Archive for the 'Überclocker ADVANCE' Category


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.


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.

Motorama 2014: How Candy Paint & Gold Teeth Happened in an Hour; Überclocker Wins 2nd Place in Sportsmans

Feb 22, 2014 in Bots, Candy Paint & Gold Teeth, Events, Project Build Reports, Überclocker ADVANCE

In the spirit of Motorama always landing on or near Valentine’s Day, here’s some robot loving.

That’s Jamisons‘ new somewhat-secret-but-not-really 30lber megatRON.  This bot was finished in the minutes before departure, as Jamison and I both had teaching responsibilities and other factors that somehow all decided to congregate this past week.

I spent much of Friday evening checking over Überclocker and making sure it was in working condition. After last Dragon*Con, the drive completely stopped working (it had gone one-sided in the first 30lber rumble). I hoped that the motors weren’t damaged and that, like at last Motorama, it was a solder joint issue, since the DeWalt motors really have no good place to solder to.

I’ve known this to be a problem, so I bought some 3/16″ flag terminals right after DC to remedy the problem. That’s how you’re supposed to connect to these motors.

A single large zip tie wrapped around the whole can, overlapping the terminals to keep them in, and I should have no more of these issues. The two solder-covered tabs above the insulated flag terminals are where the wires were attached before. This is an insecure location that’s prone to flexing.

Fast forward a few hours to the event! The trip down was “ordinary” – with Mikuvan in good repair after the last-minute alternator save (with a Big Chuck’s Automotive Blog entry to come about that), the only issue was having to slow down when snow hit as we got close to Harrisburg.

Here’s Candy Paint being last minute saved. I foisted this effort off to Adam, and a new tagalong who is a visiting student in one of the labs that operate out of the IDC, Joaquin. Joaquin had started helping out everyone with their builds (he’s from Chile – he’s technically here on summer vacation), and at 11:30PM the night before had decided he wanted to come along.

The setup from the original plan had changed to the following:

  • Instead of running 8S, I brought along two 5000mAh 3S Traxxas packs that were in my post-DARPA stash to run 6S. Unfortunately, one of the cells ended up having a broken inteconnect tab, so it was taken out and then the bot ran on 5S.
  • The 160A dLUX controller seemingly did not want to run my motor at all. Weird, but it’s also a relatively smart controller, so it might have thought my 4 turn Delta-terminated motor was a short. We brought along two spare Sentilon 100A units which are my go-tos for brick-stupid controller that can actually flow some current.

Besides those two hacks, the bot ran everything as intended.

Here’s the MIT conglomeration pit table before everything started becoming scattered and messy.

To finish Candy Paint, some field tactics had to be deployed, such as when swapping the connectors on the batteries…

The bot basically right after it was finally through inspection and ready for first matches. Not bad, eh?

During the first match, the weapon motor controller decided to fail short after a solid impact that also flipped the bot a few times (luckily landing on its wheels). The reasons for the failure are unknown – these ESCs are known to work great, then spontaneously decide to peace on the next power cycle. The pulsed short current caused one of the Traxxas batteries to fuse a cell tab; for the next match, that was cut out.

And it generated this cloud.

No, just kidding. That’s from HyperActive, in what must be one of the most spectacular kills in all of robot-time, in its match against overhead saw bot Gloomy (which looks a lot like megatRON). Here is the video (and another angle).

I have mixed feelings about this match. On the one hand – holy crap. On the other, now every well-meaning but naive member of the “You should put, like, a circular saw on it so it can cut through the other guy!” crowd now actually have a leg to stand on.

The aftermath of that fire. Gloomy’s weapon came straight down on the 1/8″ Lexan top armor, which gave way to the saw quickly – the titanium sparks seen in the video all came off the center weapon pivot. And right under it was the lipoly battery of course…

Clocker suffered a bit of damage in its second fight as the upper clamp actuator decided to disgorge itself. The construction of this actuator didn’t really leave much side support, so if it got pushed or torque sideways, the T-nut joints slipped out, which is what happened here. The real issue was I didn’t retighten all the screws from Dragon*Con. After I retightened everything, I didn’t have another coming-apart problem, though the motor eventually stopped working.

Another problem with Clocker was that I didn’t have spare wheels. In my rush to get Candy Paint ready, I neglected to order a spare pile of McMasterBots wheels, and only had one more spare. The wheel on Clocker that was the worst ended up getting that last spare, and the rest… well, by the end of my 3rd match with Nyx, they were gone.

So out comes the VHB tape. This was an idea cooked up by Dane – VHB double sided tape is anchored down with superglue, then stretched very tightly for multiple wraps, then anchored to itself with more superglue.

Now, I this this is a brilliant idea for smaller bots, or bots with less drive power, but Clocker’s all drivetrain so these tape treads shed within a few seconds of the pushing matches getting heated. For my last matches, it was like driving the bot on ice.

Candy Paint lost its last match when a wire came loose from the very ad-hoc wiring harness and got snipped by the big shredder holes in the pulley. Oops!

Here’s the final damage tally to Clocker after its last finals match (with Upheaval, no less). The amount of bouncing Clocker did broke off one of the end rollers, and the outriggers themselves are also extremely bent up (hard to see here). The clamp motor isn’t responding, but the actuator is still mechanically good. Seems like it’s due for a full overhaul between now and Dragon*Con…

I’m also considering switching the McMasterbots 40A wheels to some Banebots wheels. I can make a quick-change hex hub in the same manner as Candy Paint and make the wheels far easier to swap, and have many spares on hand. Right now, I have to hand-machine and modify each of the wheels, and as this and past tournaments have clearly shown, Clocker blitzes through wheels – rears especially.

I am extremely satisfied with Clocker’s performance this time. Much like Dragon*Con 2013, it came in second place, being out-robotted instead of something completely stupid and negligent happening. I also now have settled the score from that event with Nyx. As usual, it put on a very visually stimulating show.

Here’s the matches:

vs. Knuckle Buster

vs. Piston Wax

vs. Nyx

vs. Upheaval (two matches for the championship)

Candy Paint went 1/2 – I’ve uploaded the matches where something remotely exciting happened.

vs. Hot Fuzz

Next, it fought Cathi (a ring spinner), wherein Joaquin accidently threw the radio’s “Throttle cut” switch so the weapon didn’t spin up, then Magnificent Poncho (a pusher), whereupon it spent most of the match upside down until the blade came off. It turns out that the blade motor was wired to spin in the untighten direction! Oops.

Finally, in a MIT-on-MIT grudge match, it faced the Atomic Bumble Prime.

One additional overlooked issue was that the blade was a double bevel profile (i.e. looks like <         > from the side). Any hit to an off-perpendicular surface will tend to throw the bot upwards, which clearly happened. This could have been taken care of with 5 minutes of grinder hits, but it was just not done.

Candy Paint’s future is a little uncertain right now. The bot is mechanically sound, took no damage past cutting its own wires, and I can easily rewire it to conform to my original expectations. However, outside of Motorama, there isn’t a local event that handles full 30lbers with weapons. I could put a sanding disc on it and bring it to Dragon*Con. Otherwise, Candy Paint will probably remain idled until next Motorama, unless I feel like putting it together properly and going to some basement to grenade a few old TVs and printers.

That does it for this event! Admittedly rushed preparations ended up working out somewhat, and Clocker has proven itself again to be a pretty damn reliable bot. And I’m not broken down somewhere in the middle of New Jersey.

I now turn my attention back to daily operations of the IDC fab space, as well as my new season of 2.00gokart students. Expect some updates on that as the semester progresses! The class is now somewhat legendary among freshmen and sophomores.

The Dragon*Con 2013 Complete Roundup, Part II: Event Recap and Maker Resources

Sep 19, 2013 in Bots, colsonbot, Dragon Con, Events, mikuvan, Twelve O'Clocker, Überclocker ADVANCE

So here we go – now that Part 1 has had some time to sink in, and now that my shop is looking remotely functional again, it’s time for some part two. In this section will be the two new ‘sections’ (carried over from part 1):

  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.

This semester, the two fabrication labs I oversee in the MIT-SUTD Collaboration is once again playing host to How to Make a Mess out of Almost Anything:

Yeah, it’s going down about like that. Unlike the last two academic terms (January – August, basically), I’m not “running” a class this term, so it’s going to be way more chill. I’m not sure if I will want to run back-to-back design classes again like the consecutive 2.00gokart and “2.00GLP”, since the overall level of intensity and chaos is extremely high. I see how the department can go through design class professors rapid-fire now.

Anyways, back to the trip. It’s Tuesday night! Time to load up robots.

Dragon*Con 2013

…but first, I need to get my 200 pounds of tools, accessories, and spare parts out of the back. I left a spare tire, van-specific tool box (like my robot-specific toolbox, but everything is bigger!), and spare fluids. The floor jack was removed since there is a bottle jack for tire changes in a rear compartment. Basically I was purposefully blocking myself from doing any roadside extensive work – I think I’ve gotten everything mechanically to the point where a failure necessitating deep dissection is practically going to be catastrophic in nature and not something I’m going to do in a parking lot.

Replace all the van kibbles with robot kibbles. I guess I could have kept the van kibbles in the back anyway, since I was initially expecting more bots and parts. This stuffing was, consequently, not as epic as the Motorama Stuffing or the Last Dragon*Con Stuffing (though those vehicle did have less hatch space to begin with). The ship-out time was essentially midnight.

Around 4, we reach Flushing, New York, where Xo Has Joined Your Party. This is where the trip got a little more interesting.

In 2007, before I was a wee bunny at MIT, my parents and I drove up to visit the place. We took I-95 in all of it’s forms through DC, Baltimore, Philadelphia, Newark & New York City, then up through New Haven and through Rhode Island. My only memories of the trip are of how I-95 was utterly depressing in every way, from tolls to traffic to construction, and the general level of suck the Northeast urban cluster exhibited.

Six years later, I was meandering up the Bruckner Expressway in the wrong direction when I hazily decided that maybe I-95 wasn’t as bad as I remembered. Plus there was like an exit for it right there and if we kept going semi-lost I’d end up back in Connecticut. So, down 95 we went, across the George Washington Bridge (slowly, because construction and late night truck traffic), and down the New Jersey Turnpike, the fancy Delaware Bridge thing, then down onto Baltimore and onwards.

I’m glad to say that 95 is every bit as depressing and repulsive as I remember it and that nobody venturing out of the Northeast to anywhere should ever drive on it for any reason.

All together, I think between Queens and Baltimore I busted $35 on tolls alone, not even including the relatively minor tolls in Massachusetts. Every bridge or turnpike had its own toll authority.

I thought the Interstates were supposed to be full of FREEEEEEEEDOOOOOOOOOOOM.

In the Baltimore-Washington area, I stopped at my favorite IHOP in College Park, MD. This has been the focal point of several Otakon trips. South of Baltimore, we hit what I like to call “Facebook traffic”, where congestion is so bad and traffic is so stop-and-go that everyone is on Facebook complaining about it. This took about 2 hours to sit through because we came in at the exact time to hit traffic in both metro areas. How are you actually supposed to get to work?

We hit Atlanta around 10PM, for a trip duration of essentially 22 hours, many of which were spent fucking around with the abomination that is 95 in the Northeast Corridor. For instance, it took about 45 minutes to even get out of New York. Then factor in the fact that the cruising speed of my lovely pallet of cinder blocks was about 65 to 70mph.

The next day, it was off to the Invention Studio to get the band back together. Here’s the shot of the trip:

We journeyed a little off campus to get lunch, and in the parking lot of the local small sketchy college restaurant cluster was an Audi R8. Like most expensive cars, it was parked “haphazardly”.

This year, since I brought actual working robots, and because Pad Thai Doodle Ninja was completed the evening before the con really kicked off, and because I wasn’t trying to speedball an entire new bot in 3 days,I got a lot more wandering and people-watching time. I was especially tuned to try and find people with costumes that looked like they required some amount of mechanical construction or engineering (see my brief on this last year).

That, and giant Totoros.

Here’s a good example. This funky gun-like prop had a ton of lovely CNC aluminum work. The wielder, though, wasn’t the builder.

I spy a little of waterjetting on some of those interior parts!

The thing I’ve historically liked the most about Dragon*Con over other gatherings is that there’s no particular theme. The con covers about every niche of culture, up to and including robots. You’re not even going to find that at PAX or Comic-Con. This enables people to mash together different story universes and characters with much more impunity, for the amusement of all… such as Portalmau5 up there.

I’ll be honest – this is pretty much the only reason I went to the actual con for, besides my own panels. No, not just any group of girls in costume (that’s so last year), but specifically one series. The latest thing I’ve been fanning over is Monty Oum’s RWBY, also known as “Charles has to build shit that Monty designs with ill regard to constant-volume systems”. Most of the characters are Action Girls with giant mechanical transforming weaponry – what’s not to love? The thing that hooked me at the beginning was the RED preview.

The series so far has really pinged my “defer judgement” sense, since to me it seems a little hurried plot-wise and is seemingly laundry-listing TVTropes (site left unlinked because I don’t want to sink everyone’s productivity for the next 11 days) on purpose. But I’m proud of my ability to cherrypick favorites very specifically, so I’m still into the series for the giant mechanical transforming weaponry.

The series is so new that I wasn’t sure if anyone was into it enough to plan costumes, and I wanted to get a sense of what is already out there in terms of mechanically actuated versions. Conclusion? Zero. On the internet, and in real life at the con.

That’s where I come in.

…not right now, though. With Saturday winding down and the Robot Microbattles just around the corner, it was time to intensively practice driving. This was the remains of a laser-cut quadrotor frame that everyone’s 1lbers and 3lbers were beating on throughout the evening. I also repaired Colsonbot by printing a new motor mount carrier and replacing a stripped drive motor.

This year, Microbattles got the entirety of the International ballroom at the Hyatt Regency Atlanta. In past years, the event has only gotten half the space, and the audience had to be capped every time. The event size is now on par with the main Robot Battles, with even more entries.

So many, in fact, that single elimination had to be used for the tournaments again, and we still ran overtime. The event has been running against its time limits (and beyond them shamelessly) for the past 2 years, and this year was no different. Hopefully the D*C planning committees finally recognize this.

The Atlanta arena returns! This year, an actual 12″ sanding disc was mounted on the spinning turntable. I’m glad to see that my contraption is still functional. During the event, it produced quite a few light shows from bots being stuck in the hole, and reduced the diameter of a few wheels.

The usual suspects were in attendance. Here’s the table of G3 Robotics & Variable Constant & Guy Who Never Updates His Website.

This is a reasonable approximation of the audience during the day. The added seats and projection screens helped crowding immensely. Because the arena has a pretty high bumper rail (3″ or so), and it’s up on a stage, you can’t actually see the bots from the audience unless something exciting happens, so it’s entirely dependent on the video crew!

microbattles results

Because the Antweight tournament was single elimination, sadly Pad Thai Doodle Ninja only got one match in, against the veteran Segs (pic from years past, to the left). Cynthia put up a valiant driving effort, but the lack of “lifter lip” on the arm meant it had a hard time getting under Segs, and the bot was twice as slow as originally planned.  Near Chaos Robotics, filmer of events, recorded the match in two halves: Part 1, Part 2.

In the rumble, PTDN got into the thick of it and pushed a few people around, then got pinged a few times by DDT. The lifter arm was bent up,  but the bot otherwise had no permanent damage and still drives.

Showing why extending the front armor to the floor might be a bad idea – check out the crimps on the left side. After the DDT damage, the bot had trouble maneuvering on the floor.

Rear view of the damage. Because DDT pinged the arm while it was partially up, the force ripped the rear link out of the arm. That part was extremely thin-walled to begin with and should have been thickened, but I was afraid of it interfering with the robots’ self-righting. Turns out that wasn’t a problem.

I do want to fix up PTDN and upgrade the drives to the original 10:1 spark motors I had intended, and redo the front armor. The lifter servos will either be consolidated into one higher torque metal gear servo, or two digital servos for better range matching.

Colsonbot, sadly, was unable to colson much because of the unrepaired damage from Bot Blast. The “duallie” O-ring wheels were beginning to come apart, and the O-rings tended to slip off and get caught between the shell and the bot. It survived the event pretty much unscathed, however, and I don’t intend on making any big changes to it save for remaking the wheels into single-o-ring affairs that have more ‘stretch’ on the rings themselves to prevent them from twisting out. Colsonbot got in one match against Radiobox, and also the Beetleweight rumble where it was mostly a stationary arena hazard.

big bots

Back in the Invention Studio on Sunday night, preparing for some final tuning and drive testing. Null Hypothesis had to have a drill motor replaced, but otherwise, I didn’t have to do anything to the bots for once.

At the event, while I was testing Null Hypothesis on the stage, it randomly blipped and stopped moving. The cause was traced to the controller completely losing its gate drive power supply for some reason. Whatever the case, it necessitated an in-field replacement, which Adam is handling.

Most of the builders are seasoned & flavored veterans, but there were some rookie builders this year. It’s good to see the sport grow organically, if not somewhat slowly. This bot is an alleged 12lber – according to the builder, it weighed 14 pounds when finished. Oops! And hence, it was named. It ran without any top armor at all – something which ended up causing it to lose to 12 O’Clocker.

Omegaforce returns, with more unique wedge attachments. The outer and inner wedgelets are linked together in such a way that the outer set lifting upwards for any reason causes the inner set to drop down to the ground. The upper wedges can swing all the way backwards. So it’s a multi-tiered defense system against oncoming opponents. The actual functionality was a bit spotty.

Non-rookie builder (I met Miles at Motorama 2013) but first Robot Battles event. The center of this bot was supposed to be a lifter, but some things didn’t happen in time. And yes, it’s entirely made of wood. I was hoping to face this with Überclocker, but didn’t get that chance.

Another rookie bot that was supposed to have an attachment in the middle (in this case, a hammer) but Stuff Didn’t Happen.

Überclocker 30 charging before matches began.

12 O’clocker after its first match, which I won. I learned that the springy legs worked well, but they were not well constrained downwards and could get pushed to the point where the front wheels of the bot were propped off the ground. The contact point they make with the front axle standoff should probably be modified to capture the leg in either direction – up or down.

This is probably the most quintessential robot even picture I’ve ever taken. Equipment all over the table, Mountain Dew everywhere, and “beasting food” as I like to call it strewn about.


I try to post audience pictures of Robot Battles every year, because it really is a phenomenal show. I think the audience averages 5 or 600 people and can peak near a thousand. In quite a few years that I remember, the hotel had to deny people entrance because it became standing-room only and exceeded the allowed occupation of the room. Here’s the right half of the audience…

The center…

And the left half.

Oh, this was before matches started.


I’m extremely proud of the bots’ performance and reliability this year, as well as the show they put on. For my 10th (!) Robot Battles it’s quite refreshing to have things that worked. The robots ended up losing only due to my own mistakes, or my tendency to favor a good show over winning at this event. I actually can’t bring myself to just drop someone off the edge cleanly with the Clocker pair, and this did bring about my own downfall a few times…

Regardless, Überclocker 30 got 2nd place in the 30lb class, fighting Null Hypothesis (oops…), Overthruster , Null Hypothesis yet again, Jaws – probably my most favorite Clocker match ever, Overthruster for the nth time, and finally losing again to my eternal nemesis Nyx. Overall record of 4/2. There were sure lots of reruns this time around. Clocker was a crowd favorite in the past, and now even more so since it works pretty reliably. At the very end, during the rumble, I did lose the drivetrain completely, most likely due to the solder joints breaking off the motors – this has been a weakness of the bot since Motorama ’13 that I forgot about until now.

12 O’Clocker finished what essentially is 3rd place, since the winners’ bracket finals loser and the losers’ bracket finals winner were the same bot. In the final match, I just got plain outpushed by a more powerful and faster opponent. 12 O’Clocker was also a crowd favorite, possibly more so than Überclocker itself, if I could judge the audience well, and went 3/2.  12 O’Clocker’s match videos: Tetanus Shot 1, Oops, Omegaforce, Apollyon, Tetanus Shot 2

So what’s next for the robots? Besides the odd demo or sparring match, it’s time to make the upgrades for Motorama 2014 next February. Überclocker’s current form debuted this past February at Moto ’13, and I don’t anticipate making any changes to it at all (except for actually using the Quick Disconnect style terminals on the Dewalt motors, maybe…). The new actuator on Überclocker’s clamp worked as I expected – I could grab and hoist up opponents very quickly, and the multistart leadscrew eliminated the binding it was prone to perviously so I no longer had to be gentle with the stick – RageBridge took care of the “endstops” by entering current limiting mode. On 12 O’clocker, I want to better secure the front legs, but otherwise, the bot incurred no damage from this event.

the way up

I decided to be intelligent and finally take a route which I’d been eyeing for years, but never dared try for some reason until now:

In my opinion, this is the most direct possible shot through to New England without going near any metropolitan agglomerations. The plan was to detour north at Charlotte, NC. and follow I-81 all the way up to Motorama Harrisburg, from whence my general solution has been to go east and up-around New York City through 287, then cutting north out of CT on I-91 and I-84. The upper half of this has been tried and verified many times.

I think this was a good decision. Not only was it smooth all the way, but the western VA and NC scenery subtracted from the boredom greatly. We passed through, and stopped in, a few small towns and villages nestled in the Appalachians, places that I’m sure high flying urban folks around here don’t give a shit about. It was, in my view, a more authentic American experience.

Stopping for a fuel and breakfast somewhere north of Roanoke, VA.

daily van bro

I saw something which looked out of place across the street at a convenience store. Turns out it’s a Greenbrier, one of the original American compact vans built to compete with the VW bus! These are rear-engined, just like the VW bus, but the Ford Econoline of the same era was mid-engined and rear wheel drive, and the layout was directly ported and evolved by the Japanese. So, really this is an evolutionary ancestor to Mikuvan.

It was also on sale. I called up the seller, but sadly the price asked was out of what I had in my pocket at the time. If I were into these things, though, it would be a very fair price for a vehicle in as good visual condition, and as good running condition as the seller described.

Compared to almost all modern cars, I’m pretty damned small, but the Greenbrier was somehow even smaller. And it had 3 rows of bench seats.

The rest of the trip up through Harrisburg and beyond was pretty standard. We arrived back in around 1:30 AM (that is, 0130EDT Wednesday 9/4). And so that concludes Dragon*Con 2013. A pretty delightful adventure filled with working robots and now-most-definitely-working vans.

Well, okay, I did have to rebuild my A/C blower motor again, in the Georgia Tech parking lot. Remember those brushes I installed? They were backwards, and they ate through the copper bus wire after a few thousand miles. A random 200W scooter motor turned out to have the exact same size brushes, and saved the day.

Maker Panel 2013

Here’s where I (finally) post the presentation from the 2013 Maker Resources panel, and some related links, in one place! The panel happened on Friday evening at 7PM, and I had a pretty full house for most of it. Unfortunately I once again neglected to bring my video camera to the event, but I did notice quite a few folks taking video. If you have some high quality video of the panel, I’d like to include it here.

The panel was broader in scope than just “where to buy stuff” which I did in 2012. It put more emphasis on CAD software and transferring designs to parts using digital fabrication techniques (waterjets, lasers, etc.), and in general how to design better things. I tried to include some CAD program demos of stuff like Sketchup, freeCAD, and Solidworks/Inventor, but I actually ran so far over time that the director had to step in and cut me off (Sorry Val!). Maybe next year.

Also included as part of side discussion were the slides from last year with general parts & resources.

Here’s the list of stuff I said I’d put up like two weeks ago:

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.

12 O’Clocker: The Completion, and Überclocker Upgrades for This Year; Dragon*Con panel information

Aug 26, 2013 in Bots, Twelve O'Clocker, Überclocker ADVANCE

What a week! 12 o’clocker was completed early on, then I began to focus more intensely on upgrading and repairing Überclocker for this year’s competition. 12 o’clocker is currently working and undergoing test driving. It handles enough like Überclocker, but I hope to be able to second-nature the peculiarities of its operation. Plus, it’s fast. Just how fast? Find out now.

Continuing the manufacturing of the “solid state reactive outriggers”, I needed to drill some 1/4-20 clearance holes through the Rockwell C44 hardness spring steel. The week before, I purchased two solid carbide drills off eBay for a cool $7 each – if you have the patience, eBay is a wonderful industrial and machinery supply house – to do this one task. These are straight-flute bits designed specifically for drilling shallow holes into very hard metal. The straight flute maximizes stiffness, but of course does not allow for very deep holes.

Carbide wins over steel any day, and this process was totally straightfoward. The curls that came off this thing could cut you open in an instant – to prevent this from happening in MITERS, I hammered them all apart and trashed them before anyone could discover them on the mill.

Here is an assembled leg. The aluminum end blocks are also drilled clearance, and a bolt holds each end block together. I elected to take this route over threading the aluminum because the bolt could impart much higher fastening forces without stripping the thread.

The legs mounted. I unfortunately didn’t have any lower profile nuts, so the big locknuts on the end kind of function as 2nd-order fish-hooks. Strange how a normal 1/4-20 nut – just about the most common possible nut – couldn’t be located this time of day. I bought an entire bag of 1/4-20 Keps and grade 8 plain nuts from McMaster in retaliation.

With the bot now mechanically done, I turned immediately to electrical work. Remember the original CAD picture and how it had the cells in the middle and the RageBridges above the motors? I found that arrangement wasn’t optimal. Instead, some arranging of parts in real life found a better arrangement which kept the battery mass in the rear. This arrangement did however force me to mount the Ragebridges vertically. That, and the batteries shouldn’t be lying directly on top of the drive motors because that would be unfavorable to the motors in high impact applications… like combat. I needed to come up with a vertical rack for the controllers, and some kind of shelf for the batteries.

I went back to the 3D model to generate these required components. This is the result, after a few minutes of staring. The black vertical guides hold a hardboard (HDF, pegboard) plate upon which the RageBridges are bolted. Two auxiliary motor supports keep the battery from jouncing on the motors directly; these were originally slated to be made from Delrin, but I only had enough of the material left to do this right exactly once….and didn’t. So they ended up being made of HDF anyway.

The little squiggle at the bottom is a flexure joint to keep these plates tightly stuffed onto the motor. Unfortunately, they were made pretty much useless in HDF.

I decided to make the battery first, since it could take a first balance-charge overnight while the Ragebridge mounting end guides were 3D printed on my Up? machine. The first step is to select a group of “relatively” matching cells out of the cell medley. I generally reserve the highest voltage, most closely matched ones for EV use. This is because robot packs may be frequently swapped out and charged externally (with the implication that you’re usually using an R/C style balance charger), but an EV pack needs to be buried inside the vehicle and out-of-balance or weak cells can degenerate from lack of charge monitoring very quickly. It actually took a little while to gather enough middle-of-the-road cells. The majority of the A123 Collection hovers at 3.29 volts these days, and I was looking for cells in the 3.20 to 3.25 range. The camp is pretty well split 90%-5%-5% between good ones, shady ones, and ones that are totally dead (defined as an OCV of under 2 volts).

The end-to-end architecture of the pack meant I had to fold over the interconnecting battery braid once I was done with a joint, and I had to do these one “string” of 3 cells at a time. Usually, in a professional setting, packs like these are made by end-to-end soldering using a “hammer head” iron tip, or with spot welded tabs which are then similarly folded over.

A side effect of folded tabs is that they are well exposed on one side to attach the cell taps for balancing to.

Many of my robot and rideable things have featured custom A123 packs. If you’re interested the basics of assembling a custom pack, here’s a short writeup getting the basics of the process by a former duckling student of mine. With some… uhh, more detail and rigor, this is essentially what I train people regularly to do these days – after all, if we’re going to have a pile of donated batteries, it is better to train people to safely and correctly use them than to try and hide everything. In my opinion. If you’re a safety bureaucrat, you may disagree.

Balance taps added. These days, I usually don’t bugger with soldering and crimping my own JST terminals, but buy balance harnesses off eBay en-masse and cut them up. These are professionally crimped and molded, and usually only cost a few dollars.

While the battery pack balanced, I uploaded the print job to the Up printer and by the next morning it had produced the RageBridge rack in question. The HDF parts were laser cut.

RageBridges pulled “from stock” and mounted to the rack. I’ll totally have some of these at Robot Battles.

In the process of wiring it all up. Notice that I’ve bussed the wiring together on the RageBridges – this is one shortcoming of the current style design which I openly acknowledge. Recall that these things were designed originally to replace two Victor 883s in Überclocker. It had 2 sets of power wires already, so it stayed like that in the “production” versions.

The battery is just coated with 2 layers of heavy polyolefin heat shrink, and then unceremoniously stuffed in place. There’s just not enough room to pack all the wires in – a bit of stuffing has to be done. Unfortunately at this point I decided to scrap the glowing 12:00 idea because I didn’t have any space left in this thing to add an EL inverter.

The last few bits of distribution wiring added. Notice the small yellow and brown wire on the right side. This is a direct battery tap for whenever I decide that I have the capability of adding gaudy lighting.  The master power switch for this bot is just “disconnect the battery” – as such, the battery wires are just run outside the bot. When on, the wires are stuffed into the protective confines of the front right frame rails. The RageBridges are set to 25 amps (drive) and 20 amps (weapon motors), which is a pretty egregious waste of their capacity. I’m strongly contemplating a RageBridge “mini” version that retains the Hysterical Current Limiting scheme but can be more finely tuned for amperage at the low end – say 25 amps continuous and 50 for short terms.

With the wires complete, it was time to function-test and pack everything up! I had to play “change the motor wires” a few times to get 12 o’clocker’s control directions to match up with Überclocker

Here’s the ‘press shot’, so to speak, of the completed bot. The weight is 12.05 pounds.

Yes, it’s over, but I’ll remove one of the standoffs from the clamp arm if it’s really that bad. Or just wear the wheels down a little. Worst cast, I’ll replace the steel drive sprockets with aluminum ones.

Remember that part where I said it’s fast? It’s like, unnecessarily fast. Here’s how fast it is:

The calculated ideal top speed with these new motors is somewhere north of 20mph (30 ft/s). In the narrow hallway I wasn’t confident enough of its straightlining ability to push the throttle to full. In the narrow arena confines, it will never be able to hit this top speed, but the acceleration (also shown in the video) is blazingly fast. I think 12 o’clocker is going to warrant a slightly different strategy against opponents than Überclocker just due to it speed. The extra speed overhead will give me some room to maneuver around and behind people instead of strategically avoiding head-on engagement like with Überclocker.

I found out in sparring matches with Turboencabulator that I needed some more current on the lifter and drive, so the adjust-o-knobs were turned up to 30 amps (drive) and 25 amps (lift). Those extra few amps made for substantial improvements in the lift.

Here’s the D’aaaaaaaaaaawwwwwwwwwwwww size comparison shot with 30lber Überclocker. 12 O’clocker is currently ready for action. Speaking of which…


The big change I wanted to make to Überclocker this year is making a more robust clamp actuator. As recapped before, the issue with the Cold Arbor harvested actuator is that it was slowly destroying itself from being made of untensionable chain drives, and the lead screw was damaged pretty badly at Motorama. The shallow pitch leadscrew also made it prone to “bolting” itself, tightening to the point where it couldn’t loosen again. The reason I purchased the IGxx gearmotors was to see if they can act as a commercial replacement for my custom hacked drill gearboxes. That post concluded that yes, they could, but not in a way I would like, so I made the hybrid all-metal gearbox from two of the ones I purchased.

The gearbox was later wrapped into an actuator design:

The architecture of this is very similar to my other custom actuators. The gearset is from Vex (I’m obliged to say every time I mention Vex: When the hell did they get so legit?). In the center of the top gear is shoved a machined down McMaster fast-travel ACME leadscrew nut. The two bronze bushings supporting it are flanged to also handle the thrust loading, and not shown in the model is the gigantic loogie of grease that this whole thing will be basked in.

The lifter model refined a little and inserted into the robot model. This actuator orientation better uses the leadscrew length (instead of having like half of it as filler length just to reach the clamp arm. One thing that I don’t like about it now is that it does not actually shield the motor that much better. With a standard-can speed-400 (RS-385) type motor, it’s okay. But, I only had “long can” motors (RS-395 type) that won’t grenade at the 26v electrical system, and those stick out a little further. The standoff is there as some degree of protection and as a lower travel limit for the leadscrew.

It’s totally fine against blunt-sided bots, but a good high speed wedge drive can probably reach the motor and bend it. I almost want to re-engineer this whole system from scratch instead of just patching parts onto existing structures.

This is what the reach looks like. If I *am* facing a blunt sided opponent, then this actuator is also a nice “hard stop” for the back of the fork. It doesn’t really stick out that far.

It was time to start cutting metal. Here’s the ACME nut about to lose about 50% of its volume! The threads had to be machined off and the part turned to press-fit diameter, then cut off at 1/2″ long. I was wasting 2/3rds of it by mass, but until McMaster makes raw Acme nut stock…

The nut turned down and the gear bored out. They are to be combined using copious amounts of green Loctite and an arbor press.

Pictured behind it is one of my “troll drawings” – in which I put about 10 parts on one page with just enough dimensions to remind myself of what I’m doing. Some times it even fails at that.

The lower gear is attached to the motor by… well, not much. I machined a hex adapter from some steel hexagonal stock. It’s set screwed to the motor, and the gear simply sits on the hex. That’s it – that’s FIRST Robotics engineering for you. It just has to last the season.

What everything looks like when put together. On the bottom (motor side), the hex adapter is supported by another one of those R1212 bearings.

The new leadscrew cut to length and with attachment flat machined.

And finally, everything mounted in the bot. See how far that motor sticks out?

When the clamp is down (in a position ready to close on something), it isn’t a problem since the motor is well shielded by the aluminum body of the actuator. I guess one thing that I have to watch out for now is someone taking a high speed run at me when the clamp is all the way up.

I extended the umbilical cord from the bot to account for the new actuator placement, backing up the wire the entire way with heat shrink.

Fully installed, wired up, and with a healthy dose of lithium grease. I ran some tests where I practice “clampbot yoga” using Null Hypothesis as a chew toy:

This new actuator is great so far. With the actuator motor’s Ragebridge half set to 15 amps, I can literally run it from endstop to endstop, full speed, and still release in either direction. The RB’s fast current limit algorithm helps here, as does the high lead angle of the screw so it can never “bolt” itself together. The clamp speed has also increased to about twice what it was before. Clocker should miss less grabs now because of this upgrade.

I sparred Clocker briefly with Null Hypothesis (feat. Jamison as the pilot of Null) just to shake everything up from Motorama and to try and catch problems early:

Guess this wasn’t really that representative of a match – the floor is super slick polished concrete, first of all, instead of hard outdoor carpet. However, I did confirm my vulnerability to someone getting stuck between the springy legs and the fork. Careful maneuvering will be needed to make sure this does not happen.

I put the bot away for a few days to work on 12 o’clocker, but with that affair now complete, it was time for some pre-competition preventative maintenance.

I tore down both drive halves of the bot completely to check for issues. Are the DeWalts still in one piece? Is anything really, really worn down?

I mean, besides those wheels. They’re pretty destroyed, and only got more destroyed after Motorama from demos and sparring. I did make spare wheel stock before Motorama, so I decided to give Clocker 4 new wheels and keep the half-worn front tires as spares for now. (Due to the way the fork can load against the ground, Clocker goes through back wheels much faster than fronts.)

All I needed to do to swap wheels was to use one of the spacer rings holding the sprocket away from the wheel as a template to drill clearance holes into the new ones.

Überclocker is now cleaned and buttoned back up.

At this point, both of the bots are totally ready to fight tomorrow if need be. However, the story doesn’t quite end there. In these past few days, I also went and upgraded certain parts of my 3200lb 2WD wedgebot to prepare it for the 1000-mile (one way…) trip to Atlanta and ideally back. That’s a story for later on.

Dragon Con 2013 Panel Info

I’m coming back as a speaker this year on two panels for the Makers & Robotics track at Dragon Con. See the full schedule here!

The first one, CAD and Maker Resources, is an extension of my talk last year on where to buy things for your mechanical whirlygigs and doobobs. Except this time, I’m focusing more on how to make nice things. By this, I mean exploring using free and free-ish CAD programs to better design out your projects before laying into a piece of aluminum with a plastic safety scissor, and taking advantage of modern rapid prototyping and digital fabrication resources. Basically, How to Build your Everything Really Really Fast for Kids who Can’t Build Good.

It’s been my observation that many folks, especially those already well-versed in the EE and software side of things, are dying to get into mechanical projects, so it will focus on such possible routes to start immediately instead of mocking things up with plywood and hot glue. Having been on all 3 sides of the proverbial coin (the knurled edge is a side, I swear),I’ll explain why hardware, and especially mechanical, projects are more involved in general and how they differ from the typical fancy PCB.

The second is in conjunction with my partner in hoodrat shit, Adam, and will concentrate on Electric Vehicles. The panel last year was a primarily discussion and Q&A driven session where we used peoples’ questions about EVs to dive off, and that will remain the same this year. Hopefully some hardware will be in attendance too.

I’ll at least try to have a set of slides made for both of these; no guarantees, of course, that they are actually representative of the panel. If the media resources are available, I will record the sessions and upload them after the fact.