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Thread: PC Plod Build/Upgrade Log

  1. #21
    Extra supports added to the redesigned chassis.
    New Wedge Chassis.png

  2. #22
    So, I have a target for PC Plod's debut on the live circuit, 2019.
    This will be the 1998 PC Plod upgraded enough to compete, just for us to have some fun with and get experience with heavyweights, not aiming to win a championship or anything serious.

    Which leads me to my question for the day, a weapons system. Has anyone ever built a CAM driven axe for a heavyweight?
    There's videos of flippers doing it, especially in lower classes, and one 'proof of concept' video for a heavy flipper. But nothing for an axe.

    Here's a totally not to scale, 5 minute doodle in paint, is there any fundamental reason a system like this couldn't be done? Or is it purely the unnecessary effort to build and lack of power compared to a pneumatic axe?

    Theoretical CAM Axe.jpg

  3. #23
    Ocracoke's Avatar
    Team Kaizen

    I am sure Mortis used a mechanical axe that may have been driven by a CAM mechanism - I've been re-watching the fight between Ghetto-Bot and Mortis from the War of Independence special in Series 4 and at one point, the angle of the camera shows the motor mechanism going around. I had planned to use something like that on The Honey Badger originally (adamclark also suggested another mechanical mechanism called a quick return mechanism that could potentially be used for something like this).

    Reciprocating axe mechanisms like this are going to be weaker than pneumatic axes and even electric axes where you have to manually fire/retract the axe and there is the issue of keeping a complex-ish mechanism together during combat. The big advantage with reciprocating mechanisms like this though is the rate of fire.
    Last edited by Ocracoke; 8th December 2017 at 16:25.
    Team Kaizen - Build Diary for all the robots

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

  4. #24
    I'm not too worried about it being weaker than a pneumatic axe. I'm probably putting a plastic (or inflatable) police truncheon on the end for the looks more than to be effective with a small hammer/axe part to do actual damage, at least for the first version.
    The rapid fire rate looking impressive is part of the reason I looked at a CAM drive in the first place.

    I also don't want to be learning pneumatics right now, I've not nowhere safe to test systems.

    The mechanism breaking could be the biggest issue we'd face, although if we fix it in place with enough box steel it should survive most of the 3 minutes. Likely to chain or belt drive the CAM to stop any shocks being transferred into the motor.
    Also slightly worried about the spring stretching over time if I spend most of the fight with the axe at top height, and the repeated quick expanding and contracting.

  5. #25
    Ocracoke's Avatar
    Team Kaizen

    I possibly would not bother with a spring... when I was prototyping a axe mechanism, I simply used a bit of metal with a slot on it, a motor and a hub with one screw in it and I'd imagine it is the screw that wins the contender of "most likely to break when shocked" award. This forms the basis of the Whitworth Quick Return mechanism I referred to earlier.

    Last edited by Ocracoke; 8th December 2017 at 22:48.
    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
    The Whitworth Quick Return does look far less likely to break down, although it does look far less powerful, because there's no actual force behind the downward swing

    The spring appears to provide a decent amount of force, at least on a flipper:

  7. #27
    Ocracoke's Avatar
    Team Kaizen

    Hmm... certainly looks powerful but I would not want to be around it if that spring decides to break (might be worth fitting a blanking plate over where the spring is exposed.

    The Whitworth Quick Return does look far less likely to break down, although it does look far less powerful, because there's no actual force behind the downward swing
    Having watched my video again, I had the same concern but it depends on which way around the mechanism is turning I should think. For a axe mechanism, it looks to be that you'd want the motor turning clockwise and for lifting, run it anti-clockwise (from the angle that I shot the video at).
    Last edited by Ocracoke; 8th December 2017 at 23:18.
    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
    I have little faith in the setup used in that video, especially the spring being bent. That seems likely to be very unsafe.
    The spring would definitely need to be contained in some kind of safety channel.

    I think the Whitworth system looks like you'd definitely get a much higher fire rate, which would hopefully make up for the lower power.
    I'll have to build smaller models of both and see how they run, probably run both in a FW before committing to one or the other.

  9. #29
    Out of interest, what have you sorted with the drive?

  10. #30
    You would be better off with a scooter motor powered system I think. I'm all for different ideas but even using twin motors and a bloody huge solenoid would be easier!

    But... if you want to go down the spring route, car springs would be a good shout. If you can compress them they should have a good amount of bounce and just add a bump stop to limit the travel (I work in parts supplies if you can't tell haha)

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