Combat Robot Spinner Design Tutorial (Part 1): Theory and Math

Copperhead is best drum bot hands down.

Great video waiting for part 2

Another great video. It makes me feel totally inadequate, though. When I started out building combat robots (1987) nobody had computers or CAD. Heck, there wasn't even an internet! Our efforts were hilariously crude by modern standards. Nothing was calculated. Our 'Centurion League' machines weighed 100 lbs and cost a maximum of £100 each (one-hundred British pounds sterling).

No science, no physics, no formulae, no LiPos, no ESCs, no custom-machined components - just hunches and experimentation and many enjoyable hours spent scouring the local scrapyard with a socket set and a hacksaw looking for cheap bits of kit like starter motors, windscreen wiper motors, and old electric wheelchair controls.

Weapon-wise we had... nothing. No power, no mass, no momentum, no venom, no torque, no rapid spin-up. Pitiful. Just 12v motors and various lead-acid/gel batteries. Nickel-Cadmium batteries existed - we used them to power the Rx and servos in our RC planes - but they were expensive and short-lived and totally unsuitable for a combat robot. Don't forget we had a £100 spending limit. Putting together a worthwhile ni-cad pack for a weapon system would have cost over £150.

We had wedge-bots and ram-bots and a few very slow tippers or lifters. The nearest we got to destruction was with vertically-mounted circular saw blades: our opponents were often clad in aluminium plate [on a wooden chassis!], so the small teeth were quite effective. Small teeth were necessary because anything coarse would stall the puny brushed motor on impact. A flywheel would have helped, but just getting it moving would have burned out the windings. Sigh

RPM? 1,500 (yep!) was considered competitive. Whee. The awesome single-tooth or twin-tooth blade designs of now were simply unusable: no way to drive them. We tried a big petrol motor once; plenty of noise and speed but the exhaust was a problem indoors, and designing an effective [sic] clutch within the teeny budget proved impossible.

One thing about those early days, though: the wimpy weapons had a target no modern bot has. Its Rx aerial. We ran on 27MHz and the receivers needed a long (about 24") bit of wire situated outside the bot's bodywork. It didn't take 12,000 rpm and a 65 lb drum to kill a bot back then!

Despite the humble beginnings, though, something must have gone right because all these years later I'm still passionately in love with combat robotics. Too bad I can't afford to compete any more.

Anyhooo, I look forward to Part 2 of this. It's good stuff. :-)

Love your written bullet points. Can I get a copy of them somewhere?

Thanks to this I've finally designed my first bar for an antweight (150g) undercutter. I'm going with a standard bar as they are very easy to ballance and I'll have plenty of kinetic energy for some damage despite the MOI inefficiencies of such a design. I'm working on an asymmetric bar and a triangular bar as well for maximum experimentation and options. The triangle one gives me a lot of interesting ideas as far as tooth spacing and size goes.

How have I not watched this until now! It's soooo good! Brb designing new bars for Cannibal

Out of curiosity is there any downside to using titanium other than the cost in the beetleweight class?

My name is kdyn strouble I want to make combat robots for my show Kdyn Wars

So, I'm from a brazilian robotics team (kimauánisso) and we use 30% of weapon weight for the whole weapon system
like, we count the motors, the weapon itself, the bearings and so on...
Love your content! Keep up with the channel cuz u really help a lot of new incomers to the sport

How did you make that AR500 material inside Fusion360? I'm trying to find the density of AR500 to compare with the regular steel of Fusion 360 and get the real weight this way but all I'm getting are different values everywhere.

Extremely well presented. Watched this in one breath

I used several of the tips from this to design a nasty chicken beak single tooth for my bot, Mr Tickles. Thank you.