www.robowars.org

RoboWars Australia Forum Index -> Builders Reports

Adventures with Brushless Beetleweights


Post new topic   Reply to topic
  Author    Thread
evil_steve



Joined: 06 Sep 2015
Posts: 304
Location: Adelaide, SA


 Reply with quote  
Adventures with Brushless Beetleweights

I hate writing build reports - the chaotic and piecemeal way I build bots makes it difficult to construct some sort of coherent narrative, and I rarely take the time to take photos during the process. I love reading other people's build reports though, as I often find inspiration in the different ways people think about and go about building bots. How to reconcile this hypocrisy? By doing something more rambling and retrospective focusing not on an individual bot but on all my attempts at building brushless beetleweights.

As with my bot construction this will be updated somewhat piecemeal and chaotically as I find the time and motivation. I'm hoping though to actually document what I've tried that has both worked and failed, and in a more permanently findable fashion than the hive of scum and villainy that most bot related content has gravitated to, Facebook. I also applaud the attempts to resurrect this forum, so figure I should actually join them.


Last edited by evil_steve on Fri Nov 13, 2020 1:22 pm; edited 1 time in total

Post Fri Nov 13, 2020 12:01 pm 
 View user's profile Send private message
evil_steve



Joined: 06 Sep 2015
Posts: 304
Location: Adelaide, SA


 Reply with quote  

Attempt 1: Sworded History



I like chaos, and I like bladed weapons. Therefore, thwackbots are among my favourite bots, especially to drive. Having already built an antweight thwackbot I was keen to scale it all up, but inspired by Gabriel on Robot Wars I wanted something with a powerful drive system. Fortuitously the random bits in my shed provided a solution - old cordless drill gearboxes out of my featherweights (where the original brushed motors had crapped out in combat) mated with some 28-26 outrunners I'd bought on a whim in a Hobbyking sale.




The shafts were the right size so after swapping the pinion gears and bodging up a new baseplate they just fit together. At that time (late 2017/early 2018) SimonK ESCs were readily available and using the Chrome extension RapidFlash it was easy to reflash a couple of Afro 30A ESCs to allow "RC style" forwards/reverse drive via the Afro SimonK dongle. Packing it all into the bot was an issue, but the threaded output shafts/reverse threaded m5 bolts made it easy to attach and retain big wheels.



Sworded History did well, getting 3rd at it's first event, and pretty consistently got 3rd or 4th and most of our beetleweight events through 2018. The drive system has remained essentially unchanged since - I've had to replace one outrunner that had it's wires damaged in a fight.



However the original cutting board chassis didn't hold up so well and I rebuilt it with 3D printed nylon parts (after originally trying 3D printed polycarbonate, which had an unfortunate tendency to shatter under impact). This worked better but was heavier and the wheels became foam to stay in weight. As other local beetleweights also improved and evolved the spinners hit harder, and the front armour went from aluminium to titanium and the blade from mild steel to titanium and then to hardox.



All this made for a durable bot and a crowd pleaser at our bigger events, as it would shred bits of the foam wheels all over the place, take massive hits flinging it around the arena, and throw off pretty sparks from the armour and blade, but still keep driving. But it did less and less well as it wasn't really able to win fights either by KO or on damage, and the need to make a dozen or so wheels for every event became an absolute pain in the arse. The weight of those gearboxes combined with the need for a robust chassis/armour meant that more durable wheels weren't really an option, and ended up limiting the further evolution of the bot.

Post Fri Nov 13, 2020 1:04 pm 
 View user's profile Send private message
  Display posts from previous:      

Forum Jump:
Jump to:  

Post new topic   Reply to topic
Page 1 of 1


Forum Rules:
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum

 

Last Thread | Next Thread  >
Powered by phpBB: © 2001 phpBB Group
millenniumFalcon Template By Vereor.