Percussive Maintenance XL - Beetleweight Build Diary

I went to War in the Wirral last weekend, and brought along PMXL was a reserve. I ended up fighting twice, as a sub for main competitors and a whiteboard fight. The first was against Saw Loser: 2 Saw 2 Lose, a 4WD hammer saw from Alex Mordue. This would be the first test of the top armour package, which didn’t really stop any damage, as several blows from Saw Loser managed to cleave through the left bulkhead, which severely hampered the power of the axe. However, the drive was performing excellently, and I managed to keep almost every engagement to the front. I also managed to stop a number of attacks by jamming my axe into the path of the hammer saw! I think the geometry of PMXL’s front also helped to avoid damage, as it slopes away from the opponent, combined with the backstops on the forks preventing Saw Loser from riding up my front. I even manged to finish the fight by opening the pit and pushing Saw Loser on top of it, though the fight ended with him dangling above the pit entangled with my hammer! Overall, a very good fight, highlighting that my axe doesn’t need to be damaging to influence a fight.


Post Saw Loser. All the damage is localised to the front.


The main bit of damage - no more left bulkhead, and the axe mechanism is fairly mangled.


One of the fork bolts was pretty bent. This was a pain to remove when I got back home!

I had another fight in a whiteboard against Boom Zoom. I hadn’t brought many spare parts, so the ruined bulkhead from the Saw Loser fight meant the axe was very anaemic. However, as is seemingly becoming a trend with PMXL, I managed to mostly keep the front pointed at him. Not much more to say about this fight to be honest, just an enjoyable non-spinner driving match. However, I did somehow manage to burn out a drive motor right at the end.

The past couple of events have highlighted the need for a punchier weapon. I already have plans in motion to remedy this, which should hopefully bear fruit soon. However, I will likely need to find ways to cut weight from the design in order to fit the new weapon system in place, which I am currently looking into.

The drive on the other hand seems to be performing very nicely in combat. However, I have now managed to burn out two drive motors in 2 events, which does concern be a bit, as I’ve never had any problems with the drive motors in both of my beetles until now. I don’t know if I’m just over-stressing the motor with the kiwi-drive config combined with pushing other bots. I do have ideas on drive improvements that coincide with the weight saving I need, so we’ll have to see if that problem persists.

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Sceetles!

After a quick repair from the damage at Wirral, it was straight back into things with Sceetles last weekend. Fight night format, 3 fights with a top 8 eliminator bracket. My first fight was against Slot Machine, a punching saw bot. Unfortunately, it was not ready for this fight, but that did give me a bye.

Fight 2 was against Icebreaker, in which I was hoping to replicate the last time these bots fought at Dojo. Unfortunately, while I won the first engagement, I managed to oversteer, giving him the back of my robot, which he promptly took advantage of and punted me upside down. As I’ve maintained, the axe does not have anywhere near enough torque, so I couldn’t self-right and was counted out. The armoured skirt did its job and protected the wheel from damage, but it tore the lower portion of the skirt.

Fight 3 was a nice non-spinner fight against mini Beast, driven by an experienced and great antweight driver moving up to beetles for the first time. I managed to avoid any major driving mistakes this time, and managed to keep the front pointed to him for the majority of the engagements. I landed a lot of blows to his top plate, taking out a couple of the googly eyes, including sticking the pupil of one onto the end of my axe at the end of the fight! The fight went to the judges which I won.

Unfortunately I didn’t make it into the top 8, but I was definitely up for some whiteboard fights! The first was a 5-way melee with Sad Boi, a 4WD brick of a pusher, Nitrite, a 2WD vert, Mow Problems, a Billy-style undercutter, and the face-spinner of Zephyrus. For the first time, I put on the split-wedge config, which is what I tech check with. It runs the anti-horizontal rear and left sections of armour, with the fork setup on the right, in addition to the extra top plates for overhead attacks. This seemed to work quite well - I started the fight waiting for Mow Problems to get up to speed before diving in with the horizontal side, which sent both robots flying across the arena. The armour took a fair bit of damage, and the wheel behind it lost some rollers, but it held together and the bot was still fully functional after that! I then went face to face with Nitrite, my forks keeping him from hitting me. Remembering the Dojo Icebreaker fight, I was initially conservative with the axe. I managed to get round to his back and land a couple of hits before changing target to Zephyrus. He got on top of me and had his spinner dangerously close to my weapon uprights, but I managed to manoeuvre him off me. I then broke away for a moment before coming in behind Nitrite and Zephyrus while they were engaging Sad Boi and landed some more blows to their backsides. At this point, Sad Boi dropped the pit and both Zephyrus and Mow Problems fell in, swiftly followed by Nitrite KO-ing Sad Boi, leaving just me and Nitrite.

My forks were consistently getting under him, and preventing him from making contact with me, so I started swing the axe. The fight had moved to the corner closest to me, and I could see his exposed belt and removable link, so I wanted to try hitting one of those. As a result I became more trigger happy with the axe, firing it repeatedly close to his spinner. Eventually, he caught the arm, bending it somewhat but still functional. We broke away for a moment before re-engaging, and I fired my axe once again. He caught the axe head this time, ripping it off! I pushed him to the near corner but he was unresponsive. I then realised I had managed the shot I wanted - I had cut his link wire, handing me the victory!

I went into one last whiteboard with Nightcall, a Dojo regular. Despite that, we had never actually fought each other! We agreed that he would get up to speed first and it was worth it for the following hit, which ripped one half of my armour clean off PMXL, sending me into the air and inverting me. He went in for another hit when right me, and I tried getting the remaining fork under him, but he clipped me and flipped me over again, getting counted out due to the lack of self-righting.

Overall, a great day, and some good data collected for PMXL. the main issue which I was already aware of is the lacklustre weapon. I have plans currently in motion for a full redesign for a V2. I also want to beef up the armour - currently it is 5 walls (2mm) and 20% infill, but I want to increase the number of walls if the weight will allow. In addition, I want to change how it mounts to the chassis, as the wood screws are pulling out from the big vertical impacts. I’m thinking of moving to a tab and slot system, where the prints have a tab that goes into a slot in the chassis, and a bolt will run through top to bottom.

The next event for PMXL is Beetle Champs at the start of November. V2 likely won’t be ready for that, but that won’t stop me from working on it in the meantime! I’ve made a lot of progress on the CAD in the past couple of days so should hopefully have something to show soon.

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I went to Champs over the weekend!

The past 2 times I’ve done Champs, I’ve brought Déjà Vu/Two with me. This time, I signed up with PMXL, and managed to equal my position from last year, in the top 16.

Fight 1 was against Ray and Gold Dust. Gold Dust quickly got me upside down, and lacking the power to self-right, I thought that would be me out. However, I had my axe extended, and I discovered this fight that if I tried retracting the arm, it would angle the body just enough that the rear wheel could make contact, letting me do a sort of crab walk, which was enough to keep me from getting counted out. In the meantime, Gold Dust also inverted Ray, but was having drive problems of its own. In the end, the fight went to the judges with all of us still mobile, who rightly awarded the fight to Gold Dust.

With the forks and damaged wheel replaced, I was in the redemption rounds against AntiThesis. He managed to get a good bite on me at the start of the fight, narrowly missing my belt, instead going into the weapon mount. After the release, I managed to attack from the sides a bit before the pit was released. I managed to push him near the pit, and after some back-and-forth, he ended up in the pit.

Now in the round of 32, I had Talon, a cluster with a forked wedge and a crusher. I was concerned about having to fight two opponents at once, as even with the omni-directional drive I could very easily be outflanked. Luckily, they quickly got stuck, with the long slender forks of the crusher getting stuck under the wall and the wedge getting beached on the seam after getting flipped.

My round of 16 opponent was Icebreaker, and this fight went pretty much the same as the Sceetles fight, with a slight overcorrection on a turn giving him my side and flipping me over.

It was a bit disappointing losing two fights because I couldn’t self-right, but that’s an issue I’ve known about for a while, and will be addressed in V2. Speaking of which, I’ll make a follow-up post talking about all the changes I’ve got planned for V2!

Bonus: Tim Bouwens of Ominous was also at Champs with Wajoo, and he brought along a 1lb+ version of Ominous he uses to practice driving, and we got a picture together!

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I promised CAD!

I actually finished this a couple of weeks back but never got round to posting about it. Generally, the robot is now smaller. This has been facilitated by swapping from BBB brushed motors to brushless drive, using Alex Mordue’s Rotalink conversion guide combined with GEPRC SpeedX2 1804 2450kv motors, which each save around 20g. This weight saving, combined with the general weight saving from shrinking the bot, should facilitate the weapon upgrade.

The primary reason for the updated CAD is the weapon system. V1 uses an OpBox, which is a 1806 2300kv motor on a 19:1 gearbox. V2 massively upgrades the motor to an Overlander 2836 1120kv motor, attached to a 16:1 gearbox. This should hopefully give enough oomph to self right reliably and give the axe a harder punch. I’ve also refreshed the arm and head design, increasing the amount of material on the arm and spreading out the mounting holes so it is harder for a vert to rip the head off the arm.

I have a handful of head designs, the only one CADed so far is a generic pointed axe. I’m also planning a sawtooth designed for cutting belts, a proper metal Strapoon (which can be heavier due to not needing forks for that matchup) and a redesigned spanner head, extending one of the points so there is only one impact point.

With ready access to CNC, I’ve made a lot of additions to the CAD that I previously didn’t have. I’ve pocketed the walls to save weight, and added slots to hold motor guards for the drive motors.

Another change I’ve made is to how the armour skirt attaches to the chassis. Previously, I was running wood screws through the armour into the chassis, which pulled out on big impacts. Now, I’m using a tab and slot style mount, where the 3D printed TPU has a tab that slots into the chassis, with a bolt running top to bottom through the chassis and the tab. This should be a bit more robust than before.

I’ve already got some of the parts machined and some test parts printed, as well as the Rotalink conversions done, so I should be able to get a test drive soon. I am worried about routing the wiring though, as a test fit of the components looked a bit tight on space.

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With Burgh this weekend, I’ve been racing to finish both beetles. PMXL V2 is done and ready to be a reserve!

There’s a few compromises I’ve had to make for this event. Due to some unforseen issues with the forks bottoming out too early causing the tips to be raised, I’m currently rush printing some new front armour pieces to raise the mounting points so that shouldn’t happen (I’ll get some proper forks made at some point). You’ll also notice the black top plates - I’ve had to print PLA-ST top plates as I ran out of 4mm HDPE and the plastic order hasn’t arrived yet! Having my printer occupied with these jobs means I haven’t had time to prepare spare parts or the additional top armour packages I’d like to have, so I might bring random offcuts with me in case I need to protect against overhead attacks.

Here’s a drive test before the weapon and armour got installed. By eye, I’d guess it’s twice as fast as before!

I’ve also tested the new weapon system, and I can safely say it can self-right reliably now! The caveat with that is the belt still slips if the weapon is extended, but it can still pseudo-drive inverted like I discovered V1 could at Champs.

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So I’m back from Burgh with a pretty successful run from PMXL V2! Despite having very few spares and being completely untested in combat, V2 managed to reach the top 8 (my best ever performance at an event!) before being eliminated by the eventual winner Grab Crab!

Originally, PMXL was down as a reserve but got promoted to main competitor shortly before starting. The first opponent was Speeny, a 2WD eggbeater. The brushless drive immediately showed itself in thie fight, allowing me to quickly box rush (which I did whiff, but managed to recover). The forks also did a good job this time round, with the hook either causing me to get knocked slightly away from them orcausing them to invert themselves. There was a point where Speeny got on top of me and my axe head got caught in their wheelguard, requiring an unstick. After that, I opened the pit and managed to push them in.

I noticed that during the fight, I was occasionally getting hung up on floor seams. I think that the armour skirt is a bit too low and occasiuonally high centering the bot.

The second fight was against the terrifying Just a Wee Slice, a beetleweight version of Lice of LiFe, which has been tearing through bots at Dojo’s full combat feather events. Unfortunately, I did not have enough time to prepare an anti-horizontal config, and I also did not have enough time to prepare bulkhead protection, so all I could do was take off the forks and hope. I missed the box rush as the bot veered left slightly, and by the time I had corrected Slice was revving up. I tried to manoeuvre around the blade but he kept it pointing at me, so I had to engage it from the front. I took the first couple of hits okay, but the thrid one sliced through both weapon bulkheads and the top of my removable link, killing the bot.

Using the only spare bulkheads I had, I repaired the damage to the weapon in time for the final fight night fight against Brassed Off, a forked horizontal saw bot. Similarly to the fight against Speeny, I managed to keep control of the fight, and like before, opened the pit and pushed them in.

Day 2 started with PMXL in the Top 16, fighting against Firebolt, a 2WD flipper that had beaten DJ2 the day before. This fight went better than that fight, with my forks consistently getting under him and the drive continuing to let me push him around, though I continued to get momentarily caught on floor seams or under the wall. Towards the end of the fight, I fired the axe and it would not retract - I had snapped the belt. I immediately went for the pit button, as I was worried I’d lose the judges decision if that happened. The fight ended with us next to the pit, with me falling in just after the fight ended. Fortunately, because Firebolt’s weapon had died early on in the fight (it turned out that one of the motor wires for the weapon had broken), I won the judges decision.

I think the belt snapped because I cranked the tensioner down a bit more before the fight, as I wanted to make sure I’d be able to self-right if I was flipped.

The final tournament fight was against Grab Crab, a lifter from Joe Brown that had been throwing the competition around and was undefeated thus far. I had to delay the fight as I once again snapped a belt while testing self-righting. Despite the bot being able to self-right in testing, it once again would not do so in the test box/arena. With my last belt attached, we went into the arena. He quickly got his longer forks under me and flipped me. I had told Joe beforehand that if I was flipped, there was no obligation for him to right me and take the win, but he kept the fight going for a while by tossing me around and I eventually landed back on my wheels, so some great sportsmanship from him there. Eventually, I opened the pit but was inverted again, and this time he left me there, which I had no problems with.

Overall, I’d say V2 has been a resounding success. The brushless drive has massively increased the control that the bot has over its opponents, as it is much faster and has some proper pushing power. It’s even leaving particulate on my armour! Not sure if this is arena dust or I’m wearing down the wheels now, with the speed of the wheels.

One side effect of the full brushless setup is that I’m using a fair bit more battery in each fight - after just one fight the 4S battery was down to 15.7V from max.

I have some ideas for anti-horizontal configs brewing, and I want to raise the armour up a couple of mm to reduce the occasional high-centering. I’m also changing from a belt weapon to machined HDPE gears, after a talk with Joe. Now that I’ve lost 3 fights in a month due to not being able to self-right, I have to sacrifice the built-in clutch that comes with a belt drive for a consistent torque transfer. I should be abel to action these changes for Dojo in 2 weeks.

TL;DR - brushless drive is good. Friendship ended with belts, now gears are my best friend.

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Wicked stuff, didn’t realise this was the first outing!
Drive upgrade was great, and like you say belts suck, gears time! :slight_smile:
Enjoyed being a pit buddy and our fight.

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GEEEEEAAAAARS :heart:

Caught a few of your fights on stream - really impressive work -the brushless drive is deffo a big improvement I think to the bot overall.

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Thanks both! I’ve known that brushless drive is a marked improvement over brushed for power for a while now, but didn’t realise jsut how much it would affect my bots in particular due to the funky wheels! Definitely looking to port them over to DJ2 V5.

The final event of the year for me (and the 6th consecutive weekend!) was Robodojo! I brought along PMXL and with some ants.

After burgh, I immediately started sorting out a gear-driven weapon train instead of belts. Some MOD2 HDPE gears retrofitted nicely into the existing bulkheads with a 14T/22T ratio, with only minor adjustments.

With this change, it self-rights consistently and nicely - I did a 3 minute test of constantly self-righting with no issues! However, I had to turn the weapon down to 40%, as at 100% the first weapon test destroyed the drive gear! A higher MOD and wider gears should fix this.

I also actually prepared a anti-horizontal configuration for this event! At the top, it angles back forwards, to catch spinners riding up the wedge. I also printed off some gear/bulkhead covers, and sorted out some black HDPE top plates.

Fight 1 was against Toucan, a grab and lift that had done well at its last 2 events. This fight served as a good test of self-righting in combat conditions, which it did very nicely! I’m still getting used to the twitchiness of the brushless drive, and combined with me getting caught on floor seams, mean Toucan controlled this fight from start to finish, winning the judges decision.

The second fight was against Chucky. His lifter appeared to die soon into the fight - I think it later turned out that the servo horn had stripped. However, this meant that I could try to control this fight without having to worry too much about his weapon destabilising me. Unfortunately, I couldn’t capitalise, and he managed to push me out into the pit after getting round to my side.

Fight 3 was against Crazy Horse. Colin’s bots are always awkward to fight due to their size, and despite the improved drive I struggled to push him exactly where I wanted, which meant I lost some opportunities to get him into the pit. However, I did generally manage to dictate the pace of the fight, though I noticed I was getting hung up on the floor more often than before. The fight ended up going to the judges, which I won.

The final fight was also against Colin, this time with Screaming Banshee. This time, after some pushing and swinging of the axe, he stopped moving near the pit. I’m not sure if he was high-centred or the battery was low. In the end, he got counted out.

Overall, a good day for gathering data. The axe now self-right reliably, which is the main improvement I wanted after Burgh, now i just need to increase the power I can put into the gears, which should be simple enough to do by making them thicker. I had noticed that my drive had been deteriorating throughout the day, and after looking at the wheels, it looks like the improved drive power is enough to wear down the rollers quite quickly. I’m going to need to prepare more spares in the future to account for the attrition rate!

The plan for the Christmas break is to sort out the weapon system so I can fire it at 100% as mentioned above, and to get new forks and axe heads made.

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Gears are a beaut!

What made you go for HDPE over delrin or nylon? Just a touch more compliance?

Do you find the axe head doing much in the way of damage. I’m wondering what I can be doing to increase my chopping effectiveness and trying to copy others homework a bit.

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It was a pleasure to fight you! The self righting was flawless. Kept waiting for the moment it stripped something, then stopped working and I could stop worring about driving into the OOTA’s by accident.

A very tense 3 minutes <3

possibly my best 3 minutes of the day :wink:

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Availability - I already had HDPE stock on hand!

Generally, the axe head doesn’t do much in the way of damage, it just leaves indents in HDPE top plates. I have managed to cut a link with a well-placed swing before, and I have ideas on some different shaped axe heads to cut belts.

Upgrades are complete for PMXL ahead of BBB Beetle Brawl!

After the successful test run of the HDPE gears in December Dojo, I went about increasing their durability so I could run the axe at 100% power instead of 40%. I did this by using MOD3 gears as well as increasing the thickness to 10mm. In addition, I changed the mounting geometry so that the mounting hub was no longer recessed, increasing the amount of material around the screws by 6mm.

The other major change is to the hardox components. The new forks and axe heads have arrived, and combined with previous weight savings, means I can run a full set of 4 forks in most configs.

The standard and anti-drum configs now sport 4 forks across the front. The standard fork drops the hook which saves weight and removes a catch point for verts.

The forks also hinge up more, which should improve the effectiveness of the anti-drum forks.

Profile comparison between standard and anti-drum forks. The anti-drum forks have a much steeper tip, which will resist being curled upwards a lot more.

Two new axe heads- the first being a sawtooth cleaver deisgned to cut belts (in theory)

The second is a hardox Strapoon, which also incorporates the sawtooth design.

The top armour package is now done properly in black TPU.

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I went to Beetle Brawl this year with PMXL last weekend! Let’s get straight into it.

The melee fight was against Bad Daddy, a 4wd eggbeater, and Saw Loser. I afixed 2 of the new anti-drum forks along with the TPU top armour, and the sawtooth cleaver axe head. My plan going into this was to try to cut some belts on Bad Daddy before switching attention to Saw Loser, but an oversteer early on had Bad Daddy glance my armour skirt, inverting me. It turns out the axe has all the beans, with me doing 3 full backflips before self-righting! This was swiftly followed by Saw loser hitting the left wheel, which seized the motor. This meant I was crab walking for the rest of the fight, so I had to just go for any hits that got lined up rather than aiming them properly. I was inverted again, doing another self-inflicted somersault before recovering, before the pit was dropped and Bad Daddy ended up in it. Now with just Saw Loser, but with compromised drive, I tried to keep the axe pointed at him, but his drive was fully functional so that didn’t quite work out. I think his arm motor wasn’t working towards the end of the fight as he got a pin on me but didn’t swing the arm, after which he started reversing into me to use the spinner as a traditional vert. The fight ended with my being inverted, and once against backflipping a handful of times before righting myself! The judges decision rightly went to Saw Loser.

This awesome photo taken by Ellie clearly shows the armour doing its job. You can clearly see the split between the rear and right armour panels, and the right one is flexing out of the way of Saw Loser’s spinner, dampening the force PMXL is experiencing.

Now in the redemption, I was against a similar opponent in Attitude Adjuster, the other Scottish hammer saw at the event. With no eggbeaters to worry about, I swapped to 4 standard forks, and the standard axe head. In hindsight, I probably should have kept the cleaver, as that would have given more surface area for me to snipe exposed wires.

In the early stages of the fight, our forks kept interlocking, making it harder for us to land telling blows, though he managed a couple of good pins followed by a glancing shot at the front of PMXL. This back-and-forth continued, with me getting some good swings at him, with one embedding the axe head into his bulkhead for a moment. After some more exchanges, he eventually pinned me in the corner and landed two very well placed shots that destroyed my link door, and then popped the link out! He would later go on to finish 3rd, having removed two more links!

The ruined link door. Underneath the TPU top armour, he nearly punched through the 4mm HDPE too!

Inspecting the damage after the fight, I was very close to hitting his weapon motor wires when my axe got embedded in his bulkhead! A great fight regardless.

I also entered two whiteboards. The first was a mostly hammer bot affair, with Bop!, Happy Camper and Impulse. Bop! Unfortunately got inverted and couldn’t self-right eraly on, and Happy Camper also seemed to stop working, leaving jsut me and Impulse, who dominated and controlled the fight till the end. As a whiteboard, the audience decided the winner, so somehow I ended up winning that, though I firmly believe Impulse was the winner here.

The second included some spinners - Kairos, an overhead saw, Inferno, a 2WD eggbeater and winner of the 2021 champs, and Tsukikage, a durable 4WD lifter. Kairos took an early hit from Inferno and unfortuantely lost power.

Another photo from Ellie. The axe seemingly has enough power to make little hops now!

I managed to keep the front end pointed towards Inferno, the improved anti-drum forks proving very effective, allowing me to repeatedly stop Inferno’s eggbeater and preventing it from delivering big hits, instead giving me small pops backwards. Around the halfway point, the pit was opened and Infrno flipped Tsukikage over, who took a bit of time to self-rgiht. In the meantime, Inferno nad I kept on fighting, at one point he got behind and under me but didn’t do much damage. Tsukikage managed to self-right and got back into the fight, at which point I managed to get around the side of Inferno and push him into the pit in the closing seconds of the fight, resulting in me winning!

The anti-drum forks got nibbled a bit, but still fully functional. Nothing that a metal file can’t clean up.

Despite this being my worst performance in a beetle competition since 2021 champs, I am very happy with how the robot performed. The axe hits hard now - I had someone say they could feel the impacts through the floor! And it definitely can self-right consistently now, I just need to not go full beans! The only change I think needs to happen is a sturdier link door, and some minor tweaks to print settings for the top armour package to make it a bit more durable. I’ll get these changes ready for Sceetles in mid-March.

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I enjoyed our whiteboard, the commentary made it even better watching it back. Looking forward to seeing this at a future event.

The next gauntlet of events is about to begin, starting with Sceetles 2 this weekend. PMXL has gotten an upgrade after getting link sniped at Brawl.



Taking a leaf from a number of hammer saw designs, I added flaps either side of the axe mech, 4mm thick. They’re pretty flexible, so I might thicken them up or add some ribs if I ever reprint it.

The top armour also got a redo. It’s still 8mm TPU, but I’ve changed settings to 2mm of top layers, 0.4mm of bottom layers and 10% infill. The link door itself has been upgraded to match this spec too.

Sceetles will be interesting as they have a wood floor this time round, as well as expanding the box to a 3x2 configuration.

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Sceetles 2 has come and gone with a Top 8 finish for PMXL!

This time, the arena was increased in size to 3x2, and the floor was now made of wood. This made for an interesting time, as spinners had a bit more time to spin up, and forks would start to get caught in divots made by spinners as the day progressed.

First up was Chucky. We met in the middle and entered a stalemate, with neither of us gaining the upper hand, with us both missing attacks on each other. We then locked horns, and I got some swings in with the axe but that let Chuky get under me and push me against the call to flip me over, which I self-righted from.We then spent about 20 seconds jockeying for position, until he got under me again and inverted me. This time, the weapon wasn’t self-righting me for some reason, but I had just enough contact with my rear wheel to prevent being counted out. Chucky just pushed me over to the pit and dropped it.

When I was preparing for this event, I had swapped out the weapon module from Brawl with the backup one while I repaired it, but it turns out I never loctited the spare! So the gear on the motor shaft started freespinning after the first few uses of the axe.

Now with a freshly loctited weapon module, I fought Fission, a svert with some lifting arms. I had more weapon problems this time, as after the first swing (which looked like it landed close to his link), I lost all power to the weapon. My forks however were wining the ground game consistently, getting under his skirts, but I couldn’t capitalise on the control with a dead weapon extended in front of me. Furthermore, I was starting to get caught up on some divots in the floor. Eventually, he managed to get round to my back and popped me over, knocking me out.

Back at the pit table, it looked like the motor had completely disconnected from the output shaft. It turns out, when I took it apart at home after the event, that the pinion gear had come loose from the shaft. Back at the event, I swapped to my remaining weapon module.

The thrid fight night fight was against Adder, a brick of a 2WD wedge bot. I attached the cleaver for this, as his link was exposed on the top of this bot and I wanted to snipe it. Because he didn’t run forks, I was able to consistently get under him, push him to a wall (I think I was lifting his wheels off somewhat when I got under him) and unleash the axe. The axe finally started to work properly, and continued to work throughout the fight. I couldn’t hit the link, or push him down the pit, so the fight went to the judges which I won.

Due to it being a top 16 backet, I had a chance for the last place in that bracket alongside Oh Neil?, Meenie Mouse and Big L&D. I went with a split config for this fight, as it involved both a vert and a horizontal. However, Meenie Mouse had suffered critical damage in its last fight and so was running as a pusher. I wanted to box-rush Big L&D but got caught up on the floor. After freeing myself, I took a few swings at Oh Neil? before backing off again. Big L&D went flying across the arena, and I pursued as he was spun down now. Upside down, he has a hole in the baseplate that I managed to hook my cleaver into and dragged him around for a bit. After the release, he got back up to speed and I managed to lead with my anti-hroizontal side, and I think the ricochet caused him to land on a minibot and explode it. After a pause to remove the dead minibot, I managed to pin Meenie Mouse and swing the axe several times during the pin. I then repeated the process with Oh Neil? in the centre of the arena. As the clock ran down, Oh Neil? got under me, but I managed to wiggle off with my axe and hit him once or twice before the end.

Big L&D got very close to hitting my wheel in that exchange. I suspect that if the wheel had been hit, I would have lost the following split judge’s decision. That meant I was in the top 16, fighting against Ultraviolence. For the first time in this competition, I afixed the drum forks. We were both having trouble with the floor condition at this point, but I managed to keep every engagement forks first, which worked at keeping his eggbeater away from the rest of the bot. About halfway through the fight, he began to encounter spin-up issues, and the fight came over to the corner where I was standing, giving a good view of the bots as I got behind him and started swinging the axe at his link. After several blows, I managed to sever one of the wires, knocking him out!

Now in the top 8, I fought against Qry About It, a 2WD vert with a minibot. I immedaitely oversteered, giving Qry a solid hit on the TPU skirt which sent me flying, but I landed on my wheels. My forks won the next few exchanges but didn’t set me up for an attack. Qry hit my side again, popping me over, but I managed to self-right fine. I then took a few swings as they got onto my forks, aiming for the belt in between the disks, but missed. One last pop flipped me over with the cleaver caught on the other side of the kick plate. I managed to self-right but the cleaver was properly wedged in there and I was counted out, suspended off the floor!

Overall, a great day out if a bit of a rough start. I’m happy that the bot has been performing well over the past few events if not necessarily doing well, now it’s just a matter of getting more driving practice in. April Dojo is next for PMXL.

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Robodojo was busy this weekend, with 12 beetles and 32 ants - the most ants I’ve ever seen at a Dojo!

PMXL’s first fight was against Sabretooth, a meltybrain spinner that I’d seen at Scouse Showdown a few weeks ago. I was anticipating it getting up to speed more easily in the larger Dojo arena. I started the fight by rushing him, with the impact sending us flying apart. The fight continued with a cycle of several small hits while he was at low speed, until he got a bit more momentum to send us flying apart again. Eventually, I managed to coerce him towards the pits and a rebound off the wall sent him out.

The anti-horizontal armour seemed to hold up better than at Sceetles. I think the lower RPM and the thicker teeth on Sabretooth’s ring was a factor in that - I couldn’t see any tears through the wedge, but there were plenty of nicks in it.

Fight 2 was against End Boss, which historically has not gone well for me. This fight ended up being fairly actionless, with the majority of the time spent with us locking forks. With him having converntional wheels, he managed to control the engagements a bit better, pushing me up against the walls but failing to land any proper hits, grinding away at my forks. I held off firing the axe (a lesson learned from Icebreaker) as the only thing I could feasibly damage was his weapon belt, but my axe was on the wrong side to hit it. About halfway throug hteh fight, he managed to pick my side, which let him follow up and hit the rear wheel, removing some of its rollers. This left a moment where I got stranded on the debris, before luckily working my way off it before he could capitalise. I fired the axe at the next engagement, but it seemed to die after that swing. The rest of the fight proceeded as it started, with us locking horns, though his spinner did slow and stop. It later turned out that he had almost completely drained his battery! The fight went to the judges and End Boss rightfully won.

The weapon module was swapped out for the spare for the next fight against Shrektforce. It was immedaitely apparent that PMXL was not driving as normal, and Shrektforce was also experiencing driving issues. The beginning proceeded in much the same way as the End Boss fight, unti lthe drive problems lets him get around to the back and hit me, inverting me. For some reason, the axe struggled to fire, but eventually it tipped me back over, where I was immedaitely hit again. This happened a couple more times, before I got stranded on a floor seam. The countout started but I was able to wriggle off it. The head-on continued for a bit, with the fight coming close to the pit. At this point, he started experiencing more drive problems, which let me get around to the side and eventually push him out.

I wasn’t sure if the weapon would work for my final fight against Boom Zoom, and sure enough, when I tested the weapon before the fight, it was unresponsive, a bad thing considering Boom Zoom is a strong lifter bot. Once again, locking forks prevented his weapon from properly engaging, so while he did not managed to flip me, he did lift my front edge enough to take my front wheels off the ground, which let him control me. He eventually managed to do so combined with a push from one side of the arena to the other, delivering me straight into the pit.

Finally, there was a playoff against Nightcall and Little Grey Fergie for 6th place. I immedaitely went for Nightcall, with the resulting hit sending him bouncing back and inverted. I managed to get behind him and tip him over onto his side temproarily. He regained control but was inverted, and caught the side wall, sening him up and onto his side, where he couldn’t move anymore. I turned my attention to LGF, where my forks were getting under him but my drive could not match his. He got a good push that strayed dangerously close to the far pit, but I managed to escape. The fight came back over to the near pit, where I managed to get behind him and slowly push him out.

A pretty decent run overall, actually managing to fight End Boss without any majro hits was a highlight for me. Unfortunately, I came away from the event with some major repairs to do in the week between this and MITE next Saturday. Both weapon modules were not working, so I needed to fix them as a priority.

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Both weapon modules failed at Dojo, and after taking them apart, I found the problems. The pinion gear had cracked in one of the gearboxes, and the pinion had slipped and was no longer an interference fit in the other. Luckily, I’d already started ordering in parts for a newer weapon system, so I spent some time on Sunday and Monday integrating the new weapon modules.

The new motor uses the same 2830 1300kv motor I have in DJ2, coupled to a 14:1 28mm gearbox. The gears in this gearbox are a lot beefier than the old one so hopefully they should hold up to the abuse, and the large bore of the interference fit (3mm as opposed to 2.3mm) should help keep the pinion attached.

Because of the length of the newer motor/gearbox combo, I had to use a rasp to remove some material from the side of the chassis so the motor can would not interfere with the chassis.

Despite the longer and heavier gearbox, using the 2830 motor instead of the 2836 motor resulted in a marginal weight saving.

I should be all set for MITE this weekend, I just need to finish printing off some armour packages.

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