Archive for the 'Pad Thai Doodle Ninja' Category


Dragon Con 2014: The Wrapup, or, Operation: I FEEL GASSY, plus Panel Resources

Sep 14, 2014 in Bots, Events, mikuvan, Pad Thai Doodle Ninja, Pop Quiz 2, Twelve O'Clocker, Überclocker ADVANCE

Around this time last year, I said;

I’m back.

Somehow, and not broken down in western Maryland or something

Well, it wasn’t western Maryland per se…. but we’ll get to that. In the intervening week between Dragon Con 2014 and now, resetting the shop from its post-robot season disaster (which immediate followed the post-gokart season disaster) for the fall classes has taken up most of my time.

In addition, I’m seeing to it that the MIT Mini Maker Faire happens! In three weeks, I can hopefully roll out of bed into our own Maker Faire… but of course there’s logistics and administration to figure out before then! If you are planning on being in the area, hit us up.

The story of Dragon Con 2014 begins, as usual, with van stuffing. For expedient access to the panel slides and info, go here.

The one feature of this generation of Mitsubishi Delicas that’s saved me countless times is the squared off rear hatch area. You almost never see this any more with modern “bubble” designs, and even the two other “Van” models of the same era had cut off angular hatches (However, it seems to be making a comeback in the latest generation of Nissan Quest, whose JDM model, the Nissan Elgrand, I like way better).

I can put like 16 cubic feet straight up in the hatch area. A 18″ wide aluminum suitcase fits perfectly, oriented lengthwise, three across and three tall. So basically, the van-stuffing strategy has been, since last year, consolidate everything into suitcases and 30-quart plastic bins, pile as many as possible in the lower half of the hatch, and fill the rest with robots. Überclocker was attached to the rear left headrest the whole trip, using a spare alternator belt looped around it as a retaining strap, while every other bot was arranged creatively besides it.

This time, I stuck to my guns and just kept going on I-81 instead of even remotely thinking of touching the east coast again. Much better time was made – pretty much 20 hours door-to-door. Travelling during the daytime meant a longer sight distance, and consequently, we went faster. It’s been well-proven through the past few thousand miles of road trips that Mikuvan does well either at 65mph or less… or at 75+mph, where the engine is operating in its powerband in 4th gear… guess which half was used more often?

Well, when we could manage anyway. Summer is construction season all-around, and starting from Connecticut onwards south, there was construction and construction slowdowns and delays in literally every state.

After taking most of Wednesday morning and early afternoon to recuperate, we hit up the Invention Studio again, basically the robots & cosplay forward operating base of this whole trip. I began the final assembly of Pop Quiz, which was started the weekend before departure.  I had already done most of the work, so it was literally just throwing the package together. Pictured is the final arrangement of the components before the top was closed up.

I was originally planning on running 14.8 volts with the two 2S 500mAh packs, but some tachometry on the old motor showed me that it was basically 1000 rpm/V. I decided immediately to drop back to 7.4V and 1Ah – kind of a ridiculous amount of battery for a 1lb bot, but it would keep the weapon motor at a sane speed/load and also not make the 6V-rated Pololu drive motors too unhappy.

The batteries are wired in hard-parallel, so if I ever wanted to charge this pack properly, I’d need a two-parallel 2S battery splitter like this.

The two Vextrollers are de-cased and stacked on top of each other using clear heat shrink tubing for insulation. Stuffed right next to it is the 12 amp brushless ESC, which is hardwired next to the Integrated Fingertech Switch.

The Hobbyking 6 channel RX is also de-cased and sits up front, wrapped in electrical tape a few times since I didn’t pack clear shrink big enough. The pins are all removed, trimmed flush with the board except the pins I needed, and tiny 26 gauge signal wires soldered to the remaining stubs. Everything is according to the initial CAD models!

Dense and unserviceable? Yes, definitely, but so are iPhones and I like to think PQ is the iPhone of antweights so………

All packaged up with the new titanium top plate! 15.3 ounces – good enough. It probably weighs 15.300008 ounces up north anyway, so I still qualify for Motorama 2015.

Pop Quiz’s ‘press shot’. Notice the missing forward left corner – by this time, it already ate itself once when I was testing against a scrapped 1lb bot frame. I had ground a radius onto the underside of the blade’s leading edge to prevent this, but on one side of the blade, it just barely didn’t go far enough! That was remedied quickly.

The shorter blade meant that even when it hit its own corner, it didn’t fly away or flip. I in fact didn’t even notice it as an independent event – only after picking the bot up when enough was enough.

Being constructed alongside the antweight work was the latest version of the animatronic RWBY Crescent Rose being built by Cynthia of Cynaesthetics. I’ll let her explain the details, but this was the ‘black project’ that kept me busy over the week/end before we left. I was employed as a CAD mule since I was much faster at using Autodesk Inventor, so I pounded out the design she handed me over the course of probably Wednesday through Saturday.

The crown jewel of this design is probably the red gear-thing on the right. It’s nifty enough to warrant its own entire post. Shown below is revision 1:

It’s a one-shot 3D printed 7:1 compound planetary gear with input and output roller bearings that translates a roughly 16″ circumferential travel (so think 16″ of rope being pulled around it) into a roughly 85 degree rotation of one of the ring gears. The idea was to mechanically synchronize the deploy, though it ended up not quite working because of the difficulty of keeping the two sides synchronized.

There was a great chance that it wouldn’t work at all if I didn’t get the clearances exactly right, such that the multiple solid bodies got fused into one… but they ended up being correct for version 3. It was one-shot printed on the Dimension 1200ES machine in the shop.

Once again, I hosted a few Maker track panels and participated in others. This year’s roster was Maker Resources (my ’2.00gokart for the masses’ panel), Electric Vehicles, and a new one on Rapid Prototyping Cosplay, hosted with Jamison and Chris Lee, in which we teach the audience how to abuse waterjets. This year, we were smart and stuff, so all the panels are kept on the cloud! Links will be presented at the end section.

Above is my Maker Resources introduction. Yeah, it was about that productive.

Doing some last touch-up on Pad Thai before the Robot Microbattles 1lb and 3lb event. The front armor was too low, causing the front to drag and affecting the bot’s traction.

A clean shot of Pad Thai Doodle Ninja before the event. It only required lifter repair from last year, and replacement of some of the spring steel armor.

A picture of Pop Quiz’s first and only match. The bot seemed to work fine on the smooth Invention Studio indoor floor, but the arena floor was a whole ‘nother story. The bot has maybe 0.025″ of ground clearance on a good day. What does that mean? It could barely move in the arena!

This wouldn’t have been so bad if it were not for the fact that Pop Quiz’s weapon motor was built in 2008. Like, I went and found the blog post that described its construction. This predates even LOLioKart. Whatever I did back then was clearly not up to the bots of today, with the amount of power I’m now running through it. For example, the central shaft of the motor is a small shoulder screw with #8-32 threads, which pretty much stripped instantly on the first big hit, shown above, with “Trash Boat”. This left the weapon motor disabled, so after that, it was just a matter of finding the right floor gouge to get stuck on.

Well, shit. The rest of the bot works great (minus the paper thin ground clearance), so Pop Quiz is going to get a re-engineered motor and a few layers of heat shrink tubing over those wheels!

Due to timing constraints, the ants and beetles were forced into single elimination (again), so PQ left the event 0-1.

Pad Thai went longer in the tournament with Cynthia driving, defeating “Green Reaper” and “Trash Boat” (to whom Pop Quiz lost), ultimately reaching the semifinal where it lost to Jamison’s DDT. The spring steel armor fended off DDT reasonably well, but it was still filled with gouges at the end.

Video of this match, from Near Chaos Robotics.

Besides the front and side armor, DDT managed to get a good shot off at the unprotected rear, which cracked off a portion of the motor mount and sliced up the rear left wheel. The broken O-rings jammed into the rest of the drive and caused one side of the bot to stop working. Luckily, the motor wasn’t damaged!

Pad Thai went 2-1 this time.

Oh god, it’s Monday. It’s the big show. It’s my yearly measure of worth, made worse by the fact that this would be the 10th year since I won a championship at Dragon Con first! No pressure at all, breh. (I won the 12lb class at D*C2004 with Test Bot v3)

No changes at all were made to the big bots at the Invention Studio, since all of the work relevant to them was done before departure.

My Hyperion 1420i charger died mysteriously during Microbattles, so I put out a call to the Robot Battles e-mail list and Facebook page asking if anyone had a charger (or bench power supply) that could charge up to 7S lithium packs (about 28 volts). Dale (of Homemade Robots) brought a 30v adjustable power supply that I ran with during the whole event.

Sadly, I did not run into Dale in either weight class, so we couldn’t do a “10 year band reunion” in the finals….

Test Bot was also at this event, and frankly, it’s never looked better.

Wait, what!? Yes, that’s the old frame and running gear of Test Bot 4.5. I sold it to Mike Jeffries of Near Chaos Robotics about a year and a half ago, and his crew has revived it into Dolos. They upgraded it with slightly larger wheels (one of the causes of its downfall at D*C events, since by that point I’d optimized TB for smooth arenas), a wedge that formerly belonged to Apollyon, and a “bot hook” weapon.

I didn’t get to fight 12 O’Clocker against it, however, since it lost to Dale’s Omega Force.

Setting up 12 O’Clocker for its first match against Served Cold…

During its last match with Tetanus Shot, 12 O’Clocker lost one drive side completely. I thought it was a solder joint or stripped gear in the custom Harbor Freight mounts – Tetanus Shot is an extremely solid bot, so metal on metal collisions are going to have much more pronounced effects.  As it turns out, it was way worse than that:

The motor just straight up cracked out of its mounting holes! Looks like the bottom of the motor mounting screw holes might have been a little too thin. I have spares of the gearcases from last year….

…but of course forgot to bring them for this year.

Well, okay then.

Returning to a classic strategy, I decided to install a zip tie ratchet on the right side. This is a cut zip tie that sticks into the sprocket’s path, so in one direction it gets sucked into the chain and locks that side up. In the other direction, it is pushed away and the side moves (relatively) freely.

I used this method a few times in years past with Clockers of Lesser Drivetrain Reliability to great success, for tenuous definitions of great. The bot could move forward, in a wide circle, and then pivot about one side in reverse. 12 O’Clocker is still a relatively formidable opponent even in this limping mode, this time exemplified by how many times I still managed to get Tetanus Shot after the installation of the ratchet…

12 O’Clocker made is 1 and 1, winning against Served Cold and losing to Tetanus Shot. By the 12lb Rumble, it had also cracked the motor off the other side, so I started and stayed mostly in the center of it to smack as many people as possible while avoiding the edges. A drive-disabled 12 O’Clocker somehow managed a one in a thousand alignment with Omega Force, and I literally threw it overhead off the stage.

I edited together all the video I had of 12 O’Clocker and have it uploaded onto my Youtube channel. Here it is for convenience;

(This is in addition to the Near Chaos 12lber playlist).


Überclocker was the big hit of the show this time, going straight through with no losses and winning the 30lb championship. There’s nothing wrong with the bot right now – I can turn it around to Motorama 2015 tomorrow. The Banebots wheel swap proved to be an extremely good idea – Clocker had a traction advantage that was clearly noticeable in its matches with Nyx, against which I’ve always been neck and neck in pushing ability.

I also entered Clocker in the 30lb rumble, with some… additions… to epicly hilariously results. 90% of this event to me is a chance to let loose and be silly on stage with robots, so we took the spare pool noodles that we brought for safety covers – Jamison’s Bug Loves Robot and Überclocker both rank pretty high for pointy ends on bots – and straight up taped them to the bots for added entertainment.

I edited together all of its matches here. Near Chaos has a much better view of the bedlam that was the 30lb rumble.

Clocker’s performance was nothing short of stellar, and I’m glad that it finally works reliably. I don’t anticipate making any performance upgrades or changes to the bot at the moment. The top clamp arm actuator still has a bit of a habit of coming apart – it didn’t at this event, but it was looking close by the end, so I’d like to actually drive some screws into its mounting brackets before Motorama.

12 O’Clocker is a different story. Besides the whole motors-breaking-off issue, which is a design problem with the gearbox, it needs an aspect ratio more similar to Überclocker to be more effective. Right now, it’s dopey and cute looking with its short wheelbase and tall frame, but it translates into poor lifting performance since the center of gravity has less leverage. It’s more likely to faceplant than lift (but that makes it cuter and dopier!). But again, I’m not sure if I’d change this, since the point of it was to be silly and fast – two things it’s good at, at least!

I ran out of time this DC season due to helping with the RWBY weapon that I couldn’t really do justice for Pop Quiz and Pad Thai. Pop Quiz’s concept is sound, but that motor needs to be updated to 2014 standards! It’s been a while since I’ve made a motor, so I’m kind of itching to do it now… Oh, and throw a few layers of heat shrink onto the wheels. Pad Thai suffered plenty of body damage this time around, but none to the lifter – it was actually kept down most of the time  anyway.

The Con Elsewhere

Once you go to one Dragon Con, you kind of get the idea: it has neither rhyme nor reason, nor a theme such as comic books, Warhammer, or indie video games. It’s ALL of it. As a result, I’m always on the lookout for new and innovative crossovers and takes on media franchises. Seeing a group of Iron Men gets old pretty quickly, for example, but nothing really prepares you for…

Iron Totoro. The picture doesn’t do justice as to how huge it was, which was easily 3 people wide. There was a hotel security staff just off to the left escorting it through the (very tightly packed) Marriott hotel.

Interactive costumes are another cool feature of a convention where you’re not expected to stay within a certain industry or franchise. Here is Mr. Fingertech Robotics himself, Kurt, with hand-mounted reed switches that could sense high fives. The large LED screen displayed the current count (yes, double high fives work!), and the LED strips on his vest would change color depending on how many high fives were accumulated in a certain span of time.

I forgot the exact count, but he was well over 10,000 by the end of the weekend, and it was a huge hit just walking through the hallways.

Cynthia’s mechanical scythe posing next to a more artistically complete but non-mechanical one. RWBY is stll a series which is gaining traction, so not too many people recognized it immediately, but the mechanical deploy caught quite a few eyes. It was presented at the Rapid Prototyping panel (which also featured Jamison’s big hammer and a few other things) to great fanfare. Version 3 ought to be even more exciting…

So that’s Dragon Con 2014 in a few pictures! I’ve already made plans for next year, including changes to the panel format and possibly more collab panels. First, I’ve always thought that Dragon Con panels were supposed to be 1.5 hours long, since at other cons the panels are scheduled in 1 hour blocks. As it turns out, it’s supposed to be 1 hour of panel and halfn a hour of room clear/reset. What?! I totally only found this out when Val, the Robotics & Maker track director, had to toss everyone out of the panels I ran or participated in…. because I thought the content was going to fill about an hour and 20 minutes or so. Whoops.

We hustled out of Atlanta under the cover of early morning darkness, and followed the same I-81 route back.

Panel Resources

This year, I did a smart person thing (only you guys say I’m smart, I never said anything to the effect…) and made/kept the presentations online. So here they are:

  • Maker Resources 2014: Updated with new content, vendors, and internet memes!
  • Rapid Prototyping 2014: In collab with Chris Lee and Jamison Go. If the subset of people who 1. read this blog and 2. have pictures or video, I’d appreciate it greatly if you sent it our way. I think this panel was highly successful.
  • Electric Vehicles 2014: In collab with Adam Bercu. This was primarily a picture show since we actually did a panel thing and talked the whole time.

Operation: I FEEL GASSY

Well, this sure looks familiar.

Nope, it’s not a repost!

Around 9 in the morning on Tuesday, near the VA/NC border (by a little town named Lambsburg, as I found out), I stopped to pick up a full tank of gas from a Loves Travel Stop. Roughly 1 hour later, south of Roanoke, was when we noticed the first hints of power loss, but we assigned it to the fact that the region was mountainous. Shortly after Roanoke, in the span of less than half an hour, I went from keeping up with highway speed in the right lane to crawling at 25mph on the shoulder.

Realizing this was patently unsafe, I pulled off near Natural Bridge, VA onto U.S. Route 11, which was a much slower local road, while we tried to formulate a battle plan. At this point was when I was beginning to think that the problem was with the fuel system. The symptoms were:

  • Lack of power at mid and higher throttle. The engine could idle and run at low speeds and loads just fine, but as soon as I gave it more gas, it began sputtering and losing RPM. By itself, this could have indicated a problem with a clogged or restricted exhaust or intake.
  • I could rev the engine in neutral freely if I depressed the throttle gently; but a sudden mash of the pedal would cause it to sputter. Something load-dependent was the issue.
  • More surprisingly, though, it was inconsistent. During the various start-stop cycles at red lights and when the engine was off, the restriction would seemingly go away for a short time, but then almost immediately return afterwards.
  • When it was away, I could drive and accelerate normally. Something was moving or shifting, possibly by gravity/engine suction or pressure, or perhaps temperature, into place.

We went on U.S. 11 until Lexington, VA, where we stopped for lunch at a Taco Bell and waited for the engine bay to cool off a bit so I could possible look inside. I picked up half a tank of gas from an Exxon station, where I also checked the air intake and filter in case a squirrel actually got lodged in there or something. You  never know.

It seemed to behave normally right after the fillup, so at this point I was highly suspecting some kind of gunk or contamination in the fuel. I milked what leftover power it had for several more miles until the problem came back again, halfway to Staunton, VA

Realizing we were never going to make it home if this kept up, we stopped at a rural gas station halfway between Lexington and Staunton (in a town called Raphine)  where Adam and I dove under to extract the catalytic converter (after half an hour inside a Burger King waiting for it to cool) and to inspect it. This resulted in the following hilarious picture:

Let the shipping begin

After taking about 20 minutes to drop the catalytic converter, we found there was absolutely nothing wrong with it or with the pipe downstream. At this point, I was pretty damned sure it was fuel-system related.

We decided to play it safe and try to ask for an ‘expert opinion’, which involved a bit of calling around seeing if there were area mechanics we could limp to. We visited two – one was right across the highway, was actually a truck and RV repair shop, and run by a very friendly and wise old guy whose name we didn’t catch, but whose business was named Cash’s so I’m going to call him Mr. Cash, because that shit’s cash.

After taking a test drive, he agreed with me that it was most likely fuel related, but seeing as how this was already late afternoon and likely nobody in the area would have the needed parts, could only offer me a bottle of fuel system cleaner and some good luck. Mr. Cash recommended we visit another shop around the corner, King’s (which I assume is run by Mr. King), to get a second opinion.

Mr. King himself was welcoming but busy, but the mechanic he foisted me off to was absolutely convinced it was a catalytic converter problem despite me telling him already what we’ve taken apart and checked. I’ll give the guy some credit – they were busy when we walked in, and we were likely not going to stay and pay them to do service, so I can’t imagine I was very high on their priorities list. We left after deciding our welcome was outstayed. Certainly, if you walk into the IDC while I’m busy putting out student go-kart fires (maybe literally, mind you…) and started asking laser cutter questions, I would have responded similarly.

At this point, I decided to see if the ECU was possibly outputting any codes, since 1989 is just new enough that some sort of electronic diagnostic was mandatory. One problem: I didn’t have the diagnostic sheet from the service manual that told me what the blinking voltmeter needle did.

Solution: I found it on my own website – posted from last year, an exact snapshot of the page I needed. See, kids? This is why you blog everything, even if you don’t think it’s important!

I continued north on I-64/81 to wait for the problem to return while Adam carefully stared at the voltmeter. Sciencekart is funny, but I wasn’t about to try and stare at the voltmeter while driving for real. However, even though the problem returned, and I was reduced to shoulder-crawling again north of Staunton, VA, the ECU didn’t throw any errors.

Really? I figured it should at least return “Fuel Pump” or something, but nothing. Modern ECUs can tell you if the fuel-air mixture was even a little bit out of expectation, but the diagnostic system on Mikuvan is not sophisticated enough for that.

I coasted into Weyers Cave, VA – between Staunton and Harrisonburg – and we limped to the Shenandoah Valley Regional airport. At this point, Cynthia and Jamison needed a way to get home because they have things like real lives and jobs. They picked up a rental car from the airport, since there were no direct flights to Boston from here.

The battle plan was prepared. Adam and I would crash overnight with his friend in Richmond, VA, then return in the morning with a U-Haul and trailer. From there, we’d basically be running the original Operation: MIKUVAN again!

In what I realize must have looked like a broad daylight car theft, we pulled into the airport parking lot with the truck and trailer and pulled back out with Mikuvan loaded in under 10 minutes (Keep in mind it was still capable of moving under its own power, just for not too long, so I just drove onto the trailer). If we tried this in Boston, we’d been surrounded by black trucks and assault rifles in a few seconds, but they seem to be more chill out here.

The destination was a shopping center south of Harrisonburg, VA, with multiple big box home improvement and auto parts stores in the area.

And so, for the second time in two years, I found myself in a town with “Harris” in the name, under a U-haul trailer, in the parking lot of a big-box store, fixing a van.

The plan of action was to remove the fuel filter and then connect it up backwards, then use the fuel pump to empty the whole tank through the backwards filter. Ideally, this would knock out and wash enough particulates for us to gently nurse it back home, still 12 hours away. Pictured above is the first shot of fuel from the filter. Delicious.

Every few gallons, we’d switch the 10 gallon fuel can for a water bottle and inspect the fuel for clarity. Even at the end of 4 shots, there were still tiny black flakes and bits coming out of it. I know this is probably the past 10,000 miles of deposits, but regardless, it was rather surprising to see how contaminated and full of other substances gasoline, allegedly a highly refined product, can be even in 2014. At least, I’ve never dealt in any way with “bad gas” on any vehicle… but perhaps it’s because I’ve not personally put 10K+ miles on any one vehicle before now.

We dropped the bad fuel off at an auto shop, fully fueled Mikuvan with some Shell premium gas (I was paranoid okay?!) and went on our way. The trip back to Richmond, about 2 hours, would be the test – if I could manage this fine, then it should be okay for the rest of the trip: all of the instances of the fuel restriction would appear with 15-20 minutes of driving each time. I took the lead on the return, with Adam following in the truck and trailer. If the problem returned, I would slow down, pull behind him, and just Grand Theft Auto it onto the trailer.

Around 9:30PM on Wednesday, we rolled out of Richmond and headed north on I-95. I drove at a relatively constant speed and throttle, trying to maintain 70mph, until north of York, PA, upon which Adam took over and got to White Plains, NY on I-287.

I think I should drive with a clogged fuel filter more often, since I got the best mileage ever during that leg. Problems started returning around White Plains, more mildly but still noticeable, so we decided to play it safe and took CT-15 northward instead of I-95.

Here’s the story in a Google map.

CT-15 was a scenic but rather chaotic (being morning rush hour in the NYC metro area and all…) drive. We discovered new Tesla superchargers:

In the span of time we were taking a break at this station – like 20 minutes at most, three Teslas rolled in and out.

Hey, is this still under warranty?

An hour south of Hartford, I got the idea of calling area Mitsubishi dealerships to see if anyone had a fuel filter for an obscure model they likely never personally sold. I’m not sure why I thought this was necessary by this point, since Hartford was but a hop, skip, and faceplant away from Boston, but I was kind of tired and delirious anyway.

Hartford Mitsubishi (& Cadillac & Maserati) was extremely helpful – their parts guy was on the phone with me for 10 minutes trying different models to see if any parts cross correlated. I know for sure the same style filter is used on late 80s Monteros and Galants, as well as shared with the Dodge compact pickups of the same era…. but all of those are virtually extinct by now too, so no luck with those specific models. He ended up finding a ‘universal’ style that fit across model lines. I’ll take one.

We decided not to do the filter swap just two hours outside the finish, so the rest of the trip was spent hovering in the right lane on I-84 and I-90 to very little drama. I made it back onto campus around 1pm on Thursday.

analysis and recourse

I was not expecting “bad gas” to be still a thing in 2014 – sure, I’ve heard stories from other people, but come on, this is the future where we live in the cloud and download our food and movies alike through 4G LTE. I was also under the impression that fuel filters, like any filter, will show symptoms gradually, and not be fine on one hill, but completely go to shit by the next. The filter in question was installed after I got the engine working again in May 2013, and it’s been completely trouble-free for all of the trips since then. It was even trouble-free for 550 miles of blasting in and around Atlanta, where I was regularly pushing 80mph. It was trouble free for the first six hours of the trip, which featured much of the same hammer-dropping. It’s difficult for me to not mentally assign blame to the Love’s station, since I picked up a full tank of fuel from them and then the engine totally went to hell within an hour and a half.

It also seems getting recompense from a gas station is quite difficult.

First, a bunch of people would have to complain AND specifically point out they were the cause. Who knows, maybe the 6 other cars at the station with me when we refueled in Lambsburg also had issues some time down the line, or could have them very shortly after a few hundred more miles, but their owners will just chalk it up to the 5000 mile oil change interval running out and take it into their mechanic, never noticing the cause or caring about the final invoice.

Second, even if they were also broken down somewhere, normal people wouldn’t do what we did: we didn’t do a single thing “the legit way”. Instead of calling for a tow, calling my insurance company to find an authorized shop, getting said shop to perform all the diagnostic work we did, and paying for the replacement part in labor, we slum-fixed it ourselves outside of The System. The “tow” was a U-haul, the “shop” was the parking lot of the Harrisonburg Home Depot. I guess I did end up buying an official dealer sourced part? What this means as a whole is I don’t have an ‘official’ paper trail to back all of these claims up.

I called Love’s and they looked into the store in question, but of course got back to me with “Sorry, nobody else complained and our tests showed our fuel is clean, so we can’t help you”. Of course nobody else complained and your fuel is clean – that’s what your job is to tell me, so I ain’t even mad.  If I were to file a lawsuit, then I’d be potentially out a few thousand dollars and many months of staying on top of it, while swimming upstream against “well, nobody else complained, so what the hell is wrong with your car then?”

Oh well – unless one of you have a better idea, I’m just going to cut my losses at a few hundred bucks, pay off Jamison and Cynthia for their rental car expenses, and file this one under “Don’t Trust the System”.

I took care of the fuel filter in an hour outside of MITERS last week, and based on my (admittedly relatively short) trips around the Boston outer regions, there’s been no problems at all. Maybe it’s time to hit Vermont again for another Ford Fusion battery just to test it on the road for more than an hour at a time, because the New York Maker Faire is next week and I’d certainly like to avoid stranding 5 random freshmen on the side of the road in Connecticut.

Speaking of which, stay tuned for the work on that so far – Chibi-Mikuvan needs some pretty mission critical repairs! Time to switch vans once more….

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.