The Barber Surgeon (OK, Google, play 'Barbra Streisand' by Duck Sauce)

The Barber Surgeon

As one thread ends, another begins. Writing up the build history of Crossblow was actually really helpful in designing the new iteration, as it helped remind me of all the decisions I’d made over the years. So, with zero prizes for guessing what I’m CADing right now, here’s the full progression of The Barber Surgeon.

Origins

The design really came from two places. Firstly, as mentioned on the Crossblow thread, was Robot Arena 2. I used to play a fair bit of this, and it’s where my medieval team theming originates. A Barber Surgeon, for those who don’t know, would be the individual in the village with all the sharp knives. His job would be as primarily medical, but would also work cutting hair, and even inflicting some gruesome punishments on behalf of the law. Therefore, it seemed a good name to give a Sawblaze-inspired bot. This was back in 2018, when the saw was having a real renaissance. For anyone wondering where the rust graphic came in, that was also RA2 - it’s one of the default chassis textures, which I then added to with my own custom texture work. Rusty surfaces and bloodied saws seemed like a suitably menacing aesthetic.


An early and later iteration of The Barber Surgeon in RA2.

It even fought, in Good Robottal’s Superheavyweight Tournament.

Up until this point, it was a fairly standard 2WD/4WD Dustpan Sawbot. But in 2021, I was on a call with Jevan Woodrow, helping him workshop ideas for his first Beetleweight. At the time, he was particularly keen on mechanum and omni drive, but I had my doubts about the pushing power of these wheels. I wanted to incorporate a weapon type that only needed to be delivered, rather than needing to push, and one of the designs that came out of that discussion was this, slightly rough, MS Paint drawing.


The initial concept sketch for The Barber Surgeon

While Jevan rejected the idea, I couldn’t stop thinking about it. It hit that perfect intersection of uniqueness and potential effectiveness that inspires me. I discussed in the Crossblow thread about how Bugglebots somewhat conditioned me to want to do original things, and there seemed like a niche here. Shatter! had not long debuted, and a fresh-faced new builder called Thomas Yau had started competitng with a Mechanum lifter called Deja Vu (Whatever happened to him?). No one else had yet attempted omni wheels on the beetle scene, and Crossblow was in a great place, so I began to CAD. The plan was to build a highly mobile drive platform, that could strafe to constantly keep it’s weapon facing the opponent.

The Build


Oh, TinkerCAD…

It’s a pretty 1-to-1 translation of the initial concept into a 3D space. I made some fairly simple design decisions, lifting the 3:1 HTD5 belt system and propdrive 2836 directly from Jamie McHarg’s Sawry, Not Sawry. The drive would be the already-reliable 22mm BBB motors, running on those old K2 VEX29s. The wheels were off-the-shelf 48mm Omni Wheels, of a type widely made to be Lego compatible. These particular versions, however, were designed to fit a brass hex hub. The arm would be powered by an old Crossblow 3S servo, running on 1:1 nylon gears. It would end up using a servo extender to allow the arm to move through it’s full arc.

At the time, I wasn’t able to easily access any machining, despite using it for Crossblow III, so made the decision to go for another hand-built machine, using 10mm and 5mm black RG1000. The first step was to get a rolling chassis. I was pretty sure that OpenTX could do the required mixing through the transmitter itself, but I had to make sure!


The assembly begins.

It took a little dialling in, but I was able to adjust the individual output of each motor to get a consistent sideways movements. The rule of thumb, for a left strafe, in a 3-wheeled, kiwi-drive layout, is that the front two wheels should be running clockwise, at about half the speed of the rear wheel, running counter-clockwise. For the brushless motors in Barber Surg3on (discussed later), the current levels are 20%, 20% and 38%, so it does take a little fine tuning.

https://fb.watch/xbG9reC9JD/
The first drive test - apparently Facebook videos don’t seem to embed here

It ran! And it ran smoothly. I now had a functional drive platform to build upon. I took the rolling chassis to Lego Wars filming that May, and prepared to start on the rest of the bot. BBB had an event coming up, explicitly for new builds, which gave me plenty of time (until August) to complete the project.


Team M&B in May 2022, with Crossblow III meeting David Harrison’s Crontsblö.

Completion to Competing

In reality, the build ended up being a little more rushed than expected, as I made the late call to bring Barber Surgeon for a first test as a whiteboards competitor at Rapture Gaming festival. It went together pretty much as described above. I selected an 80mm saw blade with some pre cut mounting slots that I could widen to M3s - I hadn’t had much luck drilling through other steel blades. A pair of fixed titanium paddles were screwed to the front, the idea being that a saw bot would benefit from having a fixed platform to push into when cutting, rather than lifting itself up. The plan was to hastily finish it in time for some initial testing and stick time, then to fine tune it and make adjustments before Subterranean Showdown.


The night before Rapture, still awaiting final weapon assembly, and some 3D printed gears from Tom and Gus.

The day of Rapture arrived, and the field size had shrunk, due to some last minute disruption and dropouts. The reserve pool basically shrunk to nothing, and I was asked if I could please enter Barber Surgeon into the main competition. I agreed, somewhat warily, but I wanted to help out the EOs to put on a good event. If you’ve read the Crossblow build log, you’ll know that Rapture 2022 was not a good day for me in the slightest. Crossblow blew it’s wiring loom out after it’s first fight, and the additional pressure of running a second bot lead me to stepping away from the event completely.

Barber, however, did get two fights before that point. It’s debut match was appropriately against the UK’s other strafer, Thomas Yau and Deja Two, and we were both very excited for how the match would turn out. Barber got very easily high centred on the static forks going into the fight, but some light persuasion from Dave Weston’s pliers bent them enough that the robot could drive smoothly. It was a fairly tame fight, where we both struggled with clearance, and Deja Two ended up losing power, but it was nevertheless what I was wanting from the day - data to improve the machine, specifically with the ground clearance. It’s very important for all three wheels to be in contact with the floor at all times in order to move as expected!


Brothers in Strafe.

The second fight was against Gaelic Gladiator, a green eggbeater, built by Shane Lale, and the importance of all three wheels became even more evident, as he clipped one of them early on, bending a motor shaft and leaving me limping. I was determined to get in some weapon usage in this fight, and while I couldn’t manage a full pin and cut, the saw landed some glancing blows, before some JSTs (ew) in the circuit couldn’t handle the current draw and gave out. I ran without forks in this fight, to combat the clearance issues, instead replacing it with some bent HDPE arms, but without the leverage to push against, the saw just skipped off of my opponent.


Baby’s first (attempted) cuts.

The repairs to Barber Surgeon were not too severe, but the tight turnaround, and level of work to do on Crossblow meant I withdrew from the event for my own mental health. To add to the dumpster fire of a weekend, I discovered that, since Barber had been bumped up to a full competitor, I’d lost my guaranteed spot in Subterranean Showdown. This was an understandable, but bitter pill to swallow, as if I’d just left the bot home, I’d have had more time to finish it, and have been more focused on Crossblow. The path not taken, eh?

Going Underground

Thankfully, some dropouts meant that I was still able to attend, so I removed most of the JSTs, and added some floppy forks from Crossblow, and primed myself for Bristol. Unfortunately, my scales were a little off, so the picture below is not how it actually fought, but it’s still my favourite of this robot.


Forks, HDPE arms, and dutch angles. This was literally taken in the coach station on the way to the event!


After weigh in, sans scoop. Locking bar restrictions also (rightly) got a lot stricter, so a large clamp was borrowed to secure the arm

The event can be pretty quickly summarised. The first round was a three-way melee against Comoran and ‘Loophole’ - since the event gave priority to ‘new’ robots, Sam and Gus built half scale versions of their dominant verts, Bby Shrekt and Bad FutherMucka, and entered as a cluster. A destructive opponent is rarely how you want to begin an event, and with Comoran very quickly disposed of, I was left to fend them off myself. Thankfully, the new forks made strafing around the arena a breeze, and I was even able to pin Mini BFM for long enough to cut a gash in its lid. My attitude to most events, especially with new robots is that if they do what they’re designed to, win or lose, I’m happy. This was that fight for Barber Surgeon. Shortly after, the damage from the twin verts wracked up, as they snapped my weapon motor shaft and split my saw, taking the win.


Evidence. It worked!

It became clear, though, that I had far too high a TPI (tooth per inch) value on my saw blade. Sam helpfully recommended an 80 TPI blade as I began work on the extensive damage. At Rob Webb’s suggestion, I swapped the motor shaft for an M4 bolt, but the weapon never ran right again. A disloyal wheel quickly ended the second fight against GrabberWobba, and the final match became a glorified weapons test for the then-unknown Icebreaker. Barber limped into a final rumble with the events’ other overhead weapons, then retired. The servo horn had begun skipping, so even the arm was pretty mediocre.

I learned a lot from the original Barber Surgeon. Mainly about over-spec-ing my connectors and components, and about how nice maching really is when compared to a hand build! I was pretty happy to leave the project there and move on. A new, saw blade would be fun, somewhere down the line, but that was it. Sion, though, ever the robotics devil on my shoulder, had other thoughts. ‘What if you make it a hammer saw?’, he said. And so, after an continuing bad run of things with the Crossblow IV/King Crossblow saga, I made a return to Barber Surgeon in late summer 2023, ready for something new.


Barber Surgeon II’s entry into my little book of robot designs.

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Harder, Better, Faster, Stronger

Barber 2 was basically a whole new robot. It began as an attempt to learn Fusion360 on a project that didn’t really have any stakes, fully intending to apply those skills to King Crossblow. I definitely learn better with a practical application for my learning, though as a result, it was a very messy fusion file that had to be rebuilt several times as I learned the software!

I designed arounds parts I had to hand. As with Crossblow IV, I had a ton of excess 22mm BBB motors around, and although the reduction on their gearboxes isn’t as big, (16:1, rather than 19:1 iirc) I had some 1806 conversions already prepped. Sion had also donated some parts - a pair of SK3 motors and some 6mm drisc disks - traded for a big pancake motor I had, bound for Leviathan. The forks were 3mm Hardox, built for Crossblow IV.


In hindsight, it was huge… ‘You’ve built a boat’

Given it was never really intended to be my next build, and my green-ness with Fusion, it wasn’t exactly my finest work. But as the CAD began to come together, I felt the irresistible pull to build. I signed up for War in the Wirral, a little over a month away, and pulled the trigger on ordering and manufacturing parts. There wouldn’t be time for a metal order, so I was locked into using the 3mm Crossblow forks, Sion’s Drisk Discs, and a lighter, asymmetric design that I’d added to the same metal order on a whim. Although I knew that it would likely not self right, I put one of the 1806 gearmotors on the arm, to give it some speed.


Phwoar!

Details in Design
I’ll post a few pictures of the build. The chassis was made with heavily pocked black RG1000 and HDPE, in 8 and 4mm. I also wanted to try out TPU, this new-ish flexible wonder material, so trialled it as side armour, or ‘bumpers’ as I’ve always called them. I printed some gears from PLA, as well as some new wheel cores.

One of the main flaws with the off-the-shelf wheels was the heavy brass hex hubs that they were designed to fit. They’re long, too, dramatically increasing the footprint of the build. The robot was already pretty big, as the odd angles of the motors made it difficult to position the arm motor and front left drive motor around one another, so any opportunities to reduce that was a must. Lastly, the injection moulded wheels were costly, rarely in stock, and fragile. The complexity of omni wheels makes them very susceptible to spinners! However, the rubber rollers and plastic axles usually survived the hits, so printing my own cores, designed to fit smaller, lighter, pololu hubs was a no-brainer.


Red PLA was already on hand.

The gears were 3:1, single helical, with only a d-shaft press fit planned for the initial assembly, with plenty of spares made up!


The beautiful 3D jigsaw of CNC.

The 1100Kv SK3s meant a 1:1 reduction would put out around 180mph. I initially mounted an aluminium O Ring pulley for the first stage, hoping the slip would help on weapon hits. A 3M HTD Belt ran to the second stage, with everything running on various needle and ball bearings.

‘How do you drive that thing?’

One of the (many) drawbacks to Barber Surgeon, in concept, is that it needs five motors to run! Each wheel needs individual control, as well as the arm, and the disc! In order to simplify the wiring loom, from early on, I’d picked out a 4 in 1 ESC designed for drones - a Skystars KM55A, running AM32. This had capacity to control all three drive motors, and the hammer arm, while a Skystars Talon 40A, left over from Barber Surgeon 1, ran the weapon. This significantly simplified the wiring loom, once each channel was flashed to be reversible.

On the transmitter side of things, I realised I never covered that in my last post. The right stick is set up as usual - Forwards, Backwards, Left and Right. Strafing was controlled by the left/right on the left stick. For Barber Surgeon 1, the saw was done on the potentiometers at the top of the transmitter, while the arm was mapped to the throttle. This was awkward, and the saw was operated on a set-and-forget policy. For Barber Surgeon 2, I wanted to bring it all onto the sticks, learning Logical Switches in OpenTX from Alex and Scott. This meant that when the throttle stick - and the spinner - reached 75% power, the arm motor would pulse for half a second forward, then in reverse at 25% power on the return stroke.

Practicalities in Practice

Had everything gone to plan, had all my parts arrived on time, and had my design worked as intended on the first go, Barber Surgeon would have competed at War in the Wirral. It’s never so simple though, is it? A morning in Jamie’s workshop got the build close to completion, but my last minute crunch time was wiped out by an over three hour train delay. It was overweight and flawed in a few ways, not least the belt system, as the O-RIngs slipped a little too much. A machining error had turned the pocked lids and baseplate into a full depth cut, but even that blessing in disguise couldn’t defeat my dodgy maths, as it was still overweight! Wirral turned into a fun day out, time with friends, advice and design input, and a chance to drive Boom Zoom in a whiteboard. It was a monumental effort in the timeframe, and I was left with a design to tweak and finesse in the months before Battle in the Burgh.


Near completion, just before Wirral. If that train had been on time, who knows? Next time I wouldn’t need to leave it so late.

Back to the 'Burgh

Building 95% of a robot in three weeks was a stressful task. Building 5% of a robot in two months was far easier! I began by cutting weight, truncating the plough, switching to titanium shoulder bolts, and having a 4mm version of Sion’s drisk design cut. The battery went from a 4S 660MaH to a 550MaH, bringing the machine to 1500g.


The Barber Surgeon 2 in the 'Burgh 3 photobooth.

There were other changes too. After chatting to Alex about square nuts, I gave the pinion gear some actual mounting. Team They/Them Mayhem were good enough to print me some in nylon, while the large gear was swapped to TPU. Most significantly, the O-Rings were abandoned in favour of a full 3M HTD setup. I realised it would be far easier to mount this pulley to the motor can, so the weapon motor was spun 180 degrees, creating a lot of empty space in the chassis.

I was able to test the finished bot in my ant arena, and while self righting on that 1806 drive motor wasn’t likely to be on the cards, the weapon worked well, and it still drove and strafed as smoothly as version one.


A glimpse inside. Credit - Liam Bryant.

My main competition fights were against Brassed Off, Crab Crab, and Zephyrus. Usually a very exciting lineup! But not really worth discussing in any great detail, since I had repeated issues with the hammer arm. I’d only received the nylon prints on the day of the event, as PLA+ and TPU had proved unsuitable. I was overtightening the grub screw, causing the nylon to deform, and the square nut to be pushed off of the d-shaft , though it took a little while, and a lot of threadlocker to realise and fix the issue. Unable to fire my weapon, I went 0-3, however, I was able to solve the issue by the end of the event. Just before the arena packdown, after the stream had ended, I went in for a match against Jeremy’s Downward Spiral, itself worse for wear, without it’s signature drill, operating as a pure grabber.

In a match no-one saw, Surgeon began to work. Admittedly, a wheel did get pinned, so the drive wasn’t perfect throughout, and Downward Spiral couldn’t do a lot to me, but after the pent up tension of a year of bad events, broken robots and unfinished projects, this fight is still very precious to me. Video below. Alex Mordue’s little ‘It’s working!’ comment in the background just makes the whole damn thing.

The Barber Surgeon 2 vs Downward Spiral - ‘It’s working!’

I can only thank Jeremy for agreeing to the match so late in the day, and Dave for being kind enough to hold up packdown to let me fight one more time.


Downward Spiral damage cam - including sniped wires and some gashes in the aluminium servo casing.

What was very clear, however, was that Barber needed a redo. A redux, even. A more powerful arm motor, and a drastically reduced footprint, thicker forks - designed for the robot - and a myriad of other tweaks to reach it’s full potential. Satisfied with my progress, Barber 2 went on the shelf, and Barber 3 - The Barber Surg3on - entered the design phase. It would essentially be the same design, just refined, and would first compete at Sceetles in March of the following year.

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And so begins another chapter in the Surgeon’s lifespan! I’m surprised, with how you described it, Downward Spiral had any parts left for a photo! Looking inside, that back wheel seems awfully close to the armour, and said armour looks to be the bendy sort. Good to see I’m not the only one at risk of breaking my electronics every time I close it up, since it looks crowded in there!

I’m You, But Stronger.

The main goal with the CAD for The Barber Surg3on was simply just to make everything smaller. I wanted to redo the CAD from the ground up, too, now that I had a better grasp of the software, and throw in a few quality of life changes. The size reduction was pretty straightforward. Due to the odd angles of a kiwi drive bot, the arm motor and front drive motor end up pretty close, so I simply positioned it a little higher, so that the drive motors could be moved inwards. This created enough weight for a Repeat Max on the arm, the standard arm motor used by other UK Hammer Saws. I also spent a lot of time on the theming for this bot, so I can show you the cool technical drawing I made up in Fusion, and used as a sticker:


One of my favourite ever sticker designs. Gonna be hard to top for v4. I also did the Plague Doctor logo melded with the weapon disc.

As mentioned, there were a raft of other small changes, including:

  • Removing the heat inset nuts used on V2 and (mostly) replacing them with T Slot Nuts designed for Alu Extrusion. The heat nuts were a clean solution, but didn’t hold well in the prints. They did remain in a few places with tight tolerances, connecting the gear to the arm, and the side bumpers to the front wedge.
  • The arm gears were swapped for Double Helicals. Why I ever put on Single Helicals escapes me.
  • Purpose designed forks in 6mm, both hooked and smooth. I also had a fixed ‘duck bill’ wedge printed up to fight horizontals.
  • The rear armour on v2 was a 4mm UHMW plate, held on by heat buts, and it was a nightmare to remove and fit. The bumpers were extended to form a rear armour loop and keyed in to one another.
  • The large wedge initially designed for Wirral had a pretty tapered edge that I had to cut off. I made the new wedge smaller and bought back the taper.

Machining was done by Sion, and the printing by Rob Weston. After careful deliberation, I made the decision to bring back the rust graphic, after it was absent from the heavily-pocketed v2, and to switch to purple as an accent colour to help the bot visually stand out.


The Ikea Bärbraa Surgön


Many of the parts had recesses and protrusions to key into one another and ensure everything lined up perfectly from the CAD.

Construction was pretty painless, as there was a lot recycled from Baber Surgeon 2 that could just drop straight in. I was hoping to have made enough weight to include an asymmetric disc, featured in the CAD and new logo, that I’d had made up for Barber Surgeon 2, but had been too heavy. Unfortunately, even my lightest disc had the robot dancing around the 1500g mark, and a few screws had to be removed to make weight. Those five motors really weigh you down! Below, you can just make out the printed red link sleeve I designed, that incorporated the robot’s logo. Unfortunately, the flush fit meant that the link easily vibrated free, and it was abandoned.


Meet the family. You can really see the size difference between 2 and 3.

Ladies and Gentlemen, The Sceetles!

The robot was completed at a much more leisurely pace, in time for March’s Sceetles event. I’d already done SCAR the year before (covered in my eventual antweights thread) and was glad to be making the trip again with a completed robot!


The night before battle, borrowing Theo’s re-enactment props.

The draw was brutal - three verts in Unstoppable Force, Qry About It and Meanie Mouse. You expect gremlins though, on the first trip out, though, and Barber was no exception. It shredded a motor pulley in the test box, thanks to a slightly too tight belt, though the same setup had worked fine on Barber 2. Thankfully, I had a TPU pulley that created enough slack to continue, but new belts were bought immediately after this event. Worse still was the transmitter issues. These had first reared their head during Burgh. Basically, there was a lag, or signal decay on one of the sticks, where the stick would return to the centre, but continue putting out signal for half a second more. It made driving a little challenging, and had been solved by a stick recalibration. I did the same again here, but it did compromise the second fight. I bought a new stick with a hall sensor for the next event.

Between all the fine tuning, winning fights wasn’t really on my radar. I went 0-3, unsurprisingly, but took the punishment and came away knowing what improvements I needed to make - proper drum forks, for starters, as the unhooked smooth forks, with their thin ends just got chewed up. The drive was smooth, and I managed a few hits, despite the tight belts. But even with the new arm motor, it still couldn’t self right. Something to do with the gears and their mounting. Here’s the damage:


Unstoppable Force got underneath me and stayed there. The chassis, forward of the front motors, is empty, so that part of the baseplate was pocketed to 2mm thick, which Corben went straight through.


Qry About It jammed up the weapon by ripping out the arm spacer during a hammer attack. I decided I didn’t need it anyways, and abandoned it going forward, making more weight for future events.


The old BS2 PLA wheels were fragile, as expected, and I made the call to move to PLA-ST. The clear, thin polycarb lid was another weight saving measure that I never quite got around to ever replacing.

Barber had been run through quite a gauntlet and was still kicking. Before MITE 1, my next event, I planned to test the bot a lot more, decrease the weight in a few places, and finally get that heavy disc into play. I’d trialled it in my Burgh whiteboard, and it had done far more damage than the lighter disc with all it’s teeth and catchpoints. The hits so far had been underwhelming, and I was hoping for better going forward.

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Jack Brotherhood - now on Spotify

In the wake of Sceetles, I took a little time to reduce the weight yet further. The tapered edges of the front wedge had become curled up, so I chopped them off, removed the remains of the arm spacer, and printed the Aluminium Fingertech Mount plate in PLA-ST. The wheels, too, were reprinted in PLA-ST for added durability. They are always going to be more vulnerable than regular wheels, but I was interested to see how the filament would perform. I finally had enough weight for the heavy blade.

I also had time for more testing, both in my antweight arena, and in Jamie Mcharg’s workshop. Footage below:

https://fb.watch/xnd0dXmnCT/

I had a great time taking chunks out of the old Salvager and Flatulence chassis, and smashing up a DVD player with a featherweight. More importantly, after some careful loctite application, and great care not to overtighten the grub screw, it seemed like Surgeon could finally self-right, at least on a full charge. I felt happy, and prepared for MiniBeasts in the East. Thanks to Jamie for having me over!


Those Dutch Angles again. Barber Surgeon is just a 60s Batman Villain.


Look, Simba: Everything the light touches is our kingdom.


I did actually break a hub. I forget what this was printed from - probably PLA. New hubs were 100% infill PLA-ST.


My home testing proved the weapon could now punch through 3mm UHMW.

The MITE-y Quinn

And so it was down to Norwich for the inaugural MITE event, looking fresh with new stickers and the heavy disc. It had been designed before Barber Surgeon 2, intended as a reversible asymmetric weapon, allowing a ‘vert mode’ or for tooth wear on both sides of the disc. In reality, the rear ‘teeth’ were never going to do anything, but do look cool, like a gear. I thought it looked a bit like a bunch of flowers, so called it ‘The Posie’, to keep with the medieval medical theme.


Hot. Also new stickers. Very proud of how they came out. Note the amount of fork flop. This will be very important later.

My first matchup was against Gremlin Bait, a billet aluminium wedgebot, driven by Morgan’s partner, Faith. Never underestimate your opponent, but it seemed like a nice, non-damaging way to start the day, though I probably wasn’t going to be puncturing any Lipos.


Wait for a good hit. I was a bit jumpy early on.

It was initially a cagey match, and Gremlin bait did well to slip away from any meaningful hits, and did manage a good drive on the wedge. At one point the arm seemed not to return to it’s firing position, but I was ultimately able to reset it.

Then the fight changed, and Surgeon was able to strafe to the side of Gremlin Bait, and catch it on the forks. Four hits followed in quick succession, removing a wheel, pushing it under my opponent, driving it to the wall, and managing a perfect link snipe, bisecting the connector wire in two, right down the centre. Barber Surgeon got it’s first tournament win, and by KO, too, the heavy weapon coming in clutch!


Something something don’t bring wheels into the arena. Omni Wheel supremacy.


The Aftermath. Surgeon’s best performance to date.

I had hoped this would set the tone for the rest of the day. Sadly, it did not. My second match was against Will Thomas’ Inversion, and it did exactly that, and pretty quickly, too. Despite self-righting in the tests, Barber got stage fright under the lights, on the grippy arena floor, and stayed face down. Will played with his food a little, but the match was basically over. Even in testing after the event, I was never able to replicate that one self-right test at Jamie’s. Fight three was much of the same, in a rumble against CDG and Sniper. I fitted the TPU duck-bill wedge, but Sniper’s narrow blade grabbed into the UHMW front plough and overturned us, and that was that.


Kinda sums up the rest of the event. You can also see a heat nut poking out near the front wheel. The few that were left in the design were a reoccurring bane.

Nevrtheless, MITE was a ton of fun for that first fight alone. As I said before, the robot did what it was designed to do, which is always my yardstick for satisfaction, rather than tournament success. The self-righting, though, was a puzzle. The TPU gear seemed to be bending and skipping against the nylon pinion. So a thicker gear or higher MOD value seemed to be the solution. But could that be right? EVA-02 has a very small MOD value and still self-rights fine. As it happened, the centre distance between the existing gears made designing for anything else quite a challenge, and my ultimate solution was to trial an all nylon geartrain.

I also wanted to design some ‘proper’ weapons, as I still felt that I could be doing more damage. My efforts so far had been either copies of existing designs that weren’t optimised for this application, or my own fumbling first attempts. Under Sion’s supervision, I created some new discs in preparation for Rapture, giving me quite the set of Surgeon’s tools to choose from.


Tools of the trade.

From left to right, including the weight of the hub, screws and bearing:

  • The Heretic’s Spike - 76g. Nice and light with a big bite!
  • The Sawtooth - 76g. The new standard setup, designed to rip and tear.
  • The Scythe - 85g. An 8mm hardox axe head for sportsman matches or to feed into overhead weapons.
  • The Posie - 124g. The signature look, heavy, packs a punch.

I also replaced the UHMW plough for a TPU one that keyed into all of the weird chassis angles. I had been impressed with how the material had held up as side armour, even as a lighter print, and was keen to try it our for myself as a plough, ready to commit to a full wraparound TPU armour ring.


Barber Surgeon the night before Rapture Gaming Festival. I wouldn’t collect the nylon gears until the day of the event.

Travellers Beware: Here Be Spoliers:

I realise some people on this site have omitted a Rapture report from their recaps. I am going to cover the event for the following reasons:

  • Robot Rebellion have said that it is ok to do so.
  • This forum is directed at the robot building community, not the fan audience - so I kinda assume that you were there or knew someone who was.
  • You have freedom to avoid spoilers if you wish - just come back later.
  • The event marked a significant breakthrough in Barber Surg3on’s development.

That said, without footage or photos, this will be a brief recap that may well be revisited at a later date. Or not.


Propane. Yikes.

Match one was against Critical Fail, a Thagomiser-inspired first bot for it’s builder. The weapon, a fingertech bar, directly mounted to an antweight brushless motor, exploded on first contact with my forks. But the 10mm top armour was inpenetrable, and after an unstick, I went for the wheels. But I got greedy, seeing an opportunity to pit my opponent, who escaped just in time for me to sail into the pit myself. 0-1.

Match two was against heat seed EMP. With the nylon gear untested but installed, I hoped to repeat my previous self-righting successes, however, it was not to be. I landed a small shot to Felix’s flipping arm, but he had me over in a flash, and Barber would, yet again, remain face down. EMP capitalised quickly, ejecting me from the arena. 0-2.

Lastly was Propane. With my new drum forks fitted, I still did my best to avoid the devastating eggbeater of the flywheel robot. I almost had an opportunity, too - Propane got hung up on the pit, and I was perfectly lined up to hit his printed lid right above the battery - unfortunately, in the half second the arm takes to fire, Propane went from stuck to freed, and escaped. It quickly launched a counter attack, and I was flipped. 0-3.

Day two was all about fun and fact-finding. The suggestion came from Ryan Bratley, that even Surgeon’s comparatively shorter forks might be too much of a fulcrum point for my setup to handle. On the Sunday morning I borrowed an angle grinder from Dave Weston, and on my messiest set of forks, cut off the lugs that prevent them from flopping all the way down, to test this theory, and see if it could self right. I’d fitted the TPU gear first, since I knew a nylon/TPU pairing was a proven material setup by others.

Before I could get to the test box, however, I found myself in a non-spinner rumble, using the Scythe. Did it self right? No. Afterwards, I swapped to the nylon gear and put it in the test box. Did it self right now? Yes! I had another rumble, for a side event that I won’t spoil where I wasn’t flipped, but came runner up, due to an overtightened weapon bolt when changing setups.

My final match of the weekend started as a few spinners going in against Comoran, but turned into THE spinner rumble of the weekend. Propane, Zephyrus, Icebreaker, Unstoppable Force, Baby Dead Bod, Paradigm Spin, Comoran, and me… Ouch! Unstoppable Force boxrushed me immediately and flipped me. And I self-righted! I strafed over to Icebreaker, removing some of it’s TPU armour, before it yeeted me across the box, landing upside down. And I self-righted! Propane corralled me into a corner, toppling me over… And I self-righted! Five times in total, lasting until the end of the fight, coming second to Propane. Granted, there were a few issues getting off of my forks, but I left Rapture buoyed by a problem solved, despite my main tournament run.


A collage of grainy phone shots - Critical Fail’s bait-and-switch, EMP’s OOTA, the Scythe’s debut fight, Propane’s escape, and Barber’s successful self-righting!

In the months after Rapture, though, robots dropped off my priorities list as life took over. for Battle in the Burgh, my local event, I simply modified some more old forks, (as no group metal orders were forthcoming) and hand some new PLA-ST wheel cores printed on Sion’s incredible Bambu printer.

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Back to the 'Burgh²

My expectations were mixed going into Battle in the Burgh. Although Surgeon could now self right, it had sat unloved in storage for a few months, and I still hadn’t solved the potential chance of getting caught on my own forks. Burgh this year was only a one day event, so with very little on the line, I went along to have a good time.


Liam took a slightly better photo than mine on the day - including the kilt - but it does look like it was taken in 2008!

My first fight was against Doctor Sweep, a Steven King-Clad dustpan wedgebot from Callum Hoy. In this case, it was made from a literal dustpan! He’s posted a build log here. I quickly found I was able to outwedge my opponent’s acetate but didn’t quite have the reach to hit the main body when we met head on. For most of the fight, I managed glancing blows that slowly bent the thin metal body.


INCREDIBLE photography from RBS Media. I mean… Just look at it!

We were separated for an unstick after a particularly meaty hit, but broadly, Callum’s driving was preventing me from getting the opportunity I was looking for… until the dying moments of the match, when I managed to scoop up Doctor Sweep from the rear, and take it to the wall, delivering a final blow that ejected the link.


Hello, Link! Credit: Team Triforce.

There was a nasty scratch left on the dustpan’s lid, but I couldn’t help but wish that the weapon had been more potent, despite the KO win. Watching back Team Triforce’s slowmos suggests to me that the arm may be limiting the weapon’s bite. More on that later.

Fight two was against Sabretooth, an incredibly cool dual spinner melty, with a geared weapon system for synchronised spinning. Coincidentally, it was from the same builder as Brassed Off, an opponent of Barber Surgeon from the previous year. I slapped on the old plough and TPU duck bill, hoping I wouldn’t be flipped.


The one hit - Credit: Team Triforce

It was another KO win for me, but not one I deserved. Unfortunately, Sabretooth was having trouble, and was only running with on spinner. It managed a big hit to start the fight, but struggled to translate afterwards, and eventually died. The heat nuts holding in the front armour on Surgeon had been causing me trouble in previous events, so I had removed them, as there wasn’t really much spaced for a recessed square nut to take it’s place. Unfortunately, that one big hit had wedged the armour awkwardly against the plough and pinned a drive wheel, leaving me unable to pursue the struggling sabretooth, and making for a boring fight. The duck bill also struggled with clearance, and would need redesigning.

I was hoping for a stronger finish for my final fight, against rookie grab-and-lift machine TBD. Craig was a new builder, and the whole bot was printed from very thin, low infill materials, and only one set of the wheels were powered, so I felt decently optimistic about my chances. It was very much a fight of three parts: TBD got stuck early on, high centred on the floor. I took the opportunity to get in a hit, that landed just shy of the link, but when that didn’t free it, I made the decision to push Craig off of whatever part of the floor was high centring him, since I wanted a good fight.

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Very close!

The middle of the fight was back-and-forth, but I felt mostly in control. I got in several hits that did very little damage - apart from the one that shattered TBD’s grabbing arm - since the armour was very spongy, but I discovered later that there was incredible internal damage. TBD was still moving though, and Craig got a great drive to pin me in the corner for ten seconds, then used the remains of the lifter to pop me onto my forks. I spent the end of the fight avoiding a count out, firing my weapon to shake myself free, and the match went to the judge with that impression in their minds. A 2:1 split against me came back, though the match was very close. Such a strong resume put me into a top 16 for the very first time…

…against Ray. The little fox-themed lifter was quick, pushy and very well armoured which is kinda Surgeon’s kryptonite. While the omni wheels are especially good for escaping pins and pushes, a hammer saw relies on your driving to get a good shot, and an omni hammer even more so, since it cannot push so well. Ray’s articulated wedge immediately proved the stronger, and they were able to topple me and push me towards the pit corner. Again, I was stuck on my forks, trying to shake myself free, manging to do so just before the pit dropped. I dropped the hammer saw a few times on Ray, and pushed them to the blue corner, but Ray pushed back, and we ended in a nervy standoff on the edge of the pit, where I came off worse. A good fight, and overall, I’m not disappointed, as this was by far Surgeon’s best day at the office. The weaknesses were mostly already known, and some redesigned forks would make it an even stronger prospect.


Teamed with Dave Weston against Articfurno

A teams tournament and a Gladiator followed, and I began to consider my next steps. I chatted to Morgan, especially about how I had been underwhelmed by the potency of my weapon, and how I was considering thicker discs - 5mm over 4mm - as a solution. His response surprised me: Dolos uses 3mm sharpened discs, as a hammer saw is never going to get the same mass in their weapon as a vert, so concentration what you do have into a small point, since you can choose the engagement, had been his solution. That said, a hubmotor added significant weapon mass, and gave me a broken magnet ring casing to study. Buoyed by this understanding, I went into CAD and began work, first on Crossblow, and then on a Barber Surgeon 4…

Where are they now?

Barber one was stuffed and mounted after being stripped for parts. When I printed new wheel cores, the old injection-moulded cores were easily glued together and added back to the chassis. You can see it in the Barber Surgeon 2 assembly pics.

Barber 2 itself sat on the shelf for a while until Anthony reached out about Crossblow. A short time later I sent him the robot’s shell with any remaining spare prints and some TPU wheel cores. It no competes at Mecha Mayhem with a Scythe hammer head.


Darkest Ireland’s Home for Retired Robots.

As for Barber Surg3on, it’s still assembled and ready to go, aside from some minor parts pinching to measure up for the Barber 4 CAD. I redesigned the forks on Jed’s recent metal order, so it should be good to go for whiteboards until I build it’s successor. I don’t, at present, plan for it to compete again, though there’s still plenty of life left in the chassis.

And that brings us up to date. Tune in next time for the big reveal of where Barber Surgeon goes next…

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Barber Surgeon 4

I went into this design process with a few clear aims:

  • Firstly was a hubmotor. Morgan had more than sold me on the potential benefits to weapon effectiveness, which was on top of the benefits I already understood about simplifying the weapon system and saving both space and weight. This would also allow for a curved or angled weapon arm to prevent the hammer arm from limiting my bite.
  • Following on from that was the weapon geartrain. My current gears were both narrow and of a lower MOD than I would have liked. Not only had this made the actual transmission of force through the gears quite concentrated, but it had also made it difficult to mount the pinion gear securely - all this time I only had space for a single M3 grub screw and square nut, and that had to change.
  • Finally was some general design rationalisation. Five events and over a year into Surgeon’s hammer saw era, and I’d really got to grips with the parts of the design that worked, and the parts that didn’t. Given the design remained fairly consistent between v2 and v3, now was the chance for some meaningful steps forward.

The CAD process started differently from every other Surgeon, in that the weapon came first. Really, this is the ‘correct’ way to do robot design, but since I’d been getting to grips with an alternative drive system, that had, until now, been the starting point. The Repeat Antweight hubmotor was selected for the task, due to availability and high praises from the other Scottish hammer saw builders. In terms of weight, cost and availability, it seemed ideal, especially since making my own would probably not be any cheaper.

To this, I will be mounting a 106mm 3mm Hardox disc. At the hubmotor’s 1200Kv, on 4s, this would max out my tip speed at 250mph. Just like Dolos, this disc will be sharpened, and currently weighs in at ~65g.


Aggressive… Most… Aggressive.

A single curved 10mm RG1000 arm followed, then some nylon MOD 2.5 Double Helical Gears at 3:1. The pinion gear now has three M4 square nuts along it’s length. I chose a cantilevered motor setup purely for motor placement. As discussed before, the arm motor and front drive motor are very close in this design, and a single arm allows me to raise up the arm motor on the opposite side without fouling the weapon arms themselves.


How am I lookin’?

Another rationalisation step was to alter the chassis shape. Omni bots are always going to use space inefficiently, but I felt there had to be a better way to wrap the bot around the components than the current triangle, despite it’s aesthetic charm. A slightly flared rear end to accommodate the battery, and an arrowhead shaped baseplate was my initial approach but…


Uhm… Is that a robot in you prints or are you just happy to see me?

…it ended up starting to look kinda… phallic? Any attempt to salvage this baseplate design became a bloated mess. Since an omni has guaranteed empty space, for perhaps the first time, I had to start thinking about aesthetics instead of pure space efficiency. Ultimately my solution was one that many of us can relate to in life - be more Thomas Yau. Using an approximation of PMXL’s baseplate as a starting point, I slowly adjusted angles and cut material until I found something I was happy with…


I’m thinking maybe an orange TPU this time out?

I realised just how much I liked the angular shape of previous Surgeons, and this is what I ended up with. The major parts are closely packed, but with enough tolerance. I’m thinking of adding magnets, too. You can see the mounts for two in the ‘lids off’ angle, just next to the front drive motors, and there will possibly be some rear ones too, to keep the tail planted on a hit.


Fusion doesn’t render orange translucent material very well, apparently.

The TPU armour ring is now in four parts to avoid any heat inset nuts and tricky mounting angles. The front piece includes the plough and front drive armour loops, which mounts with woodscrews to the front and sides. A left and right ‘bumper’ piece is stacked onto the same side mounting screws, and runs as far as the tailpiece. The rear armour is another separate piece, for ease of printing and replacing.

Just like the new Surg3on forks, which are designed to be compatible, the forks here will flop and lock just before the robot can get high centred on them. I’m trying some long 4mm forks out, but I still have some old Surg3on locking forks, unmodified, that I will try to see if the new gear setup can self right where the old one couldn’t. I’ll draw your attention to the new duck bill wedge (top right) on hardox hinges.


Gonna tell my kids I built this as a cluster.

Size wise, it’s the same wheelbase, near enough, as Surg3on, but with the chunks taken out of the sides and some lower profile bulkheads. I’m doing some weight calculations, but you can see just how tiny the new Crossblow is! Drive will remain exactly the same, unless I invest in some rotalink gearboxes, as the current drive system is quite jumpy. Apart from a few fasteners and motor covers, this is it so far! I’m considering building Crossblow first, since I already have some of the forks on order, Surg3on is still functional, and the Repeat parts will take a while to arrive.

If you’ve read this far, thank you very much! I hope you’ve enjoyed this look back, and I’ll post again as soon as I have any decent updates. Any design feedback would be gratefully received, and I hope to see you in the arena soon!

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that new disc is looking tasty!

the bot overall is looking fantastic mate, i bet that new shape saved allot of weight

im looking forward to seeing what it can do in the arena, hopefully get a match sometime!

i don’t think the zeph match counts since i think we both died pretty much a the same time :rofl:

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Ultimately my solution was one that many of us can relate to in life - be more Thomas Yau

:heart:

Using an approximation of PMXL’s baseplate

I also appreciate the pun here with my team name :slight_smile:

Loving the new look Barber Surgeon, that weapon looks vicious! The chassis shape is just the natural shape that evolves from trying to cut out as much of the chassis as possible for a kiwi drive system imo.

Not sure if you’ve got a motor cover for the arm motor, I’d try to add one in case a vert catches you upside down.

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