(One half of) Accept Cookies - a FW Sportsman Cluster

Originally, I was just going to spectate at Robodojo’s Sportsman Feather event on 1st June, but a while back, Andy (Bread Dead Redemption) mentioned his other bot, Killionaire Shortbread, had about 6kg free if anyone wanted to cluster up…

I haven’t really considered building a feather in the past because my workshop is still my office, but I reasoned that if I was building part of a cluster, it would be feasible, especially with my desktop CNC helping me along. A plan started forming.

The basic plan was to get the BBB feather kit and add a weapon of some kind. I played around with upscaling my ant Runtime Exception with a front hinged flipper, but eventually settled on an axe mechanism of some kind (if you know me, you know I love my axes!). After some brainstorming with a friend, I decided to use an adjustable wrench as the weapon for some fun factor, driven by a Ranglebox Saturn 4250 1000kv motor on a 14:1 gearbox. The motor is intended as a (high power) drive solution, but I reckoned that with some additional gearing, should hopefully have enough beans for swinging the wrench around (which came up to around 450g), if not terribly damaging. Power will come from a 4S 1700mah LiHV (I intended to just use LiPo but misread the product page :stuck_out_tongue: )

Having never built a feather before, and unsure just how much everything would weigh, I was very conservative with the thicknesses of parts. 14mm weapon bulkheads, 8mm front/back and 6mm top/bottom and sides. Probably borderline for sportsman, and definitely not viable for full combat, so it’s a good thing I don’t intend for any FC for this!

The build went together quite nicely for the most part - a weekend of machining got me all the HDPE bits. Except it turned out I had misplaced some screw holes in the CAD, but that’s why I love HDPE - I just drilled new holes to fit :slight_smile:

MOD4 14mm thick HDPE gears, doubled up on either side of the wrench should survive all the impacts. The finish over the 14mm bits isn’t great, as it turned out I ordered 15mm HDPE so had to face all the parts with my dinky 3.175mm endmill!

The weapon axle is a 8mm steel bar as a dead shaft, with shaft collars on either end to retain it.

Bike tyre over the wheels for extra grip.

All finished except for the weapon motor, which is waiting on some ali parts from a metal order, so can’t test that yet. Initial drive tests indicate it has plenty of power in the drive though, as it has a tendency to rear up and flip over! It only weights around 4.5kg though, so I should be able to add some more HDPE to the front to weigh it down a bit.

As for the name, Accept Cookies - I tend to go for computing references, and Andy has a baking theme. So Rob Weston (who usually drives Killionaire Shortbread at Dojo sportsman feather events) suggested a cookie theme, both in the baking sense and the browser sense.


YEsssssssssssssssss Stunning :wrench:

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Prior to Dojo, I made some changes to my half of Accept Cookies. Because I had a fair bit of weight to spare, I doubled up the top armour and front armour, hoping that would help with the wheelieing problem. I also got some weapon tests done in the days leading up to Dojo.


As you can see, it’s fairly energetic (and definitely not foreshadowing for later)!

Fight Footage can be found here courtesy of Sean, driver of BOB4.

In the first two fights, the wheelieing problem made control very difficult, and it was hard for me to line up shots with the axe.


We eventually mitigated this by adding a wheelie bar made from some scrap HDPE, which helped to keep the nose down on acceleration.

It turns out the bot is pretty nippy when it can drive!

Drill motors + grippy bike tyre + 4S LiHV = zoom

In the first fight, I burnt out one of the phases on the weapon ESC. Luckily, I had a replacement ready, which worked for the rest of the day. Possibly some QC on those which were causing some issues?

The axe itself exceeded my hopes and expectations. While not very damaging by design, it had plenty of beans, with almost every swing launching me bouncing away! It’s very fun to use.

A selection of hits

Surprisingly, the duo of Killionaire Shortbread and my axebot (which still doesn’t actually have an individual name - maybe “Required Cookies”?) made it to 2nd place, winning 3 of the fight night fights and the semi-final fight!

I found throughout the day, my M5 wood screws were backing out, especially on the forks and the motor mount. Possibly, I need smaller pilot holes for them (I was running 4mm pilots for M5 wood screws).

Some damage did occur over the course of the day, though I think most of it happened at the very end when Malachite tossed me out of the arena and I landed on the axe.

Overall, very good fun. I can see myself going to more Dojo sportsman events in the future. I’d love to come to Bristol BEVs, but it’s a very long way from York!


Looks like a super fun robot! Out of interest, what weapon esc are you using in it?

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Amazing first outing & such a fun robot!

We’d absolutely love to have you for BEVs if you can make the journey! (17th Aug, more details in the next few weeks!)

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I’m using this ZMR 60A BLHeli_S ESC, but I have just bought some Aria 70A AM32 ESCs on recommendation.

I love it! How about Percussive Cream as a name? Keeps your theme but with a biscuity angle.