Nitro - 13.6kg FC Drum Spinner

Howdy all, not sure how relevant it is here but thought i’d dump all the photos I have taken of my featherweight robot Nitro over it’s build and events in 2023.

Prior to the featherweight, I built a hobbyweight called Semtex back in 2021, which did pretty well and was great fun to use, loud and angry little thing it was. Having always been a fan of drum robots, I ended up taking the plunge and wanting a featherweight version…


An earlier version of Nitro in CAD mid 2022, I’m glad I didn’t build this version of the robot as I think it certainly wouldn’t have been as reliable as the 2023 version!

CAD of the actual Nitro. Lots of learnings from my previous robots went into making it as robust and reliable as possible.

Drums being EDM cut, machined and heat treated in China, was very happy with the price on these. Decided on 4130 steel with a relatively soft hardness for these to avoid them breaking.

Partially built pretendo/test fit! A combo of aluminium, titanium, hardox and TPU here

The first weapon motor assembly. XTeam 4092 from aliexpress used for this. This is isolated from the frame via some TPU pads to shock mount the motor, and the 5mm shaft is supported with bearings in the main plate as well as on the other side of the pulley.


Robot mostly finished, being checked over by one of my top team mates.


Mostly symmetrical drive pods, to save on machining cost and make spares easier. These plates are shock mounted the same way as the weapon motor, and belts are used so that when the robot takes a lot of punishment, the drives will be harder to seize up.

The motors used are 5045 outrunners from Aliexpress driven by 80a Simonk ESCs. The wheels are actually large bushings, a thinner version of what is used for heavyweights such as Tantrum/Blip, which I got fairly cheaply last year in America from Mcmaster, coupled with aluminium central hubs and 3D printed pulleys.


Evolution from Semtex to Octane and Nitro (designed/built at the same time), I don’t have an addiction, you do! - First arena test of the robot, it is loud!

Round 1 fight against Ironside and Synthesis - This went about as well as I could have hoped, the robot worked and I managed to KO both opponents fairly quickly.

Second fight against the scary Explosion, and my fork/TPU combo as ground game, which proved to work well and resulted in a win after a slow start to the fight.



Third fight against the shiny Shogun, the forks went straight under his wedge resulting in a fairly quick KO.


Fourth fight was against Amnesia, which ended up being a very exciting and close 3 minute tussle, sadly resulting in a split decision loss for Nitro.


Going back through the losers melee with a bye, I was next against Telekinesis in the semi final, my other/previous featherweight build under a different driver…
Being a bit of a madman, I decided we should both full send for this and the better built robot would win.

tele 2

nitro tele

Then the final against the scary Killi Pepper, this got very dicey as I lost my weapon, due to the weapon motor assembly moving in the chassis due to some stripped mount threads, but ended up with the win as Killi Peppers links came out.

This was a great weekend and I was chuffed with the robots performance! With a few small changes to make to add to the reliability.

ff pic

After this event, I added some extra security to how the weapon motor setup mounts into the robot, with some extra keying to support the bolts that came out previously.

Dojo time!


After 4 tough fights, including a stand out one against Slice of LiFe by Euan where I took heaps of punishment after my weapon motor wires breaking but still managed to win due to his battery dying from doing so many spin ups (we counted 26!), we managed another win, photo’d here with Isaac and Euphoria, the Sportsman winner.

On to november Dojo with more small changes!

New harder weapon shafts since the previous ones bent both events…as well as trying taper roller bearings in the drum, rather than deep groove bearings which just about managed to last an event before biting the dust. Also changed the design of the weapon motor mounting plate to strengthen the mount points.

dojo nov

Some damage I hadn’t seen yet, was from Gunblade which managed to catch the weapon pulley directly here, bending the flange but not quite stopping it! Some disassembly was required…

Like the event prior, the last fight of the day happened to also be a playoff for 1st place, against Slice of LiFe. This time around, my weapon stayed reliable and I got the OOTA win without taking as much punishment to the chassis as the time before. Great footage of the fight from Euan’s GoPro here:

That just about sums up my 3 events so far with Nitro, really a case of improving on each failure as it comes to keep improving the robot further. Hopefully will get lots of further use out of the robot during 2024!

Thanks all for reading, I know this has been a long one!


All of your drum bots are such inspo, really cool to see how this one came together!

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Thanks Henry, much appreciated!