Chibi-Mikuvan: The Detroit Maker Faire Recap; Chibi-Mikuvan × MarkForged

It’s van season!

This year, in a stunning turn of events, I was the equipment hauler for the entire MIT contingent, instead of pulling both people and some equipment. I guess everyone just got sick of going 45 mph any time a hill appeared, as well as choosing between air conditioning or 10 more miles per hour. For this trip, Mikuvan was loaded with four go-karts and 80% of everyone’s pit equipment. In other words, if I had a repeat of Dragon Con 2014, we were all fucked. There is something to be said about a single point of failure here.

I also forced everyone across upstate New York to stare at this.

I am truly sorry.

I tried a new method of shielding the bodywork from bug splats and debris – instead of a tarp like last year, which failed pretty miserably, I just encircled it in pallet wrap – heavy duty plastic food film, basically. It clings tightly enough to not be affected by winds, but comes off easily. I also used the same pallet wrapping to bundle up the handlebar and motor & controller to protect it from possible weather.

The track this year was sponsored by Shell, and was therefore a bigger budget production. These low-profile “airport” style traffic barriers were laid out seamlessly into the biggest track PRS had ever seen. It was a well balanced track with several very tight areas but also an epicly long straightaway

Well, I did end up making it there, thank you very much, after only one stop to refill the engine oil.

Now, let’s be honest – this was a very epic one stop. For you see, I permitted three go-karts to be loaded up in the passenger cabin, and they took up all the available space. One, the Corpus Krotus (“Mad Max”), was across where the center two seats would be. The other two, Atomic Thing and the Frozen Chainsaw Massacre (I didn’t name any of these, only contributed to their delinquency) were side by side lengthwise. It was such an elegant packing that I’m quite eager to do it again.

It was, in fact, so elegant that I completely forgot about the fact that the engine access hatch has to swing backwards for me to get to anything. Into the well-packed go-karts, I mean. As it turns out, this might be why they make most cars with a distinct region for the engine.

So half an hour of go-kart de-Tetrising somewhere in western New York later, I was on my way again.


Van-butt for this round. Check out the Markforged bumper sticker. I had a whole lot riding on the 3d printed steering components. Namely, about half of the vehicle weight, and much more under strenuous handling.

There’s very little I can do explain the other MIT effort, the Frozen Chainsaw Massacre.  It’s a takeoff of the first Frozen Chainsaw Massacre effort, which is a takeoff of my takeoff of the Ryobi 40v cordless chainsaw‘s external and internal parts. Bayley’s site has a ton of info on the RY40511 if you want to try breaking into it also. One of the other principal constructors also documented the process (more in words than photos… LANDON) here.

This FCM uses two of the Ryobi saws, with custom firmware written by reverse engineering the controller, featuring nice things such as real-time current control.

Taking a slow drive-around of the track, before qualifier round.

After a few laps, I had determined that the caster angle added to the steering system really helped in the smoothness when turning. There was a catch, though. The rear tires are still rather tall in profile, so the sidewalls were very… pliable. I found that the rear end tended to oscillate a lot during and exiting a turn, because of how wobbly the tire was. To prevent the handling from being too squirrely, I had to drastically over-inflate the rear tires, which caused a lot of early wear, as I’ll show later.

Here is your “clean shot” of the weekend. It all went downhill from here.

You could also say it (almost) went sideways.

If this (and the subsequent landing… and many other two-wheel incidents thereafter) wasn’t a good test of the Markforged CFF parts, I don’t know what was…

Here are the… production? parts in use. By the end, the left front wheel had developed a mild camber, but it was also involved in a direct collision – details below. I’ll have to take this side apart and see what deformed!

Chibi-Mikuvan qualified third after Frozen Chainsaw Massacre (which was incredibly fast) and Phantom 48. As always is the case with Phantom, their wider track and bigger tires meant they could corner much faster than I could without doing that thing up there,even though we were evenly matched for speed.

After qualification was the Moxie Round. Basically, showing off and being an asshat in front of a large number of people. Hey, I’m okay at doing that, including on certain robot-themed TV shows!

Unfortunately, I could not find my usual Miku wig pigtails (this is not something normal people say) (ref. last year). Incidentally, Frozen Chainsaw Massacre also needed a light blonde wig for Elsa. Even more incidentally, there was a wig store in Dearborn only a few minutes of jogging away.

Great! Let’s go there and… wait, it’s a real wig store, for people with real wig problems. Very fortunately, they had leftovers from last Halloween in their basement. The above blue pigtails were made by cutting in half a blue wig and zip tying it to the anchors I 3D printed and mounted to the helmet. 5 minutes before Moxie Round began.

I’m glad to report that the combination of this effort (…) and Neko Nation played over the PA system caused Chibi-Mikuvan to win first in this Moxie Round. It seems like the demographic of this crowd had changed from majority disgruntled union workers (last year) to either majority small children who like cute things, or the Detroit Revival is being driven entirely by weeaboos and ravers, which makes Detroit somewhat appetizing.

I’m also fully aware Neko Nation is not a Miku song, but it had a better vibe than anything else I brought along.


Team “Cult Classic Racing” a.k.a “Team Florey” for those in the appropriate crowd, putting on their best Mad Max. Between the two of us, and Frozen Chainsaw Massacre, I believe we have the Moxie market of everyone from little kids (Frozen) to adults wishing they were little kids again (Mad Max: Fury Road) covered, with myself spread somewhere in between in a cultural infundibulum of glowsticks, blue hair, and cat ears.

The most questionable crossover in the Universe is being planned for New York Maker Faire.

Sprint race number 1 featured the “odd number” qualified cars, including myself. I took an early lead, only to lose it to a yellow flag penalty (which I totally did not see because rage-drive), and regained it again by the end.

To the left is last year’s overall champion, Hack to the Future.

To the right is the “Top Heavy Express… no, I shouldn’t be harsh like that. Everyone expected it to tip over, but it was very bottom-heavy and therefore quite stable, and a very steady runner. I was told it was made from a chopped up golf kart. It never quit running as far as I noticed, which is something I legitimately envy!

Here’s a video clip of me diving between two other cars on the straightaway.

That’s what 30 laps of “me” looks like on a Kenda scooter tire. Like I said, it had to be inflated over ratings – to 50 PSI – before I found the handling to be linear enough. The result? Massive center wear, as expected, from the tire ballooning outwards in the center.

Race number 2 was the even numbers, and race number 3 was EVERYBODY.

Wow, what? That’s like 20 cars on the track at once. We expected utter chaos, and there was indeed chaos. There I am starting in 3rd place.

In the truss camera video, I can be seen executing a “Storrow Drive Special” here at 2:09.

Excuse me, my Boston is showing.

All the MITERS-affiliated cars in one frame here. (Krotus was also MIT affiliated, though more loosely through alumni and Boston University, working at MITERS).

At some point during this race, I accidentally put Chibi Atomic Thing into the wall on this corner. (6:37 of same video)

Oops. I think I was attempting an inside pass that went wrong when they cut in much closer than I expected.

There are very few chances in life to say “I was stuck in traffic between Noah’s Ark and a TIE Fighter.”

Yes, there was a matching X-wing from another team, before anyone asks.

Sadly, the impact with Atomic Thing also popped my left front tire. I made it another lap and a half before noticing the brake disc sparking on the ground. Unfortunately, in a sprint race like this, if you pit, you’re pretty much done. So even though I tried to replace the tire quickly, I could not make up the position by the end and ended up coming in 12th out of 20. (According to the official race data, the “lap and a half” plus my pit stop took 171 seconds… or 6 average laps of downtime. Being short staffed in the pits – only with Cynthia as my ‘pit crew’, contributed immensely.

Lots more damage was taken in this race. I actually lost entire chunks of foam on this one. I think I was trying to mash between Phantom and the School Bus at the very end of the straight, and took it straight in the NIMBY. Sadly, action movies where the hero threads a car through a rapidly closing gap did not translate well to real life.

To resolve the chunks of foam and fiberglass hanging off, after Race 3 I smothered the area in 5-minute epoxy to hold it together. More extensive repairs will come soon!

The front left corner showing a bit of Atomic Thing….

After Race 3, I also discovered that the chopped R/C BEC unit that was producing 12 volts to keep the logic battery charged……. failed to do so. Looks like just straight up load caused it to overheat.

Given that the DC water pump draws about 1.5 amps when pumping and the contactor draws about 1 amp and it was heat-shrunk, mounted on Velcro, in an enclosed box, in a 90 degree+ Detroit summer day, I am not surprised it gave out.

So on the next day, for the Endurance Race, I stuffed a Strategic A123 Brick (which nobody at MITERS leaves the building without, especially not to a go-kart race) into the 12v system and ran only with it. The capacity was more than enough for the Endurance Race.

To my surprise, CMV lasted all the way to the end of the Endurance Race with no hiccups. By this time, over half the field had retired. CMV ended up taking 4th for lap count. Not getting around to building a 3rd battery really bit this time, as I was running out of power again by the end due to a mistake in battery handling (namely “handing your battery to some random person to put on your charger) resulted in the battery only getting five minutes of charge.

The meme will now officially never die.

This was hurled out of Krotus at me some time during the endurance race. I tried to run it over, but couldn’t really get it caught on anything.

It combined with race hosts Jim and Patrick & others endlessly reminding me that THIS ISN’T BATTLEBOTS! made for a great audience reaction.

Medals presentation at the end of Sunday! Chibi-Mikuvan wins the first sprint race, gets 2nd in total Moxie points (Hack to the Future being the better known pop culture icon garnered more crowd votes during the Endurance Race), and the two of those combining to yield a 1st place overall in the weekend!

CMV with both medals of the weekend and battle scars. I have some work to do before New York Maker Faire… namely, weld on some bumper extensions to the frame, because this ‘eroding corners’ thing is getting ridiculous.

Here is a van bonus on the way out… a European diesel box truck converted to an RV. I was in fact so excited to see this that I forgot take a Vans next to Things photo.

On the way there, not-Chibi Mikuvan began to develop a mild misfire or something in one cylinder (“idling like said diesel truck”). It gradually got worse as I got back to Boston, so I’ve been incrementally diagnosing and isolating issues since then. It will still start and run, but definitely skips one cylinder at idle and low RPMs, yet drives fine at higher speeds. After my battery of testing (not to be confused with testing batteries, something I also do), I’m fairly sure one of the fuel injectors is dying. But that’s for another post…

4 thoughts on “Chibi-Mikuvan: The Detroit Maker Faire Recap; Chibi-Mikuvan × MarkForged”


  2. Clearly Mikuvan needs a 4G63 turbo swap to haul that much stuff, stay going 75, AND have the AC on. ;)

    (might need a transmission and rear axle upgrade too, to avoid blowing them up…)

  3. The interwubs tell me that you can fit a small block Chevy V8 into one of these. Possibly “fit” though.

  4. Aren’t the steering linkages supposed to be crossed at the steering column / pitman arm to get ackerman steering geometry when using linkages forward of the front wheels (as you described the 2.007GoKart students never getting right), or does the added caster angle help prevent the toggling between understeer and too-much-steer handling characteristics?

    I’m assuming the addition of a reverse-biased rectifier diode across the fuse is to avoid motor controller death by regen should the fuse blow. Is there also one added across the contactor, or is the pre-charge resistor sufficient to prevent controller detonation during an emergency stop?

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