modded solder joints) with some thicker heat shrink, and making my charger do 5 overnight balance-charge-to-discharge cycles evened the cells out.

One last mod before MassD #6 was the permanent resolution of the clamp motor coming loose. The threads in the face of these Pololu 25D HP motors had completely stripped, so the motor was really just holding on by the electroweak interaction at the end. To remedy this quickly, I just took the faceplate off, slammed a #6-32 tap through them both, and then countersunk the original mounting holes in my actuator body. #zerosigmas is best Sigmas!

If you use these motors, or any of the similar motors from Servocity or Kitbots (or the straight shit from eBay), make sure to also take the motor off, clean the area, and use blue Loctite or similar threadlocker on the reassembly path. The motor does like to also wiggle loose – this is what the “battle hardening” mod offered by Kitbots helps prevent.

So anyways, it’s the morning of 1/28. Time to….

literally all the robots

This is what I trained for.

That’s Overhaul, Sawblaze, and two lift carts in the back. With space for another smaller heavyweight, or a dozen 30lbers and tools & equipment. And probably like 27 people. Some times it’s nice to just bring the U.S.S. BROWN C. STENNIS to an event.

This time, the event was held at the Charles River Museum of Industry, in one of their large event rooms. I once again helped with event logistics including box setup and judging. Overhaul and Sawblaze were brought along for visual stimulation, which was unfortunately because the event room has neither loading dock nor wheelchair ramp, and was, of course, a New England First Floor – 6 feet up the stairs.

Running 12 O’Clocker – especially when things started breaking – and half a robot show at the same time was a unique and singular experience. I will never do it again.

Have some 12 O’Clocker matches!

The match against Don’t Step on Snek, a.k.a Snek Plissken, a.k.a Sewer Snek… god dammit Alex, pick a name already!

By this point, 12 O’Clocker had lost basically all of its forks. They finally reached their fatigue limit at this event, one by one breaking off, until I had basically a big spatula. In the match prior, the right side motor pinion slipped its press fit as I had feared, so I went into the final match (also against Alex) one-motored. Which is fine, since Alex at this point had also started to run out of motors. The finals match was such a headdesking, facepalming occasion that I’m not even going to bother finding a video.

Poor 12 O’Clocker before the finals with the forks arranged the best I can, so SOMETHING AT ALL is still sticking out ):

Well, that’s it for the event. I broke the damn thing so much that I felt like I might as well use the momentum of the event to make spare parts. As I needed to also waterjet-cut spares for Überclocker, I threw on replacement forks for 12 O’Clocker in the same run.

Tearing down the bot completely up front to replace the fork components! This is where I discovered that despite my best attempts at anti-seize grease usage, the lift sprocket’s hub had galled onto the aluminum tube shaft, so the slide hammer was needed again just to break those two apart. I reamed all the shaft collars out again and cleaned up the aluminum shaft surface. This time, I tightened all the collars as much as I could – no longer relying on clutching the lift sprocket for torque limitng, but just setting the RageBridge current limit low enough that running into itself will not cause problems.

The new forks are slightly modified from the current design by adding more meat to the areas where the tie rods pass through. This was previously where they broke, so I made sure to add at least a majority of the cross-sectional area found in the rest of the fork.

By the way, this tube-removing service is also a problem with Clocker, especially after everything got twanged far up its own ass at the Franklin Institute event. I’m going to reconsider using a live shaft with shaft collar hubs to the forks for this reason, possibly considering a more Overhaul-like tie rod and central hub approach. Otherwise, I’m going to make an attachment for the slide hammer specifically for this purpose!

And here’s the refreshed 12 O’Clocker! Hopefully a staple of many demos to come.

The Unlikely Story of MomoCon; 12 O’Clocker Returns, #weeabot Intensifies, and I Haven’t Broken Down Yet

Momocon is a pretty big anime & gaming convention that’s been running in Atlanta for about a decade now. I’ve somehow never made it to the event – either it was inconveniently timed being the end of the Georgia school year back in high school, or I was, you know, up in Boston getting my degree in Hoodrat Stuff & Bad Things.  So when the organizers of Robot Battles and the Atlanta-area builders, including some members of the Chaos Corps, were hinting that the next event might be held at Momocon, I quietly rejoiced…..and went straight back to work on Overhaul (Which I still owe everyone the next edition of the build report for…)

Whether the original announcment went unnoticed because of the build season, or it wasn’t shouted loudly enough across the community, I actually didn’t remember anything about it until, oh, about 2 weeks ago when I was reminded by some people asking if I was coming.

Ooh…. well crap. That certainly is going to mess with my plans a little. I mean, I guess I could probably go, but it’s kind of a short-notice thing and I dunno if it’s worth flying down for just one weekend and what will definitely be a small event. And I’m not sure if it’s worth the time to drive, even if it means I could bring Overhaul and display it, bec…

hold on a second. didn’t i quit a job or something so i could do stupid robot things whenever i wanted?

Hey, I’ve spent all this time promoting #weeabot, and here is a robot event at an anime con and I’m actually debating whether or not to go? Load up the van!

But before I could do that, I had to make sure of two things. One was that I had a working robot, and the other, a working van. I’m so good at life, guys.

12 O’Clocker

I stood over my pile of small robot wreckage, wondering what exactly I could bring to the competition. I was missing parts that would need to be rush-ordered for almost all of the 1lb and 3lbers, like Colsonbot and Stance Stance Revolution. Überclocker is a wreck throughout, and I also promised that it was done for real after Franklin Institute.

Then there was 12 O’Clocker. Put together for Dragon Con 2013, it didn’t do too well because its drive motors fell off. Beyond that, the bot was undamaged. I figured in the time I had remaining between when I’d need to leave, which was about 4 days spanning a weekend, I could at least remake the drive gearboxes. Those things were originally 3D printed from ABS plastic using the Dimension 1200ES machine. Now that I had access to the MarkForged Mark Twos, I could make them from nylon, which is a much stronger material in the application.

So that was it – I was just going to repair 12 O’Clocker for now. I discovered while trying to put Colsonbot back together that I was short on Vex 29 motor controllers to have it run, so there goes that.

Here it is, dug fresh from my crypt of robots. There’s really nothing wrong with it at all that I could tell, but I’m going to fully deconstruct the drivetrain and liftgear just to be on the short side. As a reminder, the drive motors broke off their mounts at Dragon Con 2014, so the drive will be my focus.

Pulling stuff apart little by little revealed things that I forgot I had Loctited, and other things which weren’t. This was chance to correctly detail the bot. For instance, the inside bolts that hold the axle stubs to the frame SHOULD be very tight and threadlocked to prevent the axle from moving. The external retainment screws should not, in case I had to change wheels. For at least 2 of the wheels, this was backwards for some reason…

Extracting the gearbox housings…. Ouch. Not only were the motors jiggling and detached, the gearcases were cracked clean through in some places. This seemed very strange to me, since I ususally know 3D printed ABS as being quite tough and flexible. Short of the oil-based grease getting into the print and damaging the polymer, I’m not sure why this happened.

You can see that the cases weren’t just cracked, but broken through in numerous places. Here are the gearboxes entirely taken apart and ready for cleaning.

I modified the gearbox part files just a little to address shortcomings in the original design, such as the diameter of the ring gear socket and its length. I do like these things, and post 12 O’Clocker I kind of want to put some more design effort into them. They were then printed using “close to solid” fill – something like 90% density and the plastic fuses together anyway, and if you go more than that it tends to be blobby.

Reassembled and relubed gearboxes using the new housings…

Beyond that, there wasn’t much else that needed work. I went ahead and cleaned and regreased the actuator, since it was very dirty from storage, and adjusted the chain tension of the lift chain also. In all, it was about 1 equivalent afternoon’s work (spread across two, to wait for the 3D print to finish) to get 12 O’clocker back in fighting shape.

cruise control for cool & operation vanfan part II

I next turned my attention to some “deferred maintenance” items on Mikuvan that were acceptable for blasting around town, but not for any type of long haul operation. After the Great Accidental Engine Rebuild Debacle of 2015, there’s been no mechanical and driveline problems at all, but some small irritating things were left over or perhaps caused indirectly by tearing everything apart.

One of these was a consistently leaking upper radiator hose which developed during last fall & wnter. It was just inconvenient enough to get to that I just accepted putting in some more coolant every few weeks. I decided to just get rid of it for the trip, since I did not want to risk losing coolant when driving in the much warmer South. Fortunately, it turned out that the hose was just seemingly improperly seated, and the cold rubber parts did not seal as well during winter.

Next, some time in February, the front heater/air conditioning blower died again. What an inconvenient time…

Now, this thing was rebuilt in the parking lot of Georgia Tech all the way back in 2013. And I quote:

Well, okay, I did have to rebuild my A/C blower motor again, in the Georgia Tech parking lot. Remember those brushes I installed? They were backwards, and they ate through the copper bus wire after a few thousand miles. A random 200W scooter motor turned out to have the exact same size brushes, and saved the day.

35,000 miles later, those little piddly scooter brushes finally bit the graphite dust themselves…

In this photo I’ve already desoldered one, but the other definitely wore all the way through and fell off. Sadness.

I actually did not have another similar scooter motor to pull brushes from, so I sacrificed a similarly sized motor with larger 6x8mm brushes…. and manually filed them down to 6×6. These brushes were much longer, but they still fit in the same holders. Hopefully, this will last more than 35,000 miles now! If the damn thing didn’t require a dashboard pull to remove, I’d have long ago replaced it with something modern and brushless…

Beyond these two items of inconvenience, there was really nothing I could work on. I know, right?! Time to make a problem for myself.

Little known trivia: Mikuvan has a cruise control system. It’s made of vacuum tubing and actuators, and has never worked. All of the vacuum lines are cracked or broken, and some just lead nowhere or are hanging around.

I wondered again how bad things could be, so I bought a spool of vacuum line and hooked everything up the way it was supposed to go. I cleaned the chevk valve and manifolds, and also took apart and relubed (to the degree I could) the throttle cable coming from the vacuum piston. I didn’t even verify if the system was holding vacuum – just shoved everything back in.

Hey, not manufacturer-approved routing, but whatever. The servo piston is seen at the bottom right – this tugs on the physical throttle pedal based on ECU commands. In new cars, everything is by electronic signalling now, so this system is absent.

During this process, I FINALLY figured out where the last missing vacuum nipple on the intake manifold was supposed to go. It was a random vacuum line connection that did not seem to go to anything, and which caused idling problems before I found it, since it was just a big air leak. In the end, this line was connected to the cruise control system. I’m guessing it uses engine manifold vacuum to purge the system. There is a small vacuum pump (which does still work) towards the top of the photo that keeps the system on the other side of the check valve purged also.

I also found this.

I, umm. Not sure where that came from, nor what it was doing, but it’s a big M10 flange head bolt, so it definitely was doing something important. Well, time to see if anything falls off.

Anyways, the answer was yes, everything still does work. Cruise control!

It is, however, rather boneheaded. I tried testing various potential failure modes, such as setting cruise for 55mph, cancelling, accelerating to 75mph, then hitting resume. Yes, it will attempt to dramatically engine brake from 75 to 55 by just dropping into 3rd gear.

Otherwise, on uphill inclines, it will also fall back to 3rd and make a whole lot of racket and not do much. I’m guessing it’s supposed to go harder in 3rd to bring the speed back up, but it does not seem to pull on the throttle much, and instead I thunder up a hill at 4,000 RPM, and actually also down the other side, because now it wants to go faster than the set speed and is using engine braking to maintain speed.  Definitely less useful than what you would find in a modern car, but whatever, I am told the 1980s were a wonderful time regardless.

On mild hills and flat ground, though, it works great!

The Trip Down & Momocon

There were no shenanigans.

For the first time, I can say that nothing weird happened on the way down. I’m both a little disappointed and now a little fearful of what lies in wait for the return trip.

Out of an abudance of caution, I took the 95 corridor against my own advice. Generally, I try to avoid I-95 below Connecticut and above Baltimore, but it lay closer to possible bailout points (e.g. friends with couches and shops). I tried to set out at a specific time to just barely make it past D.C. before rush hour hit, but goofed up leaving – delayed by about 45 minutes, because I was actually stuck behind a garbage truck in Cambridge slowly doing its thing down a one-way street, among other issues like construction and morning traffic in Boston – such that I managed to instead hit the afternoon commute exactly, upon which I decided to give up and grab dinner, because NO.

I overnighted in Durham, NC, at the best quality sketchy-ass motel I’ve ever seen.


Unlike most previous conventions and robot events, I hauled the 18-20 hour trip alone this time, which means that it sucked ass and also I decided to conserve energy by breaking the trip into two days. In 2011, I tried hauling the whole trip in one shot (only stopping to rest enough to continue), which meant it sucked additional ass. So really it took me over 1 day – 14 hours on Wednesday and around 5 on Thursday – but I wasn’t sad and tired when I landed in Atlanta shortly after lunchtime.

Well here I am!

I have yet to figure out how to wrestle Overhaul in and out myself. I might make some kind of sliding rail system for the cargo area here…

Anyways, let’s go check out the convention!

As I said, I haven’t ever been to Momocon previously, despite it being an Atlanta convention. It started on the campus of Georgia Tech, but recently it has amoeba’d it way into the Georgia World Congress Center, which is a huge place. What I noticed in general was that it definitely had the “big convention” atmosphere of something like Otakon or Anime Expo, but the venue is just so cavernous that the crowd density is much lower. So you’re not jammed next to hundreds of people sporting the Con Funk all the time like the former 2… or Dragon Con, which is a somewhat different beast.

The action was largely on the exhibit floor, which housed all the gaming and sporting activities. The other exhibit halls held dealers and performance stages. It seems to me like the con can easily expand another 50% in attendees without it getting crowded, which is perhaps their idea.

Besides the animus and mangoes, there is an extensive gaming section – indie games, board and card games, on-site LAN party, you name it.

i n d i e b r o s.

A few dozen arcade marchines – mostly rhythm and music games, were set up here too. Right next to where the robots were gonna go!

Dealer and artists’ hall. Nothing extraordinary to me at this point, and sadly I did not find any Miku gear sufficiently compelling ):

What was awesome, and made me seriously regret not bringing Chibi-Mikuvan… was the “Fandom Replica Vehicle” section. Wow, such a prosaic name for Jurassic Park jeeps. This wasn’t nearly on the scale of an itasha show, which made me sad – actually, there weren’t any of what would be called “itasha” at all.

Next time…

These days I’m usually out to stalk the maker-y parts of conventions, so I was excited to see this group. They make all-3d-printed props, and have the same visual and phonetic branding challenges as MarkForged.

Just kidding, guys. Also, MarkForged, please don’t drop my sponsorship over that. I love you, promise.

I’m also interested whenever someone has a mechanical prop or costume, such as these actuated wings, which were linkage driven such that when she stood upright, they were folded down, but in this attack stance they were fully out. Constructed entire using garage tools, too!

Hay guise, why drag your gaming rigs all the way out here when you can play at home?

Alright, enough con-gazing. On Saturday morning, I went in early to set up Overhaul for display!

It was set by the entrance to the pit area, and I set up a table to display all the battle damaged parts. How were they damaged?

Well you’ll just have to watch the Season Premier of BattleBots, Thursday June 23rd 8/7 Central on ABC to find out!

-me, about 1000 times during the weekend. Hey ABC, pay me to be a spokesperson already.

You know what makes the best business card and sticker holders in the world? Tiny Overhaul action figures! Print your own today!

I was actually designing these slowly before MomoCon, and sped up the effort to finish them in time. In fact, one of the last things I did before leaving was dropping by the Artisans’ Asylum to pick up 3D prints for the 2nd and 3rd one.

Saturday was the “Microbattles” ants and beetles tournament, where we had 6 in each weight class. I didn’t have an entry, so I just hung around the pit area as pit boss and general event help. The audience was quite steady throughout the event. As usual, the little bots are a bit hard to see up on the stage, so I think a lot of folks didn’t quite “get it”. I did talk to many people about BattleBots, Overhaul in particular, and some other bot talk.

I’d say about 6 in 10 people did not know BattleBots was back on air (WELL I CAN FIX THAT PROBLEM), 3 in 10 have seen parts of Season 1 but were not devout fans, and 1 in 10 knew enough about the show and the robots to ask me a lot of detail questions. I made them promise to build something for Dragon Con.

Sunday, SUNDAY, SUNDAY! It’s “relatively large” bot time! I left Overhaul & displays behind the pit banner, figuring nobody would just bail with it, so it was quick to set back up.

Here’s 12 O’Clocker before matches started. In addition to it, I was appointed to pilot Morrigan. Mike basically brought the entire tournament this time, with 4 30lbers and 2 12lbers.

A view from my corner, which I was manning when 12 O’Clocker didn’t need something tightened or recharged.

Now this audience was much livelier. I guess the bots are bigger and you can generally ‘feel’ the impacts more but we maintained this kind of crowd basically the whole day.  At one point, Morrigan was making so much noise that we were overriding the rhythm games and the whole arcade crowd wandered over to see what was happening, or if they would die shortly.

Additionally on display: Giga-Nyx…. err, Bombshell, from Chaos Corps. They only brought some weapon modules. Why?!

Well, you’ll just have to watch the Season Premier of Bat….

Oh, fuck it…

This thing I had been looking forward to. The newest kinetic bedlam from Dale, T-Boner (hhhehehehhehehe) has a scissor-action flipper driven by roughly the same mechanism  as the larger Overthruster. I have an eternal robot crush on KE-powered (flywheel) flippers, but have yet to produce a design. Better yet, it’s also all-brushless, using the same SimonK-enabled ESCs that I run on Stance Stance Revolution and a couple of other people use on other small bots.

So how did 12 O’Clocker do? Actually quite great. I went 2/2, winning against Dingleframus and Hypnus, and losing to Tetanus Shot aaaaaaaaand…. T-Boner. Of course I did. There was a lot of dancing involved, and 12 O’Clocker was a big crowd favorite. 12 O’Clocker can’t excute the “spin to win” grab-and-spin that Überclocker can, but I could relentlessly beat people on the stage over and over.

As per usual, the matches were recorded by Near Chaos, and the playlist for 12lbers is here


12 O’Clocker post-event. Someone in the 12lb rumble snagged on the left side chain and pulled it off, and shortly thereafter I actually lost the right side too. A little post-mortem showed that the drive motor on the right side destroyed its pinion press-fit. It’s a brass pinion on a steel shaft, so the steel shaft won handily.

Besides that, in one of the T-boner matches, I suddenly lost the lifting fork. Turning the bot over, I saw that the ABS mounts for the drill motor had cracked and the motor actually popped off the gearbox. While that was a quick repair for the motor itself, the ABS mount basically stripped all of its screw holes as soon as I took the screws out. To remedy this, I had to drill it all the way through and use some 2″ long bolts I packed which were part of Overhaul’s hardware package that I brought along. I’m not sure if I’ve just been spoiled completely by Markforged nylon prints, or if ABS was always this bad and I just accepted it, but I am so done with ABS as a material.

With my business at the con complete after another tour of the dealer hall, I packed everything back up. I’m actually taking some downtime to visit some possible housing & shop locations, since I am (slowly) plotting my move out of Boston. That means I’ll head back later in the week. We’ll see what van-related adventures happen this time…


Thanks Cassie Fray Cosplay!