Building a 1lb Bot to Face Down 3lb Opponents

My daughter helping build her first bot

After she got the chance to watch her first competition at the fall 2019 NERC event, my young daughter started expressing her desire to “Help daddy with his robot.” Since I don’t want her messing around with a bot designed to achieve more KE than most handgun rounds, I decided it was probably best to build something a little more tame.

The same event gave me the chance to see the 1lb bot Slim Pickens taking on 3lb opponents (as part of the impromptu multibot Regret) and not only holding its own but actually winning multiple matches. This got my mind churning on the possibility of one day fielding a multibot of my own. If I’m designing a multibot with at least one KE weapon, it makes sense to leave most of the weight for the weaponed bot so it can still pack a useful punch. So that would leave me with 1lb for a wedge bot that can survive facing 3lb bots. The quest for a durable wedge bot begins!

Slim Pickens, one durable and well driven bot

Probably the most important quality of any design is durability, and that is doubly important if you plan to face opponents that have triple your weight. For a wedge bot, that means having a drive system that just won’t quit. A pair of 22mm planetary gear motors would be right at home in a normal 3lb bot, so they should give 3lb pushing power and durability to this little bot. The durable frame takes notes from the design style that has worked well with my 3lb bot, featuring metal plates sandwiching threaded aluminum spacers to form the chief structural component, 3D printed nylon walls to finish out the electronics enclosure, and press fit square nuts to provide horizontal attachment points for the motors.

1lb wedge bot design showing the overall frame design

My past experience with fabricating my own titanium wedge and hard-mounting it to the frame proved to be less than successful, so for now I am sticking with pre-fabricated wedges like BotKits’ Candy_Wasp wedge and trying something a bit different for the mounting. Another key to the (hopeful) durability of the design is shock mounting the armor and wedge attachment points, an idea borrowed from Slim Pickens which makes the bot inescapably look extremely similar. The shock mounting is achieved by sandwiching some rubber bumpers between the wedge/armor and the main frame, allowing them to flex a bit and absorb impacts instead of jolting the electronics or allowing more permanent deformation to occur. Add in using springy TPU filament to print the wedge mount, and I’m hoping that the wedge will stand up to some serious punishment.

Exploded view of the components

A single unarticulated wedge might work great for facing down opponents with horizontal weapons, but it wouldn’t be the best choice for facing down other wedges or vertical spinners with some form of feeder wedgelet. For this reason I have also designed another front attachment with two hinged AR500 wedgelets to better face these opponents. The mounting is again printed from TPU for shock absorbtion, but I also designed it to be printed in 5 separate parts rather than a single part because it allowed me to avoid having layer lines intersecting with any of the mounting holes to create a potential failure point.

1lb wedge bot design with work-in-progress 2lb vert design for a theoretical multibot

So that’s the basic design for the durable wedge. I have no plans to run it myself as an antweight bot, so it will either wind up as part of a multibot if I can convince anyone to join me for an event or potentially as an indestructible 1lb for my daughter to cut her teeth with if she is still interested when she gets older. I already have some half-completed designs for a 2lb vertical disk bot that could make up the other half of a NERC-legal bot, and if I ever make it up to the Norwalk Havoc events with their unique 1lb multibot weight bonus I could potentially just throw it in with my normal beetleweight to spice things up a bit!

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