A Return to Scale Model Testing Your BattleBots?! Überclocker/30Haul and Norwalk Havoc

We’re going to time-skip to the recent past and away from non-stop van content for a little while. It’s time to get back into some robots!

This isn’t to say I’m out of van tales – in fact, it’s actually gotten worse…. much worse…. but there’s plenty of news to report on the robot front and I’d like to do so before I become an off-brand automotive blog. I mean, more so than this site already is?!

So the event to be seen at if you’re a kool robot kid as of late is the Norwalk Havoc series which has been running as a beetleweight-centric event since 2018. I’ve mentioned it in passing a few times, usually in the context of Roll Cake and mechanical abject art I’ve made using its prize trophy. This event has been responsible for more or less creating an entire new generation of first-time competitors. It’s nice to have someone who is willing to bleed immense amounts of money onto the sport; the best way to make a million dollars doing robot fighting is, after all, to start with ten million.

After a while of doing ants and beetles, they decided to enter the 12/30lb “big arena” scene in late 2020 with the inaugural event taking place in February 2021. Well, with another BattleBots on the horizon and an Overhaul that was basically ready, I decided – hey, might as well use 30Haul to test a few more production changes before I make an even bigger financial mistake.

And so we begin. 30Haul was basically undamaged from the Before Times of 2019, and having followed the evolution of BattleBots Season 5 in 2020 from afar (as I decided that traveling out there just to hang around and mess with 10⁸ different COVID-related restrictions just wasn’t worth the potential to get detained), there were both some changes I wanted to make to the bot itself and some scale-model testing to be performed for Overhaul’s own future attachments.

First off, ever since the transition from “Uberclocker-shaped” to “Overhaul-shaped” in 2016, I’ve not had the ability to pull off Überclocker’s signature spin move. The long spring-loaded, roller-tipped legs let the bot move fairly well while holding onto an opponent. After I changed the design to become “30Haul”, the spring-loaded legs went away in favor of various wedge attachments to counter spinners (which I maintain are the cause of the decline of the sport).

Part of the architecture change of the latest Überclocker version 5 in 2019 with its broad multipurpose breadboarded front clip was so I can more conceptually detach the bot’s shape from its configurations. Overhaul v2 and its attendant 30lb version were both shaped with the frame rails extending past the lift axle’s fore-aft dividing plane, like a mild U shape. This limited what I could put there without making it vulnerable to damage, especially from the sides.

I specifically made the new “pontoon anchors” with pivot points space such that I could use either single-piece forks between them (like it currently has) or put something wider that straddles them on the outside, such as a new set of roller legs. I decided to push forward with adding these for the February Norwalk Havoc, since even though it was a “full contact” event, it would be good to have the Sportsmans-style configuration available (for the odd bot out these days that doesn’t have a small vertical spinner….)

And so, following the general pattern of the single-piece long wedge forks and using their construction sketch as a template, I started sketching out the profile:

These new roller legs were to stick out another half inch or so than the forks. Even with the longer wedge forks I ended up making, 30Haul was still prone to tipping forward if I lifted something too quickly (a syndrome Overhaul 3 itself also currently exhibits!). The longer extension meant these would really be limited to Sportsmans-style matches, but hey, nothing wrong with that.

After generating a profile, I mirrored the bodies to make the two side plates. In Inventor at least, my preferred strategy for making weldments is a multi-body part with fab files made using derived parts from the individual bodies. It’s only slightly terroristic but one of the rare habits I crossed over from Solidworks.

Completed leg design with web infill as two more disjoint bodies, and added fixturing tabs. Another reason I grew into doing this was the ease of doing cross-part (cross-body, I suppose) references for geometry such as these tabs, without actually having them cross distinct part files in an assembly. That rarely holds together long, for me at least.

Add a few nuts and bolts and here we are. The roller will be machined from Delrin, as per usual. When 30Haul is in this configuration, the rubber mounted pontoon anchors are instead going to be thru-bolted with Delrin spacers, keeping the compliance only in the (more rigid) single rubber bump stop.

Part of the success of Überclocker’s support legs is their spring compliance – freely hanging legs with just a hard stop make the whole multi-bot complex easier to tip forward, something Overhaul is struggling with now, as there is nothing to soften the initial rotation and the momentum of the lift will kick the center of gravity over the legs.

I expect similar changes to occur for Overhaul’s wedge forks – they’ll always have some amount of elastic compliance, versus just being freely swinging like they are now.

Here’s how it looks in this configuration. The (as-is) forks have a lot less prominence, but not really much worse than Überclockers-past were.

With that configuration behind me, I turned back to “spinner mitigation” strategies. Overhaul had historically featured two steel wedge assemblies I called the pontoons, named largely after the features on Overhaul 1 which were spawned from the then mega-Ron (and subsequently Sawblaze) contribution to the design.

Over the course of the 2016 and 2018 seasons of Battlebots, and from Motorama experience, I began to look away from this design. Sure, they were very effective in their job, but because they only covered a small portion of the bot, I had to drive very precisely to leverage them with the otherwise undesirable side effect of sending the weapon into the rest of the bot.

They also don’t distribute forces well, pulling on one side of the chassis. Recall that Overhaul 2018’s grudge match with Valkyrie debuted the “DETHPLOW” design which spanned both sides of the bot. I made short “T-rex” arms to fit behind them, and I do with I could have gotten to use this thing more during the actual tournament, because it did resolve the “focusing energy onto one side of the bot” problem…. but obviously not the “Fling Valkyrie into your face” problem.

I decided after watching the game evolve during the 2019 and 2020 seasons to switch to a more common bot-spanning wedge, a design I usually called the “Tombstone Snout”. It’s the present year, horizontal spinners are no longer your major concern. A rigid and angled piece of steel is sufficient to overcome most of them. It’s the verticals you really have to worry about.

I spent a little while thinking of ways to make the arms rise through the Snout. I didn’t want an open area with short arms any more, as that’s a lot of ingress surface for any opponent. So I decided to make narrow slots for a set of T-rex arms to rise up and through. For now, though, I’d concentrate on the (rather simple) flat geometry. As with Overhaul’s complex faceted wedges, I began with a wireframe sketch pile made of both 2D and 3D sketches.

From there, surfaces were made to turn the sketch edges into 2D facets.

I then apply a Thicken Surface operation to get the solid plate models. Depending on where the face is, it might be a thicken-towards-inside or outside, and determines if the piece is a driving component during assembly (place and fixture me first, basically).

I picked a good place to put the “T-rex slots” that don’t require repositioning the gear hub. Also notice the 45 degree forward-canted backstop on the top edge. That is your Valkyrie Preventer. Quite a few bots have this kind of rail feature on their front empennages, and I tried to live-add some to 30Haul before its match with BEAM (And they held on great until the end, which is when….. the thing happened).

The next step is to add the keying slots and tabs. It’s taken me a while, but I finally over the past 3 or so years became more comfortable with fixturing for welding. Previously a lot of my designs featured full-edge stitching of tabs and slots. While it was quick to put together for welding, it either 1. introduced a bunch of protrusions or 2. made the weld bead density high enough that I’d lose a lot of material strength to the heat-affected zone. Nowdays I tend to only key stuff together at the very corners and edges where they’d otherwise shift the most, or are hardest to fixture.

The final design after adding and adjusting some clearances with fillets. Notice how I trimmed off the outer corners of the wedge to slope downards to The Snout region – I wanted to prevent a glancing blow coming from the rear of this assembly, say I drove up next to or turned into some spinner the wrong way, from just blowing the whole thing off the front of the bot.

Next up was generating the new T-Rex arms. I went back to derive off the “master sketch” defining the bot for this one. These are going to be skinny on purpose, just giving me a modicum of lifting ability.

I knocked these out pretty quickly – edgy teeth for edginess, and a downward-facing tang that will allow me to use the bottom set of arms as a clamp of sorts if the actual clamp arm itself falls off.

Here’s what they’ll look like hiding inside the wedge. They live about 1/8″ below the surface.

Yes, I risk them not going back down if they are hit while raised, but at some point, you have to come down to the good ol’ LTFD: Let’s Throw Falafels Down, or so they say, and not attack an active weapon with the arms up.

The decidedly less threatening looking T-rex arms shown in a raised position. Immediately behind the center “barrier strip” is the singular standoff that keeps them together as well as serves as the pin joint for the clamp actuator.

Other small kibbles I needed to make for 30Haul – chain guide blocks, similar to those on Overhaul. The drive chains were sized for slightly loose tension, and they never fell off I guess but had become so sloppy I think they’d definitely fall off in any serious match. The guide just pinches them together very slightly.

Last up was changing the wheel hub design to one more reflective of Overhaul’s inner and outer wheels. 30Haul’s wheels were designed to be sacrificed and the bot geometry set in support of driving with one or more wheels out. In fact, at one of the Orlando Maker Faire matches, it lost a wheel almost right away to a flipper shot and I drove the entire match thereafter barely noticing.

That’s the kind of performance I want from Overhaul as well.

30Haul’s wheels tended to fall off as a single block since I made them use very long spacers that spanned both Vex wheels. Overhaul now has some very solid wheel hubs and chomky axles for the inner pair, and the outer (and optional) pair is attached via composite fiberglass-filled nylon bolts.

I changed the wheel and hub design for 30Haul to use aluminum standoffs for the inner pair and nylon standoffs with regular nylon screws. Hopefully this means the outer set has a tendency to shed first.

With all that CAD through, I sent out some metal cutting orders to my now hometown heroes Big Blue Saw (a proud sponsor of Overhaul 3!). Luckily, being nearby and all, I can just drop materials in my possession off instead of ordering through the website. I had leftover Hardox 450 from Overhaul’s build that I had the steel company cut up into 12″ x 24″ plates, one of which was perfect for one 30Haul’s worth of improvements.

Now, onto the actual bot.

It didn’t really need much work at all after Orlando Maker Faire, but it has been sitting on a shelf for a good year or so, and I slowly stole parts out of it (such as the TBS Crossfire rig) for other stuff in the works. Famous ending to many of my projects. So it was good to just take everything apart and give it the once-over.

What spare parts I didn’t make prior to Orlando Maker Faire, both from timing and the lack of heavy-hitter opponents, I went and knocked out now. This primarily involved more wheel hub parts, which were now a lot easier because I had a lathe more correctly sized for making them.

Some of the newly redesigned wheel hubs going together – this is the aluminum and real hardware layer, on the inner wheels. Notice there’s still a nylon 3D printed Fancy Spacer between the metal? I’d still rather these inner spacers bend and break off one by one versus take out the entire sprocket, if it went that far.

One wheel has aluminum threaded standoffs, the other unthreaded nylon spacers.

And they go together thusly, identical from the outside.

I finally get to make a _robot part_ with New Tinylathe, you say!? Well, New Tinylathe is also now just seeing its first year in my possession, so it’s about time. I had to make a pretty solid spacer to handle the torque of lifting, from the big lift gear to the T-rex arms since they’re spaced more tightly together and made of thinner material. The base part itself is an aluminum flanged donut with an 8-hole pattern. That is conceptually simple.

What’s less simple is the fact that I hadn’t picked up any metrology tools for the Benchmaster, Master of Benches yet, not that it deserves any. As mentioned before, I’ve gone back to my “vernacular machining” habits learned on trashy student-stop machinery at MIT and back in high school with friend’s shops. Running things into each other (carefully, with respect) is your edge finder. Open-loop holding the dials against backlash, and using Sharpie marks (who has time for layout dye?) is your “readout”. Actually using the “Normal” and “Loose” clearance fits for hardware is magic.

Trigonometry and symmetry are your friends as well. I managed to knock out this 8-bolt pattern (Of which only 7 are filled, as one of them presents accessibility problems for servicing – so fuck you) largely by feel. I’ll be damned if any of these go through.

I don’t need the entire donut for strength and would like the ounces back, so I had to cut out the center to make a spool-like piece. I did this by plunging multiple times with this insert cutoff tool, then just abusing it to make very shallow turning cuts at the bottom of the radius.

A couple of days later, the Big Blue Saw parts show up, so it’s time for some happy welding fun before I ship off to Connecticut!

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