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Thread: featherweight armour options and guages newbuild!

  1. #1
    Hi everyone!


    I’m trying to reduce the mass of my newest design. I’m having a few weight issues (feather weight) it’s a Swiss army bot currently, so the armour could be dynamic depending on the load out for example non spinner matches i could swap to something lighter to allow for my crusher.

    currently with all the armour for the drive pod in 5mm steel I’m coming in at 10.5kg with lid, I’m aiming for 6.5
    if i change the rear and sides only and the rest steel to poly 5mm I’m about 7.2kg in both instances the base is 3mm aluminium.

    The problem arose when i stretched the bot 40mm to accommodate a larger battery pack.

    I guess what I’m asking having never seen a featherweight up close what options are there and what kind of thickness should it be? i presume anything plastic hdpe, poly etc should really be 10-20mm?

    I tried adding some holes in the rear but for the weight it saved it did not feel worth the compromise.
    another option would be to reduce the size and find a battery workaround but id hate to get everything milled and find it needs dismatling completely to remove a pack!



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  2. #2
    Ocracoke's Avatar
    Team Kaizen

    HDPE is usually the default for me when it comes to Featherweights. I've used 10mm in the past which held up remarkably well for what it was on The Honey Badger but I tend to use 15mm+ these days for anything structural. Azriel (my current FW), for example, is 15mm HDPE with a 6mm polycarbonate base and lid from left over parts from previous builds. The axe carrier is 20mm HDPE.
    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
    Hi ocracoke!
    Ive spent the day modeling diffrent materials, steel of any kind seems a no go unless i want to scrap the swissarmy portion and have a fixed weapon.
    10-15mm hdpe seems close to 3mm titanium in mass but im not sure yet if i can stomach those costs just, yet i did find some grade 2 Ti very cheap but was looking for grade 5 really.
    I might yet do a mix of both materials to reduce cost.

    How do you find your polycarbonate sections does the thickness compare to hdpe? I quite like the idea of some clear peices for lights and to see the nice internal milled frame.

  4. #4
    Ocracoke's Avatar
    Team Kaizen

    I find in the FW category my 6mm polycarbonate holds up fine but with that said, polycarbobate has a tendancy to crack and shatter when met with a spinner if not angled right. In the MW category where I had 10mm polycarbonate sections on Jibril 1.6 (again lid and base), this ended up being what killing that version because again, a spinner shattered the base inches away from my batteries.

    I prefer using Polycarbonate on my lids and such because as you say, it helps show off the nice work you've done in the robot. When it comes to rebuilding Azriel, I'll be using it again for lids.
    Team Kaizen - Build Diary for all the robots

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

  5. #5
    Hi Lewis

    As Lucy said, HDPE is the usual choice nowadays, 15mm or thicker depending on what you're up against, although you could get away with thinner, 10mm lids has worked for me against axes in the past. If you plan on having a proper hydraulic crusher, unfortunately you're going to have to make compromises elsewhere to accommodate the weight, Pressure Point's armour is very thin in some places.

    One suggestion I would have is if you're going to have interchangeable weapons, perhaps have interchangeable armour panels too? I.E. have much thinner HDPE panels for the crusher setup, as a sort of attack mode, and save the steel armour for a heavier defensive setup, with a simple lifter or something? Yes it would be more expensive & more work on the day to change between them, but having the options really can expand your capabilities.
    James
    Team Phyte

  6. #6
    Hi James and lucy,

    Ive made a little progress today, ive squished it 5mm that shaved alot, im having a play with diffrent materials also mentioned above. I did find some very very cheap titanium but only grade 2, prob not any benifit over ally from what i can tell? The hydraulic setup is the most challenging thats what i set my 50/50 weight ratio over.

  7. #7
    Ocracoke's Avatar
    Team Kaizen

    From what I've read, Grade 2 Ti should be OK. It'll be marginally lighter than Aluminium at any rate but only marginally harder as well. Grade 5 is probably preferable. I use that in my MW's (and the rebuild of my FW's) axe gearboxes as I've got a nasty history of twisting steel shafts... admittedly at silly thin thicknesses.
    Last edited by Ocracoke; 6th November 2021 at 23:52.
    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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