According to the BattleBots Fandom website, there are 27 different weapon categories.
From cage spinners to thwackbots, choosing the best bang (literal) for buck is a balancing act for all BattleBot designers.
“Your goal isn't necessarily to completely destroy the outside of the robot. Sometimes you need to get a really lucky hit and unplug one wire or break somebody's PCB on the inside of the robot,” said James Nguyen, an experienced combat robot competitor and BattleBots contender, during a guest appearance on Innovator’s Insider Episode 38: Switchback and REV Robotics.
So, as part of a partnership with Team Midnight Invention, this year’s Onshape Live ’23 Design Competition gave participants a formidable challenge: Design a weapon system that can take on any bot in the BattleBox. The winner will see their design prototyped by the Midnight Invention Team.
The Onshape Live ’23 Design Competition
The challenge: Design a new vertical spinner and wedge system for Switchback, the robot designed by veteran BattleBot team Midnight Invention. The team has taken on some tough bots during this year’s World Championship VII season.
Design competitors were given access to Switchback’s Onshape Document (minus the forks and wedges) to make a copy and design their own system for the bot.
Switchback is a versatile combat robot with a number of armor, weapon, and fork configurations. It sports a four-wheel drivetrain surrounded by a heavy skirt of AR500 steel with mounting points for forks and defensive wedges. With an articulating arm on top of the drivetrain, Switchback can adjust the height of the vertical spinner, lift opponents, and self-right all in one integrated system.
But, the team wondered, could the articulating arm be designed better, tougher, stronger? By inviting CADders from around the globe to put their own ideas to the test, Switchback can prototype some exciting new designs in the offseason.
While we saw some cool ideas and nice design workflows, we could only highlight a few. Here are three winners of the Onshape Live ’23 Design Competition based on modeling best practices, functionality, and overall awesomeness.
Third Place: Rising Huckaby
Also known as the Switchbeater, this system was designed with two modes. On one side, the eggbeater weapon has sharp edges that would work well for tearing an opponent apart. By "switching" which side is faced up, the blunt side will be exposed. This side of the weapon is more round, and better for weapon-on-weapon fighting. Their vertical spinner has a higher moment of inertia and KE than the existing spinner and delivers an equivalent bite.
Because of the total weight of the wedge system and vertical spinner the back plate will need to be removed for the robot to meet its weight limit. This is not a detriment to Switchback's defense, however, because the mobility of Switchback's arm will allow it to defend this area if needed. The wedge system features serrated wedges that help Switchback get under and hold on to the opposing Battlebot. The new weapon is colored similar to Switchback's past suite of spinners and fits the aesthetic design perfectly.
Both the wedge system and the vertical spinner are made of 4140 steel and could be machined using wire electrical discharge machining (EDM) and CNC milling.
When explaining their design process, Rising shared that for both parts they started by using Onshape's Derive feature. They then used construction geometry and feature folders to draw constraints on the design of the part. They composed a reference sketch for each part and continued editing until happy with the shapes. Throughout the design process they tracked their ideas and iterations using Onshape’s versions.
Second Place: Team Razorback
This design comes from Team Razorback. The designers for this team are Aaryan and Gregory, who are both students on FIRST Robotics Competition Team 3467, Windham Windup.
Their design uses forks with serrated edges on the backsides, making it harder for the opponent to escape. It also has a small plow attached to the front armature forks that can tilt to adapt to the floor against bots that rely on a single point to get under its opponents. The weapon is a large eggbeater drum similar to Switchback’s current design. However, in order to improve total moment of inertia it is quite long in comparison. This is to prioritize hitting power, enabling the 30-pound weapon to create the most damage possible at close to max speed.
The forks coming off of the arm feature a plow that articulates to try to stop other forks. The “razorbacks” of the forks also make for an intimidating look, with some extra orange arrow insets where practical to help the additions fit in with Switchback’s existing aesthetic.
This team shared that one of the most useful Onshape features in their design process was the Part Studio in-context tool, which allowed them to get a very good idea of which dimensions the parts would need to have. It allowed them to not have to model everything in the assembly to make sure the parts meshed properly. They then could just use a surface in context to design their parts.
First Place: Share Horizons Club
And this year’s champion is Share Horizons Club! Does the name sound familiar? Share Horizons also took home the third-place prize during the first Onshape Live ’21.
This year, they awed us and the Midnight Invention team with a unique aesthetic, inspired by Thor, and excellent functions that can deal serious damage. As the winner, the Midnight Invention team will prototype Share Horizons’ damaging design.
Their design features a complex spinner design that has a large moment of inertia and a wide area to hit opponents. Balance is improved with the center of gravity coincident to the spin axis. It’s designed to rotate and hit the opponent from below while the spikes help lift it up. The unique plow design aims to catch opponents and push them into the spinner.
Designing for steel fabrication, the Share Horizons team used the Lighten Custom Feature to optimize the weight of the fork system.
Share Horizons shared that the mass properties tools in Onshape helped optimize the center of gravity and weight. They modified the depth of the hammer runes in order to balance the spinner system weight and adjust the center of gravity.
They also utilized some of Onshape’s in-context modeling functionality to design their components in context with the provided assemblies.
Onshape allowed them to work collaboratively as a team, dividing some of their modeling between Parts Studios to give them both space to work.
Congratulations to Share Horizons Club!
If you missed Onshape Live ’23, don’t you worry, on-demand sessions are available. Just register today and take your pick from four different session tracks and catch up on the latest Onshape news.