To begin 2022, the first goal was to change the tires on the machine. Bobby, who famously chewed up the Banebots 3-7/8″ 60A wheels on Demogorgon, used a Polyethelyene Cushion Foam which is both stiff enough to support the machine and handles a fair bit of abuse. Bobby uses several layers stacked on each other which gives the robot its characteristic width but I wanted to try a single 2″ thick layer and Cheetah TPU mounts.
Before that, a new 3mm Grade 5 Titanium nose piece was bent into place. A little bit of propane and a vice were more than enough to get the bend going and part was frequently test mounted onto the chassis to make sure the shape was right. After the snout was fixed, the foam was CNC’d on the router to form a recess for the TPU star hubs. The geometry allows the hub to push the foam like a paddle instead of concentrating stress anywhere that could possibly tear the foam. They are designed to directly fit over the Banebots T40 hubs that are already on the machine which allows for a quick face in case I have to switch back to the original Banebots wheels.
NHRL March 2022
Once done, a complementary flange was attached to the front of the tire to keep it on. Now that the tires were on its time to treat the surface so they have grip! The base was covered in 3 layers of rubber cement. The foam isn’t naturally very grippy so the rubber cement forms a base where 3 layers of body latex are added. The dried latex has the property of grippy rubber which is far superior to the normal foam. In practice the wheels did do an excellent job of absorbing damage, but as a result it tends to get eaten by the steel blades. In its first match against Minimizer the wheels were thoroughly eaten, forcing me to switch to the classic Banebots wheels.
Demogorgon then went on a tear winning against Smeezus, Kaleidoscope , and Firebug before losing its rematch against Minimizer . Much like Ugee and Bobby, Minimizer is one of the few machines that can reliably outreach Demogorgon and directly strike the snout. While the nose guard kepy the weapon system protected, the 3mm Ti could only last but so long against a weapon that big so it lost. Because Demogorgon uses a live shaft, the weapon acts like a third wheel which can help keep the robot mobile during a match if wheels are destroyed (which definitely happened in this match) but when it gets bent or the ball bearings in the weapon get worn out then it can also fight the drivetrain. In this case, the weapon was pushed so hard that the motor, which is driven indirectly via a 2L V-belt, got so hot that the epoxy holding the motor can together melted, separating the motor! This is the first time I’ve ever seen this type of failure mode on these motors, but it really speaks to how hard it was working to keep it in the fight as long as it was!
NHRL November 2022
Though Demogorgon had already qualified for the December Finals, I still wanted to test ways to make a machine whose drivetrain was extremely reliable and a snout which could handle any beatings. In order to accomplish this, a second Demogorgon made from spare components of the original was made to test the theory. This machine used the Vex Versaplanetaries found in Phenomenon on the same 9:1 ratio (as there were not any higher reductions for single stage) and with 1450kv D3536 Turbo motors from Amazon. With smaller diameter wheels, this pairing would be an incredibly quick pushy bot drivetrain but with the 4-7/8″ Banebots wheels this means it has a top speed ~30mph which will never be fully utilized. For the snout, it was primarily composed of Tegris cut-offs from Mammoth which have proven immensely resistant. However, since Tegris is woven polyetheylene it did not bend when exposed to a heatgun the same way that UHMW will but rather it begins to melt the little strands and ruins the material. Instead, a single piece of 3/8″ UHMW was bent and formed a loop around the nose of the machine. Usually the nose is a separate piece as to minimize the transfer of shock, but this robot was an experiment so I’d give it a try. I also used more 3/8″ UHMW to make wheelguards with the hopes of keeping the wheels around as well as allowing the robot to be more balanced on its head since its inverted configuration is also extremely effective.
Demogorgon’s weapon was pulling the robot very hard in the drive test box which led me to remove the bottom cap on the machine and try to round off the screwhead as much as possible to avoid digging into the ground. In its fight against Cappuccino the nose dug into the ground anyway and it couldn’t maneuver. The back was then struck and instantly killed the robot. Fortunately the side struck was had the controllers instead of the batteries. While this certainly wasn’t good, it was still serviceable so the robot was repaired and sent out again to test the other new features.
The fight against Blue Cheese was arguably its most destrucive one yet as the front snout was exploded. The good news was that the weapon cradle remained incredibly strong against the biggest weapon shot it could have ever received. Though its not the best way I’d like to learn it, this does prove that the method is correct and just needs some light modifications or updates for the future. The bad news has a couple layers to it. 1. Don’t use a single bridging piece as the UHMW ring connected to the side armor which transferred the force into the baseplate, bending everything like a force wave. The way the face ripples out like an explosion best exemplifies the level of energy put into the robot.
NHRL December Finals 2022
For the December Finals, Demogorgon received some nice carbon fiber pieces through CNC Madness. This switch alongside switching the front armor to 1/2″ UHMW gained enough weight back allowed to fully attach the 3/8″ UHMW side armor. Additionally, a small piece of carbon fiber Nylon was attached to the nose with the goal of supporting itself more evenly while inverted. Before this would just ride directly onto the nose which risked digging into the ground since it came to a point. This sculpted top piece spread the load and ensured a more even ride.
Once one machine was complete, the second was done in a similar fashion and both versions were ready to fight!
Demogorgon’s first fight was also the very first fight of the day against Drop Kick! It was a solid contest that revealed a weakness in the side armor (namely that it could be pulled off and bent to hamper the drivetrain). However, it did serve its purpose of keeping Drop Kick away from the wheels as noted by the cut marks on them. The most impressive damage was how the impact bent the midbracer by punching the edge of the weapon cradle. Its only a slight bend that doesn’t affect is ability to function, but the force is still incredible to see. Fortunately nothing was damaged so after checking other parts of the robot, topping off the batteries, and removing the wheelguards it was ready to fight Jamison Go and Saiko!
Demogorgon’s fight against Saiko was uniquely interesting as even though Demogorgon is a “undercutter” in intent, the body is so high because of the nose and wheels that it becomes a midcutter against a machine like Saiko. This is ironic as Jamison wanted to test the wedge attachment against a real horizontal only to find that Demogorgon hits just over it! This realization on just how high the body is will be considered going into future redesigns.
In the fight itself, the high setup allowed Saiko to incredibly grab one of the mounting bolts that held the snout onto the machine. It’s a shot that is nearly impossible to hit, but the geometry works out that Saiko can reach it and Jamison is just good enough of a driver to shove his robot’s face into it. The force pulled the nutstrip through the carbon fiber baseplate. Though carbon fiber is incredibly strong especially for the weight, its failure mode is to shatter instead of bend like the original 6061 aluminum baseplate. Though it avoided the incredible damage sustained in the losses in November, it was still a very disappointing way to lose the first fight.
Demogorgon’s third and final fight was against Richard. In no uncertain terms, Demogorgon had the advantage and would certainly had won if the robot kept its nose straight. Unfortunately, the torque twist from the weapon was so sever that the robot turned itself around and left itself completely open to impact causing an immediate gutting. The torque twisting is easily the most annoying aspect of this robot and would have to be addressed in the future.
Bone Dead Robotics 