Duct Tape Special (DTS) is a 1lb, 3D printed combot built for the Fall 2017 Design.Print.Destroy! Competition.
The final version was printed and assembled the night before the competition (a quick reprint due to breaking the first frame print.
To start, we wanted to go with a drum bot. Since this was the first robot for most of us, we didn't want to try anything too crazy. This seemed like a simple design, and wouldn't require too much mechanical design to get right.
A drum seemed to have an advantage with simpler mounting and less shear to worry about, so we went with that. The ruleset explicitly mentioned bolts/impactors being allowed for weapons, so that seemed like a natural attacking edge
For the frame, we went with a single unibody design. Yet again, less parts seemed like the way to go. The only major concern was making a large enough box to fit all of the electrical components, and to have some form of mounts for all the components.
Our First prints turned out great! These were done in PLA, so we decided to make some small changes and reprint in ABS
DTS: The Reprint
Following the first prints, we decided to reprint the frame on the iRobotics Ultimaker with some more space for our electronics. This was an 8hr print (with a little over a day to go), so we opted to skip the lid and go right into assembly.
This ended up being a good decision because we did not account for wires or some last minute changes. Luckily, the rules allow for tape in "non structural applications". After giving up naming rights to our bot, we were given the all clear on our somewhat structural duct tape.
Last Minute Electrical
After arriving at the competition, we learned the hard way that RC car receivers do not typically have failsafes. This is especially concerning in RC cars with unstable weapons strapped to them, and to say the least we did not pass safety.
Luckily, we were able to scavenge a quadcopter receiver and transmitter from iRobotics and successfully perform the surgery. Sadly, this meant the duct tape was in full effect since the receiver was larger.
The Component Breakdown
In the final robot, we ended up using FingerTech Silver Spark motors with FingerTech TinyESCs for the drivetrain, a 2204-2300kV motor with a 20A ESC, and a multicopter receiver (with mixing on the transmitter). We went with FingerTech Foam Snap Wheels for drive and a 500mAh Turnigy Bolt HV battery.
The Event Breakdown
We went 0-4 and took 5th! Which was a resounding success given the timeline for the robot. We learned a lot about what goes into combat robots, and what not to do in the future.
Our robot lost our first match against Kornizontal Spinner via a KO that detached our weapon uprights. After a copious amount of CA, we were back (and ended up shattering the weapon 2 more times in 2 different places in grudge matches).