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It’s Motorama 2017 Time! Überclocker Changes and Upgrades

Feb 15, 2017 in Bots, Events, Überclocker 4

Since Franklin Institute this past year, I’ve been spending quite some time thinking about what changes I need to make to Überclocker for the annual winter robot party, Motorama. It’s the largest event on the east coast for years running, and the ONLY one left with full-contact 30lbers; I’ve gone basically every year since 2013, and sporadically before that (2008, 2010). This year is slated to be some kind of BattleBots #season2 reunion (where Season 2 was called “Motorama, the TV Show” since so many builders who regularly participate ended up on teams!), and there are some of us who are taking the opportunity to do some… scale model testing. Quick! What is the Reynolds Number of a flying Tombstone!?

So here’s what has been going on during the past few weeks! In my summary of the Franklin event, I identified a couple of strategic issues with Clocker which would also concern Overhaul for #season3, given that they’re built so alike.

The first was having everything ‘line up’ in the front. While it also included making the pontoons more adjustable, higher priority on my mind was making sure the arms have enough constraint that they don’t just splay out. We saw this happen in the Overhaul vs. Beta match where I caught Beta with one arm over and one arm under, so the arms because angularly misaligned. Recall that Clocker 3 and before all have multiple spanning elements holding the forks together; alignment was never a problem with that, but Overhaul didn’t have those elements primarily for an aesthetic reason (to maximize the forkiness). While Clocker sort of did have those constraints at Franklin, it was just one spacer stack, and that was quickly lopped off by megatRON.

 

So I’m gonna add more, duh! These two additional spacer & tie rod stacks are located out-of-plane with the one at the end, which will yield much greater torsional stiffness.

One issue is that another 18″ of threaded rods and aluminum tubes will put the bot back overweight a few ounces. Nonetheless, I intend to just build everything out to my desires, and then try to weight-cut from there, rather than compromising early. To pre-compensate a little, I decided to order replacement smaller drive motors. The AXi motors are great, but they are dramatically overkill for power, and I can definitely afford to lose a few ounces. Going to the 42mm outrunners will save me about 3 ounces a side, which alone might be enough. In order to utilize the smaller, higher-Kv motors, I also decided to order a pair of Banebots P60s in the 4:1 ratio instead of my current 3:1s, which should allow me to keep about the same speed.

Now, the 2nd big strategic weakness I want to experiment with is where it gets a little interesting.

I mentioned in the FI post about minimizing my defensive cross-section when it comes to vertical weapons. Those things – including drums, drumlet-drumettes (smaller in diameter and width) and vertical discs/blades are actually what I fear the most designwise, because they do two things to you in a match. One is flip your bot over, from which you need to recover (and which would take precious seconds where you’re vulnerable to followup attack from a good driver), but the more insidious one is ruining any straight edges you might have had where the weapon hits. A small KE weapon will put all of its energy into your material like a singularity; it will deform wedges and protrusions, basically preventing you from having an advantage again. All it takes it one fuckup, as Clocker’s match with Duck Yeah and even better example Blacksmith vs. Minotaur show. Notice how Blacksmith more or less has control of the match before it gets dinged once.

So to counter these kinds of weapons, you would have to do two things. Number one is keep them away from you, and number two is present as small of an area for them to touch you in as possible. There’s a lot of precedent in the sport with “keep away sticks”, including one used to great effect on Icewave last time on the show. To reduce my “vulnerable edge length”, then, I basically had to distill the front wedges down to points.

I take that back: this got interesting very quickly.

 


DUAL WIELD

So that’s revision 1 of the design. See those perforations? That’s for if I mess up and somehow manage to plant these into someone’s weapon instead of besides it. This design is intended to be cut out of AR500 grade steel, which is extremely rigid and springy but won’t stretch that much, so it will preferentially break at the postage stamp line. It’s like an active salamander tail system.

The saw teeth on top are the real bad idea here. Instead of a keepaway stick, I wondered what would happen if I made it a part of the offensive strategy. Most of these little vertical weapons have rubber belts attaching them to their motors. What if I just went straight for that with a very sharp stick? Stab into the gap between weapon and robot frame until you damage the belt or take it right off. That would take some serious driving and luck to pull off, which lured me to the idea further.

There was only one thing I didn’t like, and it was one of those “come back to what you CADed up last night in the morning and think again”. One of my complaints in the FI recap was getting stuck on MegatRON when we charged at each other. These extra-long death-shanks are attached just as the pontoons are, so if I run up on someone else’s wedge I can just as easily prevent Clocker from getting back off. Which is serious bad news when it comes to avoiding a vertical disc/drum spinner, since now they can just turn slightly for a broadside.

This led to revision 2:

Yeah. “It looks like a sawfish-unicorn”, or an Overwhal. That’s right, I decided to affix it to the clamp arm instead, exactly in the fashion shown.

This position I liked a whole lot better for two reasons. One is that it’s implicitly height-adjustable, and can actually be a manipulator weapon of its own. Clocker’s top clamp arm is not trivial – it is designed and built for about 500-600 pounds of closing force. It will lift a lot of things on its own, and is more finely positionable than the lower forks. It’s also more durable with its leadscrew attachment, but the leadscrew anchor is also a mechanical fuse for if things go very wrong and it gets the uppercut treatment – it will break away and probably fling the clamp arm backwards and out of the way, leaving the forks still usable. If I attached this to the forks, and they get bent, then my life becomes very difficult.

The second is a takeoff from the height adjustability. I realized that offensive unicorn strategy #2 was that now I can reach around weapons and bring the house down on their retreating sides, where the disc necessarily disappears back into the robot. With crafty positioning (or a lot of flailing) I could pretty easily literally throw a wrench in the works and shove a wad of AR500 directly between the robot and its own weapon. This would probably result in a very sad unicorn horn and ideally more sad opponent; for me, that’s why the postage stamp holes are kept, so not only will it break away on a successful landing, but will also do it and leave me a 2nd chance if I miss.

Strategically now, I can keep the clamp arm closed and all the way down and use the horn as a keep-away stick of minimum attackable cross section, and also manipulate bots from afar, or get it caught in something else like exposed drive wheels.

….and if you thought it looks silly in the CAD, it looks 10 times as silly in real life. I actually want to make another one of a different length now!

This is another ‘attachment of several ounces’ which would necessitate shedding weight elsewhere, which I will find. One thing I designed up previously but never implemented in real life was a set of light wedges, to be made of sheet 1/8″ aluminum bent into shape. I’m going to go ahead and make them, since they’ll cut around 1 pound off the bot each (Those steel wedges are HEAVY!)

I won’t need that much reduction in weight to use the horn of course, so maybe the configuration will add something else interesting to make up the weight, or just ballast. There is literally no point in weighing less than 30.00 pounds.

So that does it for major design changes. Moving onto more minor quibbles, I wanted to go back and have a look at the wheels again. The custom 50A cast urethane wheels worked beautifully at Franklin, and I now had a bucket of Simpact 60 and Forsch URS-2160 (McMaster part number 8644K24), both 60A urethanes with much higher tear strength ratings, to try.

Now that I was confident in the process, I revisited the hub design. I just designed the first hubs with circular thru-holes for rubber retainment so they could print without support, but the circular holes caused the diameter of the hub to start getting large. I didn’t have much more than the 1/8″ tread pattern’s worth of tread thickness per wheel. With a more rigid rubber, I might be able to increase the relative thickness of the tread portion.

I updated the hub to look pretty much like a scooter or skate wheel core – through-slots replace the circular holes, and the walls are thinner. This brought inwards the OD about 1/4″, which is great!

I also wanted to play with another tire geometry. A little earlier in the year, when Big Chuck’s Robot Warehouse was just being set up, we rented a floor grinder to strip the wooden floor of the decades of industrial grunge that had set up colonies within it:

Well gee, as soon as I saw that, how could I not clone the design in one of my own wheels? So if you’ve never used a floor grinder, a big sanding drum gets shoved over this flappy-wheel. To install it, you lock the rotation of the flappy-wheel and gently rotate the drum over it (in thise case, clockwise) while pushing it on. The flappy-wheel is effectively a huge sprag clutch with the drum as the outer race and the flaps as the ratchets/sprags. When the wheel is spun by the motor and the drum gets loaded against a floor, the flaps get forced open a little from the transmitted force of friction, causing them to push out against the drum harder, which causes more friction.

After I finished going “Well huh, that’s kinda smart’ I realized this design would get very good traction in one direction as each flap gets forcibly planted into the arena floor. The reverse direction might not be as spectacualr. Before I got ahead of myself with anisotropic traction designs, I decided to just imitate the flappiness  in my current tire design.

That’s the same helical tread sweep, just with many more slits of a greater depth and narrower width. I did this for “easy” (change the number and size of swept features) for the time being. I’d like to play with a straight-cut geometry like the floor scrubber in the future.

Printing this damn thing was an ordeal. Unlike the previous wheels, the molds could no longer be printed upright without support structures due to the way the helical threads are placed. Furthermore, the deeper tread features also prevent demolding in two halves, so I had to split the mold into quarters. Attempt #1 with supports was basically a no-go, since it was almost impossible to get them out cleanly and not leave little strands and hairs everywhere.

I next tried to print the mold wedges “pointy side up”, making a flat face on the outside of the circle for them to sit on. This was okay, but the nylon warped just enough on each print to make the edges not seal at all – this was attempts #2 and #3. I guess I could have made an Onyx mold too, since it has virtually no deflection, but by that time I’d mentally moved on.

The fourth and successful attempt was a single-piece mold which simply had the upper lip chopped off. I don’t even know why I thought the upper lip was needed now. Just fill to the top and be done!

That’s the model with the lip removed.

So how do you demold this damn thing? It was risky, but I decided the one-piece mold was okay because of the spiral nature of the tread allowed me to helically demold the cured wheel from the mold. And this ended up being completely true! I back out the hex bushing a half-inch, take a wrench, and untighten the wheel right out!

This worked quite well. Here are the two first wheels to emerge with the new material and tread! I stuffed the leftover mixed rubber into an old wheel/hub combination, because wheels are wheels. Notice the white core of the two new ones – they’re made from plain ABS, since I wasn’t about to waste the Onyx material on something I wasn’t sure could ever be removed from the mold. They’ll be on standby as low-priority spares nontheless.

Next up, the Forsch Polymers URS-5160. Forsch is one of those “Call Billy” companies that I always complain about – just go look at their 1997-chic website! Except this time, I was literally told that I had to call Billy (over in BILLING no less) and FAX him the order, then MAIL them a check. Credit card? Paypal? Pffff.       

Oh, Billy also leaves at 2pm each day, so I gave up after 3 days of failing to get in contact with him because I might have trouble waking up before 2pm on most days. Luckily, someone clued me in that McMaster’s general purpose pourable 60A urethane is manufactured by Forsch, otherwise I would have given up completely.

So why the hunt for a product which tries so desperately to not be purchased by anyone? Well, it advertises around 25% more tear strength and ultimate tensile strength than Smooth-on’s Simpact 60. Smooth-on is geared towards being easy to use – everything is made 1:1 or 1:2 mix ratios, so it doubtlessly sacrifies some strength and performance for convenience. I figured that polyurethanes worked like tacos – the shadier and harder to find that a Mexican restuarant is, the better the food. This has been almost bulletproof in my experience. I made it a point to obtain a Forsch product and use it like Robot Jesus Himself intended.

What I really want to try getting my hands on is the URS-2450, which has basically the same tear strength but in a 50A durometer. May Billy and I finally meet in the grand arena of procurement soon.

I cut new wedges out from AR500 plate. These were what they were meant to be, but I couldn’t get the material in 1/8″ (or 4mm-ish) thickness in time before Franklin. This was actually cut from one of Jamison’s spare plates left over from Sawblaze. I’m preparing them for welding here by grinding the incredibly thick scale they all seem to come with off.

Stay tuned for more, though with Motorama now 2 days away, I might just be updating after the fact! Still to come are the making of the pontoons, the spare lighter drive motors, and maybe a little bit of wheel testing!

12 O’Clocker & MassDestruction 6: Where I Rebuild a Bot After the Event is Done

Feb 09, 2017 in Bots, Events, Twelve O'Clocker

LET’S GET BACK TO SOME ROBOT CONTENT!

I feel like this website has become the Life of Charles, what with real editorials and non-stop round-the-clock van coverage and my tenuous professional aspirations… This is not the man I know. Where has he gone? *looks at own hands*

But now I’m back, with some new developments for Überclocker in preparation for Motorama coming up next week, as well as 12 O’Clocker stories to tell first. This bouncy little thing has been going to events and demos since 2013 with hardly any changes – just switching motors, basically. It’s gotten sufficiently worn down to a stub in the past few months that I decided to do a full teardown rebuild with some new parts!

To tell this story, we go back to the dark days of MassDestruction #5, like 3 months ago… Wait, CAN YOU BELIEVE THERE’S BEEN 5 OF THESE THINGS ALREADY? THAT’S MORE SEASON THAN BATTLEBOTS please take me back greg ;~;

This MassD, I took a more organizational role, helping judge and run matches. However, this didn’t prevent me from putting 12 O’Clocker (at the time, my only working bot -_-) into the arena in the somewhat informal 12lb Sportsman’s Class, where pretty neat matches like this occurred. MassDestruction has become a popular regional attraction; word has gotten out, and we pretty much filled out the Artisans’ Asylum event room to capacity. Like, look at this photo.

This is “filming a music video using the flashmob mosh pit at your post-phlegmpunk band’s free unannounced concert” level stuff. What’s better is that the builder population is getting more and more towards being newbie-dominated. This is a great problem to have.

12 O’Clocker came in 2nd place (out of like….3?) at this event, which was great, but it did take some damage. For the deterioriating ABS motor mounts that retained the lift motor finally gave out completely, wrenching the drill casing apart under its own torque:

Oooooh, that’s not good. I finished the tournament using a found drill motor given to me by an Artisans’ member, unceremoniously hot glue MIG-welded into the remaining mounting block pieces. At some point in the final against Snek Plissken, I also lost the lift motors which turned out to be one of the logic capacitors on the old RageBridge 1 units in 12 O’Clocker just breaking off the board. I also ended up demolishing another motor pinion just like at Momocon; the most recent set of motors for 12 O’Clocker came from some 12V Ryobi drill motors, and it seems like they were not up to the task of being run at ~20 volts.

Fast forward another 2 months, and MassDestruction the SIXTH! was on the horizon.  With the promise of more rematches with Alex Horne’s not-Sewer-Snake, I decided on a quick tuneup by replacing the broken ABS lift motor mounts with MarkForged Onyx prints because of course I did. New drive motors were also on the docket.

The Rage Panel slides out from the bottom, so I took the bottom plate off, which also let me do a hardware inspection on parts of the bot I rarely touch after finishing. This level of surgery was also needed to finally detach those ABS blocks.

So new drive motors were a bit of a conundrum. When 12 O’Clocker was built, it was still common to find generic cordless drill motors with 9-tooth pinion gears and 36:1 reduction (two 6:1 stages, 9 tooth sun, 18 tooth planets, and 45 tooth ring) gearboxes. Nowadays, it’s almost impossible to find these kinds of gearboxes, with 24:1 being the most common such as being found in all of the Harbor Freight 18v drills and most other rebrands. The 24:1 boxes have a 4:1 first stage using a 15 tooth pinion.

Trouble is, 12 O’Clocker was already geared to go fast, and dropping the gear ratio another 50% would have made it impractically fast and probably burnt out the motors in short order. Those Ryobi drill motors that I kept slipping the pinion on were attempts to find more 9-tooth motor pinions to fit the existing gearboxes.

 

After some haunting online, I found that one of my usual Amazon suspects uxcell sold 18v rated 550-sized motors with steel pinions already installed. Well imagine that, a prepared artificially flavored drill motor!  So I got a bunch to play with. They certainly look like 550-size motors and quack like them. The cans are a little thin, pretty typical of a mature Chinese genericized product… I can pick them up with a screwdriver. Every possible area of cost cutting has been well optimized!  The bronze shaft bearings obviously have no oil in them, since they are a little rattly, but a drop of motor oil in each solved that.

What I did notice was that the pinions’ press fits weren’t that tight. It was actually easy to undo them with a flat-blade screwdriver alone. To pre-emptively avoid embarrassing public gear slips, I took the pinions off and repressed them with a healthy dose of lime-flavored Loctite.

You know what – I’m just all giddy at the fact that they’re motor-shaped at all.

At some point in one of its tournaments, 12 O’Clocker either fell off a Dragon Con stage and landed on its main sprocket, or I got beaned by some flying robot, because the sprocket developed a flat spot which caused the chain tension to vary cyclically, leading to some lost chain moments.

In a moment of either desperation or brilliance, I decided to use my Harbor Freight slide hammer kit with a hook end to pull the sprocket rim back out like you would pound a very reticient dent. I bought this originally for van repair, but it looks like it works for robot dent pulling too!

Putting things back together, sans battery. The Ragebridge 1 with the missing capacitor had that repaired; the capacitor ripped out a logic power trace when it fell off, so it just turned the controller off. All the caps were securely Goop’d in place after the replacement surgery. If you’re using a Rage or a Rage 2, you should do this just in case also.

The biggest problem plaguing 12 O’Clocker was its battery, which I balanced once in 2013 and never again since. The cells had drifted far enough apart since then such that two of them flatlined at MassD #5, and I could no longer revive them. This meant I had to cut the battery open and undo the cell joints to the point where I could pull the two dead cells out and replace them with fresh cells. I closed the battery up again after this replacement (the green tape is new and covers the modded solder joints) with some thicker heat shrink, and making my charger do 5 overnight balance-charge-to-discharge cycles evened the cells out.

One last mod before MassD #6 was the permanent resolution of the clamp motor coming loose. The threads in the face of these Pololu 25D HP motors had completely stripped, so the motor was really just holding on by the electroweak interaction at the end. To remedy this quickly, I just took the faceplate off, slammed a #6-32 tap through them both, and then countersunk the original mounting holes in my actuator body. #zerosigmas is best Sigmas!

If you use these motors, or any of the similar motors from Servocity or Kitbots (or the straight shit from eBay), make sure to also take the motor off, clean the area, and use blue Loctite or similar threadlocker on the reassembly path. The motor does like to also wiggle loose – this is what the “battle hardening” mod offered by Kitbots helps prevent.

So anyways, it’s the morning of 1/28. Time to….

literally all the robots

This is what I trained for.

That’s Overhaul, Sawblaze, and two lift carts in the back. With space for another smaller heavyweight, or a dozen 30lbers and tools & equipment. And probably like 27 people. Some times it’s nice to just bring the U.S.S. BROWN C. STENNIS to an event.

This time, the event was held at the Charles River Museum of Industry, in one of their large event rooms. I once again helped with event logistics including box setup and judging. Overhaul and Sawblaze were brought along for visual stimulation, which was unfortunately because the event room has neither loading dock nor wheelchair ramp, and was, of course, a New England First Floor – 6 feet up the stairs.

Running 12 O’Clocker – especially when things started breaking – and half a robot show at the same time was a unique and singular experience. I will never do it again.

Have some 12 O’Clocker matches!

The match against Don’t Step on Snek, a.k.a Snek Plissken, a.k.a Sewer Snek… god dammit Alex, pick a name already!

By this point, 12 O’Clocker had lost basically all of its forks. They finally reached their fatigue limit at this event, one by one breaking off, until I had basically a big spatula. In the match prior, the right side motor pinion slipped its press fit as I had feared, so I went into the final match (also against Alex) one-motored. Which is fine, since Alex at this point had also started to run out of motors. The finals match was such a headdesking, facepalming occasion that I’m not even going to bother finding a video.

Poor 12 O’Clocker before the finals with the forks arranged the best I can, so SOMETHING AT ALL is still sticking out ):

Well, that’s it for the event. I broke the damn thing so much that I felt like I might as well use the momentum of the event to make spare parts. As I needed to also waterjet-cut spares for Überclocker, I threw on replacement forks for 12 O’Clocker in the same run.

Tearing down the bot completely up front to replace the fork components! This is where I discovered that despite my best attempts at anti-seize grease usage, the lift sprocket’s hub had galled onto the aluminum tube shaft, so the slide hammer was needed again just to break those two apart. I reamed all the shaft collars out again and cleaned up the aluminum shaft surface. This time, I tightened all the collars as much as I could – no longer relying on clutching the lift sprocket for torque limitng, but just setting the RageBridge current limit low enough that running into itself will not cause problems.

The new forks are slightly modified from the current design by adding more meat to the areas where the tie rods pass through. This was previously where they broke, so I made sure to add at least a majority of the cross-sectional area found in the rest of the fork.

By the way, this tube-removing service is also a problem with Clocker, especially after everything got twanged far up its own ass at the Franklin Institute event. I’m going to reconsider using a live shaft with shaft collar hubs to the forks for this reason, possibly considering a more Overhaul-like tie rod and central hub approach. Otherwise, I’m going to make an attachment for the slide hammer specifically for this purpose!

And here’s the refreshed 12 O’Clocker! Hopefully a staple of many demos to come.

Shut Up about “Modern Technologies in Robot Fighting” Already: A Charles Editorial

Jan 20, 2017 in Bots

So I very rarely go off on polemics on this website. In fact, I can’t recall the last time I straight up roasted something, besides laying on Sparkfun periodically for getting their breakout boards amateurishly wrong, or complaining about literally everyone else’s motor controllers. I try to stay focused on relaying the technical and weaving tales of implementation while discussing mistakes and could-have-beens, because I enjoy clearing up the fog of knowledge when it comes to building. Not only do I like making my work accessible, but I hope every motor controller I blow up also creates a record of what kind of REALLY? IT WAS THAT? mistake the problem ended up being. It’s always that.

A little to this end is my tendency to never claim I know something that I actually don’t. I hope I’ve been pretty good at keeping to this philosophy, and you’ll notice in many posts that I tend to express uncertainty when explaining a problem because I don’t know everything about it at the time, and the reasoning will probably change later. Furthermore, as you doubtlessly know already if you’ve been on the Internet more than an hour, the quickest way to get correct information on the Internet – whether you like it or not – is to be publicly wrong about it.

This is a double-edged sword; I’ve wielded it cloak and dagger to get correct information from enthusiast groups & forums of technical discussion before, and it works great! Try it some time… just say something nitpickingly wrong, such as “You can totally use frequency-injection rotor saliency detection on surface permanent magnet motors with an Arduino!” and someone will be bound to reply “Well technically, it depends on your stator saturation model“.

Well Technically is the zip ties and duct tape of unsound technical reasoning – collect enough Well Technicallies and any poorly-founded conjecture will stand up on its own, suspended by the tensegrity of vague wording and handwaved speculation.

If you didn’t understand what the hell that example meant, don’t worry – I didn’t either. That’s why it’s nitpickingly wrong.

On the other side, relaying incorrect or incomplete information opens yourself to being called the fuck out, which is what I intend to do. So let me begin with

Stop. Talking. About how every problem in the robot fighting world will be solved by the Inter-fucking-net of Things. Or how builders should just try smartphone control already. Why don’t we all use DEEP LEARNING to strategize matches in realtime? Just shut up and build your first kit antweight.

It seems like every few months, someone on a public robot fighting related forum will make a contentious point about how NOBODY USES WIFI TO CONTROL THEIR ROBOTS? WHY? or champions the favorable characteristics of switched-reluctance motors which they learned about on Youtube approximately one millennial attention-span ago (Oh shit, I made a millennial joke! Is this self-deprecating humor or am I just a lawn security officer now?!). I regularly have people ask me why nobody uses Swerve Drives when all the high schooler robots do it already. With near certainty the poster is pretentiously tech-savvy about the Connected World or is an Internet of Things developer who probably has an Amazon Echo bickering with a Google Home about control of the sex lighting in the basement, ON YOUTUBE.

AND WHAT ABOUT  D R O N E S ?

Robin Mitchell of Allaboutcircuits, I am now talking directly to you. In your recent article “The Resurgence of BattleBots and Robot Wars“, you put forth such affronts as “…the new Battlebot and Robot Wars series showed little technological advancement with regards to sensors, microcontrollers, and electronic warfare.” and propositions such as “…use multiple relays that isolate separate batteries from the robot which can be switched on and off using the main controller.”

Hang on a second – let me go find a “relay” that is rated for the combined current draw of all of Overhaul’s drive motors. Want to see what it looks like? This is it:

When they get that big, they’re called “contactors”, but that is besides the point; I’ll get to reasons why automatic power failover is a nice thing but (to my knowledge) completely unseen in robot combat.

Let me be clear here – I have no personal grudge against you, Robin, nor do I have a problem with Allaboutcircuits, a site that I used to reference daily years ago and should continue making a habit of. If you’ve never built and fought robots, it’s a perfectly excusable pass on the misinformation front. Everything you presented can technically be achieved and could possibly be used productively in robot combat. However, recall the 2nd part of my thesis regarding being wrong on the internet: this article is also epitomic of all of my presented complaints about outsiders observing the “technology” in combat robots and snidely commenting on it, so I feel implored to reply.

1. On the structure of precision language

One of the hallmarks of technical misinformation is nebulous & vague wording that sounds good to the casual onlooker, but sooner or later you’ll run into someone who actually know what the hell they’re talking about. The article is absolutely infested with these missteps, starting from the very beginning about rapid prototyping.

No, rapid prototyping is not JUST 3D-printing. Rapid Prototyping is a set of techniques – of which 3D printing is just one – which ideally help you reduce the time and effort needed to produce working products or concepts thereof. Though everything I do can technically (there’s that word again) be construed as rapid prototyping, nothing about Rapid Prototyping must involve a computer or a poorly-built kit noodle-pooper.

In modern parlance it is often assumed to mean the same as digital fabrication, which 3D Printing is most definitely a part of: computer-controlled machines which generally perform one task whether it be machining or extruding or lasering the ever-loving shit out of something, which can be quickly set up (rapid) for the creation of objects (prototyping!) more or less directly from a digital design file.

Now, what does this have to do with robots? Rapid prototyping techniques (plug!) and equipment have contributed to a vast paradigm shift  in how small and large class entries alike are built, and despite not being very visible on the BattleBots TV show, a significant number of entries had 3D-printed parts inside. Hell, I’m one of the two teams sponsored by MarkForged, a 3D printer company which is on the intermolecular-bond-splitting edge of 3D printed material properties.  You can also barely find a 150 gram to 3lb (“insects” class) bot these days which doesn’t have some kind of 3D printed artifact on it, possibly even entire frames and even including weaponry in the new “Plastic Ants” class.

The newest “easy way” for builders to start is no longer piecing together R/C cars with Home Depot sheet metal, but grabbing a 3D printer. That is huge. The first moment I ever felt old was the first time I was casually talking to a freshman in the fab shop that I ran at MIT and the subject of building a 3D printer just casually came up as “Oh yeah I built one of those in high school”. Bam, just like that, I officially entered intellectual cruftdom, the derpy 80s prismatic van state of epistemological being.

Beyond the limited definition of 3D printing, you have robots utilizing laser-cut steel unibodies that are ordered direct from a steel vendor by sending them CAD files and pieced together in just hours with a welder, bypassing dozens if not hundreds of man-hours of shaping metal, fitting it together, jigging it all up for welding, and then doing the welding. Every curvy or fancy looking robot exterior on the most recent show was likely not trimmed by hand, but waterjet- or laser-cut in minutes. That is the real magic of RP techniques in robot building, and I do think a lot of the current “innovators” in this realm are recent college grads & young professionals who have seen the techniques used elsewhere and brought it to the forefront in the sport.

Besides painting ideas in broad strokes, there is also a tendency by Modern Technology people to speak generally of executions, never having to have executed them or thought about what their ideas really entail. Going back to the relay problem, the solution (to a problem I contend does not actually exist) is:

One possible method is to use multiple relays that isolate separate batteries from the robot which can be switched on and off using the main controller.

Soooo…. does that mean making a battery isolation system out of relays? They sell devices for that, often for RVs and boats with multiple batteries. Either solution (neglecting the practicality of a 3rd or nth power source exclusively for the logic) means you need “relays” that can each take the full operating current of the bot, and I showed you how big that part is. Wait – no, back up. Before we even reach that, this implies you already have multiple batteries each capable of running the bot separately for the duration of the match, unless you size them to require mid-fight changeover.

Imagine if Tombstone had 3x the number of batteries it actually needed to run a match. That would be a riot! Good luck designing this system within the weight limit while still maximizing your robot’s operational ability! Lithium polymer batteries be magic, but they’re not that magic just yet.

On top of that, you have things like

The communication system could also be improved in many other ways including the use of a microcontroller instead of using an RC module with outputs that connect to actuators and subsystems.

Okay… yo, what does this even mean? You know all R/C receivers have microcontrollers in them, right? And every motor controller? If you don’t have an R/C module (which I guarantee the author doesn’t know is a real, commonly used, and nice thing that goes into your handheld transmitter  – Overhaul uses a 400mhz Long Range module system that can conceivably let me control the bot from over 10 miles away)  what does your microcontroller use to talk to your smart watch and smart dildo that you’re using as a robot control input?

If a player switched to 2.4GHz and used a module like the ESP8266 then…”

INTERNET OF THINGS BRO DETECTED! You’d swear with the number of people singing the gospel of the ESP82x system that it will singlehandedly stop Russia from starting Cold War 2: Thermonuclear Boogaloo on the 20th here or something.

(Nevermind the fact that the preceding sentence to this misplaced quote “The radio frequency that these robots use will most likely be around the 27MHz channel” is absolutely, indisputably incorrect, as 27mhz has been banned in most larger weight classes since the late 1990s and prior to the rise of 2.4G spread-spectrum hobby radios in the mid 2000s, most robots were mandated to run on 75mhz using compterized PCM transmitters. This is just being factually wrong instead of spiritually wrong.)

Anyways, in this case, I assume what’s going on is another case of hipster engineering colloquialism – when certain people say microcontroller what they mean is an Arduino. Yes, a separate microcontroller can be used to collect all of the information proposed – voltages, currents, temperatures, etc. Again, there’s that Well Technically factor: Yes, you could collect all of this data, and yes, you could transmit it over WiFi to an iPad set up with a custom dashboard app you wrote, but all of the data in the world about your CO2 tank upstream pressure doesn’t help you when the tank has been eviscerated and unceremoniously thrown across the arena by Minotaur.

Having these onboard sensors does not inherently make the robot better at robotting. It’s like having the same telemetry in a car – it will help you potentially tune the car for performance, but does not alone make it faster. This information could very well help you discover a design issue with the robot – motors drawing too much current and heating up too quickly? One weak battery out of four? Better take care of those before you run out of postponements! Telemetry and “sensors” comes up a lot – likely because people who keep ragging on this are IoT bros – and the praise of Team Storm in the opening for adding sensors to their old and tired design to instantly make it modern , parallel to the phrasing of robots being “improved” by sensors, is a good example of my second thematic struggle with futurists in the robot world, which is:

2. On optimality of cross-discipline solutions

I don’t blame people for talking about automatic battery-switching failure detectors or first-person view cameras with dynamic robot-to-field orientation control or any of that. The fact of the matter is, they could be speaking from experience (or out their ass) in a field where such things are common and expected – automatic failover is virtually required in server power supplies (and the servers themselves in modern datacenters). FPV is increasing in popularity within the vaping rig drone community because flying a drone while “sitting in it” can be very intuitive, more so than trying to stare at it from 1000 feet away.

It is the insistence that their favorite golden engineering goose will equally lay golden eggs across all fields, without any relevant experience to back up the fact, which I am considering here – the insidiousness of Well Technically is at play once more. Again, I don’t care so much about being straight-up factually incorrect, because that’s easy to fix.

Remember the Reddit thread I linked to at the beginning. If you haven’t Reddit, the gist of it went something like:

Well, robot builders don’t like new things like WiFi – look how long it took them to use 2.4Ghz radios!

That’s because most R/C 2.4ghz systems for sale did not meet robot-specific needs, but now they do.

…But robot builders definitely don’t like new things, look at how few people use brushless motors, everything uses brushless motors!

That’s because most brushless systems for sale did not meet robot-specific needs, and still kind of don’t.

WELL GEE I THOUGHT THIS SPORT WAS ABOUT TRYING NEW THINGS

Let’s talk more about swerve drives. Swerve drive, bro! Holonomic motion, bro! Got 8 degrees of freedom on my drivetrain, bro! Any direction, any time, bro! My conversations with what must be the closest thing to the Jehovah’s Witnesses of robotics because they will never, ever shut up about DO YOU HAVE A MOMENT TO TALK ABOUT OUR LORD AND SAVIOUR TEAM 221swerve drives once they find out I build combat robots consistently goes something like:

Do any battlebots [with a lower-case B, this is important] use swerve drives?

Not any current ones, only a few have tried in the past, but none have been successful.

Oh, that’s weird. They’re the best drivetrain for this kind of stuff.

Why do you say that?

You can move and attack from any direction!

You certainly could, but durability due to the increased mechanical complexity is a concern, as well as added weight.

Well you just have to { CNC machine all of the parts from titanium, use this design I found on ChiefDelphi, place them closer to the center of the robot and armor around them };

Additionally, not many weapons and strategies can take full advantage of omnidirectional motion. It all comes down to design compromise and what you want from your robot.

Well you can just…

Those choices in brackets? I’ve personally had to absorb and nod my head to each of them. My most memerable instance involved someone literally following me for 10 minutes describing how if the robot just had 4 flipping arms, one on each side, then it would be a good use of swerve drive because it would be universally defended.

JUST.

That word is like the dual of Well Technically, like the superhero and supervillain comic story of Half-Baked Idea City. For every Well Technically rebuttal, there is a Just conjecture.

Now hang on a minute here… If your robot already has weapons on every side, does it really need omnidirectional motion at that point!?

All of this might sound like I am the sheriff of the GET OFF MY LAWN police force. And you know what – maybe I am a rookie officer in training, having been in the game for too long and the ‘stock solutions’ for common strategic problems having calcified in my design process. But let me be clear here: What really Brinells my bearing races is not that people want to try to build Cloud-powered Robots-as-a-Service, but that they immediately pose it as the best possible solution to a problem they otherwise profess ignorance to. It’s not that you can’t use ESP8266 modules in your custom radio, but the coming right out guns-ablaze and saying that it is better than R/C radios. Better in what way, being easily customizable beyond user comprehension in an application where communication errors can result (and have resulted) in the runaway of a machine literally designed to kill the fuck out of other machines? It’s not that swerve drives have never been used in BattleBots (we don’t talk about Radioactive), but it is always presented as inherently better than tank-style steering, despite the added moving parts that must remain in close alignment to work properly, because in combat robotics all of your parts always stay aligned!

What these examples have in common is that people will take their knowledge of something which has an apex predator status in their field of work (or interest) and assume that it would work just as well in another context, change be damned. Robot fighting, truth be told, is a pretty damn redneck sport in the grand scheme of technological competitions. Nothing that relies on banging two objects into eachother really hard for entertaniment can be that refined, right? We are, in some sense, a bloodsport of technology. That has historically made robot fighting easy to talk down to by people working in technological industries, especially software and AI. Add to this most bot builders being in the mechancal engineering or machining/fabrication industries, or simply being mechanically inclined, and you have a perfect fuck-shit-stack of lost-in-translation: The finery of the often extensive mechanical design work and manufacturing effort being unappreciated by someone who’s never picked up a tool, and the perception of sophistication they associate with their choice of career, or their preference of controls and intelligence complexity.

The person who followed me around the building trying to convince me that swerve drives were the Alpha and Omega of robotic drive solutions? I challenged him to build a scale model of his concept robot in any weight class, and that I would permit full normal usage of my shop for the purpose and make myself available for consultation. Never heard a peep from him since.

Don’t be that guy. If you want to explore “smartening up” the sport, do so and deliver. Probably the most under-stated thing at BattleBots Season 2 was the auto-targeting hammer of Chomp, and it’s a shame they devoted only like 3 sentences on the show to it. Very few people have ever attempted auto-firing or target-seeking weapons. They knew it was a huge risk and that it might not work, but GOD DAMN IT WAS DELIVERED. I like to think that I pushed the front of using hobby-class brushless gear in robot drives with my 6-month-long development cycle and immense risktaking getting Overhaul 2 into the arena with all HobbyKing motors and controllers. The evolution of technology in robot fighting is truly, and some times literally, trial-by-fire.

Go to a competition and learn what kind of details you might have missed while perfecting your off-the-wall design concept; enter a kit antweight and get your ass handed to you in a match to see how hard it is to maintain an entry. Then build your gesture-controlled SLAM-navigated swerve-drive Hoverboard-motored* Internet-of-Things-connected self-Tweeting BattleBot. The whole sport would appreciate your contribution, even if it gets turned off at 0:11 by an errant power-handling relay.

*I challenged myself after talking to the High Priest of Swerve Drives to design a swerve-module which could conceivably drive a 250lb Battlebot and not weigh much more than a typical drivetrain does, while being heavy duty. This actually is possible, as illustrated by DeathRoll during Season2; it had four seg-thing motors running at 36V each and was pretty maneuverable. The module ended up weighing around 25 pounds, and used a A23-150 Ampflow motor for steering. Four of these would weigh about 100 pounds, so it could happen, but would need tight integration into the frame design to have weight for anything else like weaponry.

A New Beginning, Episode III: Revenge of the Charles

Nov 22, 2016 in Bots, MIT, Bostoncaster, Cambridgeshire, Shop Ninja

I’ve been doing a lot of these posts lately, it seems. Just last year, after departing my shopmaster/instructor position with MIT and hence no longer having a workspace there, I moved in to the Artisan’s Asylum, a local makerspace (which also happens to be the largest makerspace in the USA, founded and run for a while by the now creator of MegaBots). Now, barely over one year later, I’ve moved out again…

T H E   E Q U A L S    Z E R O   D E S I G N S   &   G R E E T I N G S   C O M P A N Y

…into something I can finally call “the shop”. God damn, remember when companies had REAL NAMES that didn’t sound like a syllable uttered while asphyxiating a small animal?

It’s about fuckin’ time. The hankering for workspace had reached a crescendo over the past few months between myself and Adam, my long-time partner in hood rat stuff & bad things, also now captain of Team Brutus. My recent contract projects have been bringing me newer, more interesting, and most importantly BIGGER work, and facing the prospect of having to also work on Overhaul again in a few short months (#season3), Artisans was becoming impossible. On the other hand, Adam has simply been making do without a permanent base camp for a while. Given both our proclivities and the rapidly rising prices in the area, it was another now-or-never scenario.

 

The building: a former clothing & sportswear factory which the company sold to new owners intent on eventually developing it into MOTHERFUCKIN’ CONDOSDO YOU PEOPLE NOT. HAVE. ENOUGH. CONDOS AROUND HERE OR SOMETHING? I digress. In the mean time, which means the next few years as they figure out exactly how ugly to make the new block o’ flats (that building being my local benchmark for ugly as fuck and overpriced construction) they’ve divided up the former factory floor into a few smaller parcels to function as rentable studios or offices, one of which fell into our lap. You can tell I really love the new property development trend in this area.

It’s on a typical “New England First Floor” – which means floor 1.5, with the basement halfway down. and us halfway up. So, no driving vans in, but direct freight elevator access to a real loading dock 6 feet below. In other words, just enough to be a pain in the ass and just good enough otherwise for me to deal, as the world likes it. The inside is stupendously large for both of us who have been conditioned to think that working butt-to-butt in a shared shop with Isaiah the Last Indie Wirebender is natural and acceptable. Nothing against you wire art, Isaiah, but my robots have tried to consume your workpieces several times while I was machining, and they’re really reaching their rebellious stage lately, so it’s better for both of us.

It’s ~2,300 square feet when finished – shown above is pre-construction of interior walls – putting it right about the size of MITERS. The multi-layered heavy wooden factory floor is finished in a classic “Inconsistently Leaking Machine” fashion sure to fetch thousands of hipster Bitcoins per month in the future when it becomes someone’s hotbox closet floor ,because weed is gonna be legal real soon now in Massachusetts! Oops… I mean #MakeAmericaStonedAgain-chusetts

With the beginning of the new shop space, so shall my Artisan’s Asylum presence come to a close. Luckily, most of my life is containerized. Not only did I count on having to move relatively often, as long as I didn’t own the whole damn block I was working in, but having stuff in nicely labeled containers appeals to my inner Jamie Hyneman greatly.  I bought a dozen more totey-bins (which by the way are called ALCs, or Attached-Lid Containers, but searching TOTEY-BIN returns the correct result on Google Images!) to more finely divide some of my parts since they would otherwise get too heavy.

By the way, it’s been physically verified that Mikuvan can contain 24 of these things – 26 if I use up the front seat.

As with moving out of any space or building or home, taking a look back once you’ve restored it to the condition you found it is a little somber. Alas, great adventures lie ahead! Onwards, through the skies, and across the seas… also over a few curbs, because 26ft box truck. You know what? Driving a truck in Cambridge ain’t so bad! You just BIG your way everywhere you want to go! Want to turn left? FUCK YOU! Want to merge onto Route 28 during rush hour? FUCK YOU TOO!  Uber driver? FUCK YOU SPECIFICALLY IN THIS FASHION!

 

The robots in their new homes, free to frolick in the open pasture… oh, none of them currently work? That’s too bad.

 

I picked a convex corner to slowly grow out of. While we have a “space plan” this is the two of us we’re talking about here, so everything is really coming together somewhat organically as needed, so long as it is vaguely understood to resemble some plan, if interpreted selectively. In other words, #yolo.

My former “workbench” at Artisans is made of a 60″ wide wire shelf, and it will become the new 3D printer farm and shipping center for Equals Zero Designs. Not shown here is a collection of Craigslist workbenches that appeared in the space some time later in the week.

As luck would have it, the IDC was getting rid of its original-issue fixed desks and cubicles to make space for more researchers. The large office desks that were a familiar sight in my build reports from 2012 onwards were going to get replaced with smaller, more portable tables. So what’s gonna happen to them?

They end up with me again. The corner I was in was the first to get cleared. While the desks were taken apart and shuffled, there is a very high chance that my former IDC desk is now in our new shop, another somewhat fitting and poetic closing of one of life’s little loops.

A photo taken later in the week of moving when the benches have been arranged and the IDC tables have been erected again. Notice that they’re a little crooked. They did depend on the cubicle divider walls for structure, which were not part of the deal. I might add some additional legs or some bracing to the desk later. However, for seriously heavy-duty work like “I am putting my laptop computer here”, along with EE work, they’re fine as-is. In fact, the widthwise span has already been set up as my EE bench as of the now.

Charlesland fades into Bercustan as you move rightwards above, with the border lying somewhere on a 3D surface defined by the location of the last series of hand tools we borrowed from each other. I’m going to build a wall of lipo batteries soon and make Adam pay for it.

Now, no new workspace that we have anything to do with is complete without….

hella

new

toys

Oh my god. Holy Megabutts. What is this? Did I just buy a LATHE AND A MILL? Not even a Tinylathe and Tinymill!  A honest-to-Baby-Robot-Jesus Brigeport Series 1, and a Takisawa 14 x 30 TSL-800D toolroom lathe. HEY EVERYONE I HAVE CHILDREN NOW. MY POOR LIFE DECISIONS ENDED IN ME HAVING THINGS WHICH NEED CONSTANT UPKEEP AND PURCHASING OF EXPENSIVE ACCESSORIES ON A REGULAR BASIS AND WHICH TETHER ME TO ONE LOCATION FOR YEARS UNLESS I WANT TO SPENT A LOT OF TIME AND MONEY MOVING THEM!  

My children weigh 4,600 pounds combined! Don’t you dare call them fat,  you droplet of coolant curdle!

Getting these two machines – the result of an industrial auction – is a worthy post by itself, and we learned a lot about rigging and moving heavy things that week. There’s quite a few resources on the Internet from people who have documented their own DIY machine moves, so I will gladly contribute to it. Let’s just say it involved….

 

 

 Don’t look at me, I wasn’t driving.

So what’s next? I’m basically moved in and have been hacking at things for a few days now. Ongoing facilities improvements will occur – such as moving the machines to their final spots where power will be run to them. I’ve been kept busy by contract work for most of this fall so far, but #season3 is on the horizon and I have some new and exciting content for the Beyond Unboxing series coming up soon, not to mention Brushless Rage development.

Completing Überclocker 4 & The Leadup to Franklin Institute 2016

Oct 15, 2016 in Bots, Events, Überclocker 4

We interrupt this irregularly scheduled build report for VAAAAAAAAAAAAAAAAANNNNN TIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIME!

Contrary to most years that I’ve returned from Dragon Con by road, I did not have a job pressing need to return to Boston, so could take a few days to roam around Atlanta. This time, I revisited a couple of old haunting spots from the high school days – namely, junkyards, flea markets, electronics shops (what remained, anyway), aaaaand McMaster-Carr. When it was time to return, I decided to do something which I’d been thinking about for a while, and had been recommended by “car people” friends – hit up the mountain roads of the Blue Ridge Mountains and Great Smoky Mountains National Park. Many moons ago, my parents took me on a road trip to Harrah’s Cherokee Casino in North Carolina via some scenic routes such as U.S. 441, and I’d been reading up on the area as of late. Back then, I certainly didn’t appreciate the scenery or natural surroundings as much as I d…. nah, I still don’t, but those mountain curves I remembered as being awesome.

I solidified the plan as diffusing through North Georgia using U.S. 19/129 through Blairsville into North Carolina, then ascending via U.S. 74 eastwards until the intersection with N.C. 28. From there, I would follow the Tail of the Dragon (returning to U.S. 129) and eventually end up in Knoxville, from which it is easy to return to the Interstates. It was an incredibly scenic adventure – I definitely want to return here next year and perhaps try a different tourist trap on the way down – I’m hankering a little for the Diamondback 226.

The careful reader would notice that yes, this means I took a heavily-loaded Mikuvan filled with an entire Dragon Con of robot gear with Overhaul in the back and everything up and down twisty two-land forested mountain roads.

b o d y   r o l l

And bought the “unflattering water slide photo” at the end!

I must point out – loaded heavy in the back with about 500 pounds (Overhaul, all the robot gear and tools, all of Jamison’s robot gear and tools, and whatnot) made the handling and ride better than empty, I’m pretty sure. I tend to throw MV around like a go-kart, and the back end does get light due to the front mid-engine and front driving position. In winters, I regularly keep tools and heavy objects in the hatch to get more purchase during slushy or snowy weather. So I think riding empty might not have been any better, and it’s not like you can actually go that fast on the road while maintaining your lane. It took a few turns to “get it” (and probably warm the tires up a little) before I began really tossing it into the curves. “Continuous tire squeal” must have been concerning to bystanders…

Here’s the whole run from my high-mounted dashcam. Note that this is a very different and weird position compared to most dashcam videos – it’s mounted high up on the very tall cabin, pointed more down than forward, and Mikuvan has no front. Some people actually have said it made them dizzy due to the different motion experienced.

I think around the 3-minute mark is when I started getting more adventurous. Cynthia can be seen trying to constrain herself, her phone (recording a different perspective), and random objects in the cabin.

Anyways, fun times. But you guys came here to see Über-haul work! Here’s what went on in the few weeks before Franklin 2016. In this timeframe, I also went to New York Maker Faire to marshal the Power Racing Series race there again – Chibi Mikuvan came along as an exhibition item, but I didn’t race. I’ll need to post an update about the Detroit and New York Maker Faires at some point.

I did a fair amount of work in the remaining few days in Atlanta. One of the first things I did when I returned was drop by MITERS and use the large drill press to finish drilling some of the frame holes all the way. I then assembled the bot more completely to test the fit of everything.

Verdict: Yeah, sure, whatever. #zerosigmas

One element that has been missing up to this point which you people keep pointing out is that Clocker 4 is missing the classic Overhaul ears. Yes, yes I know, I just haven’t gotten to them yet.

The purpose of the ears on Overhaul 1 were to permit self-righting – the bot had a stable 45-degree-roll upside-down orientation that in testing, we could not get out of. Overhaul 2 addressed that problem a little with geometry, but it was still there – so the ears appear in a slightly different shape. The shape of the ears is a compromise between eliminating this 45-degree stable spot and extending far enough up to tip the bot over once it was fully on its back, using the action of the forks.  OH2 traded some of this latter ‘stickup’ distance for more sideways extension, which is why its ears appear proportionally smaller and flatter than OH1. The tradeoff is it takes a full power swing of the forks to get back over, something I was not too happy about and which contributed to a fair amount of pre-event paranoia in the team.

For Clocker, I wanted to explore the ‘high stickup’ option. This meant the ears have to be shifted forward some to not interfere with making the upside-down stable spot worse. It also makes the bot look very much like some kind of micro-fox or Gundam headpiece.

The ears are designed to be printed using Onyx with additional carbon fiber perimeter reinforcement, so they ought to be immensely beefy. They have to stand being landed on if this thing gets flipped.

I printed these while in Atlanta, but the installation came afterwards. They push into one of the circular cutouts in the clamp arm, have a flange to maintain the tilt angle, and is sandwiched together with 4 bolts.  This configuration means they don’t wrench on the side plates of the clamp arm, which are aluminum and would likely bend, instead bracing each other using the bolted connection… It also hopefully also makes them replaceable. I may pursue a similar strategy for Overhaul this coming BattleBots season, even if the ears are individual weldments.

The chain path for Clocker 4 was never quite decided, but I figured there would be a third tensioner or chain guide involved to force the chain to contact the motor drive sprocket more. This manifested itself in this slip-on tensioner that I designed after seeing the most perfect location for it also coincided with one of the frame rail trusses, so it was easy to make something that  mounted directly on it. Unlike Überclocker 3, it doesn’t have roller tensioners on eggy cams, so is not adjustable in this manifestation, maybe the next one.

Problem: I got paranoid and piled everything onto my scale, and it came out two pounds overweight. Wait, what? The CAD model says 29.5 pounds!

After significant investigation, it turned out that my beautiful PAXi motors were never assigned a finished weight. They each contributed 2.2 pounds to the bot in real life, but were modeled as only 12 ounces apiece…. basically, the P80 parts that I did assign weights for during the design of Overhaul 2….

However, I might actually swap these out before FI 2016 for modified P60s, since having the armor weight back would be nice.

Well then. Turns out I needed more than armor weight! Even eliminating 1lb each would still put the bot overweight. The remainder, I figured, came from wiring (all the 12 gauge adds up) and additional hardware.

Alright, time to borrow a P60 model and smash the AXi onto it.  At this point, I do not own a P60, so I didn’t know how easy this was to do, but it was still 2 weeks out from FI so there was plenty of time to find out.

Since the frame was designed around and cut out for a P80, I actually had to make a P60 to P80 adapter plate. This attaches to the front of the motor using its existing tie rods in counterbored holes, so the front face is flush. The tapped holes are at the P80 bolt circle locations.

A week later, a pile of BaneBots equipment appears. I took the opportunity to also investigate their new BB series gearboxes – Building Block, so named because they feature stackable designs similar to the Vexboxen. I got a BB150 thinking it was similar to a P60.

I was wrong. It’s like a P70 or something, literally almost the middle in dimensions between the P60 and P80. Their BB220 gearbox is the same square size as the P80, however.  Internally, it’s quite massive and a huge improvement over the P60 architecturally, with widely spaced bearings and a double-thick output carrier plate.  I will keep the BB150 around for other applications – it’s too big for this one. Banebots have come a long way from their early brass gear days, but I feel like people never quite let them live that down. The six P80s in Overhaul 2 speak to that well.

THIS IS WHAT ROBOTIC FRUSTRATION LOOKS LIKE.

Mabuchi 700 series motor bolt circle: 2x M4 on 29mm

AXi 4120 bolt circle: 4x M4 on….

30mm.

Look at us, we’re so brushless we need to be just different enough to piss everyone off.

Luckily, “drill out the mounting holes 0.5mm larger each” was enough and the M4 cap screws just barely slipped into the existing counterbores.

To mount the pinion, I borrowed a 0.2357″ (6mm minus 0.0005″, because what are units?) reamer from Jamison and expanded the 5mm bore with it, then pressed the pinion on. This fit is backed up with green Loctite 609 retaining compound. It mildly makes me worry, bu Jamison swears it works… alright, we’ll find out. I’d personally have gone  -0.001″.

Here are the two completed P60 & Axi sandwiches ready to mount in the bot. This setup weighed 19oz each, down from 34oz of the P80 combos, putting the bot at still a half pound overweight.

With the motors now secure, I returned to the parts of the bot I stopped caring about before Dragon Con – namely, the electronics mounting. I first cooked up this DLUX 160 bracket in Atlanta and tried 3D printing a version. It worked fine, except there was not really a way to retain the top one since the gap now crossed by the N shape was open. I closed the gap using the diagonal brace that acts a little bit like a flexure spring.

Now the DLUX controllers take some effort to push in, which is great, since they won’t easily slide around.

The bracket attaches to the bottom of the bot with four #4-40 screws.

Next up? Battery tray. Clocker 3 just cinched the battery to the baseplate but I wanted something more constraining for the full contact 30lb class. Now the battery will sit in a 4-sided tray so it can’t move, and secured using nylon Velcro straps to that. The 4.4ah 7S lithium pack I had been using in Clocker was downsized to a 3.3Ah 6S pack to save more weight.

Clocker is known to work for exactly 1 match on a 2.3Ah battery thanks to FI 2015, and I originally used the 4.4Ah lipo packs because I had them and because Dragon Con matches tended to run back-to-back with minimal repair time.

The reason the tray looks oversized for that 3.3Ah battery is because it’s actually designed to house a row of A123 cells. The Franklin museum does not permit conventional Lithium batteries in anything above the 3lb class, since it’s entirely indoors in a museum and magic lithium smoke & fire cannot be tolerated. So, A123s it is. This means most bots run on reduced power for FI since you can’t fit as much battery into the same location using round cells as prismatic ones.

Pictured is 8 A123 cells. I plan on fitting as many cells in series as I have weight for at the end.

The final 3d printed bracket of convenience is the receiver and other electronics housing. This is taken care of by using the RageBridge lift & clamp controller as a cap! It’s a hollow case secured to the baseplate with more #4-40 screws, then the Rage comes in upside-down and is retained the same way.

After the New York Makre Faire, it’s time to perform the final fitting-out of the bot. Here’s everything being installed in place…

Another experiment I wanted to try in the interest of #season3 Overhaul was tilting the rubber shock mount wubbies to dig the front of the wedge into the ground. Since these wubbies were in a regular pattern, it was easy to put an equally regularly increasing spacer height under them progressively. For weight and lack of steel fender washer purposes, I made quick 3D-printed (this word….. I swear) spacers to test a few orientations. I think they’ll make it into the final assembly because nylon is still far more rigid than rubber – there’s actually no need for steel washers.

It’s coming down to the last three days before Franklin now, and I’ve started mass producing wheels and…………… set screws. I promised to bring a bag of them to the event to sprinkle into the arena. They’re 1.5″ diameter and 2″ tall, made of genuine organic Miku Blue PLA (get yours today!).

Wiring completion was fast, as more than half of was done in Atlanta. I just had to make a few more extensions and replace the 3mm bullet connectors on the AXi motors with 4mm ones. I decided to not make a switch panel for now, opting to just do it like most of my other smaller bots and just plug & unplug the battery cable.

Checking out the weight I had left over, I decided to run a 7S A123 pack instead. I weighed the bot with the FI-illegal lithium polymer battery to establish an upper limit, and then just added as many A123 cells as I could under that limit.

Now, look at that battery and tell me that you’d rather have that bullshit than a professionally made lithium cobalt battery!

And here it is! The finished Clocker 4, alongside a toy Overhaul for even more scaling fun.

But the story doesn’t stop there. At this point, the bot was still around 6 ounces overweight (with the FI-illegal battery, which is 2 ounces heavier than the 7S A123 pack). So I at minimum still had to cut off 4 ounces, preferably more.

I decided the best way to do this was to trim off the inside corners of the pontoons. They’re actually now shaped more like Overhaul’s. The flange on the interior only reaches back about 3/4″, which should be enough to still hide the edges from intruding weaponry. This actually removed about 3 ounces per side, putting me a healthy amount underweight.

Another funny robot exercise: Trimming the pontoon bottoms to be level and also riding flush with the ground. Just throw the whole thing on a belt grinder and have at it!

Just barely under now, with the 3.3Ah LiPo pack and all remaining hardware I could think of added, so I actually have a healthy margin for FI with the 7S A123 battery.

Here’s a test video of Clocker 4 playing with the (still working, just sans actuator) carcass of Clocker 3.

As I point out in the video, it’s way more stable when lifting than I anticipated. Clocker 3 is huge for a 30lber, and it just gets picked up and whammed around almost effortlessly. I was super happy with the speed of the lifter. While the clamp could be faster, the priority was on holding force for this edition with speed only coming from severely overvolting the clamp motor. Recall that the clamp motor is the same as what 12 O’Clocker used for drive this year – I just made sure to order a bunch of spare motors.

Time to pack it up. To come is the event report!