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Thread: Team Darklight - Broadax (Featherweight Axe/Hammer)

  1. #11
    Quote Originally Posted by qbnut View Post
    The testing was done that I could identify any last-minute kinks that are obvious from a quick run. Of course you never know what will actually break until it's gone through a round or two in the arena!

    Overall, was pretty happy with the test. The drive torque caused spinning at first but I learned quickly how to get that under control, and adjusted the curves on the TX so now it's much cleaner to drive.

    Post test I looked at why the axe swing was occasionally a bit sticky and it was totally a mechanical issue. The bolts that attach to the top shaft of the axe gearbox were overtightened causing the bolts that hold the axe to the top sprocket to bind against the side of the bulkhead. Loosening the bolts ever so slightly and it's now nice and free moving.

    Arguably the tolerance is too tight and when it gets knocked about there's a slim but not zero chance it might come back, but I have no time to strip it down, tweak spacings and put it back together before Manchester then Burgess Hill immediately afterwards.

    Will have to see how it goes though I'm pretty hopeful it won't be an issue for now.
    our bots will try and help with the disassembly =D, looks great.

  2. #12
    This looks seriously awesome - I thought Battleaxe was cool, but this is a huge step up! Great work!

  3. #13
    qbnut's Avatar
    Roboteer

    Post report on Extreme Robots Manchester

    TL;DR - Brushless axes work! But Broadax needs a lot of tweaking, and more importantly, a rebuild!

    It's maiden voyage was beset by a number of issues, mostly mechanical, design and build flaws, only one electrical. Here's what happenned:

    IMG_20180421_164951.jpg

    Melee 1
    As I loaded Broadax up into the pen, I wasn't sure how well it would do... and the conclusion was unfortunately not all that well! A number of things were immediately apparent - the ground clearance was supposed to be low, but it was too low for the difference in panel heights between the steel plates of the arena. So upon transitioning from one plate to another, it got beached frequently. It needs the suspension system that wasn't done in time for the event, as Battleaxe (now after more tweaking) doesn't suffer the same.

    The spinning is because I had the channel curves on the TX set up wrong, so it span too easily. Also the transition from -100 to +100 on the stick happened too fast due to the curving which caused the ESCs to failsafe and reset all the time, thinking it was a signal fault.

    The axe worked though, and with a hell of a swing! This was short-lived though, as one of the phase leads came off the motor.

    Melee 2
    Made some adjustments to the TX, and Team Hitec (Aegis) offered me some foam wrap for the wheels, which helped to give it extra clearance and grip. Unfortunately, the drive torque effectively tore most of it away early on. So, much more of the same drive issues, but the Axe ESC gave up this round as well.

    After hours
    The after hours was effectively one in, one out until the half hour session time ran out. I think most of us uused it for ad-hoc testing. After the ESC that died was replaced, the Axe worked again for a bit, before all the screws shook themselves loose. Decided that the ground clearance needed to be higher, the axe could be fixed in the morning.

    Melee 3
    Sunday came around, and I used the morning to strip Broadax's drive and lower the wheels to 'fix' the ground clearance in lieu of being able to actually mount the full suspension system.

    IMG_20180422_112130.jpg

    Team Blacksmith also noticed that when I got the drive back together, it was all back to front! I had cable tied it all down so rather than undo it all to redo it, I mirrored it on the TX (by the way, thoroughly recommend the new OrangeRx TX6i).

    This time round, the drive worked correctly, the axe worked correctly, and it did the things it was meant to! For around 1:50...

    Then Binky gave it a hit to the side, which tore the side welds and threw the battery out onto the arena. After that, Broadax was inactive. Drumroll came in later and made sure the panel that was hanging on no longer was. And there ended my fights for the weekend!

    IMG_20180422_135638.jpg

    Autopsy
    The most glaring one, the armour welds snapped. It wasn't welded on both sides, only the underside, and the panels were edge-to-edge straight welds with no tabs. I think this was almost accidentally designed to be a weak spot. The axe needs to be stripped down and rebuilt, the bearings have separated from the bulkheads and it's all maligned. I watched the videos back, and noted that Binkys disc also dinged off the axe head, this is probably what broke it.

    The issue of ground clearance is how Binky got a bite. As I had to raise the armour from the floor, it left a 10mm-ish gap at the side corner away from whatever was the front at the time (remembering, it's 2wd so effectively see-saws on the wheels). In a 1v1 I can theoretically put the hammer down hard which would plant the armour on the opposite side into the floor, but that's nigh on impossible in a melee with 20+ robots to keep track of.

    There's a whole category of other issues, some carried over from the inherent flaws of a 'pyramid' design carried over from its predecessor Battleaxe, but mostly new as a result of some design choices and build being rushed towards the end.

    But it's not all bad news! Post fight, even though the side armour is missing, the wheels are still on, the motors and gearboxes still drive, and the batteries, whist separated, took no visible damage.

  4. #14
    Ocracoke's Avatar
    Team Kaizen

    Well done for going in despite all the issues you were having. The axe certainly sounds impressive and I wouldn't want to be hit too much by it.

    For your ground clearance issues, perhaps mounting the motor and wheel onto a plate with some captive nuts and then having some bolts run through them might allow for adjustable ground clearance before each fight so you can tailor the clearance as much as you need to?
    Team Kaizen - Build Diary for all the robots

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

  5. #15
    qbnut's Avatar
    Roboteer

    Before entry for the FW champs it will get redesigned quite substantially based on what I learned from Manchester and from Battleaxe upon which it was designed, as even in a 1v1 I think the current design doesn't really work that well - ground clearance is only one thing on a very long list. I'll keep the rough aesthetic as I do like it a lot but some of that nice symmetry will ultimately need to get traded for something stucturally better designed and hopefully competitive.

  6. #16
    is it good bye to the pyramid design ?

  7. #17
    qbnut's Avatar
    Roboteer

    Probably likely to the perfect symmetry it has, in order to rearrange the internals for a change in balance. I'll be trying to keep the general angular feel as much as possible though

  8. #18
    qbnut's Avatar
    Roboteer

    I've put together a teardown video of Broadax after Extreme Robots Manchester:


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