Recoil Build Log


After the disaster that was PMTH3 I realized there were a few pretty major changes I had to make in order to actually have a competitive robot.

First, MORE BLADE. Well actually more inertia. PMTH3’s blade was very short and stubby; while it was a nice hefty chunk of steel I wasn’t using my weight effectively, and overall I felt like the blade shape was not ideal.


Enter asymmetric straight bar. With the blade spinning at 10000 rpm, it stores almost a kilowatt of energy!

I also knew I needed a wedge. Wedglets are nice because they’re light and do help to get under people, but they can’t stand up to horizontal spinners (they just get ripped off). Luckily we have a very large quantity of 1/16″ Titanium (harder than 6al4v) leftover from the 250lbers.

For overall robot shape, for any combat robotics enthusiasts it should be quite obvious that Recoil is heavily inspired by Apex. The goal is to minimize the amount of weight for all components of the robot except for the massive blade in the front. Definitely an offensive robot.

First Spinup:

It also turns out that the blade has so much inertia that it gyro dances. This really helps to make Recoil unstable when inverted and results in almost immediate self-righting. (RIP FLOOR)


The finished product!

Hitting Titanium for fun:


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