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Thread: Ensign Wedgeley Crusher (FW Sportsman)

  1. #51
    There's another Robodojo event next weekend, so it's time to pencil in some panic-bodging for next weekend.

    In the meantime, I have made one change recently. Currently Wedgeley has only ever crushed drinks cans, but whenever he did so in the past the shaft collar on the lead screw that operates the jaw has slipped, which then pushes the shaft back and locks up the chain.

    No more!

    Now that collar is going nowhere, and Wedgeley can crush with impunity.
    Disclaimer: This means that another bit will probably fail when trying to crush future items.

    The welding was done by my dad. There is a MIG welder at the Hackspace that I will learn to use at some point, but I like the idea of this piece of welding history being involved at some point:

    Hopefully some exciting updates to follow later in the week...

  2. #52
    A strange thing happened yesterday... we finished all the fixes and mods to Wedgeley a whole day ahead of schedule. Partly that's because there wasn't too much (critical) stuff to do, but still this was unexpected. I assume something is now going to go horribly wrong tomorrow (forget to take Tx, battery explodes during fight, etc.). For now though, I'll just bathe in the glory thanks.

    First up, I had to replace the drive motor mount that got slightly borked last time, which was simple enough. Hopefully a bit more robust this time. We'll see I guess.

    The whole upper jaw mechanism needed fettling, which was a bigger job. There were a few pieces from last time that were meant to be identical that were decidedly not so, and some pieces were just fundamentally the wrong size. That made the motion of the jaw quite stiff and wonky. Nothing major here, just a bit less imprecision than before:

    Next, new teeth. Waaaay back in January I bought some M6 stud to grind into sharp gnashers for the original Wedgely, but both times have run out of time and bodged something else instead. Now, we have teeth:

    These are just cheap putty steel studs so they aren't going to cut through anything substantial, but should be enough to dig in and get some grip at least. Of course, with such FORMIDABLE AND TERRIFYING WEAPONRY we are going to need some serious safety devices:

    At the last Robodojo, we hurriedly installed some protection over the weapon mechanism immediately before facing Tantibus (i.e., an axebot). This was not the most substantial or comprehensive piece of armour, so it's been upgraded a bit:

    The "tailfins" are to protect the battery/electronics compartment and also stop the robot getting flipped over so much. Speaking of which:

    It seems like we're most prone to getting flipped over in a backwards-ish direction, and these bits of HDPE are hopefully going to tip us back onto the wheels if that happens. I doubt they'll last long, but they shouldn't be needed too many times.

    It even sort of works:

    Not really a SRiMech but it'll take a lot more to get us over now at least.

    Cheers for reading, and probably see some folks at Robodojo tomorrow!

  3. #53
    Robodojo was a mixed bag in terms of our performance this time. On the plus side, nothing broke (just a few knocks and dents as usual) and we managed to use the weapon in one of the fights to actually grab something. Unfortunately we also lost all 4 matches and Wedgeley is still completely impossible to drive in a controlled manner...

    The weekend got off to a bad start when Simon adopted a cat the day before, so he couldn't come. I suspect he did this with the express purpose of getting out of driving the robot, but I'll give him the benefit of doubt this time. At least that left a simple coin flip to decide whether Becky or I would have the dubious honour of driving in the first fight (I lost).

    First fight was against another crusher, Jamie's Reaver.

    I did manage some vaguely controlled driving here and a few grabs were attempted, but the anti-wheelie bars, along with general lack of traction and instability, meant the best I could do was avoid the more intimidating crusher on Reaver. Ultimately the wheelie bars defeated me...

    Next was Crota, upgraded with a new axe vs the sort of machete thing it had last time.

    The wheelie bars were shaved down a bit for this fight which seemed to help a bit with mobility, if not with steering. However, Becky did manage two firsts in this fight: a) it lasted a full three minutes; and b) the crushy grabby jaws grabbed some stuff, and possibly even did a tiny amount of cosmetic damage! We lost the judges decision, but only by a single point, which isn't so bad.

    Originally it looked like we'd be facing Midas in round 3, but it ended up being Parasite, another axe.

    So I think this fight indicates that the wheelie bars were in fact not shaved down enough, since we got beached again... Not much to say about this one really, I couldn't really bring the weapon to bear and ended up between Parasite and OOA pretty early on. Although we didn't do too badly in the pushing match, it was pretty inevitable we'd get shoved out from there.

    Finally we were up against Mitternacht, another crusher.

    I think this fight was broadly similar to the last one really. There was a brief moment where we might have stayed in the arena by chomping down on Mirtternacht's weapon, but I think we're still getting the hang of having an active weapon that works.

    So all in all, positive results in terms of the weapon and robot functioning reliably, but a few important lessons learned:
    • It's hard to focus on opening/closing jaws whilst also driving a barely controllable robot.
    • See above - the robot is barely controllable.
    • The weapon doesn't seem to be 100% reliable - sometimes it didn't respond at all.

    Although I don't want to do much more work on EWC, I think sorting out the driveability issues would be worth doing. I think that should be achievable and would leave us with a pretty usable, if not mega-competitive, machine to be going on with while we work on something else. In order to do that I'm thinking two changes are needed...

    1. New wheels. The scooter wheels look cool but they're just a bit pants. As a bodged solution six months ago they were great, but the contact with the ground (even after rasping 5 mm off to make them flatter) is tiny, and the rubber is too hard to be grippy. I'm thinking of having a go at CNC'ing some HDPE wheels and putting bike tyres on instead, which should be a good exercise.
    2. Gyro. The weight distribution on EWC is just so wonky it's unlikely to ever want to go in a straight line. Better grip will help, but I like the idea of trying a gyro anyway. It's kinda "belt-and-braces" to do both but I'm thinking that a tenner for one of these is worth a go. Anyone tried using this component in a robot, or have any better solutions for a cheap gyro?


  4. #54
    Last weekend Al mentioned that the pic of our locking system made it look a bit like the jaws had munched into the chunk of wood themselves... So I had to give it a go...

    Made some rather unpleasant noises in the chain drive but it did manage it; I don't think it would work on any of the other teeth (not enough leverage), but I was pleasantly surprised by this in any case.

  5. #55
    With a mere 9 days before the next Robodojo, it must be time to start PANICKED WEDGELEY UPDATES.

    The big job for this update is wheels, we need wheels that connect with the ground in a more grippy way than the current wheels. I considered getting hold of some Colsons, or other castor wheels, but I thought this would be a good opportunity to learn to use the CNC router.

    Good heavens, machining HDPE is MESSY.

    But mercifully easy to clean up:

    Machining aluminium is not messy though it takes aaaaages.

    It appears to work, in so much as the hub fits in the wheel!

    Just need to manually drill out and tap some holes now. And make another one of each of those, and also a bunch of other bits as obviously 20 mm thick wheels aren't going to fix the traction problems.

    Next week, that, plus hopefully some hilarious mishaps with a drift gyro.

  6. #56

  7. #57
    We'll be screwing some mountain bike tyre into the plastic for that purpose - though I think the thin scooter tyres we've used up to now were problematic partly because they could so easily miss the floor due to relatively small irregularities. However they only had about 5 mm or track width in contact with ground which is a bit of an extreme case!

  8. #58

    We had three fairly simple updates to make this time, which were:
    • New wheels to improve driving
    • Try installing a gyro to improve driving
    • Re-program the weapon ESC (an Quicrun 880) to... work better

    The gyro was duly installed and tried out, and seemed to respond in the correct manner. Fortunately it's got a remote gain control, so we plugged that in with the easy option to just switch it off if it didn't work.

    Becky and Simon engaged in the herculean task of reprogramming the ESC for the weapon. The main things to change were the reverse speed (half speed to retract the weapon was unhelpful) and the braking mode (it was in "double tap to reverse" rather than "switch straight to reverse", which was just confusing to drive). This turned out to be pretty straightforward, although a bit of drag brake might help in future.

    As noted in the last update, the wheels were to be machined from HDPE on the CNC router at our friendly neighbourhood Hackspace. Rather than try to cut wheels in a single piece, I made each from 3 separate parts. It was a bit more work, but meant I could avoid worrying about fancy clamping strategies.

    Here's the design of the wheel:

    The "core" is coloured yellowish, that's the bit that attaches to the hub. The core and outer parts are 20 mm HDPE, the inner bit is 10 mm. I appreciate that 50 mm is probably wider than the wheels need to be for grip, but this matches the width of the tyre I bought and more importantly LOOKS SUPER COOL.

    Here's another shot of how the core and hub fit together:

    There are 4 M4 screws per wheel which go through the outer part and the core part. Everything is also held together with (naturally) woodscrews.

    Here's a bunch of CNC'd parts that I made last Friday:

    Because the router is not very powerful, this took about 10 hours to do. Also, a 17 kRPM router is not healthy for drilling holes, so the holes were just marked and I had to do them all on the pillar drill by hand. That was a lot of holes (significantly the wrong side of 100) so I had to come up with some clever jigging.

    Simon joined me on Saturday (cleverly arriving late enough to avoid any participation in the hole-drilling) and set to work tapping holes in the hubs and chopping up bike tyre. Things were going pretty well, the new wheels were looking fine and I was pleasantly surprised (read: freaked out and confused) to find that we were on track to finish everything at a sensible time of day.

    At this point I figured it was time to test fit the new wheels in place. Just in case I'd hilariously miscalculated something and they didn't touch the floor. I know what you're thinking right, you're thinking, he hilariously miscalculated something, well how dare you. Everything fitted fine. However, I didn't determine this until about an hour later, because the old wheels, having previously enthusiastically detached themselves in many of our fights with no encouragement, absolutely refused to come off.

    I can't actually remember how I got them off, but it definitely involved a mole grip, a hammer and screwdriver and a LOT of harsh language.

    Anyway, it wouldn't be this much fun if it was easy would it? Arguably it might be more fun. Still, we got there in the end! New wheels in all their glory:

    Like I say, the tread width may be excessive but they look right.

    Around this time we were ready to head to the chippy, but there was time to add one last thing - a "nose guard" to protect against thwackbots and (to a lesser extent) hammers. This was made out of a piece of HDPE, bent with a heat gun, and the idea is to lower the jaw and let it take any impacts that could damage the jaw mechanism, especially from the side.

    We then obtained some increasingly traditional fish and chips, then hit the road to the Oddfellows Arms in Sherburn in Elmet, arriving just in time for last orders (again, as per tradition).

    Here's Wedgeley Mk 4.0 in all his assembled glory the next morning:

    The final act is, as per the rules of Scrapheap Challenge, to decorate the machine the next morning, so here's the rest of the team wielding the Sharpies:

    Next up... event report

  9. #59
    Robodojo October 2019

    We were sharing our bench with Will and Stabby McUnicornface, same as last time, and with entrants a bit thin on the ground this time there was plenty of space. After performing the rites of Sharpie anointing, we duly proceeded to obtain a tasty breakfast cob.

    As usual, we had set ourselves a number of objectives fro the day, specifically:
    • Win at least two fights.
    • Win at least one fight by actual knockout (i.e., not just the opponent breaking down).
    • Not lose by sheer incompetence (i.e., driving off the side of the arena. Again).

    Fight 1: Forge Master I
    I love watching Forge Master (I or II) fighting, it's got to be my favourite featherweight hammer, but I prefer watching other people's robots getting hammered, so I experienced some trepidation when I lost the dice roll to drive in this fight. It started badly when I turned the gyro on, and the bot just started twitching so I just turned it right back off again. Not sure what's up there.

    However, overall I was quite pleased by how this went, the new wheels have completely transformed the way EWC drives. Although we didn't get the win I at least manage to dodge the hammer blows fairly well.

    Unfortunately it all went a bit wrong at the end...

    That was objective #3 blown, but other than that I was reasonably happy despite the slightly disappointing start.

    Fight 2: PiƩce de Resistance
    Simon won the privilege of driving this time, and did a good job grabbing onto this classic machine, despite the awkward springs getting caught in the teeth.

    So that was a win, but not a KO in the sense that we actually broke the other robot, since PdR either had a drive problem or got high-centred.

    In the break between rounds, we had put Wedgeley in the box for a quick test drive and to try out the gyro. Still not sure what's up with it, but it may be that the rate is turned right down on the steering channel, so gyro sensitivity needs to be really high. In any case, it seems to run fine without it.

    Fight 3: Danger UXB
    By elimination, it was Becky's turn to drive here. Danger UXB is a weird shape that is impossible to grab hold of, so this was a tricky one.

    After nearly managing to shove UXB out of the arena, we were once again caught out by our own wheelie bar. I thought having just one this time, rather than one on each side, would save us, but sadly it balanced perfectly on the two prongs of the lower jaw. So that was frustrating, but went pretty well otherwise.

    Somewhere around this part of the day, Theo (Boring Wedgebot) was having some trouble with his wheels (the hot glue sticking the treads onto the aluminium had surprisingly failed). We still had the old wheels from Wedgeley so offered them up as spares, thinking they could just be swapped out. Unfortunately, BW's wheels were seized on, rather like ours had been, but such problems are no match for the ingenuity of a roboteer in a tight corner:

    You don't need to remove the old wheels if you just bolt the new wheels directly to them...

    Ironically, our next opponent was...

    Fight 4: Boring Wedgebot A*
    *where A is a number greater than 10
    Yes, we were now pitted in mortal combat against our own donated wheel...
    At this point, it was time to roll the dice to decide who would drive, but Becky asked if anyone wanted to before we randomly assigned it. After my short first fight, I actually did want another go so I *gasp* volunteered to drive.

    Although BW was rather impaired by its unfortunate wheel situation, I think this qualifies as an actual win, despite my incompetence at the end...

    At this point, we packed up and made ready to depart, as Simon had to get a train to Hull to get the overnight ferry to Rotterdam. Then we heard our name over the tannoy summoning us to a rumble to decide 5th-8th place for the day. This was something of a surprise, but with only 16 robots there were 8 of us in the middle with 2 wins and 2 losses.

    We considered pulling out, but in the end Becky took Simon to the train station while I very rapidly reassembled the robot and then got into the arena. Since there I was at this point there by myself, I don't have a video of this but hopefully someone caught one and will upload it. My memory is sketchy but I definitely bit some things, before immobilising myself on the edge of the arena but I think I was third-to-last, putting us at 7th overall. That's our first points on the board, which we were all pretty chuffed about.

    Wedgeley, however, will be needing some dental work after biting down on either Stabby or Midas, not sure which but I think we came off worse from the encounter...

    Cheers for reading!

  10. #60
    Ocracoke's Avatar
    Team Kaizen

    Neat write up. The wheels definitely appear to help but as a suggestion, you may wish to limit the amount of throw in the TX to make it more drivable? It is something I do in Jibril which has definitely helped with its wheelspinning madness. Those wheels look like the sort of thing The Honey Badger 2 had.

    I really should get Azriel together for the event in December, I want to fight your machine :P
    Team Kaizen - Build Diary for all the robots

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

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