Archive for the 'Chibi-mikuvan' Category

 

Chibi Mikuvan’s New York Maker Faire 2015 Adventures; Stance Stance Revolution Never Dies; MASSDestruction, the First “Local” Boston Event

Oct 21, 2015 in Bots, Chibi-mikuvan, Events, Stance Stance Revolution

First off, before anything else, I’d like to thank everyone who contributed to the RageBridge2 Indiegogo campaign. The campaign officially finished out at $8853, but if you still want to jump on the pre-order list, Indiegogo has a rolling system called “InDemand” where you can still contribute. The first production batch will be slated for those who are on the Indiegogo short list, before they are made publicly available on Big Chuck’s Robot Warehouse Equals Zero Designs. You’ve seen all the gory RageBridge development and history right here first!

New York Maker Faire 2015

Another New York Maker Faire and another Power Racing Series finale have passed! I decided a little while ago that this would be the last official race for this version of Chibi-Mikuvan. The league’s technology has greatly improved in the past 2 seasons, with many brand new teams trying experimental drives (including a few that used CMV’s concepts to great success). The damage taken at Detroit is also starting to add up, and this time, Chibi-Mikuvan took more damage than ever with the high number of entrants on a very tight track.

When Jim tries to tell you that the race is not BattleBots, he’s lying :p

The story actually begin shortly before Dragon Con, when I decided to bring CMV to Atlanta to participate in the parade. The impacts sustained during the Detroit race had caused some of the 3D-printed body mount pieces to delaminate from the body. No biggie – this was an issue I’ve tackled before. It just manifests itself in the body being flexible. But this time, I actually found out after removing the body that the mounts had stayed on fine, but in fact the entire layer of fiberglass had detached from the foam underneath!

Well that’s not very good. I ended up drilling some small holes into the area and filling the gap with epoxy using a syringe, such that I could force it under pressure into the interstitial space.

After that cured, I re-sanded and cleaned the body mounts as well as the attachment area, then reattached the mounts with a healthy dabble of silica-filled epoxy, making sure to leave a giant fillet around all the corners. The inside corners were cleaned up post-cure with a small wood chisel.

Some of the damage from Detroit was pretty extensive on the outside, too. There was a whole ‘flap’ of foam hanging here, as well as chunks missing. I wasn’t going to fully repair the area, but at least wanted stuff to stop dangling off. The solution was plenty of silica thickened epoxy, made to the consistency of peanut butter. packed into the area. I “vacuum bagged” the whole area with stretchy pallet wrapping to keep all the pieces in place while it cured. Some of the pallet wrap marks are visible on the right.

I also FINALLY built that 3rd battery pack I’ve been talking about since… uh, Detroit 2014. This one was painted Miku Blue to distinguish it from the others in addition to “because I had Miku-colored spraypaint”.

The “convoy of cars with smaller cars on top of them” arrived all around 8 to 9am in New York. Once again, I carried Frozen Chainsaw Massacre and Corpus Krotus in the back.

Because the PRS (and Life Size Mousetrap) now occupied the parking lot I always illegally park in, I wandered a few blocks into Queens to street park.

That would be a 1984-85 Toyota Van (they were all called Van) across the street. Hello there, neighbor.

The New York track was planned to be small at the start (less than half the length of Detroit), and ended up being pushed together even more by the event. While cars could easily go three-wide in Detroit, there were parts of the track where going single-line was practically the only option. This will come into play later….

Some familiar faces from Detroit are here, such as the waffle car and school bus from The Arustocrats.

The Baltimore Burners brought a small fleet, including that train-thing to the right (made from an old lawn tractor) which actually had attachable carriages. Yes, they did try running with the carriages. Once. It worked about as well as something towing three large swivel-castered objects could have worked. Together with the Intimidator (right side, another Arustocrats entry), these two formed the spice dozers of this race by being massive and surprising you right as you exit a turn.

#95, the “Lightning McQueen” car, used an identical setup to CMV for its power system, except it was geared much higher such that it did not require CMV’s famous “hump start”.

Some entirely new entries also showed up. From Team Redshirts, this kart was built with much community-enabled learning and bodied to look like a Star Trek shuttlecraft. Which coincidentally looks like a 1980s Toyota Van. Just sayin’ guys. Chibi-Mikuvan could use a nemesis.

The blue seg-thing was not a race entry.

Another new entry and team, “It’s a Bert” from Hoboken Maker-bar.

I was tasked with tech inspections for this race, since I think I know how go-karts work and stuff… or something. Primarily the focus was on the brand new entries and making sure that nothing too sketchy was happening. For example, some teams needed to strap their batteries down, others needed a bumper-like object added so they don’t run people over all the time. I am glad to report that minimal running-things-over occurred. Just enough to keep things interesting, though.

Step 1: Qualification. Everyone lines up and takes a stab at running a fast lap. How short was the track this time? The top few qualification times were on the order of 12-14 seconds. Ouch.

Chibi-Mikuvan narrowly lost out to Frozen Chainsaw Massacre, for a #2 starting position. FCM was massively revamped electronics-wise this time for increased reliability. On one chainsaw they were reasonable, on two they’re damn near unbeatable.

Next step: Moxie. Everyone dons their silly hats and jump ramps (the rest of that video is interesting too) and shows off to the crowd for popular votes.  I decided to exercise my serendipitous Dragon Con Parade discovery. Now there is VIDEO PROOF!

I specifically saved the completely thrashed rear tires from the Parade (and Detroit before that…) for the Moxie Round, where my plan was to do either donuts or burnouts until one popped. And one did, seemingly right on cue. The popped tire was on the drive chain side, so the chain did see some abrasion when it hit the ground. If it were on the other side, I would have kept going….

The two wheeling? Totally unintentional, though it looked planned.

That, everyone, is how you succeed at things. Make it looked planned.

The destroyed tire!

I’m completely unsure what was going on here, but it was just after Moxie round ended…

The MarkForged prints hanging on for dear life this. I reprinted these after Detroit using much more fiber-fill in the middle layers where the axles bolt through.

Once again, they worked flawlessly. CMV possibly had the most 2-wheeled moments in any race this time, and it took direct hits to the wheel from other peoples’ wheels or bumpers multiple times. At the end of NYMF, one of the steering linkages was visibly bent and the center link (Pitman arm) began to slip on the steering column despite tightening the clamping bolts. Therefore, my steering torque was limited during the Endurance race, some times causing the handlebars to end up at wacky angles.

Here I am almost rolling The Intimidator. I categorize its driving experience as “real-Mikuvan-like”.

Unlike most of the PRS vehicles, its steering gear is taken from a golf cart, and so the steering wheel requires multiple turns lock-to-lock compared to the direct linkage drive more commonly seen. Therefore you could, no longer hang onto it as a driver constraint. You therefore had to butt-steer (that’s a technical term) much more intensely, all while whipping the wheel around.

There were so many collisions and “scrape-bys” that I can no longer tally new damage on CMV’s shell. The endurance race, with the whole field out on the track for an hour, was where most damage occurred. There’s at least one ding from a FUBAR car to the right there, with their signature green paint. The paint damage in the other spots up front were all caused by some form of rear end collision.

The back fared significantly worse. It would seem that I both rear-ended and was rear-ended by FUBAR at some point during the endurance race.

Big exposed tube bumpers on everyone else made short work of the foam on CMV when the opportunity arose. Here, someone straight up machined a chunk of the back end off. The flap hanging off to the left actually goes all the way through – this hit was on that corner moving inwards.

If you’re wondering why the shell is sitting completely off CMV, it’s actually very simple. At some point nearer to the end of the endurance race, I came around the back turn only to be greeted by a bunch of stopped cars. Someone then plowed into the back of CMV at full speed, shearing off all four of the body mounts at once. That left the shell hanging for about a lap and a half before I pulled into the pit area.

With no way to attach the body back on in a durable fashion at this point, I shed it and ran the rest of the race shell-less, which with big-tired karts out there was quite, umm, unforgettable. It was hot glued back together only for the return trip, and currently is still bonded by hot glue.

How did it do this time?! CMV’s list of accomplishments this NYMF race were:

  • 2nd fastest qualifying time
  • Best Moxie Round judging score (from a group of very critical small children… they were brutal overall!)
  • 4th place in the short 35-lap sprint race
  • Didn’t finish (or start) the longer 45-lap sprint race. I swapped to a different chopped up BEC unit, one with higher current ratings, and it still died at some point during Race 1. This means the logic battery was left to discharge, and it died on me on the starting grid. I had to bail from the race and debug that system, and by the time I figured it out, it was not worth recovery. I ran about 10 laps in that race for fun and more crowd votes.
  • 6th in number of overall laps in the endurace race…
  • …and factored in with 2nd place in Moxie points (crowd votes), I won 2nd place overall for the weekend. Moxie basically saved my ass this time, exactly as it was intended to do! Now, to be fair, there is some discussion that the last roughly 1/4th of the endurance race I ran without a shell should not have counted – which I agree with, since at that point I was going for broke anyway – so I’d be curious to see the standings recalculated with those laps discounted, or CMV disqualified entirely from the endurance race.

 

Here I am doing my best K-Pop sensation act.

That is, giving a talk on 2.00gokart and design education using EVs. The venue was a small and quaint tent to a dozen or two spectators, and it was only a 10-minute talk, but CMV attracted a fairly inquisitive crowd by the end. So, I suppose this is my act of positive contribution to society in a weekend otherwise dominated by electromechanical hedonism. Here is the very short presentation that is the farthest I’ve condensed 2.00gokart down to yet.

Besides demos and exhibitions in the next couple of months, Chibi-Mikuvan’s 2014 shell is being retired from battle damage. With it having accomplished everything I set out to do, I will likely retire the frame and running gear as well. Any revamps of Chibi-Mikuvan will probably see the front and rear bumper structures be actually made of steel (even if just painted appropriately, or made from thinner bent plates to approximate the shape, etc.)  and the bodywork be given some kind of gravitationally stable mounting arrangement from the bottom. That way, in the worst case, I can tape it all down. And I’d want to come up with a whole new set of bad experiments to try for the next CMV… such as, perhaps, in the fashion of Frozen Chainsaw Massacrew, a different household appliance for drive.

MASSDestruction

I’m well known for turning “lol you know what would be funny” into actual things. Perhaps all of us who tend to do that also tend to gravitate together, because now the Boston area has its very own small robot arena and hopefully recurring local tournament because of a single “lol hey we should have our own event”. A certain Max Bales (of Battlebots team Euclid) decided to be fancy and move to Boston for college, and dared to ask if there were any local events.

Well there is sure now. My long-time robot compatriot Rob Masek (over at Artisan’s Asylum) decided to mobilize the Asylum troops and turn a welding class into a welding a robot arena class. The date was set for October 11th.

I elected to bring Stance Stance Revolution back from the dead after Dragon Con, since it was but a “Print” confirmation away. This time, it was back in black.

The first version was made using a generic ABS filament that we stuffed into a Dimension print cartridge to test out ways of hacking around the materials counter. The new frame which is largely identical is actually made from Stratasys ABS plastic, which is more rigid and also stronger. It would, you know, at least delay the onset of disintegration. I made no changes to the design besides correcting a few fits and clearances.

After the frame was finished, I decided do brush acetone onto most of the blade tower area to fuse the outer layers together. The layering allows the acetone to seep in deeper and solvent-fuse the outer skin together to increase strength (though not by much). This also incidentally gave the frame a nice glossy finish.

After that was a quick guts transfer.

I say quick, but this took much longer than I thought because SSR is built very “one way” for wiring. I basically had to undo every solder joint and reconnect it in the new frame.

While the bot was taken apart, I straightened out the blades (which were bent at the spokes in my last match with Silent Spring) and inspected the weapon motors. I must say I’m impressed with the construction of the Multistar 4822 motors. What I thought was detached magnets was actually steel arena grunge caught in the airgap.

The magnets were actually fine. In the interest of safety though, I mixed up some silica-reinforced epoxy and filled all the gaps between the magnets and sculpted a fillet all the way around.

Here’s some vanity… I actually had the correct colors of spraypaint to make the discs into Dance Dance Revolution colors, just like the logo.

And the evening before MassDestruction, Stance Stance Revolution is reborn!

 

The Masekdrome “Cochran Combat Corral” was a unique design among arenas in that the walls are canted inward, the overall shape being a truncated pyramid. The vast majority of arenas are just cuboid in shape. This adds a bit of design flair, as well as allowing the walls to brace against one another, being leaned inwards. I maintain that the arena should be named the “Cochran Cybernetic Conference Center” or something though… Cochran is just a name that screams “legit”.

(The name comes from a primary sponsor of the construction of the arena, so it’s not totally random!)

The tournament format was a “Modified Swiss” format with playoffs for the highest ranked bots at the end. Each bot gets four (randomly selected) fights, and the end rankings are simply who has most wins. SSR faced off first against Ginger Baker, a small vertical drum-in-wedge kind of design.

To everybody’s surprise, including mine, it did quite swell, despite being tossed around the arena a few times.

An artifact of SSR’s blade orientation unexpectedly revealed itself here. This is a 45-degree gyro-stand.

It occurred unexpectedly due to a head-on collision with Ginger Baker which decelerated one of the blade suddenly while throwing SSR backwards, and the resulting torque on the opposite blade causing the bot to kick up on side. It’s also unfortunately a dynamically stable position because of how the blades are spinning! This happened twice more during the same match and I began quickly braking the blades to get SSR out of it.

Midway through the match, things started turning in my favor as SSR was able to catch some more edges on Ginger Baker. I was finally able to execute the “one-two” hitting once with the forward blade, then immediately again with the reverse blade.

And that’s how Stance Stance Revolution somehow a match! There is only one known video if it so far, here. As more videos surface, I’ll update this post for a little while.

“Hyperderp”, a Shenanigans production in the fashion of Hypershock with a very nicely machined weapon (and that’s about it :P), is seen here flying away after a hit from RMR (a MITERS bot) the reflection of which can be seen in the arena wall.

So Will Bales shows up to my shop at 1am the day of with a box of parts…

 

Jamison was the first to ding the BRAND NEW arena polycarbonate walls with Silent Spring.

SSR unfortunately got set up in its 2nd match with Hyperderp.

It held together for a little while!

Uh oh.

Aww.

Hyperderp was able to get a direct hit in on the ABS blade towers, so one half of SSR fell off.  The other half, however still worked…

…and that’s how I ran it for the rest of the event! With the rear blade, motor, and towers removed, SSR was a full pound underweight. I made this up by literally taping a random tool found in my toolbox to the back end … specifically, a small 3-jaw gear puller.

In “Stance Stance Revolution” mode, it was somehow able to make it through two more matches – one win against RMR, and the other against the above pictured robot, simple named “WPI Robot”. It was also largely 3D printed. When will we talk about the problem of 3D-printed-bot-on-3D-printed-bot violence?

And it somehow STILL was able to do a 45 degree gyro kick, though it was no longer stable (would fall down automatically)

Stance Stance Revolution with the carcass of WPI Robot in the background

SSR somehow goes 3/1 in the first half of the tournament. Who do I get paired against first in the playoffs? Silent Spring, of course.

There was all of 1 hit in the match, and SSR pretty much exploded the rest of the way. However, it was still mobile (and the weapon was wiggling a bit), while Silent Spring actually stopped moving. Technically I had won the match, but it was utterly pointless to continue at this point since the bot was broke into another 3 pieces, and near the end, the Vextrollers both smoked. What had happened (post-match investigation) was that a broken ground wire forced all the drive motor current out the logic ground, which caused collective sadness in the electrical system.

I gave the match to Jamo right before he got counted out, and he went on to fight Hyperderp in a brütal final match. SSR also had to forfeit the 3rd place match because… no.

Look very closely at this 3lb rumble. There is in fact a tiny R/C helicopter hovering in the background. Everyone sort of stopped fighting and began to play chase-the-copter.

THIS IS WHY DRONES IN BATTLEBOTS IS STUPID!

- a few people

Here’s a better photo of the copter!

A great thing about this event which I absolutely love – a lot of younger kidlets – whether members’ children or neighbhorhood kids or friends and tagalongs – were part of the audience, and they were ridiculously enthusiastic all the time. That’s what we’re here for.

The crowd began to thin out after the main tournament, but here’s what it looked like when it was pretty empty. Seriously – next event, we need to do some better crowd control, because there were times I could barely see to drive!

At the end of it all, we collected a bunch of broken parts from everybody. This will be unceremoniously shipped off to this Cochran fellow, and I suspect this is exactly what he wants to see. I hope to be like this some day – funding the production and execution of dumb shit that teaches important life lessons. Big Chuck’s Robot Warehouse, Auto Body Center & Foundation.

All in all, a fun local event that maaaaaaaaaaaaaaaaybe we went way too hard at collectively, because after everybody packed up, the stark realization that we were all totally fucked for NERC Franklin Institute set in. SSR, sadly, will not be revived in time for FI, but I do have plans for a 0.050″ titanium welded unibody for its future version, since I now, once again, want to take my own joke too seriously.

I’m only planning on bringing Clocker at this point, with correctly machined hubs, and Colsonbot if I get around to repairing its own post-Dragon Con damage!

 

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

Aug 11, 2015 in Chibi-mikuvan, Events

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…

Chibi-Mikuvan × MarkForged: Detroit Maker Faire Preamble

Jul 23, 2015 in Chibi-mikuvan

In less than a day, I’ll be setting out for the Detroit Maker Faire on a cross-American vans-on-vans adventure (just like last year!). Detroit tends to be the biggest race in the Power Racing Series, and we’ve even been told that the pits are entirely full due to a spate of late entries. This will be interesting.

Partially contributing to that lack of pit space problem is us. For this time, I’m taking on the role of cargo freighter and transporting all four entries built in-or-near MITERS (which will have their own documentation linked here when they make it… *ahem*, people.).

Something something single point of failure…

Anyways, the four Boston-based entries from us are:

  • Chibi-Mikuvan
  • Atomic Thing
  • the Corpus Krotus (formerly Lotusaurus Wrecks)
  • the “Frozen Chainsaw Massacre”… I’ll just let them explain this one.

Last time I visited Chibi-Mikuvan, I had already printed some potential steering component candidates on the MarkFrog machine. Recall the explicit goal of trying to 3D print the entire new front steering assembly using the continuous-fiber process pioneered by MarkForged, just because. The biggest print of all is the steering bracket:

This thing takes a whole 2 days to print, and has two large bands of fiberglass (which is what takes so long – the fiber lays much slower than plastic extrusion). It also has a mirrored version.

Here’s all of the finished steering components ready for assembly. I’ve already combined the three individual parts that make up each steering knuckle.

While I was dissecting the old steering setup, one of the brake calipers basically crumbled in my hand.

Well, sure glad I found it now… I’m wondering when it became this way, since I don’t recall hitting anything after New York Maker Faire and I noticed no braking weirdness at that event.

I cut off the crudely splatter-welded Pitman link from NYMF to install the new 3D printed version. The heat of welding caused some melting on the Delrin steering column support, so I flipped it around to expose the other side instead.

New Pitman link installed and tightened down.

Using the opposite-side’s steering bracket to template drill mounting holes…

At this point, I had already locked myself to this solution in some way by cutting off the old bracket.

I had to make a quick spacer to bridge this section of the frame, which I had to cut away at the beginning to clear the right tie rod.

Components installed and tightened down. Because of the flexible nature of the plastic (compared to solid metal), locknuts are used everywhere. Non-lock nuts would eventually work themselves loose from the plastic moving.  The version numbers on the parts indicate which revision they are.

Time for the jump test…

This system of components is…. very flexible. Not that this is inherently bad – plastic will inevitably be more flexy than metal. But what I noticed is that the two fiber bands separated by some plain nylon basically makes an A-arm suspension. A very unintentional one. The maximum camber can be described as “drastic”.

 

Anyways, it was time to put together the rest of the system again for a dress rehearsal & test. The goal is to run up and down one of the back streets behind the building, trying to hit every pothole and every utility access cover thing on the street, and run up and down the parking lot curb cuts several times.

To get everything back to working order, I had to refill the water cooling loop. I took the opportunity to apply eye-embedding clips (so called because they will aim for your eyes when they inevitably slip off your pliers) to the small fittings, one of which came loose during our winter shenanigans. Basically, making small reliability fixes for known bugs.

I also cycled the battery packs a few times to check the capacity. I intend to build a 3rd battery to ensure completion of the endurance race… we’ll see if that happens.

The testing eventually resulted in the right side bracket buckling where the fiber becomes unsupported. It’s a soft fail – it simply manifests as more and more camber. The failure mode is buckling of the internal truss structure. If I had an additional element coming up and bracing against the frame, it would be much more sound. For example…

Like so. Here’s version 2 evolving out of solids. The front arm is much thicker and joined to a riser which braces against the frame to prevent rotation (which would result in moar camber).

The final version 2 with mounting bosses and fillets. Instead of 2 discrete fiber bands, this one will have a single band that is uninterrupted for approx. 35mm

Unfortunately, it was Tuesday.

The 3D printing gods did not smile upon me this week, with the Mark One stalling for unknown reasons at 75% completion. Check out the two nozzle burn marks!

Well, with each piece taking 2 days 8 hours to print, there was no chance of being able to get a set of these for Detroit. Nevertheless, I still had the printed steering knuckle parts, so the mission is not lost entirely.

It was time to…. well, un-cut the frame, I suppose? With a big enough metal 3D printer….

I designed “Bailout Bracket” in a couple of hours. It replicates the geometry of the 3D printer bracket, including the 10 degree caster angle, and is designed to be made entirely out of some leftover tube stock and 1/8″ steel plate, tabbed and welded together.

Cleaning up the surface of the whole sheet of cookies at once after waterjet machining the next day.

Here’s how the structure goes together. The finger joints fall into place and the materials interlock – really all I need to do is tack everything together along the tabs.

Which is precisely what I did.

Now, looking at this, is it objectively worse to 3D print your go-kart steering parts, or have me weld them?

WHY NOT BOTH?

I also took the opportunity to swap the version 1 knuckle to version 2, which reinforces the area around the head of the bolt some more. Not that it was necessary – I’ve been more concerned about the 5/8″ bolts embedded in the steering knuckles slowly deforming that area, but it’s actually been remarkably solid. In this case, having the whole front axle stub as a bolt – tightening everything down – aids in stiffness. The version 1 knuckles will be kept as emergency backups.

Here is the system reinstalled. This arrangement is of course much stiffer and less prone to #STANCENATION like the nylon bracket. Rest assured that after Detroit, the nylon bracket will make a return.

The last things left to do on CMV are some minor body repair to the curb gouge it suffered at NYMF, and making the 3rd battery pack. Somewhere in there I also intend to upgrade the moxie-getting sound system…

Hopefully the Detroit Maker Faire update will come soon after the event!

Chibi-Mikuvan in Make Magazine #46

Jul 09, 2015 in Chibi-mikuvan

In May, I was contacted by Make Magazine for a feature article on Chibi-Mikuvan for their July issue. This is now out and in the wild! Check out the article here.

They sent a real photographer and everything! It made everything seem so…. legitimate.

In a few days, I’ll hopefully be able to post some updates on preparations for the Detroit Maker Faire Power Racing Series race.

The Life of Charles: Untold Tales of February Through Now-ish; BattleBots, Markforg3d, 2.00Battleship, and Chibi-Mikuvan Upgrades

Jun 16, 2015 in Chibi-mikuvan, Electric Vehicle Design, Events, Stuff

Isn’t it sad that the last meaningful post on this site was in February? I think it’s a travesty. A combination of perfect storm factors has overwhelmed even my blogging habits. I’m kind of like the Waffle House test of blogging – if even I stopped blogging, you know some shit went down. And I do have some very interesting news to report. In no particular order of criticality or intensity, I present…

  1. The extent of what I can say about Battlebots on ABC before the season premier!
  2. I got a new shiny thing, a MarkForg3D Mark One continuous-filament 3d printer!
  3. Porting (heh) 2.00gokart to the water: The making of 2.00Battleship for this summer’s SUTD program.
  4. When it’s not robot season, it’s go-kart season. Time to make some changes to Chibi-Mikuvan!

(more…)