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Thread: The Making of a House Robot - Shunt

  1. #1
    Hey all, been meaning to do this for absolutely ages but kept putting it off/getting distracted/procrastinating. But no more!

    Finally time for a build diary to chronicle my Shunt replica build as, barring a couple of small alterations to more closely match the original, it's pretty much complete. Hopefully it'll be an enjoyable read for you all.

    April 2018

    I can't remember when I first had the idea to make a Shunt replica, but my earliest email to Jonno enquiring about the shell was December 2017, and he very kindly agreed to have a shell made from the mould he has. Fast forward a few months and I attended the 2018 Manchester Extreme Robots event to collect it (and took Drumroll along for some 'fun' - sorry Honey Badger!)

    The reason for Shunt is that I initially wanted to make a Dead Metal replica, but it's difficult to get a reference point for size and scale with DM. Original Shunt is my second favourite house robot, and seeing it in the flesh at the time of the reboot was brilliant. Since Shunt has a fibreglass shell, this dictates the size of the main chassis. From there, I could then work out or guesstimate the size of things such as the scoop, wheel guards, plough and axe. This would involve a lot of studying of pictures and video footage to get an idea of how the original went together and how to plan mine - I lost count of the amount of hours I spent staring at zoomed in pictures and watching the Shunt section of the Ultimate Warrior DVD!

    My aim was to keep the build secret for as long as possible, up until the reveal, though a few friends knew about it. I couldn't resist getting a picture of it next to ER's Matilda at Manchester, so hung around for a bit until people dispersed, then sat them side by side:

    shunt_build (2).jpg

    The shell seemed quite small by comparison, though would obviously look more substantial with the extremities fitted. Still, it shows that for being considered the most powerful of the original four house robots, Shunt was also one of the smallest. With the shell in possession, the first thing I did when I got home was position a tyre and a drinks bottle in place. I remember reading that Shunt's exhaust stack in Series 1 and 2 was a lemonade drinks bottle, so wanted to make mine in the same vein:

    shunt_build (4).jpg

    The wheel in the picture is 10" diameter. One thing that has never looked quite right with the Extreme Robots Matilda (and subsequently the Robotazia one) is the wheels, they've always looked too small, and that was true here too. After some more picture studying, I guessed that the correct size must be 12" kart wheels. Just one small problem, they're not easy to find! I eventually found one supplier in the UK that had them but it would be weeks before they were in stock, so I bought a pair of 10" kart tyres and split rims as a temporary placeholder.

    May 2018

    I was kept busy with work until the late May holiday weekend, so spent hours researching Shunt, determining how the chassis was constructed and what I'd run mine on, and got some materials ordered up. The guy in Argos was quite excited when I told him the steel he'd helped me carry to the car was being used to make a replica house robot :P
    Shunt's main chassis seemed to be constructed from steel angle (all the house bots in Series 1 appeared to share the same basic chassis design) so by looking at the shell I had and what the various sections of it were like, I set about making a simple cuboid chassis that would slot into the lowest-most section of the shell:

    shunt_build (19).jpg shunt_build (20).jpg
    shunt_build (21).jpg

    Due to my lack of machine precision cutting and thin plywood welding 'jig' the chassis is a bit rough around the edges and maybe not entirely square but no-one would see it. I settled on using 24V, 800W scooter motors for the drive as I had two spares from Coyote and they've done me well so far. I made some drive shafts from pieces of box-section upright and a length of silver steel which was welded to a collet which in turn was welded to the box section. Crude but effective. Then came some motor mounts and sprockets bolted to the wheels, and before long it was running around in the garden:

    shunt_build (30).jpg shunt_build (32).jpg shunt_build (36).jpg

    One of the sizes I pondered over was that of the axe arm. Again I was looking at pictures of Shunt from the RW tent and the clips from the Ultimate Warrior DVD. Reckoned it was either 40mm or 50mm height, so made cardboard mock-ups of each and took a punt at 50mm. When the stock turned up, it looked spot on:

    shunt_build (23).jpg

    It also weighed a lot! The scale of what I was working on was beginning to sink in.

    I didn't do much to Shunt over the summer months. I was working in Aberdeen at the time and my workshop was 170 miles away at my parents' house. I had a couple of weeks off in July but had signed up for the inaugural Glasgow Maker Faire at the end of July. I should take this moment to mention that I anticipated Shunt to be a slow-burner build, maybe taking a couple of years before it came anywhere close to looking like it should, so the two weeks holiday were spent working on my mechanoid R.O.R.I. for Maker Faire as well as repairing and repainting Coyote after it fought in Dublin in January 2018.

    The one Shunt thing I did work on (as well as swapping out to the 12" kart wheels which turned up) was to do some work on the exhaust stack. I found Highland Spring water bottles that looked to be about the right size, cut two in half and stuck the two neck ends together. One end would go into the body (and be secured by the lid) and the other half would be the top with the outlet pipe. One of my biggest quandaries was how to make the 'holes' in the exhaust stack, as it would need a layer of material with the holes drilled in that would wrap around the bottles. Then I stumbled across a glass drinks bottle from B&M that had a grey rubber grip on the outside with holes in it - perfect! I bought two so I had enough material to span the bottle and proceeded to butcher them for the grips. A quick test against the bottle, and it looked the part:

    shunt_build (41).jpg

    The exhaust outlet was made from 22mm copper pipe and a 90 degree fitting. A length of copper pipe also ran all the way through the bottle as I had plans to maybe fit a smoke machine and have some smoke puffing out of it for dramatic effect.

    That's all for this installment, next one coming soon!

  2. #2
    Coming soon = now, since I've got time

    September 2018

    So I mentioned in my previous post that this was going to be a slow burner project, something I'd take my time over and wouldn't be ready for a couple of years.

    Then RoboNerd became a thing!

    I made the snap decision to aim to get Shunt visually complete in time for RoboNerd. I knew I wouldn't have time to fully kit it out, but a static display piece was possible, if a little tight on time.

    First up was the axe. Shunt has a rear axe stopper at the back of his fibreglass shell and since I had my frame which fitted into my shell, I just needed to make a stopper that bolted on and protruded out the back. This was made from two pieces of 40x20mm box section; I cut the 40mm section off one side of each piece and welded them together to make a 40x40mm square. I cut up some rubber that I had left over from shock mounting stuff on Coyote and wedged it into the steel to provide some sort of padding on the return stroke of the axe.

    I then made a pair of simple uprights from steel for the axe pivot. The location of this was again determined by the shell, the small curved extrusion at the front. With a pivot point and rear stop, I now knew how long the axe arm needed to be, so I cut up the 50mm alu bar, put a slant on the axe end and curved the pivot end. One pivot bolt later:

    shunt_build (47).jpg shunt_build (52).jpg

    I also added two pieces of 40x20mm bar underneath spanning the width of the chassis. These sit on either side of the wheels and provide a mounting point for the wheel guards.

    No axe is complete without an axe head. I wasn't sure what to make this out of at first; I was looking at scraps of 15mm thick mild steel at my local metal merchants before remembering I had a plate of 10mm Hardox 450 from Series 9 Coyote that got salvaged from the mangled wreck of a post-Carbide weapon assembly. I made a cardboard template of the axe just to check sizes and, once happy, cut two axe shapes out of the Hardox plate. These were then welded together to give a 20mm thick axe head and ground to a smooth finish. Two 6mm mild steel plates were also welded on to provide the mounting point:

    shunt_build (56).jpg

    I also gave the exhaust stack a spray to make it a bit darker and painted the shell a shade of brown. Not quite the right shade, but it was enough to help with the look during the build:

    shunt_build (60).jpg

    With the addition of those parts, it was starting to look like a Shunt. Yet another thing I'd been fretting about was how to make the horns for the top of the shell. I'd thought about wooden dowel from B&Q sanded down as well as making them from foam etc. Then had a brainwave; I had 200g of polymorph I'd randomly bought from Technobots just incase, and seemed to be no time like the present to use it. Some modelling and remodelling later and the look got a little more complete:

    shunt_build (67).jpg

    Time was ticking on and while I only had the scoop, plough and wheel guards left to do, that involved a lot of cutting, grinding and welding of metal. First on the agenda was to make plates that bolted to the chassis to support the pivot arms for the scoop and plough. These were formed from 3mm mild steel. The original had a step-out/bend in the plates where the arms pivoted but I didn't have any decent bending equipment, so settled on the 'score with an angle grinder, bend by hand and tack weld in place' option, which worked well. There were also a couple of additional pivot brackets to be welded on the front to support the scoop arm pivots on the far side:

    shunt_build (61).jpg

    From here, I cut some lengths of 40x20 box section to make the arms for each end (as a side note, I've determined that these are 50x25 on the real Shunt so will be upgrading mine soon as the 40x20 ones look a little weedy):

    shunt_build (66).jpg

    I should add that I'd also welded on outrigger arms to the front wheel guard cross beam. These outriggers also had pieces teeing off them that would form the front mounting point for the wheel guards.

    When it came to making the scoop, I started with the sides. Using cardboard again, I sketched out what I thought to be as close to the correct shape as possible then went to town with the angle grinder. I also welded on some tabs with holes which would be used to fix the blade to:

    shunt_build (69).jpg shunt_build (70).jpg

    The shaped pieces you see in the above photo are the outermost edges of the scoop, then there are the tabs, and then there is a second curved plate that has a larger rear section which bolts onto the pivot arms. Multiply that by two and it was ready for the large scoop plate. This was made from 2mm steel, which i thought would be easy to bend. Well, it would be with the correct tooling, but the correct tooling I did not have! I managed to cobble together a setup that would allow me to make incremental bends but occasionally involved me hanging off my workbench like a monkey from a branch. Perseverance prevailed though, and I had a scoop blade that matched the curve of the arms:

    shunt_build (72).jpg shunt_build (76).jpg

    Putting the shell, axe and wheels on was a common occurrence every time a little bit of progress was made. "What does it look like now, I wonder?" Cue a lot of wasted time assembling and dis-assembling it.

    I decided to tackle the plough last so the next stage was making wheel guards. It turns out I'd positioned my wheels a bit higher than the original so my guards had to be a bit taller in order to fit the piece of metal that spans the wheel from the guard to the body, and I didn't quite get the angle on them right. But they would do for now. I also slowed down the taking of pictures as the build deadline approached, so 'here's one I made earlier':

    shunt_build (80).jpg

    And just like that, it began to look even more like a Shunt. This development drove me on to get it finished, but throughout I wasn't happy with the colour of the shell. It needed something else to look more like Shunt. Cue a trip to Halfords, where I bought a can of spray paint that was for a Peugeot 307 (blaze yellow I think it was called) as well as an airbrush kit and some black enamel paint. Giving the shell a light dusting of blaze yellow brought it to a much more accurate shade, and once I got the hang of the airbrush, I was able to add the black accented edges which, combined with the blaze yellow, gave the shell the 'pop' it needed:

    shunt_build (83).jpg

    Final stretch time, the plough. Again I didn't take many pictures of this, but started off with a base V-shape and some terrible welding. Used some cardboard to get the right shape then cut out the metal from that template. It was also 2mm mild steel and was also a challenge to bend properly but got there in the end. I sat the finished pieces down next to the rest of Shunt and, even without its wheels, it suddenly came alive.

    shunt_build (85).jpg shunt_build (86).jpg

    I distinctly recall standing there and saying out loud: "Holy crap, I've made a Shunt"
    I got the plough pieces welded onto the V and welded up the seam in the middle. The shape isn't quite right (on the list to redo) but you can't really tell, looking at the photos.

    Once the plough was welded, I threw it all together for its first official picture as a complete robot. I was staying at Dave Moulds' place the night before RoboNerd, so I unveiled it that evening on social media, then snapped a shot of it with Carbide because I could :P

    shunt_build (94).jpg shunt_build (98).jpg

    And so concludes Phase 1, getting it to a static display stage five months after first picking up the shell, just working on it the odd weekend every so often before the last push to be ready for RoboNerd.

    Coming in the next parts - getting it driving, making the axe linkage, fitting pneumatics and doing a full test. Stay tuned!

  3. #3
    Thanks for posting this Jamie - it's great to see this written up with all the details. I've seen the pictures before on The Facebooks (and indeed the finished article at RoboDojo) but the story adds a lot. Looking forward to the next installment!

  4. #4
    Ocracoke's Avatar
    Team Kaizen

    Great write up so far, amazing what can be done with some ingenuity and motivation, isn't it? I might have missed it but how thick is the box section used in the main chassis? 3mm?

    Fast forward a few months and I attended the 2018 Manchester Extreme Robots event to collect it (and took Drumroll along for some 'fun' - sorry Honey Badger!)
    It'll be back, ready to take on Drumroll again :P
    Last edited by Ocracoke; 3rd May 2020 at 02:30.
    Team Kaizen - Build Diary for all the robots

    AW: Amai, Ikari, Lafiel, Osu, Ramu
    BW: Shu!, The Honey Badger
    FW: Azriel
    MW: Jibril, Kaizen

  5. #5
    Zenith's Avatar
    Roboteer

    I love how this is a labour of love above all. Great work, and great read too. Looking forward to the next installment Jamie!

  6. #6
    I might have missed it but how thick is the box section used in the main chassis? 3mm?
    The steel angle for the chassis is 40x40x3mm, the box section for the scoop arms, wheel cross spars etc is 40x20x2mm and the wheel guards were 50x30x3mm (or maybe 2mm) but have recently remade those with 50x25x2mm.

    So in the previous installments, Shunt was born and built up to the point of being a (mostly) visually complete static display. The next steps were to get it moving then get the weaponry working!

    January 2019

    Work and life had kept me busy post-RoboNerd so didn't have time to do anything to Shunt for the rest of 2018. One of the first orders of 2019 was some rams for the bucket and axe. I guessed they were 40mm bore and 100mm stroke for the bucket rams but had no idea what stroke was needed for the axe. Thankfully I stumbled across a very grainy video of some house robot building/testing footage from prior to Series 3, where Malcolm James (Shunt's daddy) conveniently mentioned that the axe was driven by a 250mm stroke ram:



    I opted for some hydraulic rams from a UK company called Flowfit. Reason for this was that they had the rams that seemed closest to original Shunt in terms of pivot point and mounting options, although they didn't look 100% right. Nevertheless, I forked out for these:

    shunt_build (111).jpg

    I made up some brackets from some spare steel angle used on the chassis to fit the bucket rams, but the axe one would have to wait until I was ready to make the mechanism for it. Once the rams were on, I fitted the bucket and lifted it up - it didn't go far enough! Turns out 100mm stroke wasn't enough, even though the length of the ram was about right. I decided I'd worry about that another day though, and proceeded to fit some plywood to the base of the chassis and rig up a basic wiring circuit for drive. I'd also found time to modify the rear plough slightly so it looked less stumpy:

    shunt_build (113).jpg

    shunt_build (123).jpg shunt_build (124).jpg

    The motors and wheels run on 3/8" sprocket and chain with a reduction of approx 6.5:1, and the system runs on a 6S lipo. There was an issue with the right-hand wheel where the chain would occasionally jump off due to being slack. Dropping down to a half-link solved the issue for half a revolution of the wheel but unfortunately despite my best efforts, the sprocket on the wheel was not concentric so the chain got too tight. However with some careful driving, the looser chain would stay on (but would need to be rectified with a tensioner later). This was a limited drive test due to space, but I have to admit to finding it quite surreal seeing Shunt driving in my back garden. The video also got a comment from Tom Gutteridge (classic era RW executive producer) on Facebook who liked it, so that was something



    April 2019

    Again another few months before I could progress with Shunt. Having got the drive working, it was now time to focus on the weapons. The more I looked at the rams, the more I realised that the 40mm bore was also too small. I needed 50mm bore rams with 150mm stroke for the bucket. Following extensive searching and cross referencing with pictures, I finally found what looked like the right rams (or 99% similar) on eBay. They were from China but only took 10 days to arrive and with minimal import duty. The rams themselves were pretty cheap too; I think about £120-£150 total for all three. They're only rated to 10 bar but as I wouldn't be running Shunt above this, that didn't matter. Once they arrived, I made new brackets for the bucket rams and test fitted them:

    shunt_build (133).jpg shunt_build (134).jpg

    These looked much better and I was certain I wouldn't find anything closer short of using the rams from the actual Shunt. While I had the robot in bits, I took a moment to take a picture of back-to-front Shunt, which suitably irked the fans on Facebook but I quite liked it

    shunt_build (136).jpg

    Once that procrastination was done and dusted, I could no longer put it off - it was time to tackle the four-bar axe linkage mechanism. I knew this would be the toughest part of the build but thankfully some angles in the HR Ultimate Warrior DVD had good pictures of the various parts:

    uw2.jpg uw4.jpg

    I decided to go for the full 'prototype it in wood first' approach to make sure I wasn't making errors in steel.

    Will continue this in another post shortly....

  7. #7
    ...continued

    It was a lovely sunny Easter long weekend, so four days of build time to get the axe done. I think at this point, I had the target of getting it ready for RoboRiots (31st May - 3rd June) before it was cancelled, as well as Glasgow Maker Faire (8th-9th June) before it was also cancelled! So a bit of pressure but in the sun-kissed gazebo it was nice and chill to begin with

    shunt_build (145).jpg

    First up, having studied the Ultimate Warrior DVD some more (I really did spend hours looking through that thing), I needed a central channel for the axe ram and mechanism to be fitted to. It looked like the one in OG Shunt could be removed with four bolts, so I aimed for the same. I cut two lengths of steel angle spanning the length of the chassis, cut a sheet of metal for the gap in between and stitch welded it to prevent warping:

    shunt_build (147).jpg

    Next, I did some rough geometry measurements with cardboard before transferring to wood and testing various pivot distances. This was very much trial and error, it took several attempts to get it right. There were three different linkage pieces and four pivot holes; adjusting one of them just slightly could radically change the behaviour of the arm. Eventually I managed to get a combination of lengths and holes which achieved the desired amount of travel:

    shunt_build (148).jpg

    With the wooden parts now made, I could transfer the sizes to Solidworks and CAD up the linkage parts. I then printed out the 2D profiles, glued them to steel then fired up the angle grinder. Who needs waterjet and plasma cutting when you have CAD and a Pritt Stick!

    shunt_build (152).jpg shunt_build (153).jpg

    The steel version of the mechanism went together relatively well. The two plates on the left (4) were welded to a 25mm wide strip of steel to form the bracket that went onto the axe arm. The two arms on the right (5) had to be cut and welded together in a staggered formation so these were cadded to be longer than necessary so I had some excess material to work with. The last section I needed to weld was the arms (2) to the ram pivot (3). This was just a case of clamping the pieces together with mole grips, looking at the axe travel and adjusting it until it was right, then welding it together. Come the end of the long weekend I had something that looked like this:

    shunt_build (163).jpg shunt_build (165).jpg

    Pretty pleased if I do say so myself! My only concern was the leverage when the axe was in the fired position; it moved through the stroke fine by hand but I was worried that the ram would be pulling at the wrong angle on the retract and it might lock up. Having sorted out some pneumatic fittings and a gas bottle, I was able to do a quick test. The gauge on the regulator was in some weird scale so I don't know what pressure this was at but I reckon it was around 2-3 bar:



    As it turned out, it coped fine, and had sufficient levels of 'thud' so I couldn't wait to see it at its full operating pressure. But this was the end of the Easter weekend so I had to go back up north for work - booooo!

    May 2019

    With the way my shifts were working, I had a couple of spells of 3-5 days off in May without taking holidays, so I made use of the time to crack on with Shunt as RoboRiots was looming. I still needed to completely sort the internal wiring and plumb up the pneumatics properly including safety stuff, as well as loads of little bits and pieces.

    As it stood, I had to take the axe head off to get the shell on and off of Shunt. Since I would be needing to add a tether, this would turn into a pain of a job. Series 5-7 Shunt had its shell cut in two pieces; I was loathe to do this to my own one incase I messed it up (I couldn't just get a replacement one) but had to bite the bullet. Some careful jigsawing later:

    shunt_build (168).jpg

    ...and it turned out fine! I made a couple of brackets to hold the two halves together to keep them correctly spaced but overall it was fine. I also added some tensioners to the drive system to try and mitigate the chain jumping. Just some aluminium plate with a Nylon wheel (cut using a hole saw I think, not fun) which bolts through one of the motor mounts and could pivot to the ideal location. It helped but didn't fully cure the issue. Also made a cut-out for the link, again in keeping with the original:

    shunt_build (176).jpg shunt_build (177).jpg

    By mid May, I'd received word that RoboRiots had been cancelled due to venue issues. While frustrating, it eased the pressure a bit on getting Shunt finished, but I didn't want to let up too much as it was almost there. I rounded off May by starting on the wiring (two plywood boards either side of the axe mech, one for the bottle and pneumatics, one for the electronics) and trimming the regulator slightly so it was more compact and suitable for use. These regulators cost £20 and only need about £15 of fittings to improve them. Had no issues with the so far, and just received another one today:

    shunt_build (180).jpg shunt_build (181).jpg

    This is getting long again so I'll do one final part now to wrap up this section...

  8. #8
    ...final part (hopefully!)

    June 2019

    With Glasgow Maker Faire also cancelled, I decided to keep the holidays I'd booked for the two events and use the time to get Shunt fully working.

    I made a bracket to support the gas bottle from a portion of a large diameter steel tube that I cut up, welded that to some angle steel to bolt to the plywood and secured the bottle with two hose clamps. In OG Shunt, the bottle is on the opposite side but since I had the link on the left-hand side, I figured it would make sense to put the bottle there and have all the safety controls on the one side.

    I was a bit unsure about the safety of the gas bottle opening. I cut a hole in the front of the chassis above the link for fitting the 17mm tool in to open the bottle, but this was very close to the scoop. Speaking to the UK EOs, it wasn't really ideal but there was no other way to locate the bottle that would be accessible. To reduce the risk of injury during gassing up, I fitted a quarter-turn isolation valve inline right after the regulator so that the gas bottle could be opened without allowing gas to the system, then once the gassing up tool was removed, the valve could be opened, making the system live. It wouldn't be permitted in a competitor bot, but as Shunt was more for show/demo then an exception could be made. Original Shunt didn't have this so I suspect they turned the gas on then had to fit the shell on before it could go into the arena!

    shunt_build (184).jpg Annotation 2020-05-05 005801.jpg

    In terms of solenoid valves, I had two 3/2 valves, a 5/2 valve and a 5/3 valve. I settled on a 3/2 valve for the bucket as it would retract under gravity. I didn't want a 5/2 valve for the axe as this would mean the axe would be pressurised in the retract position as soon as the gas was turned on. I opted for the 5/3 valve as this would use gas for fire and retract, but then dump the ram gas once the stroke was complete and leave the axe unpressurised. Or so I thought. It didn't really behave in testing properly and seemed to still be pressurised once retracted. Not sure if it was user error on my part or not, but I didn't want the hassle :P

    Instead I rejigged things so that the two 3/2 valves were used for the axe (one for fire, one for retract) and then the 5/2 valve was used for the scoop but only for fire. I blocked off the retract port so basically turned it in to a 3/2 valve too. Now presumably original Shunt had its bulky SLAs in the bottom of the chassis but mine was running on a single 6S pack on the electronics board, so I had pretty much the entire bottom of the robot just for a couple of valves. It looks....sparse

    shunt_build (186).jpg

    This was before I switched to three valves so it's a little busier now, but not by much. To control the pneumatics, I wanted something like the old Electronize relay switcher that Technobots used to sell but they don't do them anymore. Instead I found a unit from Forge Electronics which was essentially the same thing but in a nicer and more compact unit. I got two, one for both axe movements and one for the scoop which only used half the unit:

    shunt_build (178).jpg Annotation 2020-05-04 221017.jpg

    They were good, but a couple of times in testing, they wouldn't engage and it would take a few flicks of the switch for something to fire. I decided to persevere though. Another issue was that the solenoids generated noise or back EMF which would sometimes cause the Vantec to cut out; a similar thing led to Coyote's loss to Expulsion in Series 10. The main suggestion was to put a diode across the solenoid terminals to prevent backflow of noise (I believe was the idea). After much debate about the flow of direct current, what side of the diode was the blocking side and what way round it should go, I eventually soldered them in. Next test of the pneumatics......nothing, except a slight crackling sound and smell of burning electronics - I'd blown the switchers. I thought it was my fault, that I'd put the diodes the wrong way round, so flipped them round, repaired the switchers (wasn't as terminal as I thought) and tried again. Once more, nothing but burning smells. The switchers had blown elsewhere this time. £60 down the drain less than a day after receiving them! In my annoyance, I ripped them out and rigged up some servos and micro-switches. The wiring and layout for the switchers was pretty, the wiring and layout for the servos was not:

    shunt_build (194).jpg shunt_build (195).jpg

    In hindsight I realised a diode across the solenoid terminals was basically creating a short. I'm not sure the diode was the right thing. It presumably would either be a capacitor that was required or I wired it wrong and it should have been in series. Anyway, expensive lesson learned. I got rid of the diodes when I fitted the servos and just decided to see how the Vantec would go. It wouldn't always cut out so might be okay for demos etc.

    Eventually I got everything wired in electrically and plumbed in pneumatically, and the robot was ready to run:

    shunt_build (188).jpg

    I did a few tests at home to get the pneumatics dialled in, but they were working pretty sweet. All that was left to do was to take it down to the industrial estate, get it fully clad and bash away at a microwave in order to make a video for the masses:



    The Vantec cut out a few times during the test (as well as a chain falling off the drive right near the start of the afternoon) but thanks to the magic of video editing, you'd never know :P
    Unfortunately a bucket fitting also blew and couldn't be repaired on site. And my video editing isn't good enough to magic that in. I managed one decent lift which just made it into the video.

    shunt_build (205).jpg shunt_build (202).jpg

    So that was Shunt fully operational, much to my glee. A 2-3 year backburner project that was done in 13 months. Oops, but not complaining! I took Shunt to the July RoboDojo event for display and a demo; this turned out to be a bit lacklustre due to issues with the BEC and the Vantec cut-out issue but still managed to smash up my parents' old TV.

    It also went to RoboNerd in August; by this point I'd switched out the Vantec for a RageBridge which eliminated the cut-out issues but early in its demonstration it threw the drive chain again (you can see it jump off in a spectator's video when I first fire the axe) so it spent most of the time trying to crab-walk its way to its prey - one of these days I'll do a demo with it that's flawless!
    It was completely worth it though for getting a snap with the Robotazia Matilda:

    shunt_build (211).jpg


    So that covers Shunt up to the end of summer last year. As it was pretty much done, it spent the rest of the year in my storage unit while I focused on other things (namely a full size RC Dalek and my mechanoid RORI).

    However, as most of you know well, a robot build is rarely completely finished, you always find things you want to change or improve. Those of you on Twitter and Instagram will know I've been using lockdown to tidy up a few bits and pieces of Shunt that were bugging me. I'll document those changes on here in the next few days once I get the photos off my phone. After that, I'll just need to remake the plough and scoop slightly (to a more accurate shape) and then maybe, just maybe, it will be finished

  9. #9
    Another great writeup there Jamie. Must've taken you almost as long to type all that as it did to build the thing!

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