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:

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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:

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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:

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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:

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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:

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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):

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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:

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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:

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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':

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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:

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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.

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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

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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!