Bone Dead Robotics

Time for the second and most famous event at the Hive: Hive Hysteria! This event holds a special place in my heart as it highlights both the tremendous effort of my dear friends at Team Honey Cracked to host above insect-level fights locally but also because so many other friends from groups such as Team Defective, Leatherbacks, and Black Cat Club all come with incredibly strong machines but notably not in the serious environment of NHRL. It’s a bit more relaxed of a pace but still competitive enough for some good fights.

Details for the event and more about can be seen at the Behind The Bots interview here!

Since Play’n Krazy was already fixed after Air and Armor, attention turned to making a new robot for the occasion.

The Rise of Vecna

The great challenge for Hive Hysteria was what to build in the 12lb class. With Demogorgon’s last return being swiftly ended by Blue Cheese it would have to be a new direction. Mind Flayer’s last outing indicated its rebirth would require more work. It was time to move to the completion of the Stranger Things naming arc: Vecna. As the most imposing antagonist with a more cerebral plan than the previous two it was important to distinguish this robot from the previous two as well.

After some months of wrestling with design paralysis I found the old hubmotor used on Phenomena at Robot Ruckus 2024 and drew inspiration. While this hubmotor was too heavy for use on a beetleweight effectively, the large bearing used should prove strong enough to handle the loads of the hammersaw. Alongside this were many of the old Versaboxes formerly used in Phenomenon. The 3520 motors paired with a 9:1 gearbox should be more than sufficient to move the arm and self-right the machine with minimal additional reduction. With these two old components as guiding lights, the designing began.

The design cycle for Vecna took place across the month of June into roughly middle of July. Originally width was the center priority, but that quickly shifted once the use of the hubmotor and Versabox began naturally constraining other factors.

Machining of the robot moved along fairly quickly thanks to the use of thin aluminum and UHMW which were happily machined by the router. To both expand design creativity and test the effectiveness of the material, the entire front was designed to be one large printed piece of TPU. After acquiring a large-format printer and swapping it to a 1mm nozzle, initial prints began. The hope was the large diameter nozzle meant thick perimeters of the material thereby allowing some flexibility to absorb damage, but strong enough where most hits wouldn’t dig in too deep. It took a bit of tuning to get the print to be fast and consistent but ultimately the method proved supremely helpful; it is a methodology that will likely be applied on future robots.

While the other mechanical placements such as the motors, shafts, and belts came together pretty quickly, the electronics placement was tricky. Ultimately the electronics were placed inside a PA-6 Nylon cage under the hammersaw’s output pulley as the center cavity was purposefully left open in case these could not fit on the side. The 3x Sequre 70A ESCs were soldered and hot glued into place then the mount itself was bolted and glued to the baseplate. While this would be a risk if someone struck it, it would be a calculated gamble as so much material was protecting it in other directions. A Rhino 80A ESC was taken from Phenomenon’s spares and paired with the Versabox to control the arm. After a bit of wire routing and fine details, Vecna came together in a little under a week of work. Time flies when you’re having fun!

Before competition, the final touch was added. Little details like this add so much personality to machines and just make them easy to identify. Definitely add names to robots in creative ways!

With both bots done it was time to go compete!

The Event

With both machines ready (and a surprise cameo by Phenomenon!) it was time to get the machines going. After getting through a brief hiccup in safety (the set screw on Vecna’s arm needed a deeper groove on the shaft to sit in), both machines were ready for their fights!

Play’n Krazy

PK began its day with a fight against Lucidra from Team Defective. Lucidra had a hubmotor made from an anodized aluminum beater so it was very similar to PK. Foolishly I left the steel forks on PK (they were there for weighing at safety) which fed Lucidra most of the fight. Fortunately for PK (unfortunately for Lucidra), their weapon shaft bent, seizing their beater and let PK wail on it for awhile before getting them stuck on their face. Though not a clean fight, it was one win and another token.

Win by KO, 1-0.

PK’s second fight was against IMPAKT. It’s become a tradition now to face it at Hive Hysteria so we fought. It was a fierce battle for the first quarter before IMPAKT began to get the upper hand. One of PK’s wheels mysteriously went down (it felt smooth after the match so likely an electrical connection) which gave IMPAKT the clear upper hand. In the second half the Scarab hubmotor seized up. After lasting to the end, it was confirmed that the magnets had shattered at some point, seizing the weapon. Despite this, the Scarab’s modularity meant this part could be switched out and it was good as new! The body of the drum was gnawed but generally useable. Hurray for repairability!

Loss by JD, 1-1.

Due to the busy day and ultra competitive fights, this was the end of PK’s day as much of the energy went to Vecna. Without much work the robot could be back up and running in no time!

Vecna

Going into the first fight against Reaper (half of the HoneyBombers) there were deep concerns. What if the assumptions were wrong, what if something vital was struck early in the day and it was unable to be fixed? This plagued Demogorgon last year so would it plague Vecna? Fortunately not.

In a strong driving match, Vecna smothered Reaper’s weapon despite many dangerous shots near vulnerable places. the Nylon weapon pulley was struck but by mere millimeters the central belt was avoided. The center frame rail was struck not far from the weapon pivot but it also did not matter. The TPU wedge held up magnificently with little damage at all (though the UHMW frame rail it threaded into will clearly require deeper threads to resist strikes to the corners). The hubmotor did not play much of a roll both for the fear of being struck by the blade of Reaper and never being used at a damaging power level for fear of breaking. Over the course of the event the programming on the ESC was tuned and the power level gradually increased as trust grew until it land a truly damaging blow. Strangely the 5mm HTD belt inverted itself on one side of drive. The machine still drove well so not real concerns but it did keep occurring throughout the day likely due to something messing up the pulley profile.

By the end of the fight, Vecna had controlled the match excellently, starting its career with a win against a very solid opponent.

Win by JD, 1-0.

Vecna’s second fight was against Psycho Smashy, a wide vertical spinner much like Blue Marlin or even Phenomenon. It was the perfect time to break out the long forks. Using a combination of the steel billet tips made for Phenomenon and 1/2″ aluminum (except for the center fork) it was a light but very stiff solution to strikes from vertical bars. Hopefully this fight would prove good data against this archetype.

The fight was a solid driver’s contest with Vecna initially controlling the fight but Psycho Smashy’s crippling of one drive side led to a quick collapse. Much like lifters, hammersaws accept a very thin margin of error and this fight showed it. Though all essential functions still worked (the bent hammersaw arm did not effect the hubmotor), it was a good indication that upping the turning speed is essential when the fork length is so great. Fortunately the TPU mount and aluminum fork bodies were relatively unaffected by the attack. The TPU material ablated easily and didn’t transfer force into the other parts of the robot and the thicker aluminum bent but ultimately maintained function.

Loss by JD, 1-1.

At this point in the tournament, Vecna was sitting at 5th place, just outside of the top 4 cutoff for the final bracket. To hopefully get enough wins to get into top 4, it was time to challenge Gamma Ray.

Vecna’s third fight against Gamma Ray was certainly a strong showing for the hammersaw. Having tuned the ESC settings better and developed more faith in the hubmotor, it was time to let it fly and fly it did. While Gamma Ray wasn’t that thoroughly damaged (partially due to the disc on Vecna not being optimized for maximum bite) it did tear very well into Gamma Ray’s TPU chassis and affected other parts of the robot. All in all, a strong showing for Vecna.

Win by KO, 2-1.

Sadly this win wasn’t enough to get it into the final bracket as the top 4 machines all managed to nab one more win before the cutoff, keeping Vecna out of the top spots.

In the downtime before the end of the event, Vecna held a grudge match against Inertial, a shuffling shell spinner. Though Inertial had a difficult day, the team were great sports and wanted to get as many fights as it could, much like I was hoping to do for Vecna. Similar to the Gamma Ray fight, Vecna was able to utilize its control to lay down some good hammersaw shots, especially its final hit which saw the weapon use ~80% power without failing.

Win by KO, 3-1.

Conclusion

Though no new trophies were taken home, it was one of the strongest debuts for a team robot in awhile. Vecna proved a worthy successor to the naming scheme and a design worth investing in for the future. Though the high competitivity of NHRL is worrisome, if it could do well here it will go there at one time or another. All-in-all, a very optimistic view ahead!

Thanks for reading! Check out some of the other blog posts and build logs!