Yomi - Build/Design Diary

If you were at Rapture last weekend, you may have seen a black Tombclone that looked like this:

i swear this wasn’t the Wish version of Baby Dead Bod, it was Yomi, my first attempt at a spinner, which to be honest, worked better than i thought it would, sure the belt kept falling off, but the internals kept working, and the few hits the bar did get certainely are encouraging.

So as i came back from Rapture, not too surprisingly, here i am trying to redesign Yomi to make it work better, CAD of new version is far from over, but this is where we’re at so far:

current changelog is as follows:

-much deeper groove in the weapon pulley to prevent belt from falling off on big hits
-shrinked chassis and made the walls thinner to save weight
-shortened support length to save weight and beefed up the support beams so they don’t get snapped again
-changed assembly method from throughbolts to hex inserts (may also replace the throughbolt for the weapon shaft we’ll see)
-better guard to prevent wires from hitting the weapon motor and pulley while also providing an easier way to pass through weapon motor wires
-new asym bar designed for even more engagement while retaining the agressive tooth profile of my standard bar (i have another asym that i made for verts but couldn’t use at Rapture due to weight issues but i’ll make sure i can run it on this new version, because End Boss, Oubley and Shrekt are scary)

current things left to look into:
-research how to setup AM32 ESCs to get faster spinup
-look into a solution for grippier wheels, seriously considering running lego tires on printed hubs, although the self-vulcanising tape that the Mothenator team used on foamies is also quite interesting
-potentially wheelguards?
-link and LED slots
-some form of back spikes/wings/whatever to not get Malice’d
-maybe extend the supports over the pulley so it’s less weak/exposed to top attacks
-potentially swap drive ESCs from V3s to the new dual channel ones for simpler wiring and weight saves

potentially gonna take it to one or both MMM events before next Rapture as a bit of a “test ride” for the improvements so i can show up next year with a robot i know works

hopefully one day we can take this from Baby Dead Bod at home to the French Tombstone


Good to see you at Rapture! Once those belt issues are resolved, I’m sure it’ll be hitting even harder!

For the wheels, have you considered using 2-part polyurethane or similar over 3D printed hubs? A lot of people are doing that nowadays, and getting good grip - Baby Dead Bod does that with TPU hubs I believe.

yeah, it clearly has the power, now i just need to make the belt stay on

i did consider casted wheels and may end up just doing that, lego tires or that self-vulcanising tape just seemed like simple solutions that would also work

Thank fuck you’re getting rid of that esc, it was insanely big :rofl:

Massive dub from you on the weekend boss :tada: robot did really well!

yeah idk how i didn’t look at the size difference between weapon and drive ESC and went “hold up, this ain’t right”

now to actually show up prepared and without belt issues!!!

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:tada: That wiring was the death of me

yeah not gonna inflict that pain on you again…

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More CAD progress, added potential casted wheels and 2 ideas for back attachements depending on how much spare weight i get, still need to go look for a new weapon ESC, but once that’s covered i could probably start throwing everything in a spreadsheet and figure out where we’re at weight-wise

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Sacré bleu, i haven’t updated this in alarmingly long… really should get off my ass and start working on this damn thing, i have revenge to claim on certain individuals and a Reverse Blitzkrieg to prepare for after all, i would be telling you i have lots of updates or started the build, but sadly, that would be lying, i do have the new weapons made and eventually will be arriving to me, thanks to Hop’s assistance, and you may be thinking “wait, weapons? i thought the only new bar was the agressive asym?”, well, about that…

Say hello to the Scythe Bar, is there any practical reasons for this? No. I just thought it would look cool, obviously not gonna run this against spinners because i’m not completely deranged, but you know, if you’re gonna kill robots, why not do it in style?

The other big update is regading the weapon supports, i decided to try switching them from 8mm HDPE to 4mm carbon fiber, hope with this is to increase stiffness, which considering this new Yomi will be a lot lower and therefore have a lot less vertical clearance on the weapon, should make self-eating less of a concern, it also happens to be lighter than my HDPE supports, interestingly, oh and it makes the whole bot less tall, so that’s a plus too?

Here’s a pic of what the bot currently looks like with the new supports and bar, i’m likely ditching the heavier butt armor with the wheelguards because i doubt it’ll actually do much in protecting my wheels to be honest, so might as well yeet it and save me the weight.

Something i am considering but will need to toy with in CAD is potential attachements on the front side, probably via 2 M4 bolts on the supports near the weapon shaft, i have two ideas at the moment:

-A TPU guard over the weapon pulley, mostly so anything with an overhead attack (or a big wheel, i’m coming for you Stratus just you wait, Dustwind will be avenged eventually) can’t break the pulley/belt-snipe me, which Wheely Big Lad did do in our fight (not that it mattered cause the belt already fell off by then…)

-A flat fork sitting underneath the support, for those familiar with the antweight robot Cheesecake, basically something like the Sweet Tooth setup that thing has, hope is to hopefully be able to hinder wedges trying to deflect me by outwedging them before the bar makes contact, big concern will be how to ensure it can’t just bend into the path of the bar when fighting verts



It has begun…

slowest builder in history at it again, drive and weapon got installed, still need to make the casted wheels and the new wiring, but this + the battery and Yomi’s old wiring was 1314g minus the weapon ESC, so we should be doing fine weight wise

Time for another update that took far too long…


Ended up going for the printed hub + lego tire route, gotta make all the lego i have sitting in a tub in my room useful somehow, might need to get a few spare tires as rn i don’t know if i have enough for a full event

this also leads to other good news, i did a weight check of the entire assembled robot + the lipo and Yomi’s old wiring, and the weight is 1356g, and i’ll save some weight from having to shorten the screw side of my hex inserts for better ground clearance anyway, maybe i could even run the printed back armor (which doubles as my anti-Malice solution) i was having doubts about having the weight for.

currently all that remains to be done besides the screw shortening operation is the wiring and the weapon belt, once all that’s done, first test can be conducted and we can ensure everything works, and probably enjoy the wonders of actually having grip!!!

on the event side of things i am currently registered to the upcoming MMM event and Rapture, both with Yomi, i’m currently unsure if i’ll be able to do anything beyond small updates between the two events

maybe if the german event really goes poorly i’ll just make Yomi V3 then for Rapture, we’ll see, my biggest concern is time the parts would take to reach here, especially if i have to get CF pieces from Hop or Nat (UK to France moment…), 3D printing shouldn’t be nearly as much of a problem since i can get them from french companies via Treatstock but some pieces like the weapon supports probably wouldn’t work as 3D printed parts at all.

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Welp, MMM is over, and let’s say things were less than stellar (and not just because i came back with a cold that’s kicking my ass because i was too stupid to take a big jacket with me)

Turns out i’m a dumbass and blheli aria on stock settings DO NOT work fine like my old ESCs did, meaning that for fight 1 and 2 my weapon was functionally not working at all.

Luckily we managed to borrow a ESC reprogrammer and a laptop (shoutout to Tobias and Daniel) so we managed to flash proper settings.

UNluckily my next fight was against a robot called Touch Grass, which basically is Long Long Man meets forks the likes of which would give even End Game pause, so basically i got my weapon jammed and got high centered on the forks in 2 seconds and pitted shortly after.

And the next fight, which is a whiteboard with the Mothenator team’s Nuts 2-like beetleweight Pink Lemonade X, made me aware of another issue with the weapon system, turns out TPU pulleys can melt quite easily and weld to the weapon belt, jamming the spinner… guess what happened fighting Touch Grass… which means that once again the weapon didn’t work and i ended up losing that fight.

My final fight was against a 4 wheel drive wedge called Gladiator, which i can basically sum up with this:


besides that damage on the wedge i also took off both rear wheels and ended up being given the wedge as a trophy, which made for a nice silver lining after a quite upsetting event run.

i’m also noting that while the belt did pop off and i ended up losing by pit, it lasted a good bit longer than the old Yomi ever did, and it seems like the weapon pulley also being TPU was the likely culprit.

With that in mind, the current changelog for Rapture is as such:
-Swapping out the weapon ESCs to Pariah 70A ARM32 ESCs
-Switching pulley material from TPU to Alloy 910
-Adding retaining flanges on my wheel hubs to secure the tire better while still enabling to individually swap out the tire

The one good thing i’m noting with this version, is a notable increase in grip from the lego tires, much better than the foamies, and drive still has yet to actually fail in battle.

Hopefully with those changes and proper testing of the weapon setup we can ensure to show up to Rapture with an actually concerning weapon.


Welp, another event that can be added to my belt, went this weekend at Rapture with Yomi after the ESC change to Pariah and the pulleys swapped to Nylon

The weapon now works a lot more reliably than last year’s Yomi ever could, which is encouraging, however:

-The spinup time is currently entirely insufficient for how agressive most robots are
-The anti-vert bar was poorly designed and was bent into uselessness in the only fight it was used
-There’s a serious possibility the propdrive 2830 currently driving the weapon is entirely underspecced for my current use

Current changelog is entirely dedicated around improving weapon system efficiency, the drive having no issues besides the lego tires needing potentially better securing on the wheels (and me remembering to tighten to the max grub screws before every fight… either that or loctite the things)

Targeted improvements are:
-adding thrust bearings at the top and bottom of the weapon stack to reduce/eliminate friction between the weapon stack and the supports
-potentially swap to timing belts to reduce slip issues and overall increase efficiency in transmitting torque to the weapon
-gear the weapon down from 220 to 200mph for increasing torque at the cost of max energy
-swap out the 2830 for something bigger in order to increase startup torque further

The end goal is a weapon that can reach dangerous speeds in an instant and become considerably harder for control bots to smother, with the hope to consequently land big hits more consistently.

Along with those upgrades a new anti-vert weapon will need to be designed as well as a thinner, cutting weapon for TPU wedges which seem extremely prominent with control bots.

Currently considering attending DRG in November for testing these upgrades, but to be honest, i’m not super keen on doing too many events a year, the events are fun mind you, but everything around those events (namely the stress of event prep and travel, the costs and time it takes to get there…) does hamper my willingness to do many events a year like some other international teams do (looking at you Luca you maniac…)