So about that Motorama liveblog…
Anyways, now that the event is done and everything has settled into normalcy again, and with the completion of the best user manual / instruction guide I’ve ever made (I think so anyway…), I’d like to make the DeWut publicly available. Get yours today!
At Motorama, 8 of them were run in various fashions. The three in Überclocker, as well as five in a revamped version of Blitz. Five 3-pound motors in a 30 pound bot. That thing was made of motors. Moto was a great durability test of the gearboxes and outputs under various loading conditions. In Clocker, they were indirect driving wheels and gear-driving the fork. In Blitz, however, they were each direct driving a hard rubber wheel. One gearbox grenaded at the event when Blitz took a pneumatic flipper directly to a corner and bounced a few times. Clocker’s fork drive held up great, to my amazement, because there were points during the tournament when I was basically using the fork as a hammer.
DeWut is one of the two love babies I’ve been working on for the past few months (RageBridge being the other…) and it was great to see my parts actually being able to stand up to some use. Speaking of RB itself, I had no issues at all with my two boards on Clocker, but a few other folks were running the beta version and I recovered some of those when they succumbed to strange issues, to be diagnosed. Blitz also lost one production board to suspected thermal overload (from driving two DeWalt motors in parallel with the current limit maxed out) and another due to possibly a metal chip short from drilling the frame. Another bot’s suffered some kind of strange failure where the board itself looks totally fine, powers on fine, but never exits failsafe mode no matter what radio is connected! I’ll diagnose all of those and hopefully find that there’s nothing seriously wrong with my hardware.
Moving, on, here’s what went down at Motorama 2013.
The first act of any event trip is, of course, car stuffing. Because we didn’t enter any 1lb and 150 gram class bots, we didn’t have to drive down Friday morning; which would have been near impossible for me anyway.
That’s 3 30lb bots with support equipment, tools, and plenty of spare parts. And a bucket o’DeWuts and RageBridges for distribution at the event. Perhap the best car-stuffing job I’ve ever done.
And yes, that is a 24 case of Bawls, the venerable (but very little known, for some reason) energy drink that I can actually stand. Bawls brings back many memories, including that time I won a free 24 case of it at BattlebotsIQ 2007, a very long time ago. So really Bawls and I go a long time back… but I just wish it were easier to find. Much probing and asking around the local MicroCenter was needed to locate an unopened case. It’s definitely niche, and I’m therefore a hipster.
7 hours later, after some white knuckling through moderate snowfall, we wind up in Harrisburg, PA. Bear in mind that Motorama is, by itself, an enormous motor show kind of event focusing on off-road cars, monster trucks, dirt bikes, and midget racers. Robots definitely seem a tad out of place, though I also think combat robots itself is a rather redneck sport (one which I wholly unironically enjoy) and everyone has this deep down, visceral appreciation of raw power and destruction that causes them to appreciate it. If you don’t, or claim you don’t… well, I think you’re either lying or in denial.
I took Clocker through safety inspection and weigh-in early, as soon as I got there, in the interest of
relaxing a bit helping the rest of the crew finish their entries.
The NERC big arena is a 24 foot box. There’s also an 8 foot small box which the 1lb and 150 gram class bots compete on Friday. One thing I find odd about NERC compared to other events is that the 3lb “beetleweight” class is run in the big arena. Honestly, the beetles look so tiny from outside, and they’re easily hidden from view by the 6″ tall arena bumper walls.
On average, I’d say the audience was about 100 people, rising to maybe 200 to 250 during the height of the tournament late on Saturday. On sunday, the main event itself was beginning to wind down, so the attendance was less.
Blitz needed some last minute touchups and modifications but was mostly ready to go. The same couldn’t be said about the other member of the Cambridge Contingency, the Atomic Bumble:
No, not Carly Rae Jepsen. That thing in front of it. Yes, the thing with 4 wheels that point the complete wrong direction for them to cause the robot to move.
We packed CRJW because I decided to sacrifice it for the greater good. Its drivetrain was basically going to get stuffed under Bumble’s baseplate (there was no time to machine new wheels, though I had packed Clocker’s 4″ spare wheels), and the steel end plates became Bumble’s knocker teeth.
This is the end result.
Built in 1.5 hours and finished moments before the inspection period ended, and weighing in at 21 pounds out of 30, it’s … Carly Rae Jepsen’s Atomic Bumble? Something. I’m not sure.
The best part about this is, it worked. It actually spun fairly well, and kept spinning for longer than I’ve seen some purpose-built spinning weapons. Here’s its first (and sadly, only!) match against Hot Fuzz.
Sadly, it didn’t last that long in its only match. I am told with great enthusiasm that AB will return soon…
How’s about some Clocker?
I actually brought more people along to this event, so I had ‘event photographers” of sorts. Clocker’s first match was the 2nd match in Sportsmans class of the day, against … Nyx. Fate, it seems, is not without a sense of irony. Mike Jeffries and I had faced off like 17 times at Dragon*Con already and we basically considered the bots to be 1 for 1 each. So, this match was sort of the determinator.
Of course, things which can only be described as derp occurred. About 1/4 way into the match, on a great cross-box wall smash while carrying Nyx, the right side #25 drive chain straight up ripped in half. Not even at the master link – the impact was clearly caused by raw tensile load transient.
With the right side totally out, but still freewheeling, I could still kind of drive and pivot around and continued poking at Nyx. But shortly thereafter, after another pickup and slam of Nyx, the left side cut out too.
Without any motive power, Clocker lost the match by a mobility TKO. A post-match inspection revealed that the left motor solder joints had actually broken off. Both of them:
My mistake was soldering these wires to the crimps that hold the brass motor brush holder to its plastic substrate. They took solder well, but provided relatively little area to make a reliable connection. Additionally, any shifting of the brush carrier manifests itself as bending of the brass material, hence stressing and breaking the solder joint.
I didn’t have much choice but to just resolder the joints as well as I could, and then coat/fillet the wire and joint in hot glue.
After the Nyx match, I also noticed that the leadscrew anchoring block for the clamp arm was getting too close to the motor; as a result, at the end, the clamp motor jammed into it and prevented itself from moving. To remedy this, I borrowed an angle grinder with a very rough grit wheel – something like 20 grit, which I am convinced is just chunks of rocks glued to a piece of heavy fabric – in order to take down thickness of the anchor block a little. Normally, this would be a quick mill job.
I overdid it a little. That’s the result of maybe 4-5 seconds of hitting the aluminum with this magical grinding wheel. I need some of that…
It actually isn’t as bad as it looks – the cut was also very off-angle, so only the edge on the face the camera is pointed at seemed troublesome. This part did not fail or give way because the clamp arm isn’t loaded in the direction in which it is weakest.
Clocker next faced Such & Such, which is a horizontal clamping bot that was also a shuffle-walker and hence granted a 50% weight allowance in the 30lb class. Because it was so huge and heavy, I had a hard time getting a good grip on it. There were moments in the match during which Clocker basically wore the bot as a hat. While I was cautious of his horizontal gripping mechanism at the beginning, at the end of the match I decided to go for broke and run straight into the middle of the bot. This was the only way which I could balance him sufficiently, and I got a great lift in.
Next, Clocker faced the venerable Jack Reacher, a well-done flywheel flipper whose first event was Moto 2013. This thing was amazing in the amount of machine work that went into its clutch-and-pulley system, and it looks straight off some kind of old 19th century steam shovel. It was also the perfect size to fit in Clocker’s fork, and the perfect shape to let me pull off a successful “robocopter” spin, the move which Clocker is basically designed to do.
Finally, Clocker went up against the quick and reliable Gigarange, basically a 30lb Test Bot without wedges (just the 4 wheels and lifter). This match was full of some pretty exciting driving, and at one point the bots got stuck together upside-down with Clocker’s big rubber bumper stuck in a hole on top of his lifter and had to be separated. I was fairly sure I had this match won until I drove him into the wall at full speed, with the clamp up.
One of the things I told myself to not do was to run people into the wall with the fork up. The reason is that the attachment for Clocker’s springy legs is the one sketchy engineering feature that I’ve been sort of turning a blind eye to – I knew it was probably going to break via shearing the shoulder screw or stripping out its thread in the aluminum frame if I actually hit something hard with it. Problem is, I tend to forget all strategy during the heat of battle and just go for it; partially a habit inherited from years of pushybot and wedge driving.
So I lost that match by breaking off the springy legs and then getting stuck on top of them. Whoops.
With Clocker out of the tournament proper, I repaired the legs by moving some of the washers around so the shoulder screw could access more of the thread in the frame. I entered Clocker in the 30 Sportsman’s rumble, which was a hit all by itself. The bot was fully functional for this round, and I think I used a third of the field as blunt-object weapons at some point.
Well, functional for most of it anyway. Near the 2/3rds mark, my clamp arm wire was cut when I drove it down too far. It was then stuck in this down position… whoops.
This is where I basically started using the fork as a hammer weapon. Even though it was rubber, and hence could really do no damage, it was still a crowd pleaser and looked hilarious. In the end, Clocker was declared the rumble winner through audience vote. Though there’s no prize for the rumble, the bot was extremely well received by the audience, which is most of my mission anyway – so long as it’s a good show, I don’t care if I win or lose (though I would clearly prefer the losses be strategic and not because of derp).
Without further ado, here’s the quick match highlight video I put together for Clocker, which officially supersedes the 1000 words before it:
Overall, I’m pleased with Clocker’s performance despite the first-event durability issues. There’s 3 major changes I want to make to it in the interest of reliability and durability for future events:
- Switching from #25 chain to either #25H (heavy) or even #35. #35 would be the trivial solution, but it is much wider than 25 and also much heavier. I have a few too-short runs of 25 heavy left over from other previous builds, and have ordered more for replacing the chains on Clocker. Based on the difficulty of sourcing new chain, my general impression of 25H is that it’s something invented by the small scooter and pocket bike industry and not actually a real thing… but we shall see. The sample I have has plates which are at least 25% thicker than regular 25.
- Changing the way the legs are mounted from the single-shear configuration it is now to a double-shear (double-supported) method. No matter how beefy I make the mounting screw for the leg in single support, I think it will still be less durable or stiff than a double supported scenario. This would entail making some kind of external plate that joins up with the frame behind where the leg mounts.
- Building a new clamp actuator to replace the one harvested from Cold Arbor. As much as I love chainboxes, the actuator is rather unreliable and likes to jam up. I’ll probably replace this with some stock solution gearbox instead of a chopped drill gearbox. I’m thinking of replacing the leadscrew with a fast-travel type to avoid binding via “overtightening” – a leadscrew with a faster thread is less likely to act like a nut and bolt and lock up, which was one issue I faced occasionally.
To conclude this post, here’s some DeWalt ownage courtesy of Blitz. This gearbox seemingly took the pneumatic flipper of Upheaval directly to a wheel: