Overclocked - a Shuffling Axebot

BBB’s Beetle Brawl has come and gone, another excellent event put on by the BBB crew!

My round 1 melee looked like a tough one, with Inversion and Kult as my opponents. Kult is a wide undercutter, and while it has been inconsistent at times, when it does work it hits very hard, making a deep run at Summer Showdown last year. On the other hand, Inversion is an understated but consistently performing lifter. To hopefully counter both, the split wedge config was attached.

Unfortunately, things didn’t quite go to plan, with Kult managing to get behind me early and swiping he legs, hampering my drive a bit. I didn’t manage to get any hits in with the axe, as Kult systematically tore both Inversion and I apart. Inversion was knocked out as I was trapped in the corner behind the pit, eventually getting my one working shuffler hanging over the pit and being immobilised that way.

The drive motors were pretty warm but otherwise fine. The inactive side of drive had melted a bit, while the other side had been fairly smashed up. My baseplate, particularly around the back, had also been chewed up a fair bit!

My redemption fight was against Don’t Stop Me Now, a pusher running 4 Mars motors. I’ve always maintained that control bots are my worst opponent to face, as I sacrifice control to do the things I do with my bots, and Bart drove this fight excellently, consistently using his manoeuvrability to get many pins on me. I could swing my axe and hit the top plate, but having limited arc from being pushed against the wall, failed to pierce the 3mm carbon fibre top plate. The fight went to the judges who rightfully gave the fight to Don’t Stop Me Now.

This fight made the battery very sad, having dropped very close to empty. I hadn’t used both the drive and axe as much as I had this fight before, and it turns out the capacity of the battery may not be quite enough in this circumstance. Luckily I had a spare battery I could use while this one cooled off for whiteboards.

I had 2 whiteboards, the first against Carmilla, a roomba converted into a drisk, Monterey Jack, a unique chainsaw-grabber wedge, and Lilith, a new rebuild bringing it to 4WD. This fight really showed off the potential of Overclocked I think, with the drive running the whole fight and letting me bully the other bots. The axe worked throughout the fight, in particular raining blows on Lilith’s metal top plates, I think bending them slightly, and at one point getting lodged in Monterey Jack and hoisting it in the air as I retracted the axe. However, at the end of the fight, the whole bot became very sluggish, as it turns out I drined the battery even more than in the previous fight!

Having recovered the first battery, the second whiteboard featured 5 other bots - Cormoran, Cormelian, Bogmeister, Fang (spinnerless due to damage earlier on in the day) and Forkhead. I ended up in the pit about halfway through, at which point someone spied some wisps of smoke from the pit. This was probably one of my drive pods giving up the ghost, because when I took it out of the arena, it was very clearly melted and fused!

At the end of the day, both batteries were unhappily discharged, so I’m going ahead and calling them lost causes. My guess is a combination of high weapon usage and melting (and subsequently fusing) drive pods causing the drive motors to draw lots of juice from them being the cause. I reckon without the current limiting on everything, I probably would have also cooked at least a motor, so yay AM32!

Overall, a very enjoyable event. Dojo is in a few weeks, so it’s a matter of getting some larger batteries and an ad-hoc fix for the very sad drive pods.

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Been a busy few weeks for me as I get Overclocked V2.1 ready for Robodojo this weekend!

First things first, a new gearbox arrived that is 19:1 as opposed to the current 14:1 gearbox. It also ended up being significantly smaller (and actually 42mm), which facilitated making the bot 16mm narrower.

The battery has been increased in size to a 720mah 4S LiHV battery (thanks Rob!), to make room for this the cutout in the back of the chassis has been filled in, so gone is the U-shaped chassis for a plain box.

The fork mounts have also been beefed up, with the tabs going int othe front plate being double widge should offer a bit more resilience.

But the thing that’s been occupying most of my time on this rebuild are the legs. In order to solve the melting issue, I decided to try machined legs out of HDPE.

These look really good, but it turns out that 2 part PU really doesn’t like to stick to HDPE. I went through several iterations of leg designs, even drilling in plane after the CNC was done so the PU would flow around the HDPE to create a mechanical connection instead of just relying on adhesion, but nothing kept the PU on the legs, expecially when I tried to drive.

I ended up reverting back to PLA-ST legs (but with improvements to the PU/leg interface to include a mechanical connection now), with the addition of 0.5mm PTFE shims in between each leg. This should give the legs a smoother friction surface to rub against and space them out a bit to further reduce the friction surface. Hopefully that does the trick.

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Love the PTFE shims! Should work well, nice lot of improvements!

You’re so consistent with the incremental improvements - always a great read yau!