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Thread: Léim - Beetleweight Spring Flipper Build Diary

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  1. #1
    Shooty's Avatar

    Barróg (FW), Barróg Doom (FW) -In Progress-, Léim (BW)
    Galway, Ireland
    So I've decided that I want to have another robot that can be brought to the UK events by plane, and so, in between working on Barróg, I'm gonna try a Beetleweight design, as they seem to be picking up steam in the past few years, and ants are a little too finicky for me. The robot is called Léim, pronounced like the word "lame", and I decided on this name for two reasons. One, léim is the Irish word for "jump", which I think fits a flipper, and two, I can introduce the design by saying "I'm Eoin, and my robot is lame".

    Far from going with a simple design for a first build, I've decided to make a spring powered flipper, which might be a first for UK BW's, I'm not sure. From what I've gathered, BW flippers are either motor powered fast lifters, or teeny tiny pneumatics flippers. Hopefully, a spring can give me more of a hop than motors, and more flips than pneumatics. The spring is wound back by a high torque servo using a choo-choo mechanism which allows a pull back and release function from a single rotation. At full tension, the springs exert 4kg of force, so that should be enough to hopefully get a little airtime from opponents.

    As for other parts, I'm using 5mm, 10mm and 20mm HDPE for the chassis and weapon, and a 80 X 100 X 1.8mm piece of titanium for the front scoop, which should stand up to most threats. Two 2S 65C 550mAh batteries wired in series will provide power over a 4S battery for more even spacing of weight and being lighter in general. Vex 29's will be used for ESC's (not included in CAD) and modified to take the amps needed. Finally, 12V 500rpm Pololu motors will be used for the drive; I know 1000rpm are standard, but I found myself overshooting a lot with my feather, and will go for more power in drive as opposed to speed. Besides, in my eyes a slow well controlled robot should beat a quick poorly driven bot any day.

    At the moment, the bot is predicted to weigh 1.2kg without bolts and wiring, so hopefully no last minute hole drilling will be involved this time round. I'm hoping to have the bot done before summers end, and get to at least one BW event in 2018, either a Beetle Brawl or the Euro Champs.

    A view of the bot with the weapon both loaded and fired.

    A rough guide of where I'm planning to put all of the internals.

    A more detailed look at the choo-choo mechanism.

    Batteries (Turnigy nano-tech 550mAh 2S 65C Lipo Pack X 2):

    ESC's (Vex 29 Type Motor Controller X 2):

    Servo (HK-752MG Coreless Digital MG/BB Servo 6.3kg / 0.11sec /28g):

    Motors (Pololu 12V 20.4:1/500RPM Metal Gearmotor):
    Attached Images Attached Images
    Last edited by Shooty; 18th June 2018 at 22:44.

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