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Thread: Just Getting Started- have loads of stupid questions.

  1. #1
    Hi everyone. Am having ideas about building a heavyweight robot once I finish the car I'm building (supercharged V8 Volvo 240 estate) and one of my questions is about motors. My budget is tiny and so I was thinking of getting some brushless pallet truck motors from work, as they'll most likely be free! My first question is this: what power is considered adequate for a relatively agile heavyweight robot?

  2. #2
    Ocracoke's Avatar
    Team Kaizen

    Hey there, welcome to the forum!

    It depends on the gearing, especially if using brushless motors. From my experience with my Middleweights, a pair of brushed CIM motors going through a 6.35:1 single stage reduction gives me ample speed (so much so that I've bad to turn it down slightly). That is on 8S LiFe batteries.

    Speed will also be affected by wheel sizes and the KV rating the motors themselves. Bigger wheels mean more speed but draw more power. Smaller limits the speed but I would figure draw less power overall and possibly be more controllable. Since these sound like industrial motors, I figure they'll be fairly big and have a low KV rating as a result?
    Last edited by Ocracoke; 5th September 2021 at 00:14.
    Team Kaizen - Build Diary for all the robots

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

  3. #3
    It's always good to hear another Heavyweight Robot is been considered to be built.

    If you can get those motors for free you should and 2 speed controllers from 2 would be ideal-

    that way you could either have 4 wheel drive or at least an independent controller for both sides.

    I imagine the controller is lever or twist grip so save that too-you may be able to run it from a auto

    return servo to keep costs low.

    In terms of power most good Heavies scoot across the arena in 5 seconds and weigh 110kg

    just to give you an idea

  4. #4
    I'll have a look at the KV rating next time I'm servicing one. Unfortunately the ESC's are integrated into the ECU's on all our forktrucks, pallet trucks, etc.

    I'm thinking of getting around the bar spinner problem by building a whole body flipper with a bit of flexibility in the hinge and ram, so that if it gets a hard whack and goes slightly out of line it won't stop it working. Is this a stupid idea?

    Like I said in my initial post, I can't start building anything until I get my 240 on the road. I think a 400bhp/400ftlb Estate would be the ideal transport for a heavyweight.

  5. #5
    Ocracoke's Avatar
    Team Kaizen

    Hahaha, I'll be transporting my MW (and a planned HW) in a 2001 Smart City-Coupe CDI. A Volvo 240 is positivietly cavernous in comparsion so no issues there.

    ESCs... Given the overall size I think these are, try looking at Triforces ESCs here (I'll see if I can find the thread later). The full body flipper idea doesn't sound bad to me. The slack might become an issue if not kept an eye on between fights but I can't immediately think of why that wouldn't work.
    Team Kaizen - Build Diary for all the robots

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

  6. #6
    Thanks for that, Ocracoke. Yes, I wasn't thinking of a floppy flipper, so to speak (heaven forbid!), more of one that could still work if misaligned by a whack from a spinner. Many flippers fail when faced with a spinner as it bends the flipper into the body and stops it from operating properly. IMHO, with a whole body flipper a misalignment would be so much of a problem before repairs could be completed.
    Last edited by I'll Play One Day; 5th September 2021 at 13:28.

  7. #7
    Ocracoke's Avatar
    Team Kaizen

    Here you go for the ESC (go to the last couple of pages): https://www.fightingrobots.co.uk/thr...estions-wanted

    Look forwards to seeing the design for this, be interested in how the misalignment would be handled.
    Team Kaizen - Build Diary for all the robots

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

  8. #8
    I'm sure I'll think of something. It's just an idea which I might realise is a bit daft further down the line. Now to look into full pressure rams. Is there somewhere you'd recommend I look on this forum to learn about the systems? I really should go hydraulic given my background, but I'm not sure if a hydraulic system could be fast enough to fling competitors around.

  9. #9
    Motor I was thinking of using (from a pedestrian controlled pallet truck) is an Asynchronous 24V 1.2kw 113KV motor, drawing 76A at full whack. I was thinking of using two- one for each drive wheel.

  10. #10
    Have just been offered some free CO2 fire extinguishers in various sizes. What size are people typically using, please?

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