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Thread: Beetleweight grabber-lifter

  1. #1
    Hey guys! This will hopefully be my first beetleweight, built for bugglebots.

    Its a grabber lifter combo, something that i haven't seen before but probably has been thought of. It works by having a lifting arm that grab the robot and lifts it up of the floor by the arm pushing the body upwards pivoting around the lifting arm.

    Just a concept so you can see my thought process

    -Generally new to combat robotics so to anyone with experience, do you think this would work?
    -Would a servo be powerful enough to power this? If so could anyone make recommendations
    -I guess il need a lot of pushing power with a bot like this, would the standard 12v 1000rpm gearmotors be enough?
    -What escs do people generally use for this weight class?

    Making this mainly to track my thoughts but if anyone has any tips that would be greatly appreciated

  2. #2
    Hi Max

    Firstly, I like this design and I do think it has potential. You might want to make the jaws a little wider to give you a better shot of grabbing larger bots, but it's unique enough to have a good shot at getting chosen & I could definitely see it winning a few fights at least. The only thing that concerns me is when you grab someone if their wheels are at the back they could still touch the floor depending on their design. If you made the front wedge longer, or possibly used forks either side of the grabber, you might be able to mitigate this somewhat, as well as give you an easier time keeping your front on the floor.

    Regarding components, if you look at the Bristol Bot Builders website they have a good list of recommended components, including servos & escs. I'd also suggest checking out ranglebox. I'm putting together my first BW myself & I bought my motors & escs here (I went with the 10a).

    1000rpm motors & servos are usable options and probably the easiest to work with but there are definitely stronger ones competitively. Admittedly I'm no expert regarding BW's so I can't suggest specifics but I know most of the BW community are on the Bristol Bot Builders & unofficial Robot Wars facebook group so you could ask there. If it were me I'd use the servos & 1000rpm motors for now, go to a few events, get the physical aspect of the design nailed down first, then if you feel you need to upgrade the internals from there.
    Team Phyte

  3. #3
    Shooty's Avatar

    Hey there Max! Really love the design, as someone who tried making something different for my first bot I'm surprised how similar of a concept you've gone for with a grabber that grabs and raises the wedge of your bot up with one motion, yet how different and unique the design is, really awesome, especially how it can be invertible! I do have a few things that can be considered that should help your design.

    For the lifter, you're gonna want something with a bit of a pinch, and ideally a jaw design that can catch on any changes on the top armour. For the power for the lifter/grabber, servo options could be based on other competitors. Lance-A-Frog used a Turnigy MG959 30kg (can output 30kg of force at 1cm), Crabsolutely Clawful uses a RoboStar SBRS-5314HTG 53.1kg Servo. You can also use a gearmotor that's been geared WAY down ( This one is 42kg), though that would require an ESC as well.

    For drive you're gonna want two things. First, it it's only two wheels it needs some power behind it. Maybe go 500rpm for better torque, or even go brushless. There's a few useful links for getting brushless beetles now on Facebook thanks to people like Cosmin Gorgovan (Wee Woo) and Alex Mordue (Saw Loser). You should also try to have as much weight as possible at your back, as if you're grabbing a machine at the front you're at risk of tipping over and not being able to drive at all.

    Finally, I'd look at the geometry of your grabber. At the moment, if the bot's lifting something, your support underneath is essentially in the shape of a triangle, and as such it could be easy to get tipped over to the side. I'd look into ways of making the claw wider in some parts for stability.

    Overall though I really like the design, looking forward to following this thread in the future!

  4. #4
    Ocracoke's Avatar
    Team Kaizen

    Hey there, welcome to the forum!

    To try and answer your questions from my perspective:

    -Generally new to combat robotics so to anyone with experience, do you think this would work?
    Your design does look good, similar type of concept to my BW, Shu! though that is a lifter, not a clamper. The clamping action will need to be quite quick I think as BW robots are usually pretty fast in the own right.

    -Would a servo be powerful enough to power this? If so could anyone make recommendations
    I am going to say maybe. Although a servo will work for this application, you don't want it under strain for too long otherwise you are liable to break it and the receiver I would have thought. It is heavier but I would have gone for a geared motor.

    -I guess il need a lot of pushing power with a bot like this, would the standard 12v 1000rpm gearmotors be enough?
    I would go with Shooty on this one and say ~500rpm motors might be a better choice for this. 1000rpm motors are OK and probably would work but when pushing, you may find it not enough against the opponent, especially if they are pushing. I'd also very much look at getting grippy rubber wheels. If you can't gain traction, you cannot push, regardless of your motors.

    -What escs do people generally use for this weight class?
    Shu! used a Sabretooth 2x5A in its last appearance at the European 2018 championship. I know some folk here haven't had wonderful experiences with them but its generally not been too bad for me. Azriel (my other beetle) uses a pair of fairly generic RC car brushed ESCs to move with.
    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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  6. #6
    Looks like a really neat concept! Hope it works out, good luck. And welcome from one newbie to another!

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