Register To Comment
Page 1 of 2 12 LastLast
Results 1 to 10 of 19

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

  1. #1
    Deathly Hallows's Avatar
    Roboteer

    Status
    Offline
    Name
    Simon Hallows
    Robots
    Beetleweight Evil K'Weevil Featherweight Alligrator concept
    Location
    Scotland
    Posts
    187
    Blog Entries
    12
    So after the learning experience of Alligrator I have a new idea.

    Basic idea is to repurpose an MY1016 to power an axe/hammer.
    I'll reuse the electronics for controls too.

    New brushed geared 24V DC 500rpm motors for drive.

    Chassis shape I have some ideas but not fixed yet. But it will surely approximate a triangular prism. The slopes facing forward and back. The weapon should be a self righter.

    After the issues with chain drives I am tempted to use fixed gears or a belt drive would be an option to reduce the shock to the weapon motor. Any recommendations?

  2. #2
    Ocracoke's Avatar
    Team Kaizen

    Status
    Offline
    Name
    Lucy
    Robots
    AW: Amai, Ikari, Osu, Ramu / BW: Azriel, Shu! / FW: The Honey Badger / MW: Jibril
    Location
    Somewhere on the Wirral
    Posts
    815
    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 02:16.
    Team Kaizen - Build Diary for all the robots

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

  3. #3
    Deathly Hallows's Avatar
    Roboteer

    Status
    Offline
    Name
    Simon Hallows
    Robots
    Beetleweight Evil K'Weevil Featherweight Alligrator concept
    Location
    Scotland
    Posts
    187
    Blog Entries
    12
    Been away on business trip last week. Unfortunately looks like I'll be away a lot over the next few months. It's going to be hard to find blocks of time so this will be a slow build. I have a horrible feeling that this year will be a washout. But if I can keep designing, making part lists and building when I am at home, but I'll get there eventually.

    I'm still thinking about the axe mechanism. Whether to fix the larger geared spur to a live axle and the weapon arm to that live axle. Or fix the arm to the larger spur and have a dead axle. This second option is my preferred as it has less failure points, and I can probably drill the necessary mount points myself in a solid gear.

    I've had some time to play in CAD and started building the first parts. I have some new 24v 550rpm geared motors. These are a lot lighters than the MY1016's.

  4. #4
    Deathly Hallows's Avatar
    Roboteer

    Status
    Offline
    Name
    Simon Hallows
    Robots
    Beetleweight Evil K'Weevil Featherweight Alligrator concept
    Location
    Scotland
    Posts
    187
    Blog Entries
    12
    I have made some small purchases.

    Banebots wheels and hubs arrived
    Some steel bar for the arm
    A steel rod for the axle for the axe
    Also a motor controller that should handle the amps needed for a full stall on the axe.

    Here I am wondering about using and Arduino to control it. I realise it adds complexity, but it could react a lot faster than I could to the stall, reset and fire again. More pondering required...

    I won't have time this weekend to build a test rig, but the weekend after, that's what I want to do. Build a test rig for controlling the axe

    Tested the new wheel drives. Seems to be a big difference in speed between forward and reverse could. More severe than I have seen before. Should be possible to address the balance with controller.

    I have started working in onshape cad to convert my sketches to real drawings.

    It's ticking over

  5. #5
    qbnut's Avatar
    Roboteer

    Status
    Offline
    Name
    Craig J
    Robots
    Sawcerer (FW), Broadax 2 (FW), Battleaxe (Sportsman FW)
    Location
    Stroud
    Posts
    95
    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
    Maxamuslead's Avatar
    Roboteer

    Status
    Offline
    Name
    Mark Smith
    Robots
    "Blacksmith" (FW) in a bag in bits "Forge Master" (FW) battle worn "Forge Master II" (FW) in CAD
    Location
    Lincolnshire, Threekingham
    Posts
    438
    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
    Deathly Hallows's Avatar
    Roboteer

    Status
    Offline
    Name
    Simon Hallows
    Robots
    Beetleweight Evil K'Weevil Featherweight Alligrator concept
    Location
    Scotland
    Posts
    187
    Blog Entries
    12
    Thanks - your right. The switch speed could be too high, though I could program a pause.

    I'm going to see how it can go together next weekend. The motor controller is not the typical unit and built for an Arduino but nothing to stop me wiring the pwm signal to the RX directly. It is a real experiment. I intend it to run max speed no ramp up, could be a dead end, but worth a bash.

    I'll give details when I try it out.

    I'm sure I'll get the controls for weapon sorted. I am having more issues trying to imagine how to fix the weapon shaft to the motor. So I fit a small spur gear to drive shaft say a 1.5mod 20t then a larger 1.5kod 80t as the final drive. So 4:1 that will make it around 700rpm. That gear will have a central bore of 15mm. Now I can get a gear that has a hub with two M6 threaded mounts if I want a live axle, in which case I would have to then fix the weapon arm to the axle. 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.

  8. #8
    Ocracoke's Avatar
    Team Kaizen

    Status
    Offline
    Name
    Lucy
    Robots
    AW: Amai, Ikari, Osu, Ramu / BW: Azriel, Shu! / FW: The Honey Badger / MW: Jibril
    Location
    Somewhere on the Wirral
    Posts
    815
    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, Osu, Ramu
    BW: Azriel, Shu!
    FW: The Honey Badger
    MW: Jibril

  9. #9
    Maxamuslead's Avatar
    Roboteer

    Status
    Offline
    Name
    Mark Smith
    Robots
    "Blacksmith" (FW) in a bag in bits "Forge Master" (FW) battle worn "Forge Master II" (FW) in CAD
    Location
    Lincolnshire, Threekingham
    Posts
    438
    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 11:20.

  10. #10
    qbnut's Avatar
    Roboteer

    Status
    Offline
    Name
    Craig J
    Robots
    Sawcerer (FW), Broadax 2 (FW), Battleaxe (Sportsman FW)
    Location
    Stroud
    Posts
    95
    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.

Register To Comment

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •