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Thread: Team Deathly - first trainer bot

  1. #21
    Ocracoke's Avatar
    Team Kaizen

    Could you not flatten off a side of the shaft (or cut a keyway in) and then get a wheel hub that uses a grub screw to hold the hub onto the shaft (like this for example?)
    Team Kaizen - Build Diary for all the robots

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

  2. #22
    Quote Originally Posted by Theo View Post
    This is the same problem I have at the moment; the wheel bore being that ever so bit big. Tape has worked ok for me in testing, but won’t stand a chance in combat, plus the motors also just spin if I suddenly apply power. I’d suggest Banebots wheels but they only do awkward American measurements to my knowledge. Smaller wheels might work better if you can sacrifice the ground clearance, around 100mm would work better and reduce the motor spinning freely. If it’s just for testing, though, this setup should do for now but I’d advise you to fully modify them (locking down the clutch mechanism) for combat but that’s for another day.
    Thanks for the advice. In my case the large washers and PTFE really held them solid. Turning up the torque on the blots would be very solid. I could further strengthen by drill 4 small holes through the washer and hub and bolting them in. Even some small screws, fixing the washer to the hub would work for this class I think. As you see they are chunky hubs. Plan for now is lighter wheels with smaller bore. But if I find a solution I may put them back on. This is only a 'test bed' but they looked so tough and chunky a real shame.

    IMG_20171108_185022.jpg

  3. #23
    Quote Originally Posted by Ocracoke View Post
    Could you not flatten off a side of the shaft (or cut a keyway in) and then get a wheel hub that uses a grub screw to hold the hub onto the shaft (like this for example?)
    Ah I think I see. I can imagine fixing the wheels securely is a major task for many robots. Certainly using drill chucks is easier at this stage. I was looking at the drill motor mounts on the forum and if I did use those I would need to find another way. For now I hope this next set of wheels have 8mm or 10mm hubs (there seems to be some confusion on the website). Either way some 80-100mm bolts, suitable washers and nuts should give me what I need to let me get it ready to whip around the garden patio.

  4. #24
    Why I chose fairly big wheels - I gave it some thought and I see some advantages:

    - A larger wheel makes more contact with a surface than a smaller one
    - The rolling circumference is larger, so a higher top speed is achieved for same RPM and more control at low speed
    - Larger wheel can flex more shock/energy absorption
    - Allows more flexibility in mounting position so in theory with correct design the ride height could be adjusted

    In all my designs I intend to use the biggest wheels I can get away with for the above reasons.
    Last edited by Deathly Hallows; 9th November 2017 at 08:50.

  5. #25
    Ocracoke's Avatar
    Team Kaizen

    The converse of using big wheels is that they present a bigger target if mounted outside of the bodywork so you'd need to consider how you'd protect them.

    The Honey Badger 2.x
    uses some RC car wheels from a 1:6 (I think) monster truck which measure some 110mm diameter by 40mm wide wheels, which are secured to the wheel hub by some M5 bolts. They have been thoroughly abused, way more than its intended application but are still in round and in one piece.

    As an aside, it stuck me when I first saw your robot, it looks vaguely like a old Battlebots competitor, Das Bot from Season 1.0 (http://battlebots.wikia.com/wiki/Das_Bot).
    Team Kaizen - Build Diary for all the robots

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

  6. #26
    Not raining and I had an idea how to fix the wheels. So this still has temporary axles and is just a test bed. Hell it's quick! I think I got my calculations wrong for my speed estimate. I need to measure them again, I wonder if the diameter was just the hub? With so much weight at back it definitely needs wheelie bars. I need to retain the battery and build a cover or at least roll bars. Then I can play with this and improve my driving skills while I design the my first real robot. I would plan to have inside wheels if possible. Weight could be the issue though, I need to weigh what I have already and see what I have to play with for chassis, armour and weapon.

    Note: the sticks have ramping on and I never got more than a few degrees of movement. When I tried I wheelied and flipped. May need to adjust the gearing to slow it down a tad.


  7. #27
    Ocracoke's Avatar
    Team Kaizen

    I doubt at this stage you'll have an issue with weight- mine weighs at 9.6kg with a similar "rear heavy" setup where I even went and added about 600g of ballast to the rear to keep the rear wheels from breaking traction. The wheelie problem you may find simply goes away when the body and weaponry is added.

    Looks good though, keep it up
    Team Kaizen - Build Diary for all the robots

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

  8. #28
    Very progressive speedy building-I made a similar baseboard a few years
    back with the drill layout identical, I was going to make a fleet of four
    for pay as you battle events but lost interest.
    There's no reason you can't continue with this concept into a fully
    working featherweight.
    I found that when the drill was reversed the spindle tended to come
    loose in the chuck so you could maybe weld it in and the jaws shut and
    also the bearings in those drills are designed to take a downward force
    not support a laterall weight so you would need to fit a bearing and extend
    the spindle at the other side of the wheel.
    Some kind of weapon will pevent the front end flying up when you drive.

  9. #29
    Cheers - thanks for the feedback.
    Yes when I ramped up the spin (couldn't help my self a little vistory spin) at about 80% power the wheel flew off. But by then the thing was a blur. That was hand tightened. Now I have used two grips and taken it as tight as it will go. When I convert this to a battle bot I will probably change the connection if I find a good alternative.

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