3lb Beetleweight Combat Robot
Stats:
- ~10 mph Shuffler Drive
- 1.1lb Hardened Steel Beater Bar
- 4s 1550mAh LiPo Battery
- 2814 Brushless Weapon Motor with Custom Machined Aluminum Mount and Pulley
- Custom Carbon Fiber, UHMW, and TPU Chassis Construction
Achievements:
- NHRL Active Rank #9
- NHRL 2025 Rank #8
- April 2026 NHRL – Winner
- November 2025 NHRL – Top 8 Finish
- February 2025 NHRL – Top 8 Finish
Highlights:
April 2026 NHRL
Quarterfinals versus #11 TurboFIEND
November 2025 NHRL
Round of 16 versus #6 Chainsaw Kitty
Design:
Blunder is a 3lb Beetleweight combat robot designed between my Sophomore and Junior years to compete in local and regional events with Team WPI.
As it utilizes Shuffler Drive, Blunder receives an additional weight bonus of 1.5lb. This weight has gone into making expensive custom parts durable and additional reliability into the shufflers.
Version 1 fought at two events, NHRL February and April. My debut in February ended in a Top 8 finish, only losing to the eventual champion and (arguably) most successful NHRL Beetleweight ever, Silent Spring.
Version 2 was a redesign completed between my Junior and Senior years with a focus on improving reliability and driving characteristics. Debuting at NHRL in October 2025, its first two events were filled with minor failures that ended each run quickly. Check out the Blog section to see previous event reports and current updates!
Check out Blunder’s match history HERE!
As always, my CAD designs are public for all to learn from! Feel free to check out Blunder’s V1 CAD or V2 CAD! Any design elements I chose are free to take, but please do not fully recreate Blunder for yourself.
Manufacturing:
As is the goal of WPI’s Combat Robotics team, Blunder was intended to be a teaching project and allow me to become more comfortable with machining large-scale parts.
The main structure of the robot consists of parallel UHMW 2.5D parts. Machined in-house, they are extremely cost-effective and impact resistant.
I have made quite a lot of these parts and taught others to use the mill as well.
I have also made a number of custom aluminum parts. These shafts run through the center of the shufflers and provide both structure and locating features for the cams.
These pullies attach to the motor for the weapon, fit for a 2L V Belt, and drive the weapon system while allowing for slip and shock isolation. The bores are a transition fit for the motor shaft, reducing the reliance on perpendicular set screws.
Most importantly, I created custom machined ring gears to decrease the reduction on off-the-shelf gearboxes.
