Archive for the 'CRJ Wallbanger' Category


Hurricane Robot Videos

Oct 30, 2012 in CRJ Wallbanger, Null Hypothesis, Project Build Reports, Stuff, Überclocker Remix

Due to the sheer amount of ass-weather that is currently hovering the Northeast, I’ve taken the off-day to actually edit all of my Robot Battles 2012 video! Enjoy the following compilations of Null Hypothesis, Überclocker, and the Carly Rae Jepsen Wallbanger.



Little video snippers from Mike Jeffries, Dale, and Xo were used for some parts where my video was incomplete.

The Dragon*Con & Robot Battles 2012 Recap

Sep 07, 2012 in Bots, CRJ Wallbanger, Events, Null Hypothesis, Überclocker Remix

It’s over.

Again. And this time, it wasn’t total ass. This is probably made obvious by the fact that I’m making the recap report so soon after the event, as opposed to past years where I forgot about everything for, say, a month or two. Here’s how it all ended.

Überclocker (Unicorn):

With a drivetrain that finally approximates reliable, Überclocker actually managed to win matches! Later in the tournament, however, and pretty much expected, the repaired fork gearbox began failing and finally left Clocker without the lift portion of the fork. I briefly was able to use the clamp as a lifter (due to the much larger motor now there), but Clocker ended up losing out of the tournament due to …. unscrupulous… driving.

Null Hypothesis:

Well, it sure worked well as a fast pushybot, so I can’t say it failed, but I just didn’t practice driving in confined spaces enough and most of NH’s losses were due to ‘stagediving”. However, it faced two other powerful drivetrain bots, and I think NH caught several seconds of combined airtime over the course of the tournament, finally losing just due to being outmaneuvered.

The Carly Rae Jepsen Wallbanger:

Oh, poor CRJ. It really only had 1 match in the 12lbers, due to the 12s being run single-elimination out of time constraints. But the one match was fairly good – it caught some air glancing  off Apollyon before getting pushed out, then whacked a few people in the 12lb rumble before getting scooped up.

The Ragebridges:

I’m glad to report that for the first time ever, all of my competition robots ran a full-custom motor controller design. The Ragebridges, with their Semi-Intelligent Current Limiting (a.k.a constant-current mode) worked flawlessly, and the CC mode came in so very handy when Clocker’s lifter gearbox shattered and stalled out both motors. I didn’t realize it at first, so I spent a few seconds pulsing the fork control stick up and down, which certainly could have smoked the motors if there was no limiting. None of the boards had the 15v instability and resetting issue after I changed the regulator inductors, and while they did get hot, there were no burnouts or smokage, probably aided by the CC mode.

But robots wasn’t all that happened. Quite a few things went down during the week, too.

The first mission was to get down there. Same as last year, I rented a car with a sufficiently large trunk/hatch, because air freighting or ground shipping were totally uneconomical (and I would have had to build a crate weeks in advance). Joining me this year with his large blue and green EV magic boxes was Adam Bercu, fellow robot builder of many years and also purveyor of fine murdered-out C80 “melon” motors. I brought along several demoables for the Electric Vehicle intro panel that we were hosting, including Chibikart2, the Kitmotters (demo stand and working motor from Johnscooter), and some random R/C parts and batteries. Adam took up the bigger end of the scale with prismatic Li cells, the giant Manzanita “micro” charger, and a large series DC motor controller along with other doodads.

The con itself was quite a time as it always has been. This year, though, I began noticing far more mechanical and home-built costumes and…. other things.

News flash: Eteks are now steampunk.

Update: Steampunk now officially meaningless.

As much fun as I make of steampunk, stuff like this still tickles me correctly because it shows that more people are getting down to building, no matter how silly and brassy it looks. The fabrication on this mono-tri-wheel-thing was pretty well done.

The same group also had a pretty sweet mono-moped with a ring wheel. Does this constitute a hub motor?!

IS IT STEAMPUNK!? I can’t tell any more.

Other mechanical costume parts abounded, like these deploying… something wings. Not too sure if they’re angel or paraglider or what, but watching it in action was awesome.

They were driven by a single motor meshing with a nicely finished geartrain. The drive parts were all waterjet-cut. This was present in the Waterjetting & Digital Fabrication panel, for good reason.

There was also plenty of more decorative elements involving LEDs and lighting on costumes. I’m not sure what the above character is (furry-rave-angel-quarterback-gunner?), but she had a very well made arm cannon doodad and plenty of LED accents everywhere. While throwing LEDs on things might not seem impressive to the average jaded engineer, for many people doing so is an introduction to hooking up a battery to a thing they made and having it work. That’s how it all begins.

I’m definitely supportive of more people making electronic and mechanical costumes and costume parts, and it kind of makes me want to do it more. I think I suffer a bit from costume one-upsmanship envy because I don’t want to start until I make a fully functional mech or something of that scale.

With the expansion of the Robotics Track to include the maker/hacker movement in general, I’m hoping to see many people make engineered costume bits in the future.

Besides the functional stuff, there was the usual plethora of paper mache and foam oversized objects. I’m fond of oversized tools, so here’s a giant wrench. Hey, one of those 3 is Alice Cooper, right?

Sadly, there was no space in the car for Excaliper, my giant 5.5-foot (real steel) vernier caliper that I brought one year and waved around.

Before the con itself, however, there were more robots. We didn’t go down a whole week beforehand just to sit around and drink sweet tea.

Above is Adam’s emergency 30lber build in progress. Nicknamed “Blitz”, it was built essentially over 5 evenings. On Monday immediately after arrival, we stopped by the area Harbor Freight and raided them of almost all of their 18v cordless drills. This was the same time I bought the cordless saws for Carly Rae Jepsen. The next day, we dropped by and bought some more.

A few days later, before the big show. Also present during the week was the other quickly-built-for-fun 12lber, Turboencabulator. Blitz’s design was based off the heavyweight champion Sewer Snake, which has a non-actuated extension of its main lifter weapon that swings forward when the lifted is driven under the robot, making for a flipper-like effect.

Also happening during the week was the installation of the new arena hazard in the Bot Arena, courtesy of yours truly and the arena build crew.

Yes, that is the secret thing I worked on through most of July and August. It doesn’t look very exciting from up top, certainly. In lieu of me explaining what is going on, it might be worth watching some of the antweights videos from this year (videos courtesy of Mike from Near Chaos Robotics)

I still need to put up an epicly long build report for this sucker one day.

This contraption is the control panel for the hazard. It has buttons and does things.

Let’s get down to robots. This is the new Atlanta arena.

Seriously. Isn’t it fucking gorgeous? Not only that, but it’s so outrageously modular. It takes a group of 4 guys maybe 15 minutes to set up if we have practice and tools nearby. Rigging the wiring for lights takes longer, but if you needed instant no-frills robot fight, that’s it. It’s also grown to nearly double the space, from 6 x 6 feet to 8 x 8 feet.

The hole. It’s supposed to have a 12″ sanding disc, but I forgot to bring it and nobody seems to sell those in the Atlanta area in a reasonable timeframe. So we had to make do with these little sanding pads. They fell off as quickly as expected.

If you haven’t figured out from the video, the turntable also goes up and down, creating a whirling pit of annoyance.

I didn’t get many good arena shots since i was primarily recording video. Plus, my free 4-year-old fake-DSLR doesn’t stand up to the professional and camera-penis-contestant photographers there anyway. Above is Dominant Mode briefly before it rocketed the pushybot most of the way across the arena.

The tournament this year was really boned for time – we were supposed to have 3.5 hours, but only ended up getting 2.5, and another event was scheduled to set up during out takedown/loadout time. As a result, many matches had to be cut short and the tournament had to be switched to single elimination mid-stream. Next year, though, this should not happen again.

The day after was the big day!

Again with the last minute random even details, the hotel sadfaced at the robots destroying the brand-new stage risers they had purchased just this year. As a result, a few dedicated builders put together a MDF and carpet overlay for the MDF and carpet stage riser surface. Steel plate annoyance bumps were also bolted to this upper layer, but not very securely – the 30lbers started plowing them off one by one.

There were too many 12lbers to run double elimination, but the 30s ended up being double.

Carly Rae Jepsen Wallbanger lost once to Apollyon for a net 0-1 record.

Überclocker won against Nyx and subsequently won against Scary-go-Round before losing to Pinball and then Nyx, for a 2-2 record.

Null Hypothesis faced Pinball immediately and lost (but not before catching some serious air by ramping off the front wedge of Pinball), then lost to Nyx, for a 0-2 record.

The carpet ended up being a little fragile on its own with no strong, bonded substrate (unlike the stage riser carpet). By the end, there were so many holes and tears in it that the duct taped used to fix the stuff became a hazard in its own right. The lint was also very tenacious and got into drivetrains. Quite an interesting element to add to the game, though the builders are now thinking of a better solution for future years in case the hotel requests stage condoms once again.

Yes, that is a sword on Clocker. After all, I did name it Überclocker Ünicorn, right?

After my match with Scary-go-Round, the lifting fork was pretty much totally useless. Both of the gearboxes had shattered completely from the impacts and the motors were totally locked up. I got as much postponement time as I could in order to pull the gearbox and take out the broken gears, a process which took about 20 minutes exactly as I found out. I restored one gearbox to functional status (leaving the other one freewheeling) , there was not enough time to put it together for the Pinball match.

The top clamp has enough force to lift 30lbers, so I just needed an extension to get it to the ground. Hence, emergency death-shank provided by Jamison. It worked exactly once, but not really.

Next version of Clocker is designed with serviceability in mind…

The carpet also destroyed the McMasterbots wheels. Clocker managed to grind the two back wheels right down to the plastic core, which compromised its traction a fair lot near the end. These wheels are clearly one event use – they’re too soft to just leave on, so I guess I need to make them easily replaceable and have plenty of spares hanging out.


I’m glad to say that many people besides just me had cameras at the events, so Clocker and crew have alot of footage from their matches. It’s almost to the point where I don’t have to do anything!

I’m waiting on some video from other people before editing together my own bots’ summary videos, but in the mean time, NCR has a list of almost every match, and Dale’s Homemade Robots has several compilation videos.

outlook for the fall

That’s it. My annual robot party has ended, and it’s now back to the grind of taking classes. This fall I’m going to play a bit of a catchup game in that regard, so I’ve promised myself no large engineery things. Let’s see how long that lasts.

Clocker will be dismantled now, to force me to rebuild it. The earliest I might be able to call it is Motorama 2013, in February. NH will be kept totally as-is, but it won’t go to Moto 2013 (the only category it would be legal in would just make it be more disassembled, not necessarily reversibly so). CRJW might become the inspiration for a new true “melty brain” translate-while-spinning bot next year.

This semester, I’m going to focus on little things which don’t need time spent fabricating. It would be nice to get the Ragebridge boards compactified more and get rid of the discrete Arduino (or “the ATMega328 breakout board” as some have called it). Not to say it won’t use the current Arduino code, but the chip will just be integrated on board. I’d like to reduce the square footage by 25% or more this way. I’ll also try to characterize the Semi-Intelligent Current Limiting some more to see how fast and effective I can make it. Given the discovery of mismatched component values and incorrectly placed parts, tinyTroller might make a reappearance since it has the same power side architecture.

Next, it’s my intention to reduce my gargantuan pile of robot debris some more. I’m currently split between 4 different shelves and storage locations, and even those are becoming hard to handle… I may put quite a few things up for sale here, and if I do, they will be on a separate page.

As for the distant future, next Dragon*Con I intend to make more appearances at the Maker/Robots track. I do want to run Resources and EVs again, but also I want to add How to Shop on McMaster-Carr… one of the seminal skills that hobbyists and amateur engineers have to learn that really makes projects nice.

The Carly Rae Jepsen Wallbanger: A New 12lb Robot Premier at Robot Battles 2012

Sep 03, 2012 in CRJ Wallbanger, Project Build Reports

Excuse me while I try to explain why this thing exists.

Basically, I spent 3 days at the GT Invention Studio putting together a new 12lb bot after binging cordless saw motors at Harbor Freight. The bot is a “full body” spinner, classically called a “thwackbot”, which has a very quick and powerful drivetrain (made of the aforementioned cordless saw motors) to spin itself at high speeds. I have no reasonable explanation for the Carly Rae Jepsen part. It doesn’t really need to exist.

But the benefit of it existing is one more entry for me at Robot Battles 2012, as well as a chance to explore another possible way to press cordless tools into service for robotic drivetrains. I haven’t had a 12lber in a long time, and this thing is fun to drive.

Long story short, the Model 67026 18 volt cordless saw from Harbor Freight is usually on sale for $25 to $30 and contains the following:

Beefy. I actually binged 3 different types of cordless saw: a jigsaw, a reciprocating saw, and the cordless circular saw. I might make a Beyond Unboxing post about the three some time, but right now the conclusion is that the jigsaw and recip saw are too specialized to be of immediate use to a robot drivetrain.

Unlike the average shady cordless drill, these gearboxes have random Chinese off-brand 775-size motors. That’s already a pretty substantial horsepower increase.

Unscrewing the gearbox itself from the weird cast output structure, I found that the ring gear was actually well-contained and modular. A large iron-bronze bushing pressed into the ring gear cup supports the 12mm-stepping-to-10mm output shaft. The nub thing is the spindle lock for changing out blades and doesn’t transmit any torque.

The gearbox is a single stage planetary gear with teeth much larger than drill motors – looking close to 1.0 module (24 pitch-ish) with an 8mm face width, though I didn’t measure diameters. The ring gear has 42 teeth and the pinion has 10, making this a (42/10)+1 or 5.2:1 gearbox. With a 3800RPM rated output. That’s pretty damned fast, so it might not be directly useful for a drivetrain in most cases, but certainly with external reduction or just tiny wheels.

I decided to find a way to use the gearcase by itself, without the strange casting. The iron-bronze output bushing of the motor lends itself well to using a stacked plate configuration to approximate the stepped profile of the business end of the gearbox. Behold:

The first (innermost) layer supports the plastic gearcase, and the second layer holds the bushing in place. The dimensions worked out very nicely.

So what does the rest of this thing look like?

I generally have trouble explaining my design rationales, so that’s it. I basically decided it was going to be a 2-wheel-drive “thwack” type bot. A few frame drawings were made and discarded before they reached the 3d model stage. One plan was to make the bot essentially round and have steel knocking teeth on the outer radius (looking much like a “shell” type spinner), but it was deemed impractical in the limited time I had. Another design had the wheels inboard, only 3 or 4 inches apart, to maximize the inertia of the frame. I did want to retain significant mobility, so a very narrow wheel track with the motors facing inwards was ruled out. I then started the frame design constraint by spacing the motors far enough apart to install a Ragebridge board if needed, since I had packed a spare.

Finally, realizing that the easiest way to mount the motors was with thru-holes and standoffs, I elected to make the robot entirely from standoffs and plates, which can be quickly whipped out on the GTIS waterjet (yes, even when I escape MIT, I cannot escape my waterjet addiction).

Four long sticks of grade B7 threaded rod clamp the frame together. It’s an essentially one-piece frame that can’t be messed with without taking the nuts off and hence loosening everything. However, when the rods are cranked, the frame should be stiff enough to not deform under the hits it can deliver.

Exercising my Atlanta resources for the first time in years, I went to Metal Supermarket in Doraville and bought some 1/4″ steel plate and 1/8″ aluminum, then drove to McMaster-Carr (yes, to McMaster – this was something that regularly happened during high school FIRST seasons) for the rest of the parts. I also bought some wire and connectors from Hobbytown USA in Duluth, another one of my old robot trip stops

This is the series of 2 plates mentioned previously. I had to do quite a bit of “deburr-boring” to get the holes to the proper dimension – must have screwed up measuring the roughly molded plastic.

The wheel mounting arrangement is a little unconventional. The wheels are 3″ “McMasterbots” wheels, the same that I will also be using on Überclocker. The width of the wheel, plus a little here and there, is perfect for suspending off the 10mm portion of the shaft. A small spacer, machined to the correct length, will be the axial constraint method. The shaft otherwise has no snap ring grooves or shoulders to axially locate it when force is applied into the end – i.e. pushing the shaft into the ring gear. The spacer will act as a thrust bearing in this situation, and I made it appropriately out of the iron-bronze output bushing found in a typical drill motor (it can be seen on the shaft in the picture).

The end of the shaft has a convenient double-flat profile, so the wheel hub is just a single waterjetted biscuit of aluminum with a matching double-flat bore.

The holes in the wheel were drilled in-place using the hub biscuit as a template. The wheel bore itself was enlargened to 10mm first using a lathe and drill. This whole thing is retained by the original blade locking screw from the saw.

Here’s the bot laid out in pretend form, before I threaded the long rods through.

And here is the whole frame bolted together.

I like those middle rail bulkhead things alot. At first, I was intending to waterjet whole rectangles with thru-holes, but decided it was a waste of material. I split each rectangle into sides, and each side actually looks like a little open-ended wrench that slides over the threaded rod (see previous picture – they’re next to the frame standoffs). Therefore, I can install them after threading all the standoffs through, in-place. The idea was to have a fast way of dismounting electronics if I needed.

Speaking of electronics, I decided to fall back to a classic solution of mine: A123 cells. I have 2 strings of 15-cell nicads drawn in the model, and the intent was to use the stock batteries that 18v drills came with. However, the cells are very low quality in those cheap things, and I’ve measured them as dumping *10* amps, max. In a sub-C package.

Kind of derpy. Even with two strings in parallel, the voltage stability would be unacceptable with those 775 motors throwing the bot around. On the contrary, the A123s can happily shit out 60-80 amps briefly.

I made a “flexy” pack since it needed to span the bulkhead and the A123 cells were too wide to fit in the design. The pack is 6S1P, and there will be 2 in the robot for 6S2P, or 19.2v at 4.4Ah. Much more substantial than the 18v and 2.3Ah the drill packs would have offered, and these weigh less.

Instant robot.

I’m gonna have to remember to add more zip ties to the thing in order to retain the batteries radially.

These motors hit 3800rpm at their native 18 volts. This results in a linear speed of something like 35mph tops, but I will never get up to that speed on stage, clearly. The bot does handle quite well for being so fast, because it’s also extremely wide and has high traction. The maximum rate of spin with the motors going full opposite is about 800RPM, for a linear tip speed of around 40mph.

Way too fast for Robot Battles – there is a 20 feet-per-second max anything speed rule. Luckily, on 50% dual rates set by my transmitter, the spin rate is much closer to 20FPS. So this bot will just be run with my radio’s gentler stick settings.

So what’s controlling this rig? I brought along my spare 65A Botbuttz controllers in case the Ragebridges in any of the bots failed or needed emergency replacement. These are brainwashed Hobbyking brushless ESCs which have been convinced they can only drive brushed DC motors reversibly. With firmware being open-source and developed by members of the robot community, nice things not normally found in cheap single channel ESCs such as exponential response and ultra-narrow deadband are possible. So in other words, this thing is smooth. They also run perfectly on 6S A123s, and were a good amperage match for the 775 motors.

So here’s the side of the thing, with steel knockers. They’re unhardened, so I don’t expect them to stay sharp very long.

Here’s some test video!

This thing basically goes up in 7 hours. I don’t expect it to last very long, but it will probably be a (and only one) hit.