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Thread: Gremlin - A simple 3D printed antweight pusher

  1. #1
    So I thought I would post my efforts leading up to Okracoke's Botfest pilot next weekend.

    I decided to keep this one simple and make a wedge type design. I may have a go at something more interesting on my next attempt.

    Despite it having to do nothing more than drive around and not get smashed to bits, it was still remarkably hard to keep the thing within the size and weight limits! Nevertheless I eventually reached a CAD scheme that would. The basic design was a printed "monocoque" with no actual assembly of the armour or chassis. Inside is a couple of pockets that the battery and radio can squeeze into, with two motor mounts and a hole for the heat-sink of the speed controller to radiate out of.

    battery and radio.PNG

    motor mounts.PNG

    Just about got the thing to fit inside the four inch cube (with some tactical chamfering required)!

    Cube.png

    For the battery I went with a little 2s, 180mAh lipo, 25-40c. Motors are the 6v gearmotors that are fairly ubiquitous on Ebay, 30:1 gearing if I recall correctly. They came with a handy plastic mounting bracket which I factored into the CAD scheme.

    https://www.ebay.co.uk/itm/6-12V-300....c100011.m1850


    The speed controller is a Sabretooth dual 5A, which in hindsight was probably overkill! It rather dominates the weight of the thing...

    Wheels I got from nutsandbolts, neat little 3d printed ones, just the right size

    https://nutsandbots.co.uk/product/25mm-toughhub-wheels/


    For the radio receiver I went with the OrangeRx R410X DSMX Compatible 4Ch/6CH PWM/CPPM 2.4Ghz Receiver cos it is tiiiny. This meant a new transmitter but my existing Turnigy receiver was just a bit chunky.

    After the traditional set of initial failed prints, the thing eventually came out quite nicely. Just meets the weight spec. The frame is rather tough too, feels very rigid. All assembled fine, although screwing in the motors was fiddly due to the overhanging wedge. It is definitely worth the effort to do the wiring before screwing stuff in for an antweight, they are tiny and fiddly, and PLA is a bit melty when exposed to solder!

    IMG_20180712_200250283_HDR.jpg


    Fully wired up she works just fine. Quite happy with the handling etc, I might even put the lid on when I fight!



    Hope to catch up with many of you next week.

    If the design is of interest to anyone, happy to PM the .stl files.


    5C

  2. #2
    Ocracoke's Avatar
    Team Kaizen

    Status
    Offline
    Name
    Michael
    Robots
    AW: Osu, Ikari, Ramu / BW: Shu!, ??? (planning) / FW: The Honey Badger / MW: Kaizen
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    Looks very neat, well done The Sabretooth is a bit overkill but it works. I'd possibly suggest a polycarbonate top, if only to show off the innards.
    Team Kaizen

    AW: Osu, Ikari, Ramu
    BW: Shu! (Build Thread)
    FW: The Honey Badger (Build Thread)
    MW: Kaizen (Build Thread)

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