Bone Dead Robotics

Background

The October NHRL was an off-rotation event. Most people recognize that whenever Phenomenon or Vorion attend an event I’m generally doing better than when they’re not there and that is accurate. Those two machines are where the vast majority of my focus and efforts are put into (besides future ideas). Fortunately this year both machines only needed to make a single run to achieve maximum effect. Vorion’s run was very solid with only a loss to the best machine in the class and even then it got very close to crippling the beast. Phenomenon’s peerless run through the June event was also enough to affirm the solid nature of the design, but I am still wary of the hubmotor. While it didn’t have any issues, I still worry about it’s strength in the face of really solid machines like Yahoo, ARES, or Chonkiv whose weapons are enormous by comparison. Therefore, the goal is to see if I can use a prototype of Phenomenon’s weapon, which uses the same body and bearings but a smaller motor, to test it even if it is still not quite as much power as the 30 would see. To hit this goal of testing, I decided to bring back Mind Flayer since it’s big wheels allow the use of a blade that’s the same diameter of Phenomenon’s weapon. Ideally this means if a horizontal were to hit the side of the blade it would create a similar bending moment (though not as much as a full 30lb weapon). Therefore, Mind Flayer will be temporarily switched from its weird physics to a more standard Huge-shape with a hubmotor middle.

In addition, Cattywampus will be debuting at NHRL! After a great run at GSCRL and a fair run at SWORD with losses only due to electrical problems, the time was right for a weird bot to make it to the big stage. With this being a Halloween-themed event, Mind Flayer and Cattywampus felt like a great creature duo to keep the theming up. It’s good to have an event where the expectations are lower and the pressure is off. Eventually this pressure leads to burnout and kills creativity and that’s something no one wants to see.

Mind Flayer

The event prep began with the building of a new Mind Flayer. The designing of this machine was fairly simple as it was mostly importing the drivetrain from the previous design, adding the weapon from Phenomenon, then connecting all those pieces together. A few neat ideas I wanted to try out were the TPU front armor, which allowed easy inclusion of angry eyes that I enjoy furnishing on machines, and protective top armor splines. Since this machine is fairly small, these will hopefully help keep normal robots away from hitting the tops of the chassis since there’s so little extra space in the machine.

The structure for Mind Flayer is a fairly simple box with the hubmotor and back wall acting as a juncture. This is the critical difference and limit of the machine opposed to other big wheels: Mind Flayer is small in exchange for stronger reinforcement through the chassis. Most big wheels have a larger diameter shaft which directly links two boxes. This allows for incredibly large blades and correspondingly tall wheels to outreach most robots. Because the hubmotor doesn’t have a through-bolt but instead only screws threading into the endcaps. Since they are made from 6061 aluminum with 10-32 screws threading into them, it’s very possible for any good 12lb horizontal spinner to strike the side of the blade and split the robot in half so a solid back bar was included. Its also important to note that the core of this hubmotor is a prototype for Phenomenon’s system based on the Propdrive 4248. While I had many of these on hand from damaged motors, it was ultimately too weak to spin Phenomenon’s blade. I was optimistic that it could spin a bar with a considerably smaller MOI than the blade but only time will tell on that. It is also sporting a blade made from a new material sold by Jake Hoffman of Maximizer Merch.

As the box began to be filled with things, the machine began to take shape. The wheels and Titanium tail were pulled directly from the older version to get a better idea of what can and can’t be done. The main difficulty with this machine is fitting all of the electronics into each side of the machine. On the weapon side especially it becomes incredibly dense as the weapon controller takes up more area and the battery that drives on that side will invariably be drained to worrying levels as the weapon is forced to spin up repeatedly.

The first step to get space was to create a new power switch. Based more closely off of the AB90 by function but similar to the Lynx switch by shape, it is an anti-spark switch designed for the 850mah 6s Lipos in this robot. It’s a fairly simple design with a 3/16″ top and bottom copper plate with a resistor connected to a washer where the power key creates a temporary circuit that allows a small amount of amps to flow so when the main screw is connects the tabs there is no spark. Afterwards, once the screw is removed, the circuit closes leaving only the main connection.

I also used shoulder bolts to retain the wheels both because of the shafts being a liability in other big wheels as they get bent as well as them being very easy to self-contain with a locknut on the other end. To maintain stability, I added a simple wood screw into the UHMW. While it does risk some shock going into the wheel if someone strikes it, I expect the screw to bend first and it to be easily removed and replaced with another screw without requiring any more effort.

The next step of robot prep was to prep the weapon ESC. I’ve already had great success with the Rhino 80A in Phenomenon so I was confident it would be an easy fit for Mind Flayer. Unfortunately in a robot this small even wire orientation really matters so it had to be resoldered with adjusted wire directions and then covered in new heatshrink. With that adjusted, both sides began a fun game of Tetris to pack the electronics.

Now that the electronics were mostly together, it was time to build up the finishing touches on mechanics. One may have noticed the 3/8″ blade leaves a gap in the hubmotor body so a little aluminum spacer ring was machined and pressed onto the hubmotor body for a firm fit. A few minutes on the router and some deburring and voila you got a weapon that fits together properly. The next thing was to beef up the tail. The previous piece was a fully flat piece of 1/2″ UHMW, but the tail was only mounted with plastite screws to make sure nothing interfered in the area where the blade is. Instead this integrates mounting blocks for little titanium mounting plates and Tegris tails. Its probably overkill, but overkill is the best kill. As a finishing touch, I made a weapon lock that can almost double as a robot carrying handle.

As we approach the last touches, the lashes, paint, and tread were added. The lashes are just heat bent PLA+ which proved to be both very springy and surprisingly strong as they were even able to lift up the robot when rested on. Besides looking very cool, the idea for them was that since this robot is a very small big wheel with no heavy armor then these will serve as a form of passive armor where they may hold the other robot away from the main body as simple keep away sticks if they outreach the blade yet ablate first if directly stuck to further protect the aluminum plates. In addition, they’re all made from the same base shape so if I think a robot outreaches me they can be flipped to reach forward and hold them back while in normal configuration (as shown) they are back to allow maximum weapon reach. Air is a underrated form of armor and I hope to lean into that more over time. The tread is actually bike lining with a plastic ziptie going through holes in the wheels to tie it in. The nails I tried (visible in some pictures) were supposed to work as pseudo cleats but the torque the machine produced whole driving ended up bending these over and made them useless in a little over a minute of driving. The zipties are light enough to not add a lot of weight, but they’re also very fragile once struck by another machine.

And now for the beauty shots! I think it fits the spooky vibes of this event well. There was testing that also delayed development of this until less than a week before, but that will come as event day arrives.

Cattywampus

Not much changed for Cattywampus. After the SWORD event, the only real learning was the tail had to be strengthened. Pinevictus shattered the NylonX material so now it was time to make a UHMW tail. Ideally the this should resist even when directly struck but it also means more force is likely to be put back into the tail gearbox which increases risk of shock. The rest of the machine (except the head) was the same as it was in GSCRL and SWORD as these parts were holding up well and no obvious weaknesses showed up yet.

Event

The first thing that was obvious at this event is how big Mind Flayer is compared other big wheels. Grandeur is similar in size to Slam Plan or Ugee so its really apparent how far off this is from the others; its abundantly clear it would lose those against its brethren.

The issue Mind Flayer had from testing to competition was the balance of the ESC lease breaking off and/or the hubmotor burning out. In testing one of the leads on the Rhino pulled off during testing, though I didn’t realize it, which then ended up cooking the hubmotor. Because of that it created a loop where it ultimately killed 3 ESCs by the end of its run.

During its fight with Mareep, this issue was fixed, but it ultimately didn’t matter. While the blade did work, repeated spinups ultimately killed a phase and burned itself up. While it was all mechanically there, the motor couldn’t handle the power for long proving that the upgraded version in Phenomenon was by far the better plan. While Henchman Sam did look to see if there were other motors I could try, ultimately I couldn’t and so Mind Flayer only went 0-1 for the day with a forfeit to Blackjack making it 0-2. The good news is all the drive components and batteries are still good so they can easily support a new Mind Flayer in the future (or maybe a new Demogorgon??)

I found the Fingertech power switch from SWORD had in fact broke so it had to be quickly replaced before safety. Cattywampus also went 0-2 for the day but for understandable reasons. In its first match against Gh-Astley it was doing well for awhile but, due to it being a good horizontal, was able to strike the tail and kill a gearbox. However, in my haste to fix Mind Flayer for its fight, I did not notice more insidious issues namely that the drive ESC on one side had its negative power tab and drive motor wire torn off. While I was able to find the motor wire fairly easily, the negative terminal being torn off was near invisble without more time to dig so it went into the fight already down a drive side. While it did control well, it ultimately was unable to overcome its handicap and lost, knocking it out of the tournament.

I was a little less bummed about it though as this robot never fails to delight which the NHRL media team picked up on too. Hopefully it makes it to a TikTok or Reel near you! I was also happy as this meant preparing for the Robot Ruckus event only two weeks from then fairly easy.

Takeaways

Overall it wasn’t the return to the 12lb class I was hoping for but it was helpful in supporting the bots’ developments at different levels. The power switch worked really well so I will definitely keep them for other 12lbers and may adapt them for use in the 30s if the need arises. Cattywampus’ continued evolution and delight once again cement it as the necessary balance for the more competitive and serious machines. Even with its difficult time succeeding, I enjoy testing weird ideas on it for its own sake and hopefully that means once it does reach success it can create an impact no one has ever seen coming. For now, on to the Ruckus!