The short version

Mostly Harmless won the obstacle course challenge and decimated the targets in the arena, but got its ass thoroughly whooped by the fearsome drum spinning Ascend robot in the finals. To the audience’s disappointment, the whooping didn’t take too long. The robot was on its back - dead in the water after just a few seconds.


Robot fighting is a spectator sport and the audience demanded more carnage. We took it upon oursevlves to deliver it - in an informal free-for-all fight that was arranged after the official tournament had ended.

This fight lasted significantly longer due to the friendly hands that kept flipping the robot back on its wheels and then throwing it back into the arena. “Mostly Harmless” was finally able to extract its pound of flesh - and then some.

Design afterthoughts

  1. The carbon fiber shell absorbed most of the impacts and protected the interal PLA structure from most of the damage. 30% infill goes a long way if you have something that can shield you from hard impacts. At one point something (probably Mostly Harmless landing on its back) impacted the arena saw blade hard enough to dislodge the contactors of the motor assembly beneath the steel table. This impact did nothing to stop the AliExpress motors from spinning or to stop the AliExpress electronics from functioning correctly.
  2. I had added killswitches on top of the robot. This was to be able to shut down the rotor, in case I lost control of it. Having these gnawed off in the open position did not improve my chances of winning. Neither did the lack of a self-righting mechanism.
  3. The blade and rotor assembly turned out to much more robust than anticipated. I had expected the 1mm steel blade to shatter when impacted orthogonally by a spinning drum, but it didn’t.
  4. With the exception of the damaged killswitches, the electronics, wiring and drive mechanism survived after having taken a significant amount of beating.
  5. The robot had a relatively chunky rare earth magnet providing downforce. This was not enough to overcome the upward directed forces from the spinning drum. MOre magnets - or drum killing fibers will definetly be needed in the next version.
  6. It was a really good thing that no one else had a high speed saw blade attached to their robot - since it would have sliced through the carbon fiber shell like it was air.

All in all, it was a good fight.

I sincerely hope that more people will build robots and join the next tournament. Robot building in this 2 kg weight class doesn’t have to be complex or expensive. You can find most of the components needed in your average RC car. Just bolt on some armour and a weapon that goes BOOM. Then - let it rip and hope for the best.

I haven`t had this much fun in a long time. Big thanks to Omega Workshop for arranging the event.