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Thread: Deathly Hallows - FW - No-IP-Rocs

  1. #1

  2. #2
    Ocracoke's Avatar
    Team Kaizen

    Fixed gears for the drive. I've seen the setup on Satanix with speed 900 motors (and I think shakey's got a brushess setup for sale at the moment) and it works really well, nice and robust.

    Belts work but only when they have tension. For an axe, I found fixed gears work when the casing for the gears are robust, which mine wasn't. I am sure some of the HW axes use a fixed gear system when driven off of a pneumatic ram and I am sure Hammerhead (one of Team Shock's FWs) had a similar system? I'd probably try a toothed belt if only to have something easily replaceable if it breaks.
    Last edited by Ocracoke; 20th August 2018 at 01:16.
    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

  4. #4

  5. #5
    qbnut's Avatar
    Roboteer

    If it were me I would keep it as simple as you can.

    With most transmitters you can set an exponential curve that means the slightest twitch on the channel puts it at 100% throttle / throw. You might find that's sufficient depending on the axe mech. This is what I do on all of my axe Featherweights.

    Whilst you could Arduino it, there's more to go wrong, plus if the intention is to full-on the channel on a transmitter button press, your chosen ESC would need to handle a 0 -> 100% change without errors for the speed at which you want to change it, as some would see that as an invalid value change if too fast. You would have to experiment to find what the absolute fastest change value you could get away with is.

    Another more technically challenging solution I have seen is you cut out the middle man and instead code custom firmware for your ESC itself to do it, though that's an advanced solution.

  6. #6
    ok for the axe. t8f (8mm scooter google it)chains work great for a scooty axe they have bean proven to work and can take the power. For ESC i suggest time THIS it is the replacement for the tz85 and it best ESC which is still in procduction. i would suggest a Feathertwo Single channel but they are out of production and people who have them are not that willing to sell. on the Arduino front i did dabble with the idea but speaking to Shakey it is a bad idea as the Arduino can get confused and fire the weapon randomly. the only person i know who has used a Arduino in full combat is Rory Charlesworth in Aegis acting as a limit switch controller.
    For drive 550rpm sounds really low so either you are looking at beetle gearboxes or a really high reduction, you got a link to them ?

  7. #7

  8. #8
    Ocracoke's Avatar
    Team Kaizen

    Alternatively I could not fix the larger gear to the axle, but fix the weapon to the gear. This is could drill and fix with bolts or I'd need to get welded. ( Wish I'd bought that welder at Lidl a few weeks ago). The prior option has two failure points and unless I drill a hole in the axle I am not sure this is really that strong. The latter option seems to me stronger but if the weapon failed it would mean a new gear.
    This is how I built the axe on Kaizen. A CIM motor drives a Mod 1 16T gear which in turn drives a 48T gear on a dead axle with the axe directly bolted onto the gear, giving it a 3:1 reduction.
    Team Kaizen - Build Diary for all the robots

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

  9. #9
    Ok what scooter motor you are using. How heavy a axe head and how long a handle. This will effect what ratio be the best. Also gears are very heavy. I really do suggest using chains but if not. Use 12mm bushing as they have a 15mm outer thickness. Stick them into the weapon spur gear and use a dead shaft. For attaching the axe to it bolt it. However attaching the spur gear to the Motor will probably need a welder. Side note HDPE bot great at keeping gears meshed. It deforms too much.


    EDIT: like this

    Capture.PNG

    But i a chain drive will be lighter and just as effective
    Last edited by Maxamuslead; 6th September 2018 at 10:20.

  10. #10
    qbnut's Avatar
    Roboteer

    I have made two axes bots with chains and one with spurs, and I'll say that there's no right or wrong solution - each has advantages and drawbacks. You do have to be more precise with spur gearing and as mentioned above, mounting them into HDPE doesn't really work, you would need more rigid bulkheads to use them.

    On the other matter, go bushings all the way. Whilst bearings work they make maintenance hard, as you have to take the whole thing apart to change or fix. With bushings and a dead shaft it becomes an easier job to just slide things out if you need to fix.

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