Blastwave IV

1lb Drum Spinner (2023)

For an overview of Blastwave as a design, please go here

Blastwave IV Logo Blastwave IV Circle

Overview

Blastwave 4 was a hastily-made attempt to solve a number of problems I noticed with Blastwave III. Since Blastwave III did not compete in 2022 due to car trouble q(-_-)q, I had a lot of time to think about ways it could fail. As with all of my combat robots starting in spring 2023, it was modeled in PTC CREO, as my Fall 2022 internship made me enjoy that cad package more than Fusion 360.

One potential failure mode that I noticed when doing the fight writeups on this very website for Blastwave I and Blastwave II was that I kept losing lids. I had switched to using standoffs pressed through the body on Melon Brawler 2, and realized that this would be a great way to prevent this issue from happening.

Blastwave IV Standoffs

Another way I was concerned about failure occurring was through the sides of the chassis squishing the drum and impeding spinup. The plan for this was to utilize the shoulder screw from Blastwave III, but cap the head between some aluminum plates to prevent it from moving outward. A section view can be seen below.

Blastwave IV Shoulder bolt

As with previous Blastwave iterations, the chassis would be printed out of PLA. While that was an unorthodox choice, I did not have a printer at the time that could print with anything more exotic. I had purchased a Voxelab Aquila S3 in August 2023 with the intention of printing new bots with Prusa's PC Blend, though this printer had so many issues that I just worked on getting PLA printing reliably. Would this cause me issues later on down the line? (probably, since I'm foreshadowing it this heavily)

Another concern was the battery, I had to run a very small battery due to weight constraints, which I was also concerned about. In addition, the C rating was much lower than the recommended values. By the time I realized this, it was about two days before the event and there wasn't time to fix it.

The final weight of the bot came out to about 453g.

Blastwave IV being weighed

Speaking of the event.... Minnesota Monster Mash!!!

Blastwave's first "fight" was against Stomp_Bot_2. I withdrew from this match, since I didn't want to fight myself.

Blastwave Vs Hangry Bee!!

Blastwave's first actual fight was against Hangry Bee, a pretty cool vertical spinner, where Blastwave vibrated across the floor when the weapon was running, and then stopped working due to apparent electronics issues. My first thought was that the battery was too low to function, but that wouldn't explain why driving didn't work when the weapon was on, and replacing the battery with a new one worked flawlessly. The C rating of the battery was still significantly lower than what was recommended, so I'm currently chalking this failure up to the battery.

Blastwave IV Vs Hangry Bee

Blastwave Vs Beginner's Luck!!

Blastwave's second (and last) fight of the event was a grudge match against an undercutter called Beginner's Luck. This fight was an object lesson for why PLA should never be used in combat robots. Blastwave was in pieces by the end of it.

Blastwave IV Vs Beginner's Luck Blastwave IV Aftermath

WHAT'S NEXT?!

This was a pretty disappointing showing, all things considered. Despite my repeated insistence that I'd retire Blastwave if V4 failed me, I can't stop myself. I learned too much and have too clear a picture for how to fix it.

Plans:

  • Switch to TPU chassis to improve resilience
  • Switch to higher capacity battery with a higher C rating
  • Move away from 20mm gearmotors to reduce weight

To see how these plans worked out, please check out the Blastwave V page.