Bulbaroar - A Square peg into a round hole

Because @Jack bullies me if i don’t make forum posts :smiley:

Bulbaroar, the story so far, mostly in CAD. Part 1 of X

It all started with Hooligan. Which was objectively terrible and made me sad when it sucked repeatedly so got scrapped. 6 months later I was looking to make another spinner and started CAD’ing up a beater to get CNC’d in china and realised I didn’t want to spend £100 on a part which may be awful, or be on an awful robot, or generally be pressure.

So got this added to a lazered order. it’s a 10mm thick 70mm chunk of ‘Hardox 500’.

The rest of the bot came from my spares shelf. LIke many people here I get carried away in times of plenty and had sever robots worth of unused spare mars drives, drive esc’s, some unused 70A weapon esc’s so decided to put it all to use in a ‘budget, use up your shelf’ kind of way.

Origional plan was to take it to the East Essex Hackspace, chuck it on the massive industrial lathe they have there and turn the ends down, but we had a hell of a job trying to centre it in a 4-jaw chuck enough that it would be actually centred not “rougly close”. It was pretty badly kerfed so we eventually gave up and bounced soem ideas about, eventualy thinking "why not just print some round bits and stick on bearings.

Quite rapidly from there I designed this weapon stack and started on the real work.

The V1 CAD. Around this time BBB Summer Showdown was announces so i decided to rush build the bot as a pokemon theemed eggbeater for my kid to drive, so i’d have a less stressful day. (Yeah, right)

I’ve no photos to hand but v1 Bulbaroar was born just in time for ShowDown though what came next was a bit tough for the wee lad. It didn’t drive very well, the puit was broken and stuck down and the draw was what we call “spicy” but ended on a high (though went the distance for a JD loss) to Fang Reloaded.

Roll forward a monthior two and MITE II was announced and after checking with the EO’s it was OK to bring 2 bots, polished up the upgrades to Toucan after Rapture and turned my mind back to Bulbaroar aiming to give it “one more event before binning it”.

This utter abomination was born. The mid wheeled 2wd Bulbaroar. Oh jeeeez wher to begin.


Firstly there were enough good bits to make thigns good. It really, really hit stuff hard. Bounced a few bots off the ceiling hard. Sadly it drove really badly again, was imbalanced and the massive 65mm direct drive side wheels had a habt of shattering the Mars gearboxes they were attached to. Still it went 2:1 got into the RO8 playoffs then died to a brownout. Same RX from Hooligan. that went in the bin. The mid brushless motors with weapon belts over the top plan was also terrible. it ripped wires our of a brushless drive motor :frowning: oh well. it was fun and i returned from the event with a smile and some mojo.

Chetted with @Joe and swapped my Champs entry to this bot and set about CAD’'ing up some fixes. Keeping it 2wd but moving the wheels and motors back to the back, slipping them inside the chassis, wrapping the rear in TPU was about all it needed. Behold - Bulbaroar 1.3. The pride before the fall.

Suffice to say it did my usual champs thing of laying waste to all before it in the Opener, then getting flat out murdered in the first RO32 bracket fight. Still it had a great WB before going home. It still hit, but doesn’t drive well. Undeterred i fixed up the worst of the damage and went to RoboDojo a few weeks alter and came 6th out of a pretty stacked field of 12. Again, the drive was the main problem. Oh and sniper hitting it so hard the chassis pulled out and dropped the weapon bar. apart from that it was great. hmmmm.

Overall the damage wasnt’ too bad but after 2 heavy events in a few weeks I left CAD alone from mid Nov until early Jan. Robots are stupid.

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Not feeling remotely energised after 6 weeks off CAD, I forced myself to start work on fixing my recent batch of design failures, pulling out a notepad of fixes i’d written on the train back to London that day. While the chassis was scrap, all the electronics were fine and the bar was mostly OK. The bearings were shot but they are expected to die, wheels were awful etc etc, but - I had plans and the support of lovely friends. So off we went to CAD land deciding to:

  • Make it better
  • Keep it’s goofy cool appearance
  • Try to add 2-4 more wheels
  • Probably add magnets.

Knowing this is all heavy I spent some christmas cash from bored relatives on a Repeat Dual ESC but besides that he only cost was petrol to the Hackspace as I had enough plastic, and a new roll of TPU. A perfect Jan hobby right ? Right. For all it’s work, this is really a budget build as it mostly uses spare rive train parts from Toucan, some £10 surpasshobby weapon motors and a £8 beater bar.

Jan Dojo is approaching fast at this point so CAD’d up this absolute unit with the assistance of the squad, keeping everything that made it wonderful to look at:


Then off we go to the Hackspace to use their Workbee to cut some plastics:


And to cut some Ti for the front wej should I Fight Sniper again (Foreshadowing? lets see)

with a few days to go to print spare wheels and fixing I ended up with this and a real happy glow. It’s nice when a build makes you happy right ? I’d kept and modified the TPU inserts used in V1.3 at Champs to keep all the wires away from the brushless motors, managed to fit in 4wd and magnets, though had no idea how well the’d help. From driving it around on the floor at home though it was planted, fast and reactive.



(On a side note i had to go on a detour to build a new test box, but the new one is rockin’)


So I tossed it into a rucksack with some spared and went to York for Jan Robodojo.

i’m waiting for the footage to get released to do the next part, but it pulled off this trickshot: https://youtu.be/QiT3P-UyW7U

Cya in a bit.

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Ooh very nice! I’ve always wanted to make a BW drum! Looks like a good design, sleek and the front should be fine against undercutters. I’m a bit worried about forked robots getting to your side and rear, since the ground clearance looks a bit high, and perhaps the eggbeater doesn’t have great reach. Being hard to high-centre is pretty good though. Overall it’s very snazzy!

Thank you.

I am a firm believer in Ground clearance and don’t really think it makes much of a differnce against forks. A sharp pointy bit of or metal will get under you at 1/2mm as well as at 5mm. One of the failures of the earlier versions was dragging on uneven floors which are all too common in beetle arenas, catching on debris and generally being fouled or the frame beign slightly tweaked so it would never go where i wanted it to go. When your defence is “point the front at them” and “be where you want to be” these are bad things.

As the sayign goes. if it can drive at DoJo it can drive anywhere. and it now drives at dojo.