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Bit of advice on my drumbot please

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  • Bit of advice on my drumbot please

    right, hoping to start making a new one this friday, ordered some 20mm nylon 6 for the 2 bulk heads that will support the drum and the drill motors, theres gonna be a 3mm ali or mabye even 2mm ti baseplate and the rest is hardox with the exception of the lid

    but i need some advice as to whether i go 2 or 4 wheel drive off a pair of drill motors some pics are below........

    [attachment=1:39vw2ait]BILD0001.JPG[/attachment:39vw2ait]

    [attachment=0:39vw2ait]BILD0002.JPG[/attachment:39vw2ait]

    not fully settled on a design yet and the insides would be set out differentally but i'd use the 75mm wheels instead thou to save on the weight as wheels that big aren't really needed but im really stuck as to what set up im having, the benifits of 4 wheel drive were purley due to the drum being 3.7 kg i was worried about it being front heavy and not driving properly so with 2 wheels either side of the drum it would get rid of this problem and drive better, but then of course then theres all the extra weight from extra wheels and mountings etc and the robot slowly starts to get less compact as it'd have to be made wider to house the wheels and belts so i'd have to skimp on armour. or with the 2 wheels i'd use that size of wheel but i've tried making the robot to have as much weight as possible over the wheels and i've also put them as close to the drum as possible. Althought 4 wheel drive would look better visually, part of me just wants to keep everything simple and 2 wheel drive and see what happens,

    then of course theres the problem of it not being invertible, but i think i could live with this because once its upside down anyway the drum isnt effective spining downwards, i could use those massive 150mm wheels again but i don't fancy it cause that take away too much power from the motors and pushing power is very low, but any ideas anyone?
    Attached Files

  • #2
    Re: Bit of advice on my drumbot please

    I'd personally try to setup 4 wheel drive. No use having a stonking weapon if you can move it near the enemy effectively! And surely 2 belts and 4 pulleys, with bearings and mounts, isn't going to hugely affect your weight? That weight could be made back quite comfortably by cutting holes in bulkheads and smaller batteries?

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    • #3
      Re: Bit of advice on my drumbot please

      Hmm... the drum setup you are using isnt going to work! That kind of setup doesnt work, as the COG on the drum moves up and down (or something like that )as it spins, and there are going to be some very bad vibrations.
      Attached Files

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      • #4
        Re: Bit of advice on my drumbot please

        heyy yeah i forgot to say i already new this, the 2 bars were a rush job to get my old drumbot working and they were a very bad idea. im grinding those off later on in the build and getting 2 ring teeth made with 2 teeth on each. not fully decided on that thou yet

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        • #5
          Re: Bit of advice on my drumbot please

          get tom to make you 4... two in the middle on one side, and one on each end with teeth on the oposite side.

          go 4wd... with self-righter.

          and get brushless stuff... thought you wanted to make a proper robot this time?

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          • #6
            Re: Bit of advice on my drumbot please

            YE CALUM! BUILD A PROPER ONE!

            just forgetting the fact that i can build robots properly yet but still

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            • #7
              Re: Bit of advice on my drumbot please

              or you could buy a robot you dont know how to use and just start loads of new threads talking about all the projects you want to start that will never materialise? dribble dribble.

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              • #8
                Re: Bit of advice on my drumbot please


                dont forget your ic car at kidderminster dave.

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                • #9
                  Re: Bit of advice on my drumbot please

                  i was only joking dave, calum knows i dont mean it

                  i realise that i was posting about trash, at least i do now

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                  • #10
                    Re: Bit of advice on my drumbot please

                    ah forgot about that terry, good job you reminded me... i mashed up the main central gear... best order a new one.

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                    • #11
                      Re: Bit of advice on my drumbot please

                      Hmmm, 2WD or 4WD? I have to admit, the 4WD looks waaay cooler and it looks a little Growler-esque but with a hulking great drum in place of the jaws. In addition to that, if your drum breaks down in battle, 4WD could benefit you more when you have to resort to ramming people around.

                      Other than that, I don't think there are any advantages of four wheels over two. With two wheels, your turning (particularly on the spot) will be much quicker which could serve you well if you need to spin round quickly to attack someone. As mentioned, it'll also be lighter and more compact, leaving more weight for armour or weapons. Your pushing ability will be slightly less but probably not that significant in the grand scheme of things.

                      If you can adjust the design slightly to accommodate invertibility, I'd strongly recommend it. A self-righter will take up weight and be a lot of work (thinking back to how many problems Dave had trying to get 360's one working) and for me, just stopping fighting when turned upside-down isn't appealing. Just my opinion though
                      Then again, it could end up righting itself with the drum anyway; that's what Gary discovered with Boner at the 2010 champs with the Speed 900s in. If he spun it up while upside-down the drum teeth would hit off the floor and gradually bounce the robot a bit higher with each hit until it flipped itself all the way back over.

                      Regarding brushed/brushless, I find the Speed 900s are only really effective if the drum is over a certain weight. They worked great in old Drumroll/Boner because the drum weighed 4.2kg, but my current one weighs 2.1kg and there's just not enough energy in it to do any decent damage. I know the obvious fact is that there is a lot less weight in the periphery so there's not as much energy built up to transfer, but with more speed comes more energy, so brushless motors are probably the better option for the lighter weapons. That's what I'm going for anyway; seemed to work well at the 2010 champs until I busted a tooth

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                      • #12
                        Re: Bit of advice on my drumbot please

                        quick reply cause im on my phone, but thanks jamie bin talkin to dave and recon im going for those big wheels again i got a decent speed too on only 8.4 volts at the uks. having them as far forward as possible shud hopefully stop it having the same problem as last time D:

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                        • #13
                          Re: Bit of advice on my drumbot please

                          Originally posted by calumco
                          jamie bin talkin
                          Am I the new leader of Al-Qaeda or something? :shock:

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                          • #14
                            Re: Bit of advice on my drumbot please

                            Apparently so

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                            • #15
                              Re: Bit of advice on my drumbot please

                              2 wheels, I'd go for the small ones and have a dummy set on the top side pressed against the powered two to run via friction upside down. Get a decent brushless setup and that drum will fly.

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