My first attempt at a bot actually started its life being designed as a knockoff of the Trilobite kit from Kitbots.com. I started here because the general advice for anyone getting into the sport is “start by making a wedge bot”. After brushing up my CAD skills in duplicating the Trilobite design, I decided that just a plain wedge was too boring for me, so I wanted to spice it up by making a lifter. Most designs for a lifter wind up leaving you with a lifting arm that is much more delicate than a full wedge, so I took some inspiration from the heavyweight Polar Vortex and decided to make a beetleweight full-body lifter as my first bot. Lapsed Pacifist is born.
The chassis is constructed with 1/16″ 7075 aluminum top, bottom, and back plates, 1/2″ UHMW side rails, and 1/8″ UHMW bulkheads and wheel guards, all held together by nutstrips. The first version of the bot featured a 1/4″ thick flat aluminum front wedge since I hadn’t yet figured out how to make better curved wedges yet. This put way too much of the weight of the bot up front and left the wheels with too little traction, so I ditched it for a titanium wedge after the first event.
The bot debuted at the Franklin Institute 2016 event. It was plagued with radio reception issues and lack of traction from the overly heavy original wedge way up front, so it made a disappointing 0-2 record at the event. At this point I wasn’t overly happy with the design, so I moved on to design my next beetleweight, but I kept it around and upgraded the wedge and receiver in hopes that it might get the opportunity to redeem itself.
I registered my new beetle as my entry for the Franklin Institute 2017 event, but I brought along Lapsed Pacifist just in case I could throw it into a rumble or something. When some competitors dropped out at the last minute, I went ahead and registered it as a last minute entry for the tournament. When the organizers were ready to get started, they announced that the first match of the day was going to be me vs … me.
The first matchup of the event was Lapsed Pacifist against Enraged Erector Set, my new beetle vertical spinner. With only 5 minutes to go and not wanting to simply forfeit one of the bots (I came to fight, not just win), I had to find another driver with a compatible transmitter, open the bot, dig the receiver out, bind it, and cram it back in with no time to mess with any of the fancy mixing that controlled the lifting arms. So the first match of the event for Lapsed Pacifist was a fight that it was predetermined to lose, it was reduced to an under powered 2wd wedge, and it was driven by another driver against me. Not a great start.
This match mostly served as a good practice round for my new beetleweight bot, which managed to take a good chunk out of the top panel before I called the end of the match. After replacing the top panel, Lapsed Pacifist finally got it’s first match where it was functioning at 100%… and then promptly lost to Big McLargeHuge.
After a disappointing 0-4 record, Lapsed Pacifist has officially been retired and recycled for parts.
Angry Erector Set
My first antweight, Angry Erector Set, was conceived and built while I was starting a new job and slowly moving between two states, so the only tools I had access to were a Dremel tool, a set of hex keys, and a soldering iron. The chassis is made from two sections of Actobotics aluminum u-channels bolted into a “T” shape with the motors and electronics stuffed inside, and a FingerTech chipper blade and hub mounted directly onto the weapon motor. Bot designs don’t come much simpler than this: except for enlarging a few holes for weapon motor mounting, power switch, and power light everything simply bolted together.
I named this bot Angry Erector Set due to the aluminum extrusions that it was made from, but by the end it was more of a case of “Lessons Were Learned”.
- Aluminum is relatively heavy to make an entire 1lb chassis out of
- Aluminum is a less than stellar armor material
- Unmodified brushless motors do not fare well direct driving spinners
- Improperly mounting gear motors makes them prone to unscheduled disassembly
- An aluminum clamping hub is not great for holding a blade on through repeated impacts
- If your BEC/Battery is not up to the task you can brown out your receiver when you punch your weapon throttle
Angry Erector Set managed a 1-4 record between the Franklin Institute 2016 and Motorama 2017 events. It managed two interesting accomplishments during the Motorama event. First, the one win under it’s belt was against the Doom Kid with Commander Doom, so there’s that. Second, it must be one of the few bots that has lost all of the wheels on one side and become more mobile because of it.
In it’s last career fight against Odium, the right gearbox was damaged enough to lock up the wheel and make driving very hard. Eventually, the right wheel fell off completely, and it was then than something magical happened. With the right wheel gone, the chipper blade started to drag the ground on the right side, dragging the bot forward. Suddenly the bot went from only being able to turn left/right to going forward or left depending on how I controlled the remaining wheel. I was back in the game! …For about 20 seconds until the blade hub popped off and defeat fully set in. This match may not have been a victory, but it was one of my most memorable moments of my robot career so far.
Enraged Erector Set
Because the design came about at around the same time as Angry Erector Set, My new beetle design, Enraged Erector Set was also made using the Actobotics construction set. With the exception of the wedge (1mm grade 5 titanium) and wheel guards (1/8″ UHMW), the entire frame was made with aluminum extrusions and a dremel tool. Having seen some issues with direct drive weapons on Angry Erector Set, I tried to make a sturdier setup for my can-mounted drumette by using a motor with a larger 4mm shaft and supporting it on both ends with bearings.
Since there were almost no off-the-shelf options for vertical spinners, i needed to design and make my own. To try to keep the cost down, I designed a very simple single tooth drumette to fit over my brushless weapon motor. I made up a schematic drawing, put together the CAD file, and brought it to a local machine shop. They said that they could make it for me, just in time to finish the bot for its first event.
I had assumed they would just use the CAD file to CNC the part, or at least go from the drawing since it was so simple and square. What I found when I went to pick up the part was something that looked like they had roughly cut the tooth profile with a band saw, bored an over-large, off-center hole, and called it a day. I will never be going back to that shop again.
The part was practically useless, but with only two days until the competition i had to find a way to make it work. With a lot of goop to take up the extra space in the motor hole I was able to get the motor mounted, and with a lot of grinding i was able to make it something that resembled balanced if you squinted hard enough. It wasn’t perfect, but at least it was ready to compete!
After the first event, my two weakest points had been my wedge attachment and the crappy drumette. I tried to double the number of attachment points to help keep the wedge on, and use flat head screws to give opponents nothing to grab, but countersinking thin titanium without the proper tools is hard, and i wound up just using button head screws in the end to make it work well.
I wanted to get the new drumette water-jet CNC cut to avoid any further issues with lazy machinists, but the resulting taper wouldn’t make for a good fit on the motor can. My solution was a drumette made from a stack of thinner disks bolted together. Several small tapers still fit the motor pretty well (particularly with a bit of goop in there), and if any one plate got damaged in battle i could replace it instead of needing an entire new drumette. It worked beautifully, with the drumette being balanced enough that I could finally spin up to full speed and actually get some gyro tilt when it turned. Ready for the next event!
Enraged Erector set debuted at Motorama 2017, and managed a decent 1-2 record. The first two matches were against wedges, where I managed a win and a loss. The third match put me against Sparky, another vertical spinner, who proceeded to rip of my wedge and wheel in under 10 seconds and end my run.
Franklin Institute 2017 gave a chance to try for redemption with a newly mounted wedge and a shiny new drumette, and the bot gave better a slightly performance for a 2-2 record for the event (and a 3-4 record overall). The first match against my backup beetle, Lapsed Pacifist, was a guaranteed win, but it gave me a good opportunity to practice driving against an opponent. I managed to beat Dempsey Roll in my second match, but it took a good chunk out of the front edge of my wedge.
The most eventful match of the event was against Mondo Bizarro. His powerful weapon managed to dent my wedge, twist my frame, and rip my weapon motor out of its mountings. I made it to the end of the match, but I was crippled and stuck on my back as the final seconds counted down. After some emergency repairs in the pits, one final match against the good driving of Quicksand and my luck had run out for this competition.
The unmodified motor in the drum may not have held up as well as I might have hoped, but I’m fairly happy with the stacked-plates-as-a-drum design at least as a concept. I could see myself reusing the idea for a future vertical spinner (maybe with some laser cut AR500 plates belt driven on a dead shaft), but i don’t have any plans for that at the moment.
Enraged Erector Set has been retired and recycled for parts.
The parts that got recycled from Lapsed Pacifist and Enraged Erector Set went into a new non-competition bot, which I have dubbed Training Wheels. Training Wheels was created from leftover Actobotics components and designed to be a simple and safe first bot for my daughter, currently two years old, to learn to drive around the house and play with robots like daddy.