Archive for the 'Pop Quiz 2' 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).

I’M HAVING FUN GUYS. I SWEAR. NOW GET OFF MY CASE.

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 2014 All-Robots Update

Aug 26, 2014 in Bots, Events, Pop Quiz 2, Twelve O'Clocker, Überclocker ADVANCE

Every year, after duckling season, what is it time for? ROBOT SEASON! For the past 2 weeks, I’ve been making repairs and improvements to the (still yet to be settled, mind you…) 2014 fleet for Dragon Con, my annual end-of-summer robot party, as well as helping work on another thing.

This update will be quite short and to-the-point, seeing as how we’re setting out in about 8 hours or so. Robots at the top, panel information at the bottom! Normally, all of this would have come earlier with more interspersed information, but my shop obligations (namely restoring the place from a complete tornado disaster) take priority.

Überclocker

I’d mentioned near the end of Motorama that Clocker desperately needed a new wheel solution, and that I was looking at the Banebots hex-hub wheels to pull off a similar fast-changeable wheel solution like Candy Paint & Gold Teeth.

So I designed just that. A 0.75″ Delrin hex rod chunk functions as both the hub and the wheel bearing. Grooves cut into the hex mount retaining rings to keep everything in line axially.

Notice that those are “duallie” wheels. I decided to go for double wheels because these Banebots wheels are also not known for hard wearing and long lives, so I figured spreading the damage out could help. Clocker would probably burn through a set of singles very quickly, and while these hubs are meant for faster wheel changes, I still don’t want to do that every 2 matches.

The result is that the bot got wider by about an inch total. Not bad, but I still had to remake the axles.

I tried finding Delrin hex material, but it doesn’t seem nearly as common as other plastics in this shape and I’d have to buy 4+ feet from something that wasn’t McMaster-Carr. Well, I need it yesterday so I changed the material to Nylon instead, which is still more than sufficient, and I could buy it in much smaller quantities. Nylon is nice and all, but I still prefer the machining properties of Delrin.

And so the 100th build picture of Überclocker is in in a state of disrepair. I took the lids and most of the drivetrain parts off to inspect everything for damage or required rework. Overall, besides the bent front legs (and totally bald tires), everything is in good shape.

After trying to stretch a traditional circular retaining ring (“circlip”) onto the hex hub, I realized the points of the hex are just too wide to use that style – the legs just bent permanently since the deformation was basically up to the next shaft size. Well a trip to the hardware store netted some E-clips, which slide on from the side. Perfect!

Four duallie wheels made!

I ordered some 7075 aluminum round stock for the new axles and standoffs, since the length I needed was greater than the amount I had remaining from the last build. The four highly polished shafts (1200 grit wet sandpaper, using Tinylathe as the power source) are the wheel axles.

Everything being installed…

With this part finished up, I began restoring the legs. The only thing wrong with them was that the mounting points bent. They’re mounted each hinged on one 1/4-20 cap screw surrounded by a heavily preloaded standoff. Even though this extremely rigid, it still doesn’t like the whole bot bouncing off them. I had to replace the bent bolts and resurface the standoff to be square again.

Furthermore, one of the legs had a broken end roller with the remains of the shoulder screw embedded inside the aluminum leg. After cursing for a while trying to get the stub out, I decided to brute force machine it out and press in a large “insert nut” of sorts.

Removing the broken screw by milling straight down through it…

Making the insert nut, which has a press-fit outer diameter and 5/16-18 threaded ID.

The repaired thread in the leg. This is no longer as strong as the contiguous virgin metal, but it’ll work for now. I ran out of both stock and time to get new leg beams cut out.

Buttoning everything back up!

The ‘glory shot’ for this time around!

I’m highly satisfied with how the new BB wheels handle. What I wasn’t satisfied with was once again how closely I routed the chain to the wheels! I always seem to manage to design a chain drive with a critical but obvious failure owing to me trying to think of chains as precision components.

Nope. Chains are made of ass, and I need to design like ass to use them properly. Oh well.

In this test match between Clocker and Jamison’s somewhat new 30lber (which he’ll certainly update about, right brah?), the right side’s master link clip was torn off by some scrubbing wheel action. The left side’s master link had its retaining clip oriented inwards (away from the wheel). I resolved this by flipping the chain around so the master link clips were all on the inside. I’ve yet to lose another chain, so here is hoping to continued good luck.

Überclocker has no other changes besides the new wheels and the requisite screw tightenings.

Twelve O’Clocker

It’s well known that I have everything in multiple scales, so it’s time to pull out 12 O’clocker again. It did not compete at Motorama 2014 due in part to the lack of a Sportsman’s Class for the 12lbers, so DC2014 will actually be 12 O’Clocker’s second event.

It works fine. Hell, I could have thrown it right back in with no changes at all, but I did want to make a modification to the leg retaining system – specifically, making it actually function. The current leg retaining system is a big washer and standoff, which works fine for the upward direction that the leg is loaded in normaly, but if someone takes a good run at me, the leg gets pushed downwards and props the front of the bot off the ground.

Well, that kind of defeats the point. Here is the new design.

It’s just a clippy thing. That holds the leg from moving in either direction. Cool, huh!?

The profile shape is waterjet-cut, with a single drilled cross-hole. It’s still topologically equivalent to a standoff!

And here they are, installed!

That’s it for 12 O’clocker pictures. What, were you expecting more?

I did make some minor adjustments such as face-machining the leadscrew nut gear to reduce the amount of surface area subjected to sliding. This will hopefully make the arm less likely to “bolt” itself onto an opponent – the motor should always be able to free it up now. I also tightened up the chain drive so it doesn’t, well, Clocker itself.

12 O’Clocker will receive no further mods, since it really has been working the WHOLE TIME!

Pop Quiz 3!

Whoa! I still have this bot!

Last seeing action some time in 2011, it’s been hanging out in a bin I call the Mass Grave of Little Bots since it contains Pop Quiz, Pad Thai, and Colsonbot alike. As well as enough parts for another 2 or 3. I never repaired PQ after DC2011 since I had other bots to tend to, but little bots are always fun to dork around with, and with two working “big” entries (12 and 30lb, anyway… this isn’t 2002 any more where 340lb was “big”…), why not try to revive them?

Pop Quiz won’t be the only 1lb bot I try to revive – the entire Mass Grave is being brought down to Atlanta for some party time at the Georgia Tech Invention Studio. Whatever we all get running will enter, but I will not try too hard on the rest.

As for PQ itself, it’s going to get a complete from-the-ground rebuild, so it’s time to increment the number. I wanted to go directly to Pop Quiz 3.14, but I think I’m past naming bots after silly math jokes now.

Here is an overview of the new design:

Major deltas from the 2011 version: A much, much shorter blade. Titanium top and bottom. And a one-shot 3D printed frame that isn’t made of chunks of smaller prints.

Why the SHORTER blade? Are you crazy? Isn’t robot fighting always about who has the biggest pen0r spinning weapon?

Well, I mean, yes, but the longer the blade, the more likely the bot will just destabilize after a hit or, as Pop Quiz in 2011 did all the time, just hit itself and take off. That’s counterproductive to winning, or doing anything besides flailing around upside-down.

In the past, horizontal blade spinners have won, such as Hazard. Notice how relatively short its blade is – it’s principally a defensive wedge/pusherbot that just happens to have a pimp-slapping device on top of it, not a blade with wheels as so many spinners are designed today. PQ2 was designed this way, and the blade was easily 200% of the bot’s own width. Exacerbated by a lack of rigidity, it was a master of self-eating but not much else.

The blade this time is only 7.5″ across, a little thicker, and made of hardened steel instead of titanium.

I’m also moving it away from a battery disconnect switch to a Fingertech switch to reduce the vulnerability to slicing off its own power wires. Except there’s a problem: The Fingerswitch is too big for this bot. Everything is too big for this bot.

A few minutes of consultation with the designer, Kurt, and some other bot folks, led to this: the integrated Fingertech switch. I was just going to harvest the internals out of a stock switch and insert it into the 3D print file.

Besides this mod, the internals will remain basically the same. In fact, I’m almost straight up transplanting the working electronics from PQ2 into PQ3: Vex #29 controllers for the drive, 7.4v 500mAh lipo battery, and four little Sanyo-esque motors.

I added some small changes to the frame (such as the Integrated Fingertech Switch), but for the most part, this is the 2011 frame, except this time I’ll actually 3DP it in one piece instead of 4.

When I opened the old PQ up, I was greeted by ….. a giant lockwasher? This must have been underweight!

The Spektrum BR6000 seen to the very left (the front of the bot) will be changed out to a Hobbyking 6 channel receiver to match the rest of my objectively downmarket radio system.

The weapon motor. I haven’t been in here in a long time, either. This thing still ran well, and I made no changes to it.

Here’s the new frame, in black ABS plastic!

A few weeks ago, I ordered a bunch of small 500mAh 2S lithium batteries from Hobbyking of the same specification as the old ones. However, the general trend in lithium cells (as reflected in the auto industry, fast food industry, and smartphone industry) has been to get thicker/larger/bigger. I had to un-package the Hobbyking stock battery in order for it to fit in Pop Quiz’s 0.400″ thick frame!

The new top and bottom plate are no longer carbon fiber, but titanium. I caught a great deal on grade 5 Ti sheet on eBay.

I used the MIT Hobby Shop‘s new MicroJet to cut this piece out. It operates above water, so the light show was quite intense!

The steps to finishing Pop Quiz are basically stuffing the electronics and everything back in

So that’s pretty much the state of the bot as it stands now. Again, everything else will be either finished or not finished as we hang out with the GTIS folks, who are apparently also building their own entries this week. Old habits die hard…

Dragon Con 2014 Panels

As per usual in the past few years, I’ll be either hosting or co-hosting a few panels:

  1. Maker Resources: How to take advantage of the great abundance of resources on the Internet to build better things. Obtaining and using CAD programs. Digital fabrication services, 3D printing, waterjetting, electronics design, and so on. Focused on mechanical and electronic projects, and somewhat derived from my 2.00gokart lectures on resources.
  2. Rapid Prototyping Cosplay. With Jamison and Chris Lee, featuring a whole lot of others. How the rise of accessible digital fab processes has spurred the growth of aesthetic and functional costume parts, and how you can get involved.
  3. Electric Vehicles: with myself and Adam Bercu, a rundown on the state of the art in electric vehicle technology in both the commercial/automotive realm and the DIY/hobbyist realm.

More details on these will be released as they get closer. I’m going to try my darndest to get these recorded this year – I say that every year, but I really swear to Baby Robot Jesus this time, guys!!!

I’ll check back in after we’re in the ‘hood.

The Post-Everything Updates, Part I: Robot Battles

Sep 12, 2011 in Bots, Pop Quiz 2, Überclocker Remix

That’s it! The event is over once again. If by my lack-of-enthusiasm-induced time delay is any indication, I didn’t win anything. The robots performed about as much as I would have expected given the effort that I put into them this time around (read: like none). In the antweights, Unmodeled Dynamics…no, that’s not the name of a robot, though it could be… ended up causing Pop Quiz an early loss after winning one match. And in the 30lbers, Überclocker proved to be a little behind the times now in terms of speed, ground clearance, and maneuverability, winning only one match.

I didn’t even get to twirl anyone this time around. That is how bad it was. No con pictures this time either, since I really only stopped in for some of the Robotics and Science talks and otherwise didn’t have a good enough camera to feel like taking pictures of people. Also, without a consistent videographer this time, I don’t have complete video of both robots’ matches. So, no highlights video just yet.

The events, though, were phenomenal. The insect-class event ended up attracting 36 entries – 19 beetleweights and 17 antweights. This makes it the largest insect-class event on the east coast so far, and many of the robots were from new builders. Because of the number of entries, though, the tournament had to be converted to single-elimination (historically has been double-elim) to fit in the given convention time slot.

Pop Quiz

As the testing session video reveals, Pop Quiz has a slight “sudden unintended takeoff” problem stemming from the frame’s flexibility and the low blade height. I’m interested in seeing this under some serious high speed video equipment because the development takes milliseconds. I’m guessing the combination of robot movement, slight nonplanar mounting of the blade axis (due to floor bumps or varying wheel instantaneous heights) causes gyroscopic forces to flex the motor mounting area, which because of the very low blade clearance causes it to strike the robot corners. The blade then quickly destabilizes and hits the ground due to the bot’s very low height.

Either way, sort of annoying. There’s nothing wrong with Pop Quiz right now. It in fact works just fine, so I’ll probably retain it as a demobot. However, I’m definitely out to build a better antweight – of what style I am unsure of at the moment (but I really, really do want to name it Unmodeled Dynamics)

I have one complete video of Pop Quiz’s second match, which ended in a PopQuizCopter-induced loss.

Überclocker Remix

Oh dear. Where do I even start with this one? Clocker’s now 3-year and 4-tournament record is starting to show – the design flaws of late 2008 are slowly getting worse with time, compounded by my apathy. This year, the stage has pretty much become so damaged (purposefully, since it was historically a good wedge inhibitor) that Clocker was being hung up everywhere. The 2.5″ colsons have worn down alot, so much that I had lots of trouble maneuvering. Additionally, the lack of (functional) chain tensioners resulted in the chain being caught and damaged by the stage surface for the first time. To mend this, I made some quick zip tie tensioners (continuing the tradition of fixing Clocker at an event with zip ties):

The zip tie wrapped around both sides of the chain and prevented it from sagging and touching the ground. This worked – right up until it caught on the master link retaining clips and ripped them right off. The result was a broken chain in the bot’s third match. By that point, I really had stopped caring and just wanted to continue the show, so I elected to run one-sided (and without the infamous Zip Tie Ratchet even!)

Past that, the robot’s lack of actual forward-pointing sharp things (The ends of the fork are actually fairly blunt) meant that I was easy to get under from the front. Finally, opponents were finally able to take advantage of the bot’s 23 inch long flat broadside.

At least the motors worked this time!

Clocker version 2 (“Remix”) is now retired. I’m going to be rebuilding the bot from the ground up to emphasize manueverability and terrain handling – terrain referring to bumps and inconsistencies in the arena surface of up to 3/4 inch. Yes, this thing is going to have a boatload of ground clearance, will be much faster, and also with more “grabber clearance” so I can latch onto the more irregularly shaped robots. In order to fix the huge broadside problem, the sides of the bot will be rounded like Cold Arbor (it has prove hard to attack from the sides due to its tendency to “roll” into or away from the pushing force).

I haven’t designed out everything yet, but have been making a few “concept sketches”. One of which is below (though it’s unlikely to be used)

Pop Quiz Pre-Event Smackdown

Sep 04, 2011 in Bots, Pop Quiz 2

After obtaining 4 set screws, I put PQ2r2 together for the final shakedown test.

Okay, so it turned out to be more of a shakedown than I thought. The blade is just off balance and possibly just tilted in-robot enough to cause the sudden instability and “popping” in the video. To mitigate this, I’d have to spin up just before approaching an opponent.

Because of the missing battery half, the robot only weighs 13 ounces. It’s fairly maneuverable with the four Sanyo style gearmotors and soft wheels, so I hope if it’s too light to be an effective spinner it can still get under people and shove them around.

Microbattles event in about 10 hours!

Pop Quiz 2√2 is over

Sep 03, 2011 in Pop Quiz 2, Project Build Reports

The past week or so has seen me throw 500 miles on a rental car as I dash back and forth between home base, the Invention Studio, and Freeside Atlanta (and a hardware store or two, among other places) working mostly on Pop Quiz.

Thank Robot Jesus for free mileage.

Technically, Dragon*Con has already started (today being the first day of the con), but the robot events aren’t until Sunday and Monday. That’s fine, because Pop Quiz is done.

Well, it’s missing four set screws. But that’s another trip to the hardware store.

Step one: Clean up all of those 3d printed parts from last time with a bit of crafty knife work.  The small surface imperfections in the plastic print mean the motor mounts are extra-cozy – a bit of pressure is needed to seat the motors into them. This is good, since I’d rather have that than wobbly loose motors.

Holy panel gaps. After laying out the frame pieces on the baseplate, it’s clear there’s a small mismatch in boundary sizes. This is probably due to shrinkage of the plastic from the hot build environment to room temperature.Either way, about a millimeter on all sides will need bridging with epoxy, thick CA glue, Goop, or some other substance.

By the way, this is the last good picture for a while. For reasons I can’t fathom, my usual camera has now decided to take pictures only in the ultraviolet spectrum (that is to say, mostly black with some odd color patches on normally brightly colored objects). So I currently am split between using my HD camcorder as a camera (something it is surprisingly terrible at) or doing it up Jed-style and using a cell phone camera. Most of the build from here on will use the latter option, since it’s portable and with me most of the time anyway.

Horrible picture #1: redoing the battery pack. I neglected to bring Pop Quiz’s anticipated battery, a 500mAh 2S from Hobbyking that is the battery used now in MIT’s 2.007 robot building course. It’s the only small lipo I’ve found with reasonable capacity that is 10mm thick, or as thick as PQ is tall.

I did bring the 3S lithium pack I originally bought for Ballcopter. Not sure what I was intending to do with it, but it was simple enough to knock a cell out of the pack. This 2S arrangement is now also 10mm thick.

Horrible picture #2, with my HD camcorder (the HD aspect ratio gives it away). This thing has even worse low-light performance but holds a sharper focus otherwise. I’ve decased the Spektrum BR6000 and test-fit it in its final location. That gap width was designed around the internal board, so it’s a snug fit.

The battery lead, also the main power switch, routes through a small cutout in the back. Hopefully it won’t fly upwards and get sniped by the overhead blade.

Back to the cell phone camera. That thing seems to have no white balance ability to speak of – the pictures only appear without a yellow tint as in the battery picture if I point it at a blue or green object, like this convenient receiver board.

I de-headered the BR6000 one pin at a time by heating up the solder joint while pulling upwards with pliers. I have never cleanly (reversibly) desoldered male header pins, or any high pin count through-hole component like them. This time, since I was going to hardwire the controllers anyway, I just removed the entire header block.

I took the VEX 29 motor controllers out of their cases. They are actually very compact – no more than 3.5mm thick, and approximately 14 x 25mm footprint.

They normally run directly off a servo cable using the 5 volt line. To get 7.4 volts to it, I had to break out the 5V and ground pins separately to the battery, and then solder a signal + ground wire on top of that. The white and black signal wires run off the bottom of the picture, while the appended battery inputs go to the nest in the back of the bot.

I gave the bare boards a wrapping of clear heat shrink afterwards.

A view  from above with all the wiring in place. The signal connections have been hardwired and everything turns on without exploding.

The Vextrollers do seem to work on 7.4 volts (actually closer to 8.4 volts since the lithium cells were fully charged), making me think that they are actually capable of higher voltage operation. There is nothing on the board which directly indicates they would survive voltages higher than 10 to 11 volts, but it’s worth a shot. Time to put one on a power supply.

The majority of small bots like Antweights and Beetleweights tend to run 2S lithium systems anyway – at only $10 each, the Vextrollers seem to be a great potential resource if that limit applies to your design. This makes them way better than the overpriced specialty robot controllers.

I put the top on for test fitting and to check that everything does pack down. With the top plate’s screws in place, the robot frame is forced to be totally flat again – otherwise, due to the very slight warpage in the frame pieces, the whole thing becomes concave.

Back at the Invention Studio, I popped the wheel hubs out of some 1/2″ aluminum round stock. This was a fast lathe and mill-facilitated drilling operation since the parts were all small and all the same.

The tires  are some very soft (40-50A) silicone flexible tubing I got from McMaster. The outside diameter is 0.5″, and the ID is about 0.25″ so I turned the hubs slightly larger than that. I’ll probably drop some CA glue onto the joint to really keep the tires on there.

After wrapping everything up, the final bot. The frame pieces have been CA glued to the base and the ‘panel gaps’ also filled with thick CA. The structure is overall fairly rigid, a fact definitely helped by the carbon fiber sandwich design. The final blade height is 0.65 inches.

The bot is definitely underweight – I have yet to weigh it, but since I designed for 4 lithium cells and ended up using only 2, I think its at least an ounce and a half underweight. This might be taken up later on by more steel bits added to the inside.

Otherwise, the only thing I couldn’t find to finish the whole thing and have it driving was tiny 4-40 set screws for the wheels. The blade spins up very quickly, however, and PQ has already successfully lifted off and batted itself once.

Onwards to Microbattles!