Following the victory of my previous 1 lb robot BRANDONBOT, I once again had the privilege of serving as team captain for my biggest robot yet: Sawii. With only 4 months to design, model, and manufacture a brand new 15 lb robot, I knew the challenge was on. What I didn't know, however, was that it was going to be 4 long months of many, MANY lessons to learn.

What is a hammersaw?

A "hammersaw" is a type of combat robot weapon identified by two main features: a spinning weapon (the "saw") attached to the end of a rotating arm (the "hammer"). Since most combat robots fight with their weapons in front, builders heavily armor their sides while the top is left thinner to optimize weight. Hammersaws exploit this choice by attacking from overhead.

ACT 1: PROLOGUE

The Design Process

In addition to the complex weapon system, I also decided on kiwi drive: a complex, omnidirectional drive system. I wanted the robot to be highly agile to outmaneuver, pin, and slam its weapon down onto its opponents as its strategy. Fortunately, I quickly scrapped the idea. 

Lesson 1: One complexity is fun. Two complexities are a mess.

With kiwi drive out of the picture, I began working on a block CAD for our robot. As a way to have fun, I decorated our robot as a cat wielding a Wii remote replacing our saw, giving our team our glorious name: Sawii.

Lesson 2: Work hard, play harder.

As the months went on, Team Sawii continued their work on each system of the robot, with me overseeing, combining, and improving each contribution. With this being all of our first times building a 15 lb robot, we found ourselves lost and/or confused many times. However, with the help of advice from Berkeley's previous team captains and setting deadlines for new versions, improvements in Sawii steadily came one after another.

Lesson 3: Ask for help. Then ask for help again.

The Final Design

After 4 long months of designing, calculating, and working with our sponsors, we we finally received our manufactured parts featuring:

• 6061 Aluminum chassis from RapidAxis

• AR500 Steel saw from SendCutSend

• 4130 Chromoly steel forks from SendCutSend

Upon receiving the parts, I further machined them; I cut and tapped shafts via a lathe while the aluminum rails were drilled and tapped via an end mill. 

Lesson 4: Don't know where to drill the holes? Don't use a Sharpie!

Preparations

Although we had scheduled our parts to come in 2 weeks before the competition, an unfortunate miscommunication in measurement systems led to delays in our parts arriving. The result? We had 4 days upon receiving our parts to machine, assemble, and test EVERYTHING. Thankfully, we managed to complete the robot in time.

Lesson 5: Even American manufacturers prefer metric over freedom units.

Our Downfall

With a working weapon system and fully assembled robot, I was excited to compete. As the driver of the robot, I knew I was in for a fun time. That being said, how did we perform at the competition? 

We didn't.

Unbeknownst to us, instead of competing, we would spend the entire day troubleshooting Sawii's electronics. In an attempt to optimize our budget, we were given old electronics, recycled from last year's robots. Electronics that didn't work how they used to anymore.

THE ULTIMATE LESSON: Reliable isn't cheap. Don't be cheap.

Throughout the competition, we could only reliably get 3 out of our 4 motors to work. Although we tried replacing the electronics, poor performance in the older components led to the failure of the entire electrical mechanism. Regardless, we were able to get ONE match against the winner of the competition: a fast control robot named Lunar Eclipse.

Despite not being able to destroy and get destroyed by other robots like I had hoped, I still ended up having a great time at the competition and now get to keep Sawii as a souvenir while it hibernates for another opportunity to perform. Where would that be? Ideally, Sawii goes on a diet, cutting a few pounds to compete at a 12 lb competition in the near future. 

Regardless, I learned a lot and now look forward to my next big role: the new Vice President of Mechanical Engineering at Combat Robotics at Berkeley!

CAD files, Bill of Materials, and more can be found on my GitHub.

MEDIA GALLERY