Archive for the 'colsonbot' Category


Dragon Con 2015: The Before, During, and After; Stance Stance Revolution, Überclocker, and Operation STRUGGLEVAN

Sep 25, 2015 in Bots, colsonbot, Events, mikuvan, Stance Stance Revolution

I’m back yet again!

The flurry of RageBridge 2 development in the past few weeks was primarily to make sure I had a few demo units ready for folks going to Dragon Con 2015. Basically, I sent a batch down ahead of time to be integrated into some bots that were going to compete at Robot Battles, as well as prepared some for a few new local builds. There were some other things going on also, including Clocker repairs and upgrades, and yet another entirely new random beetleweight. Oh, and the harrowing tale of having Mikuvan’s engine accidentally rebuilt before departure, and the followup shenanigans!

1. The world’s first dual counter-rotating 45° spinner, because why not?

2. Überclocker’s front leg upgrades

3. The convention and Robot Battles report! Plus, panel information.

4. Operation STRUGGLEVAN; Followup from Post-Detroit Maker Faire to “How many times did I pull over to replace something this trip!?”

Stance Stance Revolution

First, we start with a heavy dose of what:

Oh no! Which way is it facing!? Which way does it spin? How does it move?! Don’t worry if you’re getting a headache looking at it. This is entirely by design.

What you are looking at is the world’s first counter-rotating 45 degree spinner! An answer to a design question literally nobody saw coming.

It all started, really, after the debut of Plan X on ABC BattleBots, with its primary weapon that spun downwards (really it could spin either way, being reversible). For the next little while, every time a new robot was presented, everyone would ask which way it spun. That led to many joke Facebook Group threads, including a snippet of this one…


Featuring Near Chaos Robotics

Well I ended up not calling it Double Helix, because shortly thereafter, I had an epiphany… the blades would have some demon camber and it had an uncanny resemblance to Counter Revolution, so…

Logo courtesy of Cynthia!

Already, I’ve taken this joke too seriously.

I sat down with a blank CAD screen to decide how I wanted to do this. It was literally going to be Counter Revolution deformed through its center axis. I planned for a beetleweight, to act as the dopey-cop counter to Colsonbot. So it was probably going to be a 3D printed unibody, like Colsonbot, for convenience so it could be put together quickly. After all, heaven forbid I take this joke too seriously.

Let the Eschering begin… I created this mockup a day or so later and posted it to great fanfare and cries of “MY EYES!!!”

The blade design was a simple porting of Jamison Go‘s DDT, for which he had several spare blades. I played around with them, but ultimately decided to go with a custom blade design.

Creating those 45 degree struts meant a whole lot of messing with reference planes and other reference geometry. I first created a rotated, offset plane from the center axis of the robot, the blade tower midplane, then made an offset plane from THAT to set the width between the towers. The towers were brute-force mirrored across the midplane, then the parts which stuck out the bottom cut off flush. This is a look at the finished frame – all these steps were taken in the first few features, as seen on the left.

The bot as seen from the front. With the midplane method, it was easy to adjust the blade “offset”. The blades aren’t shown in their final positions either, since at this point I hadn’t looked at how to drive the blades. I decided to try and push the blade “exit point” from the frame as far to the corners as possible so it was easier to aim – “Try to hit with the corners” was going to be the strategy.

After some debate, I decided to just go simple and use pancake-style multirotor motors in a direct drive configuration. My last vertical KE weapon bot, Nuclear Kitten, used a custom-machined hub motor. These days, the flat multirotor motors are much the same form factor. I didn’t expect this configuration to live too long, because those motors are not built to take direct impacts from solid steel things. Direct drive sort of went away as the energy levels present in small bot contests went up. But it would live just long enough to make everyone’s heads spin!

Shown above, the “blue” motors are some Quanum 5208 multirotor motors. I was looking for motors which had the same stator diameter & size as NK’s old motor. However, they were ultimately too heavy.

Stepping down a pay grade (or stator diameter range) were the Multistar 4822s with 40mm stators, and which were nearly 80 grams lighter. It became apparent to me while shopping for motors that putting what is basically two full size weapons for a beetleweight in one bot was going to be difficult. The 4822 motors weigh only 98 grams (less with their long wire pigtails trimmed).

Luckily they were available in a U.S. warehouse, so I was able to get them in a few days to fully model them up, as shown above.

Here’s more brainfuck for you. It might actually hurt a little more to look at from underneath.

The underside and drivetrain was going to be a contortioning game. I planned to use two 22:1 Silver Spark motors – it wouldn’t be quick, but would provide basic maneuverability for the weapons platform. The question was where to put everything else. Even simulating component placement using bounding boxes, I knew it was going to be impossible to stuff everything inside. The weapon ESCs have to go outside, mounted to the blade towers, as you’ll see.

Some finalizing work, and here’s the design. With ripped off logo and all!

A 1/8″ diameter shoulder screw forms the idler axle, and the Fingertech switch is mounted awkwardly outside one of the two symmetrical cutouts permitting wire access to the weapon motor controllers.

CAD family shot next to Colsonbot! I guess Colsonbot would be the Captain Shrederator of the world of perverted miniaturized BattleBots 2015 entries I’m making here….

I wanted to use the MarkFrog to make this frame out of nylon with fiber strands, but unfortunately it was too big in every single dimension. To make it in Nylon would have mean better impact strength, but GUYS GET ME A BIGGER MACHINE PLEEEEEEEEEEEEEEEEEASE! Jamison’s new DDT is all printed on this machine and it did excellently at the event. Maybe I should have scaled this to an antweight instead…

Thus, I popped the frame out in ABS plastic.

The Multistar motors arrive, so it’s time to design the blade. From looking at their product photos, I decided to make cutouts in a blade with a large inner diameter such that they sat on the endcaps, instead of being supported only by the shaft. I was also intending to use the prop adapters (which bolt on) in an external bearing to offer some semblance of double-support. Now, the aluminum these things tend to be made of is so soft I don’t think it even matters (How do they even machine it without it bending?!), but it made me feel better.

I was able to finish out the blade design and cut it out of prehardened 4140, the same plate that I made Nuclear Kitten’s blades out of all the way back in 2008! 4140 prehard isn’t THAT hard – Rockwell 30C or so, so it’s not the best choice and far inferior to a heat treated blade… but something about taking jokes too seriously.

The blade centers were dished inward a little to sit on the motor can.

Retainment was through a big aluminum machined washer. This bolted through the prop adapter, necessitating longer screws – which… GREAT! Because the screws that come with these motors are suspiciously soft for looking like black oxide cap screws. 10.8? 8.8? Probably more like -1.8.

Blades mounted. The outboard bearing is some small 6mm bore flanged bearings I had, from some unknown appliance which died valiantly (and probably chaotically) for the cause.

Remember when I said the weapon ESCs had to go outside the bot? They’re nestled in the blade trench, a half inch away from whirling death. I put in an indentation and cable tie anchoring point specifically to use a zip tie to hold them together. The motor wires are cut super short and soldered directly to the controllers.

I’d like to pause for a bit and discuss these controllers. They’re the “Afro” series from Hobbyking, and besides making me wonder how they came up with that name, I also really enjoy their extensibility. You see, the DIY multirotor community has been working on a better firmware suited their needs for years. They now have a massive database of upgraded firmwares for many of the ATMega-based brushless controllers. the Afro line evolved out of this community’s needs, and in fact contains a bootloader onboard such that you can upload new firmware using only the PWM wire – no need to try and find the programming pins on the boards. The firmwares offer many configurable options, including reversing.

Hmm. It’s piqued the interest of a few robot community folks, one of whom put together a guide on how to update the firmware to a “bot compatible” one. I performed these mods on my ESCs and did a demo video on how it affected a relatively high inertia load like a blade. The result was stellar. I dunno what Mr. SimonK did with the state estimator part of the sensorless firmware, but I can hard-reverse repeatedly without killing the ESC, and it will try to keep track of the motor all the way down to zero speed. The starting routine seems far more robust. A Hobbyking controller with stock firmware would have died instantly.

The best part is, there’s a guide on how to find the pin settings for your ESC – which opens the realm up, if I feel like exploring it, of putting it on one of these. A few builders have already done brushless drive experiments using this, and the results are far better than a stock Hobbyking car ESC with reverse functionality. Only a few bots have dared run brushless drive before now, but I suspect the smaller classes will see an explosion of ESCs of brushless drives, saving weight to get the same performance.

It also means that Brushless Rage is obsolete ;_;


Here is the real-life contortioning game. The receiver also ended up having no place to live because of the battery wires. So it gets piled on top of the battery! Luckily the battery (which is shared with Colsonbot) is short enough….

A final weigh-in… just barely under the 3lb limit!

SSR leaves very unique 45 degree impact marks on testing subjects.

Here’s a testing video showing a few hits on the empty Dimension cartridge. As you can see, it flies. One issue is the blade hitting the ground since it swings so low. I suspect in an arena with a wooden floor, it could dig in and send the bot flying, which would be most excellent indeed.

Another interesting behavior: When it hits, it tends to twirl around. I kind of want to practice the “one-two” of hitting with one blade enough to spin it around to hit with the other. This is a result of the blade having a horizontal, downward component to its impact. In this case, the rear counterrotating blade is spinning the correct direction to twist the bot opposite the direction of hit-induced turn, keeping it upright.

Finally, you can see that with enough bouncing, it will self-right very easily, doing a barrel roll in the process.

This joke is ending up more hilarious than any of us could have thought.

And a final beauty shot, if you consider it a beautiful thing.

I ended up replacing the idler rollers with hard plastic ones. I tried to link the two wheels on each side with O-rings, but the o-rings would keep sliding off since they also touched the ground. It handled well enough with “corner drive”.


Alas, poor Clocker.

After Motorama, it was sort of in a heap with a broken off front leg replaced with a chunk of cutting board. I remade 2 of the stripped hubs before a demo session to high schoolers over the summer, but besides that it’s not changed much.

For this Dragon Con, I wanted to move back to double-supported legs. Basically, while the single supported version 3 legs worked well, enough bouncing around caused the attachment parts and hardware to start stress fracturing, eventually breaking off.

Clocker version 2 had double-supported legs, but they were built in such a way that it was very difficult to service the drivetrain… and if there’s one thing Clocker v2 needed, it was drivetrain service. The reaction to this led me to the single-sided legs, but now I think if I put a liiiiiiiiiiiiiiiiiiittle more mental energy into it, I could design the legs to use the same screw head as the drivetrain side plates, such that it doesn’t take forever to remove.

Wild idea, huh?


Growing the design from simple geometry. The legs pivot on a flanged standoff-like entity which is fully tightened to the frame. On the other side, I moved from single-shear to double-shear support for the spring.


Other side, with hardware loaded. The use of 1/4″-20 button headed screws allows me to use the same 5/32″ allen key driver to zip the entire outside on and off.

 Time to take the whole thing apart! I also ended up remaking the front axle standoffs and straightening out the inner side rails, because the single-point bending of the leg had also affected them significantly. The new legs slide right together (due to correct nozzle offset on the waterjet cutter – the one it defaults to usually leaves far too much material!) and bolt through using large standoffs. No more using the 1/8″ intermediate plate as the fastening device as on Clocker v2.

 Bolting together the springy-leg trunion side.

What the installation looks like after the flanged standoffs are installed. There’s one on each side. The inner side is Loctite’d to prevent rotation, while the outer side is free to be removed. The fit is deliberately loose to let it take some damage without binding.

 And a final overhead view of the bot. No, Clocker’s not running RageBridge 2 beta units. I leave that to my guinea pigs loyal subjects.

Dragon Con 2015

This year, I fell into a classic convention trap – doing so many panels and things with your fan track (Makers & Robotics) that you pretty much forget the rest of the con existed! I was involved in 4 panels and looked on at many more. In fact, analyzing my camera contents, I in fact only took one photo of Miku cosplayers.

That’s 99.18% less than the historical average.

First up, my Maker’s Resources panel, which was condensed down to ~1 hour (SORRY VAL!) and focused more on getting people set up with CAD. With Autodesk furiously pushing Fusion 360, it is in my opinion the current “missing link” for mechanical hobbyists and well-featured CAD programs. I got the hang of it a week beforehand, and was prepared to give a live demo, but sadly, showing off Inventor and Solidworks and Fusion 360 was too much for my computer to handle.

I was also involved in the Rapid Prototyping for Costumes panel with Chris Lee, Jamison, and Cynthia, who debuted her version3! RWBY scythe project to some dramatic fanfare.

Next up, a few of us from JACD took part in the Battlebots New Season panel with quite a few other competitors who ended up deciding to attend after hearing that the BattleBots organizers were going to be in town. Unfortunately, I had to miss the “Highlights and Memories” panel, but I told everybody to make fun of me as much as possible so I’ll await the video results from that.

Finally, I also took part in the Power Racing Series panel hosted by several local Southeast builders. We had a whole lineup of entries I was otherwise not used to seeing from teams and builders who have mostly gone to events in the region – I’d witnessed the construction of these cars on the PRS Google and Facebook groups, but they weren’t at Detroit Maker Faire. There isn’t usually much region cross-pollinating due to the races being spread far apart and the stakes not being (that) high (yet).

Luckily, this time I changed that. If forcing everyone on the New York Thruway to stare at me was bad enough, this time I trolled all of I-81:

After having rigged CMV enough times for New Yorks and Detroits, I figured that it had already traveled 1 Dragon Con or so of mileage, and therefore was eligible to be brought down to Atlanta. In 2014, I decided against this idea because there was no race and I questioned my rigging ability. As it turns out, if your load experiences several hundreds of pounds of load, or multiple G’s of acceleration, enough to break or unravel the straps, something very bad has already happenedWith this in mind, I was far more comfortable driving long distances with Chibi-Mikuvan strapped to the roof, distracting small children and tired vacationers alike. The green pallet wrapping is for bug splat prevention on the front white portions.

So this year, I signed up for the Dragon Con Parade…

PC: Jen Herchenroeder

The PRS racers got their own ‘block’ in the parade, and we (mostly) stayed together and showed off to the crowd. At the first major intersection, I decided to try something stupid and initiate some donuts. To my utter disbelief, this worked. I think it’s a combination of running in “infinity mode” (50A regulation fuse bypassed) and the rear tires being practically bald from the Detroit race. I proceeded to pull this stunt any time there was open space – most of the street intersections sufficed.

Dragon Con Parade

That is starting to look like some kind of old 16-bit racing game. Still waiting on someone to find video of it all, but with sufficiently worn-out tires, CMV can do powered donuts on dry asphalt. Hmm…. more moxie awaits at New York Maker Faire?

Immediately afterwards, we all TORE ASS DOWN COURTLAND AND PORTMAN STREET AND THROUGH THE MARRIOTT *ahem* maneuvered most of the karts into the lineup for the Power Racing Series panel.

From the evening before, a lot of the cars in a row at an impromptu car show in the Marriott. I didn’t bring CMV with me everywhere, so it sat this one out back in my mom’s garage.

Since I’ve basically been part of the Robotics & Makers panels since its inception, I’ve steadily watched not only the content variety grow, but also the skillset of the audience. This time, during my Resources talk, I’d say a strong plurality had designed something and either fabricated it manually at home, or had something 3D printed or used a makerspaces’ tools. When I polled for how many people had used CAD, a solid 75% of hands went up, and Solidworks in particular was something like 1 in 5. Damn, what do you guys need me for!?

I’m sure some of it is “audience self-selection”, but the strong gains each year in those who have tinkered with stuff on a hobbyist level impress me nonetheless. All the panels I led or were involved in were packed houses. I’m happy with anything which shows more and more folks are becoming involved in the Makerverse.

Stolen from builder Collin Royster, here’s a photo of the PRS panel. Chibi-Mikuvan is well-hidden behind the front table from this perspective.


Jim brought Nightmare up from Florida for the BattleBots panels and for general shenaniganry. I was briefly considering bringing Overhaul… sadly, it proved to be too impractical since it didn’t tessellate well with anything else, and I do not need 250 pounds on the roof. So there goes the prospects for the wimpy hotel room grudge re-match!

The staff of Big Hero 6 above are actually the three ladies of Team JACD: Hanna, Lucy, and Cynthia, who discovered their names are a great basis for their own team. Hence they splintered from JACD. I guess they were finally done with putting up with our bullshit. For Dragon Con, team HaLuCyNation built Destroying Angel:

It’s a 30lb rear-hinged lifter using 3 DeWut motors, a RageBridge, and a 6S lipoly battery. In other words, all parts that were hanging around. It was put together in little more than a the week prior (though designed for a month or more beforehand).

Moving onto Saturday evening, it’s robot time. Here, Colsonbot is getting a ‘body swap’ to the latest version of the frame. This version trims another half ounce or so off the weight by eliminating the front left and right chambers. There’s still plenty of electronics volume left. Hypothetically, this permits dual weapon motors, though I only brought the one.  There’s no other changes. I completed this swap in about half an hour, since it just entailed desoldering and resoldering.


This year, due to a Certain Robot-Oriented TV Show, both Robot Battles events had record turnout as well as a flock of new builders. The schedule was pushed to the max, even with two small bot arenas running simultaneously. The tournament had to be single elimination for expediency. Yet I’m super happy, because the builder population had been stagnant for years. Just look at how much Clocker vs. Nyx vs. Dale’s Homemade Robots there have been for the past few years.

Colsonbot won yet another match mostly due to driving – the four 11:1 Silver Sparks actually make for a very nimble drivetrain for a spinner. In its first match against Moxxi, a (mostly) wedge with a small undercutting blade which was not working well, I lost the heat shrink “tire” of the 28mm NTM motor in like 10 seconds. Therefore, the rest of the match was a pushing contest.

I’m considering moving the motor size down one notch and actually running two weapon motors, due to the limited space there is to put a “tire” – what worked the best after that match was actually winding electrical tape tightly against the rotation direction (such that it did not put force on the tape’s leading edge) for a few wraps. In its rematch against Moxxi, it spun up quite well and knocked stuff around.

It then face Jamison’s Silent Spring twice. Once by draw (no knockout or hole-shot after 2 minutes) where both bots worked consistently:

The next match was a win when SS stopped working, but Colsonbot was too damaged to be repaired in time for its next match.

It was extremely vulnerable to Silent Spring’s under-cutting blade, which took out the weapon motor and its surrounding mount area. Somehow not a single drive motor, even though the wheels were missing bits!

At least it kept driving until the end. I suppose I could have ditched the spin and made Colsonbot into a pusher, but there wasn’t really a point in doing so and it would only add to the tournament scheduling chaos. So Colsonbot exits the tournament effectively 1/1.

As for Stance Stance Revolution…

Poor Stance Stance Revolution.

In an eerie replay of Tombstone vs. Counter Revolution, I drew Silent Spring as the FIRST! beetleweight fight of the tournament! And it ended about as fruitfully.

After a flurry of blade-to-blade impacts, the ABS unibody fractured at the places it was the thinnest, and SSR broke in half. Now, to be fair, both halves DO still work….

It was really meant to be made from Nylon (using the Markfr4ck), a much higher-impact and resilient plastic, but after looking at the section areas that broke, I need to reconsider some of those parts. I intend to bring SSR right back since it’s too hilarious to not keep working. So that was it for the little bots. Damn you Jamison – I shall exact my revenge some day, probably at Franklin Institute next month.


robot battles

It’s big bot time!

This time, I had no 12lber. 12 O’Clocker required quite a bit more work than I remembered, and I couldn’t fit it into the last week’s schedule before departure.

Then I remembered I had a 12lber back in my parents’ garage.

Ahh, good old Test Bot v3.

Now sporting two different kinds of ballast – the old nickel drill pack wouldn’t revive, and that SLA brick has been in there as ballast for as long as I can recall. A spare RageBridge 1 was installed, and a tiny little lipo pack which can source more current than either of those two old batteries ever hoped to. So now I have a 12lber! It’s actually still dramatically underweight at 11.1 pounds. How did this thing ever make weight?

I mentioned earlier that both Robot Battles tournaments saw record attendance and new entries. I’d say that there were around 10 totally new bots this time, in addition to veterans who left but returned and people who have built before, just not for RB at Dragon Con. Here are a few samples of the new entries… I hope they have staying power for tournaments to come.


This pair of 12lb wedges was built by a father-son team local to the area. Named “Busted” and “Rusted”, they actually got paired up first for the first 12lber match, which was hilarious because they were also both new bot drivers…. and the bots were slow. I’m not sure what drive motors they were using, but taking it easy doesn’t even begin to describe the slowness. Lots of potential from the design, though, so perhaps a simple motor upgrade is in order for next year….

Here is “Aluminum Box”, a valiant first bot effort with a set of fairly standard components – drills on 3″ colsons. It didn’t have a weapon, but could push pretty well if it got a grip. Since this kind of design can hardly go wrong, I suspect it will have more attachments and shenanigans if it returns in the future.

I have a bit of investment in this newbie bot since the high school builders not only came all the way from New York City by train (That’s a level of dedication I will never reach, and probably never reached), they’re using a set of donated DeWuts.

A 30lb pneumatic flipper bot that did more lifting than flipping, and which used a lot of Vex gear. The lid stays put – only the center arm pops up. Unfortunately, it lost after being unable to self-right. Bigger piston time?

Jim (of Nightmare) with a wholly new 12lber, ShaBoomBox, which allegedly was put together mere hours before departure. It’s literally made of P60 gearboxes, using them as structural blocks to bind top and bottom plates together. Hey, it works. Jim has had enough practice with this kind of design since he has an antweight, and heavyweight built off the same concept.

Terry, a returning veteran, shows up with the 30lber version of Ventilator. I remembered the 60lb Ventilator way back when Robot Battles was still running 60lbers on stage (basically, before they got too terrifying with new high powered parts). Pretty sure this is in fact it with a different hammer mechanism (with less swing) and without the big round shell…

HaLuCyNation gets some Dragon Con TV press attention before their first match.

Alas, poor Clocker.

The careful reader will notice that in its update section, I merely said “I remade the stripped hubs”. No, I didn’t remake them better, I remade them as-is. That decision pretty much ended the way everyone expected, including me, because no matter how loud I was screaming “This is going to be REALLY SKETCHY” at myself, I didn’t listen.

Clocker, therefore, did not do too much this tournament. It had two tournament, with 2 (effective) losses, and the only win being against HaLuCyNation. In fact, the problem first cropped up in the exhibition match where the organizers of BattleBots themselves(Trey and Greg) drove the bots. Gee, with that embarrassment, will I ever be allowed back into Season 2!?

Subsequent to the match against Destroying Angel, I ran out of drive options. I decided to throw it into the rumble as a stationary arena hazard, grabbing whomever I got shoved up against…

…and won? All of the “plate and standoff fork” robots briefly got tangled up, then something happened which made everyone else bail off the stage. I still can’t quite figure out what happened, but… Yay! Clocker won something by doing absolutely jack shit! Perhaps that should just be my strategy from now on, seeing as how I seemingly insist on shooting myself in the foot in terms of mobility every time. The hex hub system is nice…. if I can bother to do it right. Part of the issue is weight – Clocker is bumped right against the 30lb limit with the plastic hubs, but that was with the previous thick aluminum pole legs up front. I actually didn’t re-weigh it right before leaving. Most likely, I have the weight for aluminum hubs like they were originally meant to be.

This event was supposed to be Clocker’s Last Tournament™, but I refuse to let my machinery die of stupidity… so I’m just going to make the aluminum hubs for Franklin Institute ಠ____ಠ

Test Bot fared a little better for itself. I was quite out of practice driving it, and being underweight didn’t help pushing traction as much. It lost to Omega Force after a spirited pushing and driving match ending in a 360 degree flip (There were 2 halves to this match – after the first one, the unrestrained battery knocked the logic power inductor off the Ragebridge 1 board, which I jumped 5V to using an offboard BEC) It then won against Aluminum Box before losing to Test Bot v4. Actually, I meant Dolos, but I sold the TB4.5 frame to Mike, whose friend is operating it with modifications as Dolos! In other words… good, the newer version was better than the older one.

In the 12lb rumble, I sent Test Bot into the fray (after starting it in a nonsensical position because come at me) and lasted up until the end when I ran straight into the loving hug of Hypnos, which TB seemed to fit perfectly square into.

Now that I have Test Bot v3 back in my possession, I’ll probably keep it operational (and loaded up to 12 pounds) as a handy practice bot.

That concludes all the robot shenanigans this time. None of the bots I brought made a spectacular showing, and it might seem that I’m losing interest in them with my hurried repairs and modifications, but what balanced it out was helping so many new folks out with their bots. I think I’ve been around the block enough to “get it”… and seeing so many new builders this time, many of which I connected with online before and dispensed questionably-sagely advice to, in attendance at this event meant to me that I really built like 5 or 6 robots :p

Overall, the time constraints and preferred format of Robot Battles was showing its limits here this year. You can only have so many bots before the “show” is forced to become a tournament. The “two out of three” system really adds to the length of match times, and with the convention seemingly unwilling to allot more time to RB, some hard decisions about the future of the tournament might be needed if the popularity of BattleBots keeps up.


Be prepared for the most action packed van adventure yet!

Not that it’s a good thing. In fact, I’d strongly have preferred to not deal with any of it, but now that I’ve had to fix it before, during, and after Dragon Con, everything finally works great! Can I go to Dragon Con now?!!

The story begins during Detroit Maker Faire. I didn’t notice exactly when in particular, but at some point I stopped to refuel and noticed that hey, it sounds a little like an idling school bus. An idling pulsation that was steady, and which went away once I stepped on the throttle a little but which was noticeable when trying to accelerate at low speed. It gradually became worse and worse as the trip progressed, but I was at least able to make it back into town. While unsteady at low speeds, it was smooth on the highway despite noticeably lacking some power.

Thus began the teardown. I was thinking a fuel system problem, specifically perhaps a malfunctioning injector. Too bad the symptoms literally pointed to everything; from said injector or perhaps an ignition/spark plug issue, all the way up to blown head gaskets and cracked pistons.  Give that I had some time after Detroit Maker Faire, I dove in and did some testing as well as replacement of parts I had on hand.

I started with the obvious – using a timing light to double check that the spark plugs were getting voltage. I also just went ahead and replaced the plugs, since the ones that were installed were “Original-as-of-when-I-got-it-running” crappy plugs picked up at Autozone in 2013. Nothing seemed out of the ordinary.

I next tried a vacuum test. It turns out you can deduce a whole lot about the state of an engine if you have a vacuum gauge and know a couple of other variables about the engine. It was easy to shove the gauge into the brake booster vacuum line and run it a few times. But to me, it showed nothing out of the ordinary either, besides the manifold vacuum being a bit short of normal.

Well, with a whole lot of physical things wrong with the vibrating metal bits of the engine seemingly ruled out, I decided to take an intermission to just also replace the fuel system parts.

The injectors are reasonably accessible, but to reach them, a few hoses, connectors, and surrounding components had to be disconnected. To not utterly fuck up on the assembly, path, I marked the steps with numbers. So clearly, if I have to do this again, I can just follow my own breadcrumbs!

In a “Well, I’m already this deep” moment, I swapped in a new ignition coil for the old one, because why not!

A kit of new Bosch spark plug wires also made it on. The ones in there were unmarked and of unknown vintage and quality, so why not!

All of this above effort, of course, did not affect the problem at all, which was persisting – not getting better nor worse, but staying just out of reach such that I could still trundle over to Harbor Freight but most definitely not to Dragon Con. Well, it was T-minus 3 weeks at this point, and that was not a preferred state of things…

One thing I noticed, especially during the latter half of the Detroit trip, was how much more quickly it was losing oil. Specifically losing – it wasn’t burning, but just puking everywhere out of every opportune area. For instance, this is what the oil cap area and valve cover looked like after a trip to Home Depot or something.

That oil vapor also looked really suspicious, though the Internet seemed to suggest some amount of vapor is normal. Regardless, the “oil being forced out of places” scenario seemed to support the crankcase being pressurized abnormally, since it is supposed to be constantly evacuated by the PCV System. The problem being “just” the PCV valve seemed unlikely, because why would it only run badly in one cylinder? I double checked and cleaned the PCV valve anyway.

The rabbit hole was beginning to get a bit deeper.

I borrowed a compression testing gauge to check those numbers. Really I should have done this first, because

  1. 182 PSI
  2. 180 PSI
  3. 32 PSI ಠ _____ ಠ
  4. 180 PSI

The number 3 cylinder showed very little compression. No matter what, at this point, the head had to come off. I pinged the good folks at Smooth Automotive (within hobbling distance, and with whom I’ve done plenty of business already) to get an assessment – yes, head gasket failures into oil passages (hence the crankcase) can happen, but it’s more likely to be between cylinders 2 and 3 (which was ruled out, because cylinder 2 had good compression) or into a coolant passage, upon which I would see effects in the cooling system or engine butter, neither of which were present.

What it effectively meant was that I was at minimum needing a head gasket and at most…. there’s no bottom to the rabbit hole until it is reached!

With Dragon Con departure being now 2 weeks away, I decided to throw it in, and let them work their professionlulz magic. You see, a more sane person would PUSSY OUT rent a car, perhaps, but that ruins more than half the point of the trip for me, so I was willing to play my Automotive Wheel of Fortune game for now.

I got to watch the process firsthand and pester them with “Ooh, what does this do?” questions. Here is the single overhead camshaft in all its glory. They got it to this stage within… oh, like half an hour. Gee, it’s almost like you guys do this every day or something. For instance, I didn’t even know that the giant octopus of wire harnesses and throttle cables just came off as a single block to be set aside.

Oh god. The head came off. WHERE IS THE HEAD? WHERE DID IT GO?

Right here. I can’t explain why there’s exactly 1 white valve, but everything else has been leaking oil into the cylinders – Mikuvan is well known for an occasional small smokescreen on a cold start, a classic sign of worn out valve guide seals.

Here is a “literally, leak-down test” in progress. What it showed was that cylinders 1 and 4 were well-sealed, cylinder 2 and 3 were less so. The difference between 2 and 3 is that this photograph was taken the day after, and according to them, cylinder 3 was gone within a few minutes. With cylinder 2 showing good compression when I tested, cylinder 3 became the culprit.

And there it is. At the end of it all was destroyed piston ring lands. This was unfortunate, because it took the better part of a week (of on-and-off work – I’m clearly far from the only customer) to get here, and now many parts need to be obtained. Besides the obvious such as new gaskets and seals, and a timing belt set, I needed at least 1 new piston and ring set. Nobody in their usual parts supplier lineup had any. I would not have expected any different, really, because who the hell stocks parts for an obscure model of 1980s van that was mostly sold in California?!

Fortunately, Rock Auto had 1 full kit of pistons in stock. I will forever love Rock Auto, because this post has been a rolling advertisement for them (all of the parts I replaced myself came from them at some binge-purchasing point…)

And here they are!

We decided to only replace piston #3 for now. The cylinder wall did not exhibit scuffing or other damage (….somehow), and since all the other cylinders showed good compression, and time was of the essence, it was the quickest way to get rolling. If the cylinder wall itself was damaged, that would have been the end of the game, and I would have better spent my time welding up a mounting cage for a Siemens 1PV5135 motor. Besides, now that I have witnessed this whole process, I can do it all myself! Muahahahahahaha. That will end splendidly.

None of it ended up being exceptionally difficult, but just in areas I had never been and did not want to waste time fucking around before a major trip. The pistons are easily accessible with the oil pan and cylinder head removed – the “big end” bolts are in the open, and they pop out from the top.

While this work was occurring, the cylinder head was also being rebuilt by an associate shop specializing in engine block and cylinder head operations, Arlington Automotive Machine. New valve guides and seals, reground valve seats, and new hydraulic valve lifters were in order since all of the (original?) ones had long died (This manifested itself in the classic “tappeting” sound when the engine hadn’t yet warmed up).

All told, this adventure cost me $1700 not including parts. But the end result not only worked beautifully, it also sounded way, way better. It also revealed where all the exhaust leaks were, because now that the engine was properly running and the valves were actually stiff and responsive, the rustiest parts of pipe and the most weathered of gaskets began giving way! Yay!

and we haven’t even left for dragon con yet

It’s Tuesday afternoon, September 1st, and it was time to leave for Dragon Con. Cynthia and I packed everything up and rigged Chibi-Mikuvan to the roof.

An old heater hose explodes before we made it to the highway. Oh, right, the water pump was also replaced as part of a front-end operation (“When you’re down this deep…”) and the newly healthy engine and increased coolant pressures made the old pipe very sad. That is a photo of the broken portion of the pipe drooling coolant, which I took from underneath on the side of Memorial Drive in Cambridgeshire.

I hobbled back to Smooth Automotive running air-cooled half the way since the coolant loop bled out very quickly. I was horrified at the prospect of potentially cooking my BRAND NEW HEAD GASKET to overheating like…. 2 days after getting it done, so when possible, I shifted into neutral to coast, and gently revved the engine to fan itself. This hose was in the rear heater core loop, so the quick hack applied was to bypass it entirely. I plan on un-bypassing it soon, since fall is approaching.

Next, somewhere in southern Connecticut, I lose the speedometer. Something felt a little weird, so I look down and was pretty sure I was not going 0mph.

What the f….

That’s the speedometer cable I’m holding, which attaches to the output of the transmission through a little worm gear. It has a collar which screws onto said attachment point. This collar seems to have loosened up and gradually backed itself out.

This is the only photo I have of the process…

No, I didn’t cut off the cable. The driving spline portion which mates the two haves is probably still hanging out on I-95 somewhere, but in essence, it’s a small metal key that fits into the slot in the cable end and has a mating slot in the transmission end. Just a simple peg with two keyed portions. So what piece of material did I have which could approximate the key?

I purchased those jigsaw blades on a whim from some hardware store years ago and they’ve been sitting in the center console since. It turns out the steel stock they’re made from is a perfect fit width and thickness-wise to act as the speedometer cable key.

So I broke off a chunk of jigsaw blade, dipped it in motor oil for lubrication, shoved it in there, and went on my way with a speed reading again. Maybe I was actually worse off for this, because I definitely drove with more care when I didn’t have a direct speed readout.

Fortunately, all seemed uneventful for the rest of the trip until I got close(ish) to Atlanta – around “late South Carolina-ish”, I started getting some intermittent power loss at high revs on the Interstate.

cue ominous music

Being extra paranoid, I scheduled a check-in with Suwanee Auto Repair, which appeared to be very reputable for my area, with focus on the fuel system since that’s what it felt like (highly scientific terms here…) They reported no abnormalities with fuel pressure, injectors, and filter, and also recommended I get some water remover for fuel (e.g. HEET) in case there was water contamination in the fuel system. With nothing else presenting itself locally, I was comfortable driving back up to Boston, but with one catch – I’d return to the I-95 route which I had sworn off, because it was much closer to civilization in general and I had possible bailout points and friends with trucks along the way. Just, you know, paranoia. Just because the van is working, it doesn’t mean everyone’s not out to get you.

The order of events on September 8th was:

be south of Richmond, VA

> can’t rev past 4,000

be nearing Richmond, VA

> can’t rev past 3000 or go past 55mph

be in Richmond, VA

> stall out in the middle of town for a good 10 minutes

gently hobble towards Advance Auto Parts

> barely keep up with 25mph local traffic, limited to basically high-idling

Something was not happy. Falling back onto the symptoms I knew well from last year, I was still 99.95% convinced it was a fuel system problem. But swapping in my “crash kit” fuel filter – which I now keep a spare of in the back at all times, because fuck the world – didn’t resolve the problem at all. It would simply come back after less than a mile. Something was causing a severe constriction in the fuel feed, worse than last time. And like last year, I couldn’t cross-debug anything else that was wrong, the ECU blinked no Hobbyking-esque codes, and even calling up Frank at Smooth Automotive for some heartfelt remote diagnostics ruled out anything else.  Once again, I was stuck in Virginia with a van of dubious functionality. And a town ending in “burg” was nowhere to be found, so what should I do!?

As I was low on fuel at this point anyway, I decided to grab a gallon or two more, in case I had to hobble to a shop or to a hotel. I didn’t want to get a full tank, in case I had to drain it at the side of the road.

> runs beautifully

This got me thinking. Something about just getting gas caused it to start running again. But not all the way – I could still barely rev past 4,000 RPM. Whatever is upstream of the fuel filter is causing the problem. It dawned on me that it might be the fuel pump itself, but I replaced that in 2014… before the Dragon Con 2014 trip which ended in me feeling gassy. But the fuel pump itself has a intake filter on it, the little sock-looking thing filled with fuel-resistant teddy bear plush.

I still am wondering why there is a filter on my filter and why these two filters can’t be 1. the same one and 2. outside the fuel tank. But the bottom line then was that I had to drop the fuel tank to investigate. Dusk was settling, and I faced a choice between finding a shop which could look at it ASAP or winging it to at least Washington D.C. where I had some cohorts summoned. The area of north of Richmond I was in (Google Maps tells me it’s called “Glen Allen”) was healthy with automotive services, but they were all booked and busy – the earliest opportunity being the next day, with no guarantees.

Therefore, I made a betting-man’s decision to try and drown whatever was causing the blockage with fuel. I went back to the same Shell station and filled completely up. I even rocked Mikuvan left and right by pushing on it while filling up, which probably made me look like a lunatic to everybody else. All to try and dislodge any material that was hypothetically in the fuel pump intake sock.

Using this witchcraft, I was able to cruise to Baltimore without significant trouble keeping up with traffic. By the time I got past Baltimore, the issue had begun to return, so I stopped to top off again. The problem was that the clog was clearly pulling itself back together quicker than I could run through fuel – which, with restrictions to begin with, I was getting spectacular gas mileage. This was utterly unsustainable – I was going to have to drain and waste a full tank of gas in the near future if this kept up, and if that is the case, I’d rather lose 1 day and have the fuel tank totally cleaned and inspected.

I decided to call ahead to my dad, who luckily lives in New Jersey right now,and explain to him slowly how his son has insisted on getting in trouble with his old broken truck again. The plan was to coast fashionably into New Brunswick and find a shop in the morning after some sleep. Driving 50 to 55mph on the New Jersey Turnpike is one of those things I strongly prefer not to do again.

In the morning, I rolled into E-G Tire & Auto Center in Dayton. The E-G part stands for Edison Generator, which is a way more badass name – I asked why the business changed names, and it seems that the owner simply spun off the car repair business when he sold Edison Generator-the-business-that-does-electrical-stuff. I’m quite fond of “old style” company names, because fuck stupid postmodern one-made-up-word startup names, and power to Big Chuck’s Robot Warehouse & Auto Body Center.

Oh, luckily they’re a tire shop too, because on the way there, this happened.

Welcome to New Jersey. Fuck you and don’t come back.

This was about 70% my fault and 30% Fuck You; I’ve gotten a bit careless with shaving curbs in Boston and Cambridge, admittedly, but New Jersey-class curbs are made of sharp stone mixed with some domestically-produced Fuck You. In fact, this happened across the street from E-G, but because it’s New Jersey, the nearest way to turn around to get to them was a mile away. Not wanting to risk driving and damaging the rim, I had to mount the spare tire in clear view of the tire shop that’s going to fix it.

In fact, they recognized Mikuvan by make and model, from my pre-arrival call, and had actually been watching wondering why I was just parked across the street highway whatever New Jersey calls its roads where you cannot physically ever make a U-turn.

E-G was a nice and friendly place to hang out while they dropped the tank and had a look. In fact, the chief tech’s son was a huge BattleBots fan, so I got to provide my first random celebrity moment, I suppose? No, that did not discount my labor rate.

Here is the fuel pump intake sock as-extracted…

You can’t really see it here, but if I squeeze the little bag, the whole thing turns black and it feels very, very mushy and most definitely not like a synthetic fuel-resistant teddy bear. This part was replaced, along with the main fuel filter again, just in case – they are fairly cheap, and as long as We’re This Deep and very paranoid….

By 3PM on the 9th, I was back on my way again.

I decided to save the old intake sock as a memento piece to my statistically improbable luck with fossil fuels. Here it is cut up to reveal the inner layers!

The observant might be wondering why Suwanee Auto Repair didn’t catch this as a problem. While I think they could have dug deeper or performed a more thorough test, I really only gave them Friday before Dragon Con to do so. With the understanding that I needed it back by closing time, they did not inspect the fuel tank because I asked specifically to check the filter and everything forward of that (e.g. injectors) – since that was what bit me in the past. Good quality repair work always takes time, as my experience with Smooth Automotive showed. Unless you literally know exactly what is going down, it is better to let theprofessionals you hire do their work thoroughly. If I had been wrong about the fuel pump intake, then my trip to E-G would also have been frivolous (minus the dose of good ol’ New Jersey Fuck You).

So that’s the story of how I made it back into town with 3 winter tires and 1 dorky all-season, an accidentally-mandatory engine rebuild, a piece of jigsaw blade embedded in an improper location, and a refreshed fuel system! Now that everything works incredibly well, I’m back making midnight speedruns to Chinatown! going to New York Maker Faire this weekend. All said and done, this trip cost a little north of $2100 for all the servicing and repairs needed.

See you at the side of the Milford service plaza on 95!

Colsonbot’s Revenge – Bot Blast 2015

Jul 20, 2015 in colsonbot, Events

Two years ago during Motorama 2013, the concept of Colsonbot was born during a “well, just how shitty of a robot can you possibly make?” discussion (which itself is sort of the precursor to assbots) over post-event builders’ dinner. A couple months later, the first Colsonbot was born, in time for Bot Blast 2013.

After Bot Blast, it seemed like the Colsonbot meme had run its course. Hurray, I made a small twitchy meta-joke that involves a robot which, itself, is a wheel! With Colsonbot really unable to do anything else (…by design), after Dragon Con 2013 I removed most of the broken parts and the rest of it lived in my “tomb of little bots” along with the husks of Pop Quiz and PTDN. It seemed like nobody else would ever find out what a Colsonbot does.

Dramatic lighting reveal

Until now.


Alright, alright, I’ll stop. This isn’t BattleBots. This is serious robotics going on here. After a year of peer-pressure, I’ve finally caved and am rebuilding REBOOTING Colsonbot. Bot Blast 2015 was coming up quickly, and a few of the MIT folks were planning on going, so why not?

The only issue with the first design was the reliability. Due to the limited space inside a 6″x2″ Colson wheel – only about 4″ diameter x 1.1″ tall, I couldn’t fit much more than “antweight class” equipment – four little Sanyo-esque gearmotors from Pololu, and a short 28mm outrunner motor. Ultimately, the shell was too much for that small weapon motor to spin, so it overheated. The Pololu motors are also too fragile to be used in the 3lb class in the direct-drive configuration they’re mounted in, so three of them ended up damaged.

For the former problem, I decided to rotate the motor 90 degrees so it could be much longer. Consequently, this stuck into the space where the battery pack used to be, and by moving the battery, I needed to drop two of the drive motors. Basically, I started having to play “part tetris”:

It was at this point where I realized that I was basically building an antweight and entering it into the 3lb class, and even as a joke, that would just get owned too quickly. I also remember that we bought a pile of 8″ wheels for Overhaul, which were not used since we went with another tire choice. They’re 8×2″ Colsons. What can gaining 2″ in diameter get you?

A whole lot. I was able to move up to “Silver Spark” motors; four of them, which means now this is actually a competitive drivetrain. There is now so much open space I can go with two weapon motors. Suddenly, Colsonbot became less funny and more competitive.

The challenge now was to wrap a frame around this hypothetical component layout. I decided it was still going to be 3D printed, to keep with the theme, so I started with a solid cylinder in Inventor and began hacking away at it. The frame is built in the style of old Colsonbot and also Pad Thai – a unibody with removable “chunks” which clamp the motors in place.

Here’s a draft of the frame before cleaning up details. I’ve included 2 weapon motors here for layout purposes, but at this point I already figured the weight was going to be too much since the 8×2 Colson is a whole lot of rubber.

A top view of the frame. I decided to go actually crazy and design the frame for injection molding, in case… I dunno, thousands of Colsonbots.

I added hoods and lids for the electronics bays next.

Same goes for the underside.

Notice how the drive motors hang out a little. The gearboxes are still gripped by the clamping plates on the bottom, so they should be well supported still, but I needed the ground clearance or else Colsonbot would be barely able to move.

Here’s how it looks inside the body of the 8×2 Colson.

At this point was when I actually got a chance to machine out the wheel and weigh it, and the results were not promising. This base weighs about 1.6 pounds. Trouble is, so did the wheel, and I had cored the plastic out as far as I thought was reasonable (leaving less than a 1/8″ thickness of the center web of the wheel. The result? Colsonbot needed to lose up to 3.5 ounces to make weight. Unless I made a mistake in material density and weight estimate for the base, it would mean drastic measures:

Like amputating a whole side of the bot, to relieve not only the weight of the 2nd motor, but also the frame materials!

I decided to instead hollow out the frame even further, lightening the volume surrounding the drive motors and removing some of the circular overhands. Now it’s looking even MORE like an injection molded machine part!

Populating only 1 of the spin motors (and consequently only 1 motor controller) should get me down to just under 3 pounds; any remainder was to be made up by sanding down the outer diameter of the wheel, to remove the rubber weight.

Here is the 8″ wheel, before machining, compared to the 6″ Colsonbot.

The frame fresh out of the 3D printer support removal pot, with 2 motors fitted for testing. This material is ABS plastic, a 3d printing staple.

Transferring the goodies directly from old to new….

Most systems wired in now, after an evening’s work.

Those wheels are actually rubber wiring grommets, pressed onto 3D printed hubs. I was cleaning the shop of old student projects and research when I found a whole bag of them. I noted how grippy they were and how they were conveniently 3/4″ in diameter, which is what I needed for wheels. You may see them in other bots in the future…

Notice the spin motor’s outboard bearing, sitting in a little indentation on the right side. This is to ensure the motor doesn’t move or bend the mounting surface behind it once the wheel is tightened down. It’s a SMF83ZZ type miniature flanged bearing.

With the received wired in, now I’m testing directions and control channel orientations. Everything on my little bots is “hardwired” with no connectors simply due to lack of space. This means if I get it wrong on the first try, it’s a pain to change.

Well, I DID techncially get it “wrong”, but only to the point of the robot being “backwards”. Meaning what I had intended to be “front” – the righthand side here – was actually the rear of the bot.

That’s okay. It’s round. Nobody will know.

The small indentation on the underside  is to fit a small chunk of LED tape. I had the “bright idea” of replacing two of the LEDs with different colored ones – white and green – and making a kind of navigation light setup, but once the wheel was put on, you couldn’t really tell anyway. It adds to the Chaos Factor..

Once I had turned Colsonbot Italian with LEDs, it was time to close up the underside and put the wheel on. The very tight clearance shown between the drive wheels and the.. uhh, big wheel turned out to be problematic at Bot Blast.

And a final weigh-in… Wow, I over-estimated the bot’s weight by 1.9 ounces. Since I physically weighed the post-machined Colson, I can only surmise that the wiring was lighter than anticipated or, more likely, Inventor’s weight data for ABS plastic might be over-estimating for 3d printed material which is not perfectly dense.

Here’s a “press photo” of the finished bot.

The completed drive base. It’s actually very quick and maneuverable due to the 4 wheel drive with 11:1 Spark motors.

Since I really didn’t use the space under the two wings of the larger electronics cavity, for further weight reduction I might remove those from the next revision so it looks more like the other end. This could free up enough weight for me to run two motors…

butt bot blast 2015

I didn’t have enough time to go to Bot Blast myself, due to the needs of the Singaporean Navy (more details on that soon!), so I handed Colsonbot off to Jamison, who proceeded to take Colsonbot through FIVE matches for an overall 3-2 record.

Wait, what? That’s like, better than pretty much all of my actual bots have done in competition the first time. And that means three people lost to Colsonbot. How on earth…

Well if you look at the tale of the tape…

Okay, I’m going to hell for that one.

Here is a playlist of Bot Blast matches. Colsonbot’s two losses were to a vertical drum type spinner where it got flipped over, and at the end, to a solid pusher bot. The wins were all by good driving – the quick drive base was essential, because let’s face it – the wheel isn’t capable of actually dealing damage, despite a few good traction-based connects.

The friction wheel on the weapon motor ended up wearing out and coming apart, but besides that, Colsonbot took no repairworthy damage. It’s crazy well-armored and bouncy, which probably helped. I do intend to bring it to Dragon Con, perhaps with those new frame updates.

Up next! It’s almost Detroit Maker Faire. What’s Chibi-Mikuvan up to?

The Dragon*Con 2013 Complete Roundup, Part II: Event Recap and Maker Resources

Sep 19, 2013 in Bots, colsonbot, Events, mikuvan, Twelve O'Clocker, Überclocker ADVANCE

So here we go – now that Part 1 has had some time to sink in, and now that my shop is looking remotely functional again, it’s time for some part two. In this section will be the two new ‘sections’ (carried over from part 1):

  1. Operation GIVE ME A BRAKE: Brake system and inspection all-around on Mikuvan!
  2. Pad Thai Doodle Ninja, an Antweight 4-bar pushybot I designed and built in like 72 hours!
  3. The trip down, the con, and how the bots did at the event!
  4. The links and documents associated with my two panels at  Dragon*Con.

This semester, the two fabrication labs I oversee in the MIT-SUTD Collaboration is once again playing host to How to Make a Mess out of Almost Anything:

Yeah, it’s going down about like that. Unlike the last two academic terms (January – August, basically), I’m not “running” a class this term, so it’s going to be way more chill. I’m not sure if I will want to run back-to-back design classes again like the consecutive 2.00gokart and “2.00GLP”, since the overall level of intensity and chaos is extremely high. I see how the department can go through design class professors rapid-fire now.

Anyways, back to the trip. It’s Tuesday night! Time to load up robots.

Dragon*Con 2013

…but first, I need to get my 200 pounds of tools, accessories, and spare parts out of the back. I left a spare tire, van-specific tool box (like my robot-specific toolbox, but everything is bigger!), and spare fluids. The floor jack was removed since there is a bottle jack for tire changes in a rear compartment. Basically I was purposefully blocking myself from doing any roadside extensive work – I think I’ve gotten everything mechanically to the point where a failure necessitating deep dissection is practically going to be catastrophic in nature and not something I’m going to do in a parking lot.

Replace all the van kibbles with robot kibbles. I guess I could have kept the van kibbles in the back anyway, since I was initially expecting more bots and parts. This stuffing was, consequently, not as epic as the Motorama Stuffing or the Last Dragon*Con Stuffing (though those vehicle did have less hatch space to begin with). The ship-out time was essentially midnight.

Around 4, we reach Flushing, New York, where Xo Has Joined Your Party. This is where the trip got a little more interesting.

In 2007, before I was a wee bunny at MIT, my parents and I drove up to visit the place. We took I-95 in all of it’s forms through DC, Baltimore, Philadelphia, Newark & New York City, then up through New Haven and through Rhode Island. My only memories of the trip are of how I-95 was utterly depressing in every way, from tolls to traffic to construction, and the general level of suck the Northeast urban cluster exhibited.

Six years later, I was meandering up the Bruckner Expressway in the wrong direction when I hazily decided that maybe I-95 wasn’t as bad as I remembered. Plus there was like an exit for it right there and if we kept going semi-lost I’d end up back in Connecticut. So, down 95 we went, across the George Washington Bridge (slowly, because construction and late night truck traffic), and down the New Jersey Turnpike, the fancy Delaware Bridge thing, then down onto Baltimore and onwards.

I’m glad to say that 95 is every bit as depressing and repulsive as I remember it and that nobody venturing out of the Northeast to anywhere should ever drive on it for any reason.

All together, I think between Queens and Baltimore I busted $35 on tolls alone, not even including the relatively minor tolls in Massachusetts. Every bridge or turnpike had its own toll authority.

I thought the Interstates were supposed to be full of FREEEEEEEEDOOOOOOOOOOOM.

In the Baltimore-Washington area, I stopped at my favorite IHOP in College Park, MD. This has been the focal point of several Otakon trips. South of Baltimore, we hit what I like to call “Facebook traffic”, where congestion is so bad and traffic is so stop-and-go that everyone is on Facebook complaining about it. This took about 2 hours to sit through because we came in at the exact time to hit traffic in both metro areas. How are you actually supposed to get to work?

We hit Atlanta around 10PM, for a trip duration of essentially 22 hours, many of which were spent fucking around with the abomination that is 95 in the Northeast Corridor. For instance, it took about 45 minutes to even get out of New York. Then factor in the fact that the cruising speed of my lovely pallet of cinder blocks was about 65 to 70mph.

The next day, it was off to the Invention Studio to get the band back together. Here’s the shot of the trip:

We journeyed a little off campus to get lunch, and in the parking lot of the local small sketchy college restaurant cluster was an Audi R8. Like most expensive cars, it was parked “haphazardly”.

This year, since I brought actual working robots, and because Pad Thai Doodle Ninja was completed the evening before the con really kicked off, and because I wasn’t trying to speedball an entire new bot in 3 days,I got a lot more wandering and people-watching time. I was especially tuned to try and find people with costumes that looked like they required some amount of mechanical construction or engineering (see my brief on this last year).

That, and giant Totoros.

Here’s a good example. This funky gun-like prop had a ton of lovely CNC aluminum work. The wielder, though, wasn’t the builder.

I spy a little of waterjetting on some of those interior parts!

The thing I’ve historically liked the most about Dragon*Con over other gatherings is that there’s no particular theme. The con covers about every niche of culture, up to and including robots. You’re not even going to find that at PAX or Comic-Con. This enables people to mash together different story universes and characters with much more impunity, for the amusement of all… such as Portalmau5 up there.

I’ll be honest – this is pretty much the only reason I went to the actual con for, besides my own panels. No, not just any group of girls in costume (that’s so last year), but specifically one series. The latest thing I’ve been fanning over is Monty Oum’s RWBY, also known as “Charles has to build shit that Monty designs with ill regard to constant-volume systems”. Most of the characters are Action Girls with giant mechanical transforming weaponry – what’s not to love? The thing that hooked me at the beginning was the RED preview.

The series so far has really pinged my “defer judgement” sense, since to me it seems a little hurried plot-wise and is seemingly laundry-listing TVTropes (site left unlinked because I don’t want to sink everyone’s productivity for the next 11 days) on purpose. But I’m proud of my ability to cherrypick favorites very specifically, so I’m still into the series for the giant mechanical transforming weaponry.

The series is so new that I wasn’t sure if anyone was into it enough to plan costumes, and I wanted to get a sense of what is already out there in terms of mechanically actuated versions. Conclusion? Zero. On the internet, and in real life at the con.

That’s where I come in.

…not right now, though. With Saturday winding down and the Robot Microbattles just around the corner, it was time to intensively practice driving. This was the remains of a laser-cut quadrotor frame that everyone’s 1lbers and 3lbers were beating on throughout the evening. I also repaired Colsonbot by printing a new motor mount carrier and replacing a stripped drive motor.

This year, Microbattles got the entirety of the International ballroom at the Hyatt Regency Atlanta. In past years, the event has only gotten half the space, and the audience had to be capped every time. The event size is now on par with the main Robot Battles, with even more entries.

So many, in fact, that single elimination had to be used for the tournaments again, and we still ran overtime. The event has been running against its time limits (and beyond them shamelessly) for the past 2 years, and this year was no different. Hopefully the D*C planning committees finally recognize this.

The Atlanta arena returns! This year, an actual 12″ sanding disc was mounted on the spinning turntable. I’m glad to see that my contraption is still functional. During the event, it produced quite a few light shows from bots being stuck in the hole, and reduced the diameter of a few wheels.

The usual suspects were in attendance. Here’s the table of G3 Robotics & Variable Constant & Guy Who Never Updates His Website.

This is a reasonable approximation of the audience during the day. The added seats and projection screens helped crowding immensely. Because the arena has a pretty high bumper rail (3″ or so), and it’s up on a stage, you can’t actually see the bots from the audience unless something exciting happens, so it’s entirely dependent on the video crew!

microbattles results

Because the Antweight tournament was single elimination, sadly Pad Thai Doodle Ninja only got one match in, against the veteran Segs (pic from years past, to the left). Cynthia put up a valiant driving effort, but the lack of “lifter lip” on the arm meant it had a hard time getting under Segs, and the bot was twice as slow as originally planned.  Near Chaos Robotics, filmer of events, recorded the match in two halves: Part 1, Part 2.

In the rumble, PTDN got into the thick of it and pushed a few people around, then got pinged a few times by DDT. The lifter arm was bent up,  but the bot otherwise had no permanent damage and still drives.

Showing why extending the front armor to the floor might be a bad idea – check out the crimps on the left side. After the DDT damage, the bot had trouble maneuvering on the floor.

Rear view of the damage. Because DDT pinged the arm while it was partially up, the force ripped the rear link out of the arm. That part was extremely thin-walled to begin with and should have been thickened, but I was afraid of it interfering with the robots’ self-righting. Turns out that wasn’t a problem.

I do want to fix up PTDN and upgrade the drives to the original 10:1 spark motors I had intended, and redo the front armor. The lifter servos will either be consolidated into one higher torque metal gear servo, or two digital servos for better range matching.

Colsonbot, sadly, was unable to colson much because of the unrepaired damage from Bot Blast. The “duallie” O-ring wheels were beginning to come apart, and the O-rings tended to slip off and get caught between the shell and the bot. It survived the event pretty much unscathed, however, and I don’t intend on making any big changes to it save for remaking the wheels into single-o-ring affairs that have more ‘stretch’ on the rings themselves to prevent them from twisting out. Colsonbot got in one match against Radiobox, and also the Beetleweight rumble where it was mostly a stationary arena hazard.

big bots

Back in the Invention Studio on Sunday night, preparing for some final tuning and drive testing. Null Hypothesis had to have a drill motor replaced, but otherwise, I didn’t have to do anything to the bots for once.

At the event, while I was testing Null Hypothesis on the stage, it randomly blipped and stopped moving. The cause was traced to the controller completely losing its gate drive power supply for some reason. Whatever the case, it necessitated an in-field replacement, which Adam is handling.

Most of the builders are seasoned & flavored veterans, but there were some rookie builders this year. It’s good to see the sport grow organically, if not somewhat slowly. This bot is an alleged 12lber – according to the builder, it weighed 14 pounds when finished. Oops! And hence, it was named. It ran without any top armor at all – something which ended up causing it to lose to 12 O’Clocker.

Omegaforce returns, with more unique wedge attachments. The outer and inner wedgelets are linked together in such a way that the outer set lifting upwards for any reason causes the inner set to drop down to the ground. The upper wedges can swing all the way backwards. So it’s a multi-tiered defense system against oncoming opponents. The actual functionality was a bit spotty.

Non-rookie builder (I met Miles at Motorama 2013) but first Robot Battles event. The center of this bot was supposed to be a lifter, but some things didn’t happen in time. And yes, it’s entirely made of wood. I was hoping to face this with Überclocker, but didn’t get that chance.

Another rookie bot that was supposed to have an attachment in the middle (in this case, a hammer) but Stuff Didn’t Happen.

Überclocker 30 charging before matches began.

12 O’clocker after its first match, which I won. I learned that the springy legs worked well, but they were not well constrained downwards and could get pushed to the point where the front wheels of the bot were propped off the ground. The contact point they make with the front axle standoff should probably be modified to capture the leg in either direction – up or down.

This is probably the most quintessential robot even picture I’ve ever taken. Equipment all over the table, Mountain Dew everywhere, and “beasting food” as I like to call it strewn about.


I try to post audience pictures of Robot Battles every year, because it really is a phenomenal show. I think the audience averages 5 or 600 people and can peak near a thousand. In quite a few years that I remember, the hotel had to deny people entrance because it became standing-room only and exceeded the allowed occupation of the room. Here’s the right half of the audience…

The center…

And the left half.

Oh, this was before matches started.


I’m extremely proud of the bots’ performance and reliability this year, as well as the show they put on. For my 10th (!) Robot Battles it’s quite refreshing to have things that worked. The robots ended up losing only due to my own mistakes, or my tendency to favor a good show over winning at this event. I actually can’t bring myself to just drop someone off the edge cleanly with the Clocker pair, and this did bring about my own downfall a few times…

Regardless, Überclocker 30 got 2nd place in the 30lb class, fighting Null Hypothesis (oops…), Overthruster , Null Hypothesis yet again, Jaws – probably my most favorite Clocker match ever, Overthruster for the nth time, and finally losing again to my eternal nemesis Nyx. Overall record of 4/2. There were sure lots of reruns this time around. Clocker was a crowd favorite in the past, and now even more so since it works pretty reliably. At the very end, during the rumble, I did lose the drivetrain completely, most likely due to the solder joints breaking off the motors – this has been a weakness of the bot since Motorama ’13 that I forgot about until now.

12 O’Clocker finished what essentially is 3rd place, since the winners’ bracket finals loser and the losers’ bracket finals winner were the same bot. In the final match, I just got plain outpushed by a more powerful and faster opponent. 12 O’Clocker was also a crowd favorite, possibly more so than Überclocker itself, if I could judge the audience well, and went 3/2.  12 O’Clocker’s match videos: Tetanus Shot 1, Oops, Omegaforce, Apollyon, Tetanus Shot 2

So what’s next for the robots? Besides the odd demo or sparring match, it’s time to make the upgrades for Motorama 2014 next February. Überclocker’s current form debuted this past February at Moto ’13, and I don’t anticipate making any changes to it at all (except for actually using the Quick Disconnect style terminals on the Dewalt motors, maybe…). The new actuator on Überclocker’s clamp worked as I expected – I could grab and hoist up opponents very quickly, and the multistart leadscrew eliminated the binding it was prone to perviously so I no longer had to be gentle with the stick – RageBridge took care of the “endstops” by entering current limiting mode. On 12 O’clocker, I want to better secure the front legs, but otherwise, the bot incurred no damage from this event.

the way up

I decided to be intelligent and finally take a route which I’d been eyeing for years, but never dared try for some reason until now:

In my opinion, this is the most direct possible shot through to New England without going near any metropolitan agglomerations. The plan was to detour north at Charlotte, NC. and follow I-81 all the way up to Motorama Harrisburg, from whence my general solution has been to go east and up-around New York City through 287, then cutting north out of CT on I-91 and I-84. The upper half of this has been tried and verified many times.

I think this was a good decision. Not only was it smooth all the way, but the western VA and NC scenery subtracted from the boredom greatly. We passed through, and stopped in, a few small towns and villages nestled in the Appalachians, places that I’m sure high flying urban folks around here don’t give a shit about. It was, in my view, a more authentic American experience.

Stopping for a fuel and breakfast somewhere north of Roanoke, VA.

daily van bro

I saw something which looked out of place across the street at a convenience store. Turns out it’s a Greenbrier, one of the original American compact vans built to compete with the VW bus! These are rear-engined, just like the VW bus, but the Ford Econoline of the same era was mid-engined and rear wheel drive, and the layout was directly ported and evolved by the Japanese. So, really this is an evolutionary ancestor to Mikuvan.

It was also on sale. I called up the seller, but sadly the price asked was out of what I had in my pocket at the time. If I were into these things, though, it would be a very fair price for a vehicle in as good visual condition, and as good running condition as the seller described.

Compared to almost all modern cars, I’m pretty damned small, but the Greenbrier was somehow even smaller. And it had 3 rows of bench seats.

The rest of the trip up through Harrisburg and beyond was pretty standard. We arrived back in around 1:30 AM (that is, 0130EDT Wednesday 9/4). And so that concludes Dragon*Con 2013. A pretty delightful adventure filled with working robots and now-most-definitely-working vans.

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.

Maker Panel 2013

Here’s where I (finally) post the presentation from the 2013 Maker Resources panel, and some related links, in one place! The panel happened on Friday evening at 7PM, and I had a pretty full house for most of it. Unfortunately I once again neglected to bring my video camera to the event, but I did notice quite a few folks taking video. If you have some high quality video of the panel, I’d like to include it here.

The panel was broader in scope than just “where to buy stuff” which I did in 2012. It put more emphasis on CAD software and transferring designs to parts using digital fabrication techniques (waterjets, lasers, etc.), and in general how to design better things. I tried to include some CAD program demos of stuff like Sketchup, freeCAD, and Solidworks/Inventor, but I actually ran so far over time that the director had to step in and cut me off (Sorry Val!). Maybe next year.

Also included as part of side discussion were the slides from last year with general parts & resources.

Here’s the list of stuff I said I’d put up like two weeks ago:

The Dragon*Con 2013 Complete Roundup, Part I: Operation GIVE ME A BRAKE and A New Surprise Antweight!

Sep 08, 2013 in Bots, colsonbot, Events, mikuvan, Pad Thai Doodle Ninja, Twelve O'Clocker, Überclocker ADVANCE

I’m back.

Somehow, and not broken down in western Maryland or something. The past week has been so chock full of adventures that I didn’t even have time to post it day by day like I originally wanted to. The Dragon*Con party got back into town at 1:30AM Tuesday, and now that I’m done unpacking everything and catching up to the last week of shop shenanigans, it’s time to spew it all out before I forget. This post is going to be the length of a small novel and will have 4 official subdivisons with this being the first half. If I start dividing something up at the start, then you know it’s gonna be bad. High energy food supplies and plenty of water are recommended.

A flurry of things happened in the week surrounding 12 O’Clocker construction. Besides working on the bot, I was also racing to make sure Space Battleship Mikuvan could make it 2500+ miles without breaking down or being patently unsafe outside of reason (with me, just the qualifier “unsafe” is insufficient). And on top of all that, I was designing on-and-off an entire new bot.

Here are the four parts. The first two are in this post, the second will be going live later and the two bottom links will be updated accordingly.

  1. Operation GIVE ME A BRAKE: Brake system and inspection all-around on Mikuvan!
  2. Pad Thai Doodle Ninja, an Antweight 4-bar pushybot I designed and built in like 72 hours!
  3. The trip down, the con, and how the bots did at the event!
  4. The links and documents associated with my two panels at  Dragon*Con.

 Operation: GIVE ME A BRAKE

In continuing the tradition of naming major van work after very bad puns, the brake system inspection has been designated GIVE ME A BRAKE. I’ve known for a while that the brakes on this thing were “functionally obsolete” – meaning, nothing bad was happening, and it could definitely stop every time, but it took more effort than any other brake-booster equipped vehicle that I’ve driven and the pedal was on the soft side. For bumming at rather low speeds around the city collecting its own parts, I had no reservations. But before a 2500 mile road trip where the option of breaking down is not available, I decided to at least give the system a visual once-over, and replace some of the major components. At the very least, even if it cannot go I should still be able to stop.

It helps that months prior I had picked up the majority of a new brake system on Rock Auto on some serious discount. New rotors and drums were had for basically $10 apiece, and I also bought new shoes, pads, shims, springs and hardware, and other goodies all on clearance. I’m hoping this doesn’t mean I’ll never be able to get parts again, but for the next few myriad miles it should be all set.

Because I’ve already been surprised multiple times by the severity of mechanical degradation, I also bought a bleeder vacuum pump kit and like a gallon of brake fluid. So this was going to happen eventually anyway, and I took the impending Dragon*Con trip as an excuse to use some of these parts and tools for which I was beginning to feel a bit of buyer’s remorse.

The plan was to work from the rear and move forwards. I’d already gotten visuals on the front disk system in Operation: LOST BEARINGS, and they were serviceable, albeit heavily scored. The rear drum? Never looked at them. All I know about drum brakes are that they are this carefully balanced arrangement of springs and punched metal levers and this weird ratcheting thing that will explode if you touch them, or so everyone warns me.

I spent a while on the Internets watching videos of drum brake repair, and I keep wondering to myself who ever thought this was a good idea. Like, I’d have figured cable-and-cam actuated disk brakes (like almost all scooter and bike brakes) would have been way easier a solution at the beginning of it all.

Anyways, let’s begin. One night I decided to just dive right into it and started by removing the rear wheels.

With my trusty Harbor Freight impact driver (this whole thing is basically a Harbor Freight ad, by the way), I removed the lugs which have clearly been impact-gunned on like you’re totally not supposed to but everyone does anyway. Mikuvan is RWD, so when the wheel comes off the drums are kind of loose on the wheel studs already.

Or they’re supposed to be. I guess years of cyclic fretting causes these things to become stuck together. Someone’s helpfully smeared a layer of antiseize grease onto the wheel contact surface already.

The drum has a M8 tapped hole in it specifically for you to insert a bolt and use it to jack the drum away from the hub.

So here it is. This is the thing. Now what??

When I tapped the drum off, a small mountain of brake dust fell out (the piles on the ground to the right). There were more cakes of it in the crevices by the dust shield, and way more behind the axle hub. After an extensive cleaning and soaking with brake cleaner, the above pictured setup emerges. Before, it was all sort of this even black color. I’m sorry, Earth.

As dirty as it might have been, everything was remarkably new and in good condition. This suggests to me that the drums were serviced (relatively) recently, and rear brakes tend to wear far less than front ones. The lining thickness was almost original – maybe less than half a millimeter thinner than the brand new brake shoe linings.

I played around with this mechanism for a while and got to see finally how the parking brake links up to the shoes, and most importantly how the damned self-adjuster barrel works. Self adjusting brakes are one of those automotive things that I sort of hand-wave and accept that they work and exist, and to not try and figure it out. The other items on that list include manual transmission synchromeshes (“some kind of coney thing bashing into another coney thing and it all works”) and all automatic transmissions (“insert analog hydraulic computer, get different speeds”)

I determined at this point that the rears most likely do not need any parts replaced, if the work was done symmetrically.

Well, was it? I ran around to the other side to see:

This drum took quite a bit more effort. I did eventually get it unstuck with a large gear puller, but not before I thought that maybe some pressure was still remaining in the lines, so why not try and bleed the system to relieve it and see if that would get the drum off?

(Spoiler: The rear right shoes seemed to be adjusted out more than the left, so it was grabbing onto the small wear lip inside the brake drum. The puller just sort of munged everything over that lip.)

Harbor Freight, I’m counting on you to save the day. More scarier words have never been said.

This thing attaches to the bleeder valve and allows you to pull a vacuum before opening the valve, so nobody has to be at the brake pedal to pump it in time with your opening and closing. Create a vacuum in the canister, open the valve, a small amount of fluid (or air bubbles) is extracted, and close the valve before the pressure approaches ambient again.

I’ve noticed that this van is great at 3 things:  raining bearings at me, dropping little flakes of rust everywhere, and emitting brown and black mucus when I least expect it. I knew that brake fluid degrades after a while, but eww. Armed with a jug of new brake fluid, I decided to perform a full rear system flush (the fronts would wait until I have them apart). Out come the Gatorade bottles…

The bottle on the left doesn’t really capture the blackness of what came out for the first few minutes, since it’s diluted out with some newer stuff. I used the rear right wheel’s bleeder valve, which is the furthest point in the circuit, so both rears were cycles. Check out those deposits in the right bottle…

Anyways, here’s the right side assembly after some cleaning. Looks identical to the left one, so I decided to put everything back together. Since I messed with the adjuster on the left side, I decided to rough-adjust both sides using the brake drum as a guide (“Just a little drag”) and let the self adjusters handle it in the parking lot later.

The next day was dedicated to the fronts. I’d already removed the front hubs and calipers before to replace the front axle bearings, but had not tried removing the caliper slide pin or dismantled the caliper in any other way.

I spent the better part of half an hour trying to get the slide pin loose to swing the caliper to the shown position. Why? Because some fucker who serviced this before definitely impact-gunned it on. With a MUCH bigger impact gun. It took me 10 seconds of straight impact wrench bashing to get the damn thing off.

Blame it on weaksauce Harbor Freight wrench or whatever, but stop impact gunning my shit.

After removing the caliper body, the rest of the steps were fairly intuitive.

And back on. The C-clamp shown was to reset the piston to clear the thicker pads.

At this point, I could remove the caliper as a whole in order to take the front hub and disk off.

Here’s the left front hub removed, showing the nice and scored rotor with a giant ugly wear lip on it.

The disks are bolted onto the hubs, and I removed them by clamping the disks in a vise and impact gunning the bolts out. These used discrete nuts – the hub wasn’t threaded or something, so it was an adventure trying to apply back-torque with a breaker bar to some very corroded nut threads. Was it too hard to thread one of these things, guys?

All new disk mounted and torqued not with an impact gun. I cleaned out the grease cavity and bearing races completely because cleaning the hub caused a ton of grime to fall into the bearings, so they had to be cleaned out and repacked.

Front left wheel buttoned up. Now that I have a vague idea of what I was doing, the right side went much more smoothly.

This time I was a little smarter and made myself a shop rag seal for both sides.

This is the scene at the height of entropy, when I had all the doors open and all my tools out. I was convinced someone was just going to come by and steal everything while I was working inside.

But they’d be stealing Harbor Freight tools – so am I really worse off, or them better off?

Time to complete the system flush. Hey, did you know I had front air brakes? I didn’t know either!  The first thing that happened when I opened the valve was a small riot of air bubbles. That would explain the soft pedal for sure.

(I guess it’s more “air over hydraulic”, eh?)

The total amount of brakerade generated. It’s interesting to see the different shades between rear and front. The next day, I took this to the local auto recyclers for disposal, where they presumably lit it on fire in the back or something. By this hour, all the traffic in the area had totally cleared out, so I took “wearing in the pads” as an excuse to take the longest, most convoluted possible way back to home, starting with gentle low speed stopping and progressing into trying to see how fast I could stop before a red light while not locking up or doing a stoppie. Brake responsiveness and pedal stiffness were greatly improved by the work, which I suppose was the goal.

Continuing on the trend of extracting brown mucus from various places, I decided to change the differential oil since it’s probably another one of those things which was last serviced 153,000 miles ago. This process was relatively painless – untighten the drain plug, unscrew with your hand, then feel the viscous brown goo envelope your hand as you wondered when you went wrong in life and became a van mechanic.

The smell was horrid. Old gear oil additives seem to decompose into various phosphate and sulfide components over time and it was actually like 20,000 eggy burrito farts at the same time. I refilled the diff with some Mobil synthetic 75 weight gear oil. I’m actually not sure if this entire rear solid axle is oil-flooded or not, but it takes like 2 liters of the stuff and the bulb volume under the fill hole is not that large.

While I had my waste oil bucket out, I also changed the engine oil completely and installed a new filter.

Look closely at the picture of utter chaos a few lines back and you’ll notice I have little devil horns up front. They’re a set of these things that I turned into an adjustable roof rack using some spare 80/20. There was a point a month ago or so when I was extremely concerned about cargo space – when we possibly had like 5 robots and up to 3 large props travelling down, so I took some recommendations for roof racks. These little things seem to be convenient if you don’t want to drill and rivet into bodywork, and so long as I have a 10 foot long rain gutter on the sides, it can be slid anywhere.  I can bolt entire Chibikarts to the roof now. This might get exciting.

So, that’s the state of the van on last Monday night before our scheduled Tuesday night departure. It ended up that said large props and numerous large robots weren’t happening, so this is decor for the trip, but will surely come in handy some day.

Working roughly in parallel with this was the design and (mostly) fabrication of an entirely new bot.

 Pad Thai Doodle Ninja

I some times take interest in how people name their projects and builds. For myself, I began it all by building Test Bot which literally was a test bot to see if I could put together parts in a meaningful fashion, and the name just stuck. I tend to be very direct with names – for vehicle type projects at least, it’s usually [noun][thing] or [adjective, usually a size or qualifier][thing]. Melonscooter, Kitmotter, Johnscooter, Tinycopter, Chibikart… even Mikuvan.  it’s a naming method which I see as sort of idiosyncratic of my stuff, and which also spread to some of my former students or MITERS peers.

It’s harder to call for other things. It’s easy to see where LOLrioKart came from (if you’ve been living under a rock since 2009, it’s like Mariokart), but not so much Überclocker. I myself have even forgotten where I got the idea to take overclocker and turn it Über, and 12 O’Clocker was a jocular offshoot of that since it was a 12 pound bot. So I guess I name things by “least resistance” – I’ve never spent hours or days thinking of a name for a project. Nor do I do that for products: RageBridge was originally “Ragetroller” because I was enraged by the lack of good motor controllers in the robot universe, and DeWut!? was only a short step from DeWalt, whose drill motors I unashamedly press into duty doing things their engineers would have never suspected.

So of course what I’m saying is, I have no clue how the hell the name for this bot came along except for this image:

Look at the very bottom left.

This modern art example came about because somebody brought a bag of Internet-themed word magnets into the shop, and shenanigans ensued on the local Rancid Dragon (a greasy spoon Asian takeout place) restaurant menu. Pad Thai Doodle Ninja just had a good floooooooow to it. This bot was named before I ever started the CAD, which is rare.

So what is Pad Thai Doodle Ninja? I started itching for a new antweight right after finishing 12 O’Clocker the week prior. I could have re-entered Pop Quiz  from 2011 with a new, one-piece 3D printed frame, but that thing had a tendency to take off without warning (protip: long blades on horizontal bar bots are awesome but impractical). At the same time, in conjunction with my sentiments expressed in the original 12 O’Clocker intro post, I did want the return of Test Bot in some way. I miss driving a bot that’s 100% drivetrain, or mostly drivetrain with a single degree of freedom weapon. Not since I built Überclocker in 2008 has this been the case with one of my entries.

So why not make a tiny Test Bot?

It would come together quickly, once again being a 3D printed frame, and would only use parts on-hand and from McMaster (which is basically next day turnaround). I sort of rushed into designing this, so there are no early CAD pictures. Here were the goals:

  • Four wheel drive using two motors, some 20:1 Fingertech Sparks I had on hand, rear motor in a fashion similar to Test Bot 4.5.
  • Servo actuated 4-bar lifter using unmodified servos so the stick position is arm position (using some HK939MG mini servos I had already from the thrust-vectoring deathcopter project)
  • Sloped front with embedded lifter, possibly a short hinged wedge. Armor to be made with 0.015″ spring steel shim stock overlaid on the 3D printed frame
  • Able to self-right.

This last one is kind of tricky with 4-bar lifters. You really have to take into account the center of gravity of the bot, and the length and extension of the arm, in order to facilitate this. Generally, 4-bar lifter bots flop onto their backs and come to rest on the arm whenever it is then deployed, as the CG is too far forward, and no self-righting is possible. Check out this classic video of former Battlebots heavyweight Biohazard to see how a 4-bar could self right.

Notice how its center of gravity is far enough back that the bot hinges on its rear edge and does not come to rest on the arm. The arm’s retraction then keeps the CG within the line drawn between the arm’s contact point and the bot’s rear edge, and it gathers enough momentum to push back over. Making the bot able to do this meant making the arm extend all the way back across the bot. Notice also how Biohazard had a ‘tang’ at the very back of the arm, a part that sticks up – this aids in the maneuver by making the contact point with the ground further forward, so the ‘line’ is longer.

This goal meant that I was continually watching the bot’s center of gravity in autodesk Inventor, and also continually modifying the linkage to suit. The arm had to have a certain amount of extension to make sure the CG was in the right place, and that extension had to jive with everything else’s placement. Here’s an example of a 2D sketch linkage I used (many times, with different lengths) to check the arm geometry:

Notice the nonplanar attachment points for the arm – meaning, the pivots aren’t all on flat lines with each other. So the virtual arm (the top link) actually doesn’t sit flat whereas the real arm takes the mounting point shift into account and does.

Making little sketch linkages in CAD programs is one of those things which distinguishes a geometric modeler from a parametric modeler. The former just treats your lines as a drawing, and if you move an endpoint or something the line length and orientation changes, with no effect on other neighboring elements. In a parametric modeler, you can add things such as dimensions (exact lengths, regardless of orientation), and geometric constraints (this line must always be perpendicular to that one, or this point must lie on that line, etc.) and these constraints are dynamically solved as you force the elements to move.

This is the frame of the bot about 1/3rd through design. I modeled the basic proportions after Test Bot, but shifted the rear motors out such that the wheels could touch the ground if the bot were tilted up. This necessitated mounting the motor much differently than in Pop Quiz (2 piece top-down clamp mount) or in most of my other bots (face mount) – the motor mounts are actually C shaped and slide in from the back.

Also modeled in this early picture are the two metal gear miniservos and the battery, a 3S 460mAh lithium polymer pack left over from one of the copters. The choice of wheels was going to be my insectweight default: O-rings stretched around a custom 3D printed rim. The outer set of rings will double as power transmission to the front wheels. O-ring drives are pretty popular in these smaller weight classes, but as I learned early on, there’s a catch – O-rings have to be stretched over their wheels, or else they’ll just roll sideways right off! Typically the stretch is 25% or more. The same is true for O-rings used as drive belts.

About 50% done, and a few hours in. I’ve kept the center of gravity marker turned on (the yellow ball) to check that at all points in the arm retraction, it lies between the arm’s contact point (just barely behind it) and the bot’s upper rear edge. I’ve also now put in the mounts for the servos – a top down clamp.

A drastic change from the previous snapshot to now is the addition of solid wedges. I’ve historically not been a fan of solid wedges, but I think hinged wedges would have been too fragile in an antweight when faced with modern weaponry. It would also let me use a very thick section of 3D printed ABS, which would increase the strength of the frame. At this point, I was also extremely underweight, so the thicker the better, right?

The 0.015″ spring steel shim will be inset into the side wedges and front, and be retained by infinite #4 self-tapping screws. Attachment of armor to the substrate is just as critical to its effectiveness as what material you use. If an extra hard steel with good backing is used, weaponry will tend to glance off and not catch and rip the material.

Spring steel bits added. This arrangement of top armor leaves the servo and drive motors serviceable without removal. The front armor slopes down further than the bottom of the frame to complete the front wedge.

In retrospect, it would have been better to leave the front armor also stopping at the bottom of the frame, so there’s only one point of contact with a potential opponent – the lifter. During the event, any bending of the front armor caused the bot traction problems.

View from the front. One thing that is missing from this image, but made it into the final “production” arm, is a little tang in the back of the main arm link similar to Biohazard’s. The “ears” are both for adorabu and as a front stop to prevent bots from just driving right over the top, since this bot is so short (about 0.9″).

Sunday before the departure, construction began on Pad Thai Doodle Ninja by waterjet cutting the steel armor and aluminum arm parts. I also started the build of the one-piece frame on a Dimension 3D printer. Pop Quiz was originally slated for such a one-shot print, too, but I elected to use Make-a-Bot (when it was still a thing) to keep the resources ‘local’ so to speak.

Tossed in with the build were the auxiliary components including servo and motor mounts, and the little o-ring wheels.

I thought I had a set of 10:1 Silver Spark motors, but it turns out I either gave them to someone without thinking (This happens more often than it should…) or never had them in the first place. Instead, these 20:1 Gold Spark motors will have to do. It means my top speed is only going to be about 3 feet a second, which is quite slow for my tastes.

The o-ring wheels have the D profile already in their bores, but also have a cross “drilled” hole that I’ll tap for a 4-40 set screw regardless. In Colsonbot, I had trouble with the D bores stripping in the soft plastic.

The waterjet-cut pieces were out of 1/8″ aluminum for the arms, and my 0.015″ spring-temper steel shim stock for the armor.

I heated up the spring steel shim with a torch while it was in a vise in order to make these bends. The area of bend will be weaker than the rest of the steel, but I tried to keep the heat local as much as possible.

The holes are sized such that they’re just about .01″ too small for a #4 countersunk screw to pass through. This ensures that I have a reasonably flat surface up front, but is much stronger than if I had actually countersunk the screws fully. As will be seen, the screws stick up just a little bit.

One thing I forgot to do was mirror the last set of outside holes to the right side. Whoops…

There will be 3 standoffs between the inner and outer frame in those hole positions so I can mount the rubber O-ring drive without having to cut it every time. To make these new holes, I had to turn a 0.2″ peg that stuffed into my 0.2″ counterbored hole in one of the positions, use that to establish a coordinate system, then countersink the rest (though with 0.25″ cutters). The servo mount backs up the plastic material from sinking down due to cutting pressure, and the elaborate clamping prevents the plastic from fluttering.

This was the status of the bot before we left on Tuesday night. I was going to wait until we got to the Invention Studio and set up a forward operations base of some sort.

Bright and early on Thursday at the Studio. I packed Colsonbot and the semi-retired Pop Quiz; Colsonbot was actually going to be entered, but Pop Quiz was only along as spare parts if needed. On deck were machining some arm standoffs, modifying the lift servos, and then wiring the whole thing up.

Normally, I’d use some custom-machined spacers in these kind of applications, but the GT machine wasn’t very well suited to producing small stuff. It’s large in swing, gearheaded (and noisy), and the tooling was not in the best condition. So, to speed-finish the bot, it’s time to resort to plastic washers! This wasn’t as bad as I make it out to be, mostly because plastic does have some ‘give’ so I could tune the friction and slop of the joint using a threadlock-glued pivot screw.

The front link attaches directly to the servo output arm. I was preparing to run 2 servo lift on this bot in order to get more force – with 2 servos, the calculated max lift force when the arm is fully retracted (therefore in the worst mechanical advantage position) was 1 pound. So in other words, it can dead-lift an entire 1lber from the lowest position. Now, typically, when an opponent is lifted an edge, you’re lifting somewhere around 50% of the weight.

As I found out, these servos aren’t very well matched in how they handle the same range of PWM pulses. In fact, one servo traveled about 10% more than the other, while Y-connected to the same radio channel. This meant that the servos fought each other when the arm was at either extreme of extension. Digital servos would be far better matched.

In making the 2-servo version, I also had to “mechanically reverse” one of the servos since they faced each other across a mirror plane. Normally, Y’ing each servo to the same radio channel meant they traveled in the same direction while looking at their own outputs. But I needed them to travel in the same direction in a global reference frame, so one servo had both its 3-lead potentiometer feedback reverse, and the motor wires reversed.

Doing only one of the above would make the servo run straight into one end stop and smoke itself.

At this point, the bot was about 0.9 pounds, so I could as be as liberal with giant wires and solder blobs as I wanted.

Still with two servos, and getting through the wiring now. The black amorphous blob at the top is a small 3A switching regulator that gives 5V straight to the servos. I wasn’t about to try and hitch the servos directly onto 11.1v volts, because they would just grenade almost instantly.

The bot is mechanically together at this point. Notice the standoffs in the center between the frame rails that attach the outer wedge ‘flaps’ to the main body. If this thing were actually one piece, I’d have no way to actually mount and dismount the O-ring belt besides cutting it each time.

Completed bot on the googly-eye scale at 0.88 pounds. The extra amount down from 0.9 is presumably made up of wiring that I trimmed short or something, because I definitely added more screws…

Drive testing of this thing caused it to burn up and strip one servo, mostly due to them fighting themselves with the arm fully down. Going to one servo would have meant losing the ‘dead lift’ margin, but getting into a situation where the bot had to dead-lift an opponent seemed far less likely than a normal edge lift.

The left side servo was gutted, leaving only the output gear to act as a bearing.

The bot was a full 0.12 pound (or about 2 ounces) short at this point, and it was failing to self-right because the CG wasn’t far back enough. It would some times get in the right position with a forceful actuation of the arm, but with one servo a forceful thrust was out of the question. So I bought some fishing weights and melted them down, an ounce apiece, to append to the rear of the bot on top of the motor mounts.

Here’s the “before” shot, the pretty clean bot (no weights have been added yet).

And with the 2 extra ounces in the rear, the bot could self right every single time!

I handed PTDN off to Cynthia to drive for this Microbattles tournament. The event report for both big and little bots, and match videos, will happen in the next half of the post.

Colsonbot Rage-Finish and Bot Blast Recap

Jul 23, 2013 in colsonbot, Events

Well, here it is! Colsonbot was finished in the intervening 3 days between the previous post announcing its arrival and when we all shipped off to Bot Blast. The event was a blast indeed, and I’m furthermore glad we even got there in the first place! Here’s the whole story.

This is the friction drive module fully assembled. A little printed rim attaches around the motor, around which I sling some stretched-out O-rings. I recommend everyone who is considering O-ring friction drive make sure that the rings are not bought “on-size”, since if they are, at high operating speeds they will stretch out and be more likely to pop out

Tension in the friction wheel mechanism is maintained with a stack of wave washers. I was hoping for enough space to put a very short coil spring, but it ended up that I really only had 4-5mm to play with. So, wave washers it is.

Since this bot is way more unibody than anything else I’ve built, I needed to construct most of the wiring harness first before installing the motors. Here are some of the Pololu 30:1 HP “Sanyo-flavored” gearmotors being prepped with wires. I call these motors “Sanyo flavored” since originally the first on the market in the robot world was the 75:1 Sanyo micro gearmotor.

Other electronics being prepped include two Vextrollers, one of the left over 18A ESCs from tinycopter version 0, and a gutted Hobbyking receiver. Everything had to come out of their packages for this bot since the space was extremely tight.

The wheels are also 3D printed affairs. They’re little duallies made with O-rings. The center bore is pre-flatted to mate with the Sanyo motors with a set screw hole on the flat to keep them secure.

The installation sequence is wheels on motors, then motors into their mounts.

The center shaft of Colsonbot is a single hollowed-out 5/8″-18 fine threaded bolt. The hex head was machined down to 1/8″ thick, and it rests flush with the top of the battery cavity in a hexagonal cavity which prevents it from turning as I tighten the clamping nut.

Wiring on the bot can be described as “ad hoc”, to keep it politically correct. I used no connectors at all – there’s not enough space for the ones I had. To reverse motor directions, etc. meant desoldering.

Most of the wiring is done with 30 gauge wire-wrap wire, with heavier currents such as the brushless controller and two Vextrollers done up in 24 gauge.

First power test! This was just to verify that everything was still working and hooked up the right way.

Starting to add the other snappy-lids to keep things constrained. The electronics are mostly just piled inside the cavities. I had thought of making little exactly Vextroller shaped cavities, but realized I would never have put up with that level of cleanliness. It’s just a little too Apple.

Lids attached. The external wire run is unceremoniously held down by a glob of used Kapton tape harvested from the Hobbyking battery.

Time to put everything together and find out exactly how not a 3lb bot this is. Turns out the answer was not even 2 pounds. Great…

I knew Colsonbot would have a not-enough-weight problem since it could literally be made of lead and be fine. There’s just not enough volume of bot inside the wheel. Colsonbot’s base by itself, at 10 ounces, would actually make an excellent 1lb shell spinner with a 6oz real shell. This is something I’m considering for Dragon*Con, now a little over a month away.

With a second 5/8″-11 jam nut and a bit of thin PETG plastic, I made this direction indicator since otherwise I had no idea which way the bot was facing underneath!

And here is the soft underbelly!

Check out some of the test footage:

Colsonbot being  a roughly square 4WD setup, handles extremely well and it’s also quite peppy. It really does not need this many motors. As can be seen in the video, it “gyros” extremely easily due to the large spinning mass. I originally wanted to put a “mast” up high over the wheel so it could flip back over, but I decided to keep the wheel illusion. If Colsonbot gets flipped, it will tend to stay upside down and wobble like a coin.

This work was done on Thursday evening. I left Colsonbot alone after that to help out with the two new stragglers we inhaled: Jaguar (by the way, check out his excellent Instructable on his even more excellent Orbit Wheel pod things) and Julian. Of these two, Jaguar decided to start a new robot some time around 1AM Friday.

bot brast

Great, now we’ve increased from four to six people. I was really getting worried about Mikuvan’s mechanical integrity at this point – six guys and another hundred pounds or two of robot gear times 800 miles round-trip plus mountains. If I was going to grenade something, it was going to be on this trip!

On Friday afternoon, I gave the engine cavity a more thorough check over. My primary focus was on the timing belt, since I had observed some leaking oil on the front underside of the engine, leading me to think leaking camshaft/crankshaft oil seals, which would throw oil all over the belt and cause quicker deterioration. Otherwise, I had already done a mechanical once-over after the Adafruit Adventure. To my surprise, the timing belt cavity was dry and there were no signs of abnormal wear on the belt, and the tension was still good. So where the hell was all my oil going, then?

That’s the back side of the engine where it mates to the transmission. I see a new sludgebunny colony is starting to form. This is the area I cleaned a few months ago to see where the oil leak was, and… well, this just tells me it’s coming from everywhere. The side of the block is still well-coated in grunge.  I definitely have no idea where this could be originating from. Valve cover gasket? Rear crankshaft seals?  I’ll write it off to built-in underbody corrosion prevention for now.

Since after the New York trip the oil level was low, I topped off this time with some heavier weight oil – some Mobil synthetic 10W-40 (the manual calls for 10W-30). Time to see if those “for high mileage engines” claims have any merit. The slightly more viscous oil might reduce the rate of runoff if nothing else.

Whatever the case, it was time to ship out. Space Battleship Mikuvan was temporarily commandeered to become the MITERchan Party Van. Having only like 105 original HP and surely less available nowdays to push 6 people and robot gear, this was pretty much my most conservative road trip ever – essentially spent all at less than 70mph and almost all in the right lane. If you know me well, then you know this is basically the opposite of my usual style. The van is teaching me some humility.

Somehow, 6 hours later, Waffle House.

Every time I wander out of New England, I must stop at a Waffle House, so this time we met up with aaronbot a hour outside of the event venue at a Waffle House in Scranton, PA.

On site at the event… and there’s more than one Colson! On the left is Agent Colson, built from a 6×1.25 wheel – it’s flatter, but only 2WD, and also direct drive from a small outrunner. Colsonbot was originally going to be a DD from a large diameter (e.g. multirotor motor) outrunner, and that idea is still being entertained.

Check out the lineup of newbie bots. From left to right is Glorified Doorstop, DEL-RAN Bumble (by Dane), and Speed Bump (by Jaguar). Don’t let those eyes and zip ties fool you – the front of the bot is to the right. I’m glad that somehow in the last week we managed to generate an entire Battlebots team.

Motorama should take walk-up registrations like Bot Blast, because hell if you could get MIT students to commit to anything more than 1 week ahead of time. Trust me on this one.

The event was held in a regional mall, nestled between JCPenney and Payless Shoesource. Quite a contrast of venues from the typical grungy warehouse or barn you find these ‘bot events in. Because of the proximity to curious onlookers, the audience was pretty steady and numerous for most of the day.

I don’t have as many pictures of everything this time, since I was either sleeping under a table or filming matches (And I’ve posted random robot pictures dozens of times). But here’s Agent Colson after one of its first matches, where it may or may not have hit the ceiling. Sad…

The box is a nicely build 12 footer which fit beautifully into the mall’s… band pavilion? Free Speech Corner? Not sure, but it sure worked well.

Colsonbot in line for its first fight…

Colsonbot performed flawlessly during this match (of course it didn’t win anything), but afterwards I noticed the weapon motor was shifting in its slidy-mount. The motor was chosen as a compromise – the one I purchased from Hobbyking that was intended for the bot just didn’t fit. I used instead a Hacker A20-50S, which was admittedly undersized.

It didn’t get hot enough to burn out, but it did get hot enough to warp the ABS housing, causing some tension loss in the friction drive. I literally bent it back while the motor was still hot.

Both colsons being serviced in some way…

In my second match, I sort of went for broke at the end and tried to keep spinning. This resulted in the motor melting the ABS to the point where the friction wheel just sort of welded into its mount, stopping Colsonbot. I still had drive ability, though, so spent the next half minute just getting punted around.

Colsonbot suffered no particularly permanent damage at Bot Blast, and was a great first version run. Now that I know how this version performs, I can better build the Next Generation Colsonbot.

Boy, some “joke” this has turned into.

For Dragon*Con, Colsonbot will return. I’m currently thinking this as the list of changes:

  • 2 motors, since 4 was a bit excessive, and O-ring belt drive to mimic the stable 4WD drivetrain
  • Fitting the larger and more robust motor in the bot as a result
  • Possibly switching to tinyESCs or something to kill the electronics volume even more.

Finally, here are Colsonbot’s two matches from the day!

Returning from the event was entirely uneventful, save for a short section of I-84 in southern New York which seemed to climb straight up a mountain for 5 miles. I realized it was hopeless after fully opening the throttle, falling back into 2nd gear, and was still losing speed. That stretch was done at 40mph with the heater fan on full as I watched the engine temperature climb slowly towards hot.

Clearly, I am never going on a cross-country roadtrip with this contraption as is – I will never even make it over the Rockies, and if I take the southern route through Arizona, would just light on fire regardless. By the way, Newburgh’s Stewart Airport which we passed next to is the site of the original Three Legendary Derpy Van showdown.

So now that Bot Blast is over, it’s time to start prepping for Dragon*Con. More on that later. The final thing to take care of is…

build your own colsonbot

Here’s the entire Solidworks 2013 CAD folder for Colsonbot. Also included are the ready-to-print STL files for all the major components. You’ll need:

  • A Hacker A20-50s or similar motor
  • An appropriately small ESC for the motor – I used an 18A Turnigy Plush
  • Four Pololu 30:1 micro HP motors
  • Two Vextrollers
  • A 3 cell lipoly battery, this one in particular is known to fit (but only if skinned)