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Thread: Bolts - The Scrappers

  1. #1
    So, we just had our first event, Extreme Robots in Colchester. Firstly, thank you to those who we spoke to over the weekend, who helped fix some of our issues and gave us advice for the future.

    This is Bolts v1, the version that we took with us to Colchester:
    Bolts v1.jpg
    A simple wood and plastic wedge with big wheels. Needless to say we experienced the teething problems expected from a new team and their first bot. So here's a summary of the event for us.

    Fight 1 - Signal Issues stopped us from entering, we'd never encountered it before and it worked fine the second we got back on the bench, so we looked puzzled and ignored it for now.
    Fight 2 - I drove Bolts rather badly, being impatient throwing it into full speed and slamming into a couple of walls. Both gearboxes lost their bearings after the spring holding them in came loose. Also, someone, we think Oddbot, punched a nice hole in one of our wheels.
    Fight 3 - Despite our efforts we were still having gearbox trouble, working fine on the bench it couldn't move under its own weight, the gearboxes just clicking as if over torqued. It wasn't until after the show that evening we realised how to fix this.
    Fight 4 - After replacing motors/gearboxes to a set of spares we got back into the arena. Peter drove this fight, proving he was much better at it than I am. Sadly during repairs we have to break the heat press on our wheel nut to replace the wheel with a hole in it. This led to a wheel rolling away during the fight, which we expected. We didn't expect the other to come rolling off shortly after.

    Overnight we took a look inside bolts and found that, somehow, we managed to shred one of the motor mounts we bought from Alex, leaving our gearbox spinning freely, and we didn't have spares.
    We also had a revelation when we realised our gearbox trouble came from the fact that the ring holding the spring down was the torque ring in the drill we took them from.

    Fight 1 - Peter drove again, with new motors and tightened gearboxes we ran well in the arena. Until we came face to face with Explosion. As we were flipped over a wire came out of a connector block, killing one motor. Trying to drive with only one side meant the hot glue, kindly donated by Chris, that was holding our broken mount failed and the gearbox began spinning again. Finally, after losing our drive Explosion came back one more time to throw us over the wall and out of the arena, a personal highlight of mine.
    Fight 2 - After reconnecting the wire and re-gluing the mount we were feeling confident we'd be able to enter two in a row for the first time. Of course, confidence is a killer, and our signal issues returned to stop us making it to the arena.
    Fight 3 - Another failed start for us, the glue holding the mount once again failed, this time on the entrance to the arena.
    At this point we decided that we couldn't repair on site and we called it a weekend. We had a two hour drive ahead of us and packed up early, said goodbye to those around us and left early.

    We learned a lot for our first event, and saw a glimpse of how much more we haven't got a clue about. We already have ideas about how to improve for Bolts v1.1 so expect a post about that soon. Thanks again to the people who gave us a hand and took the time to have a chat. We'll be back.

  2. #2

  3. #3
    Upgrades being considered for Bolts v1. (In no particular order)

    1. Shorten the body. Bolts was the largest FW by surface area at Colchester and has loads of unnecessary space inside it.
    2. Minimise the wood. The 10mm HDPE withstood far better than I expected, reducing the wooden under chassis would save weight to use elsewhere, such as a weapon or thicker HDPE.
    3. Replace internal connector blocks with XT60s.
    4. Shock mount the internals.
    5. Get new, wider wheels with more grip, we were sliding all over the arena with little control.
    6. New transmitter/receiver. Devo 7 with Deviation firmware has been recommended. Solving our signal problem from the event.
    7. Redesign the front wedge. Metal sheet, or full metal front plate.
    8. Move up from 12V to 18V motors and batteries.

    Possible Weapons

    1. Chain Flails, the original weapon planned before we ran out of weight and time to incorporate them.
    2. A linear actuator powered lifter in the middle of the top panel.
    3. An automatic or exponential flipper, similar to what is seen here:

    or here:

    4. Whatever you call this style of lifter. It looks interesting and is built into a similar body shape to Bolts.

  4. #4
    Ocracoke's Avatar
    Team Kaizen

    It is interesting how much the upgrade list reads like the considerations and eventual implementation I did for The Honey Badger, certainly items 2, 3, 5 and 7. I wish you well on this one.
    Team Kaizen - Build Diary for all the robots

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

  5. #5
    Decisions have been made about where the focus of the next version of Bolts is going.

    For those not aware, the name Bolts came from the original decision to use chain flails, as an ode to Nuts who inspired the choice. So, in staying true to that name we're pushing back towards shrinking the body as much as possible, making it more square, and attaching chains with some form of weight on the end, to make a sit-and-spin thwackbot.

    Right now we're in the basic design phase, where I throw all the internal components onto a piece of HPDE and see how closely I can fit them together.
    This means we're sticking with the Argos drillmotors for now, because they're cheap and simple, we've identified the problems we had and know how to fix them, and motor mounts are already available from Alex here on the forum.

    Any advice from anyone who's built a flail bot before would be greatly appreciated. But I do have one specific question:
    Some spin bots I've seen have had mis-aligned wheels, in opposite corners of the body, what're the benefits of this over regular parallel wheels?

  6. #6
    R9000's Avatar

    I think the idea of the mis-aligned wheels is to have 4WD-esque stability without having four actual wheels contacting the ground and causing friction. Basically the corners of the chassis without wheels will scrape along the ground rather than have you roll forward or back when you're trying to go in a straight line, but the small contact area of the two wheels on the floor makes it easier to spin on the spot. Also it means you can lay your drill motors out closer together if that's what you want, as opposed to having them end-to-end. Take all this with a pinch of salt though, I've never built a thwack/flailbot myself.

  7. #7
    The stability was my guess. Considering the large ground clearance our wheels give we'd have a lot of tilting, so I think we'll go for mis-aligned wheels. But I may as well test both layouts and see what works.

  8. #8
    Offset wheels on non-flailbots are for stability/4WD as mentioned, makes the robot less likely to veer off to one side when driving forward. But for flailbots, it's more likely to be for space saving. A standard back-to-back motor mounted 2WD robot will have to be around 300mm wide minimum, but with offset motors this can drop to around 150mm if you so wanted.
    Jamie McHarg
    RogueTwo Robots

    With great power, comes great reliability.

  9. #9
    Misaligned wheels on my flail bots has been purely to get the wheels closer together for more spin speed.

  10. #10
    That looks like Flat Damon! It even has the same wheels - How did they stand up?

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