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Thread: Attitude Adjuster (Beetleweight)

  1. #11
    I'll see - it could be that I just double up the armour around the battery. My thinking was that there are a lot of scary drum spinners that would love to chomp through the top if it was upside down!

  2. #12
    Ocracoke's Avatar
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    I have flashes of Bourbon and Ion in my mind, yeah, they might make it in.
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  3. #13
    Made quite a bit of progress since the last update, so I have a lot to post here (evidenced by the fact I maxed out the images that I can attach ). Apologies that all the images are sideways :/.

    I have access to a laser cutter that can cut perspex, so I made a drilling template for the side bulkheads, based on my CAD. I drilled out the holes for the side bulkheads and then used a Forstner bit to drill out the holes for the drive motors, making a satisfying shaving as they did so.

    IMG_9829.jpgIMG_9828.jpgIMG_9825.jpg

    I then added the threaded inserts to the back of the side bulkheads and drilled holes in the rear bulkhead using a similar method. However, the holes didn't quite line up so I had to use a Dremel and needle file combo to make it fit. Then I could fit the drive motors to the side bulkheads and attach the rear to the sides!

    IMG_9895.jpgIMG_9899.jpg

    Then I was ready to attach the front to the sides. I decided to use the "really long wood screws" approach, so drilled out pilot holes and then attached them.

    IMG_9900.jpg

    ...And then I realised that the front was upside down. Oops. Anyway, I put the chassis on the right way up and attached the Fingertech foam wheels and had a rolling chassis to decorate the spare room.

    IMG_9901.jpgIMG_9902.jpgIMG_9904.jpg

    I decided to make use of the laser cutter to make a perspex prototype of the weapon bulkheads, again based on my CAD, so that I could see how the components all fit together. If only I could laser cut the HDPE and polycarb for the rest of the robot! I only had access to 3mm perspex so I had to make 3 layers per side. I jammed all the components inside the robot after putting together the perspex weapon bulkheads and realised that it's going to be a tight squeeze with the wiring...

    IMG_9913.jpgIMG_9907.jpgIMG_9912.jpg

    With the robot looking vaguely robot shaped, I was about to go on holiday for 3 weeks. However, before I left I decided to cut the polycarb baseplate using a mitre saw. This was a mistake, as the sheet of polycarb shattered, and bits went flying everywhere. Safety goggles are important, people. I learnt that I should've used a jigsaw to do this. Oops. This was the result.

    IMG_9918.jpg

    When I got back I focussed my attention on the baseplate. I again cut out a prototype in perspex, and duct taped it to the bottom of the robot. Again, if only I could do the rest of it in the laser cutter! I used that to cut out the real baseplate out of polycarb, using a jigsaw this time. I discovered I can't cut straight at all, but I've made it work for this. I decided to attach the baseplate using brackets similar to Fingertech's Nutstrip (https://www.fingertechrobotics.com/p...?prod=nutstrip). Sadly, this isn't available in metric, so I made my own. I had two bits of 6082T6 aluminium bar stock, which I drilled M4 holes at 12mm intervals. The first one seemed straight enough, but the second one went a bit wonky... I'll probably scrap that one and do it again.

    I finally made enough to be able to cut it into strips small enough for me to attach the baseplate. I went for 6 bolts, 3 at the front and 3 at the back. While the weather outside was "taps aff", I was doing some tapping of my own. I eventually tapped enough brackets to be able to attach the baseplate. I now need to update my CAD to take these into account.

    IMG_0332.jpgIMG_0335.jpgIMG_0333.jpgIMG_0322.jpgIMG_0337.jpgIMG_0334.jpg

    Today I worked on the wiring. I made a wiring loom for the main wire, which includes a removable link. I stole the method of attaching the ESCs to the main battery from somewhere, but unfortunately I can't remember where. It involves crimping ring connectors and attaching them together using an M3 bolt and nut. I then put everything together and once again had something that I can scare the cat with.

    IMG_0352.jpg

    As I saw earlier, there isn't a lot of room to play with in there when you add in the wires, so I'm a little worried about that. One possible option if space is tight is to swap out the Sabertooth for Vex 29s or Botbitz 10a ESCs. A lot of builders seem to be wary of the Sabertooth, and it's a little bit big and heavy. For now though, I'm glad to have something robot shaped. Tomorrow is the last chance I'll have to do something uninterrupted, before I have to go back to work. I'm planning to tidy up the wiring and possibly try and do the weapon bulkheads. I need to finalise the design for that piece, or I might just start building and see what I end up with...
    Last edited by scott; 27th June 2018 at 22:54.

  4. #14
    One other thing, I have a piece of 1.2mm Grade 5 titanium for a wedge, how am I best to cut and drill this? I was thinking about using the abrasion cutting wheel of my Dremel, and using a 4mm cobalt drill bit, is that along the right lines?

  5. #15
    Drilling with a Cobalt Tool is a good idea, just use low cutting speed and cool the drill.
    You can also use a normal sawblade for metal and cut it with a hacksaw.

  6. #16
    Member

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    if using conbolt drills, go slow and use lots of coolant. i was able to drill through 3.2mm Hardox with some cobolt drill bits from Toolstation - about £3-5 each 5mm-7 about

  7. #17
    Lots of progress since the last update. I've been accepted for the Euros with Attitude Adjuster, so that gives a good deadline to work towards.

    I cut some weapon bulkheads, using the tried and tested technique of the table saw and the mitre saw. I used a 20mm forstner bit to cut out some holes, and measure the distances this time instead of laser cutting a template.

    IMG_0723.jpgIMG_0724.jpgIMG_0725.jpg

    The biggest game changer is learning how to use the 3d printer at the hacker space. It only uses PLA, but that should be enough for what I want to use it for. I started with a battery holder for the 3S lipo.

    IMG_0763.jpg

    Then I made a holder for the electronics at the back of the robot, so they don't get in the way of the weapon. I also made a couple of armour mounts. I put in some threaded brass inserts using a soldering iron. I also put some brass inserts in the chassis to hold the weapon bulkheads on, and to hold the top armour.

    IMG_0789.jpg

    Today I finally got around to finalising the design for the axe and cutting some titanium! I used my Dremel to cut it initially, then finished with a hacksaw, and drilled with a cobalt bit. Going slow with lots of lubricant made it super easy, and there were some fun sparks. I now have an axe head.

    IMG_0912.jpgIMG_0909.jpgIMG_0911.jpg

    I weighed the robot chassis for the first time, the bolts and brackets must weigh more than I thought!

    IMG_0897.jpg

    Also considering going brushless. I tried the axe for the first time with a 300rpm gearmotor and was disappointed with the power. It was slow and couldn't self-right. I picked up some brushless DYS BE1806 motors that have already been converted with 1000rpm gearboxes, and I'm considering transplanting the 300rpm gearbox onto one of them. I also have a 500rpm motor as a last resort. I also picked up some cheap Afro ESCs on ebay and flashed them with SimonK.

    When testing my flashing, disaster struck! I accidentally plugged an Afro in the wrong way, and promptly blew it up. The battery also doesn't seem too healthy (feels a bit swollen :/) so I'm planning to not use it again in case I burn my house down, and have ordered a replacement. I will now not do anything with a lipo unless I use the wiring harness that has a fuse and removable link.

    Finally, been doing a lot of soldering. Added connections to all my ESCs so that I can't plug them in backwards. I also need to make my wiring loom A LOT smaller. There is not a lot of room for the wiring in there. I have about a month until the Euros and not much free time in September, so I will have to try and make time when I can!
    Attached Images Attached Images

  8. #18
    Small update for today. Spent a few hours making the axe, so now I have a weapon. It has an aluminium shaft, aluminium supports for the axe head, 2mm titanium axe head and a 3d printed spacer between the head and the supports. I saw in the FRA rules there's a section requiring a tether, does anyone know if that's something I will need to implement in my beetleweight? If so, what should be tethered, just the axe shaft? What do other people use for tethers?

    Also, it is still satisfying when the robot looks like the renders

    IMG_0996.jpgIMG_0995.jpgIMG_0993.jpgIMG_0991.jpg7f292364-7cf6-4006-bbf5-49cd54b5bb60.PNG

  9. #19
    Ocracoke's Avatar
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    I don't recall tethers being a thing at the BW level, best check with the event organisers. Certainly at the UWE Beetle Brawl in February, I can't remember seeing any but then again, I don't recall there being that many axebots around.
    Team Kaizen

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  10. #20
    RogueTwoRobots's Avatar
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    If I remember rightly, tethers are more for Grade 3 arenas and lower (aka non-spinner) so the tether is to prevent the axe head, or part of the shaft, flying away if it breaks off and potentially breaching any wall or netting. As far as I know it's not required in spinner-capable arenas as a flying axe head will have much less danger potential than the amount of shrapnel that gets pinged about. To my knowledge there aren't any active/regular beetle arenas that aren't suitable for spinners, so you should be fine. If in doubt, contact the organiser for any events you're planning to attend.

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