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Thread: Team Health & Safety - First Time Builder

  1. #81
    Zenith's Avatar
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    Greg Cathalina
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    With the main chassis done I thought I’d do the honorable job of actually weighing most of the parts to get an impression of the eventual weight.

    IMG_20170919_155440.jpg


    The outlook was grim. This was the total amount of weight of all present parts, with one glaring omission: the 210g lifter motor. This naturally would send the eventual machine overweight. My eventual calculations, including all various bits of metal fasteners and the like, predicted a weight of over 1600 grams.

    Now even though TINAD Mk1 was never actually weighed at the Euro Champs (confession time OOOO) one needs to play fair in these instances, so this meant I was to experience what has become a rite of passage among roboteers: putting the machine on a diet. You immediately start looking where there’s excess fat that can be trimmed off. There’s some titanium edges sticking out? Cut them off. That piece of plastic is too wide? Narrow it down. There are some unattended pieces of flat metal or plastic? Drill holes.

    After shaving of some more plastic, I grabbed some cardboard, put on the wheels and mocked it up to get a feel for the new design.

    IMG_20170921_175643.jpg

    I must say was rather pleased... all chassis parts were new and different, but somehow the machine looked very similar - something which (in my opinion at least) a next evolution should always strive to do.

    Having the mock-up I also got to test-fit the components that I’ll be using - it’s all nice and dandy to have the dimensions on paper, but the actual practical dimensions are slightly more important. There were however a few concessions I was not willing to make (and which I’ll probably end up regretting but hey, one needs a challenge every now and then).


    1. Them new RC wheels are staying. Yes, they’re more than three times as heavy as those foamy Fingertechs the Mk1 was sporting but OHMYGOD do these look sexy. And they grip, oh yesss they grip. I know it’s a bit style over substance but hey, I also ride into battle sporting a Playmobil figurine which interferes with selfrighting so there’s also that.
    2. Speaking of which - Tina the mascot stays. She’s 12 grams but you can’t compromise on awesomeness ofcourse


    Nevertheless, for slimming down I carefully looked at each part and decided on a plan of attack.


    • The wheelguards could be slimmed down from 5mm to 3mm HDPE. The 5mm was overkill anyways - two vertical spinners hit either side head-on and barely got halfway through.
    • Both the baseplate and the top plate would change from Ti to 3mm HDPE. This would also give me a chance to prevent them screw heads from protruding the baseplate. The Mk1 top plate was made from 2mm Ti, which was ofcourse INSANE.


    In the side rails of the chassis I saw there was also some excess meat, begging for a hole to be drilled into it. Being HDPE it wouldn’t save that much, but as it’s not in a vulnerable place behind both a wheel ánd a wheel guard I’d say every bit helps.

    IMG_20170928_135357.jpg

    The beauty of the interlocking structure occurred to me again though. You can just pick the chassis up from any corner and even though there's not a single screw or bolt keeping plastic together, you can still fling it through the room and it will not come apart.

    Fitting the lifter motor it dawned on me there was some extra space I could make use of - mainly to make the chassis 10mm narrower, which would spare me some further weight.

    IMG_20171001_123340.jpg

    However, this in turn also meant I had to take a bit off the lifter motor axle. I took the motor apart, shaved off the excess metal from the shaft and then put it back in. I also saw it as the perfect opportunity to loctite all the screws holding the gearbox in place.

    IMG_20171001_180340.jpg

    After some fiddling about, this was the assembly of the lifter motor. It's still lacking shockproofing but it gives an idea of what to expect. The added bonus of the HDPE front plate is that it gives some springiness to the motor assembly.

    IMG_20171001_180650.jpg

    And here's how it looked inside the new chassis. As you can tell space is quite limited, but as there's more room higher up everything should fit. All motors are now tested and seem to be working perfectly.. I'm looking forward to fitting all the electronics in there.

    (not so much looking forward to then putting the thing on a scale but alright)
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    Last edited by Zenith; 1st October 2017 at 18:21.

  2. #82
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    It's about time I gave you an update on proceedings... just to proof I haven't been slacking.

    IMG_20171006_191449.jpg

    With the addition of the lifter motor I thought it was time to get to the innards. Three motors needed to be soldered in, and I reckoned it would be wise to first solder some wires to the motors to simplify future soldering jobs (and god forbid, internal repairs).

    IMG_20171006_204800.jpg

    I also fiddled a bit with the rest of the internal circuitry. Place of the power plug, removable link... it was LITERALLY coming down the wire.

    Now, you will noticed that the lifter motor assembly is not fixed to the base plate or any other of the chassis members - it simply slots in place between the front and back of the robot.

    IMG_20171012_093834.jpg

    The reason behind that is quite simple: accessibility. I'm not going to get my finger stuck in any impossible crevices trying to fish any wires out, so to remedy that, I chose to make the entire lifter assembly removable, and also wired on an XT30 plug to disconnect it from the electronics.

    IMG_20171012_093852.jpg

    That makes everything just a whole lot easier, I'd say.

    The next hurdle was also a good one. If I wanted to get all the ESCs and whathaveyou in there, I was going to have to do the lights first as the major electronics should go on top. So much for saving the aesthetics for last, huh?

    IMG_20171012_121210.jpg

    Wiring the flashing lights proved a bit of a pain, but as soon as I figured out not to put the 4 of them in series with the power LED and its satanic resistor buddy, all was well.

    You will notice (yes, a lot of noticing in this entry) that the front member is also not screwed down into any of the chassis. This is to enable me to remove the lifter assembly - the front chassis member is held in place by the top plate, which screws down on top of it. This forced me to leave some excess wiring for the front LEDs.

    IMG_20171012_121540.jpg

    Anyways, the new lights look great. I then wired up all the ESCs and went for a test drive.



    Bear in mind that this assembly is missing the front wedgelets and lifter assembly, so I don't expect it to do wheelies in the future.

    SPEAKING OF THE LIFTER ASSEMBLY,

    IMG_20171008_153313.jpg

    I finally got round to bending an actual weapon in there. Looks quite neat, although I still have to test the system properly.

    IMG_20171012_142241.jpg

    On schedule when it comes to weight, too. It'll be rather tight though, as it's still missing a Lipo, the front wedgelets and wheeguards in this picture. Tight spaces seem to have become a thing whenever I'm building.

    With the drive sorted out though, now comes the task I dread when building.

    IMG_20171012_130003.jpg

    And that's trying to fit this spaghetti into the chassis bowl alongside the lifter motor AND battery.

    Anyone got a spoon?
    Last edited by Zenith; 12th October 2017 at 13:42.

  3. #83
    Zenith's Avatar
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    Greg Cathalina
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    Deary me, it's been quite an adventurous week.

    I went right ahead with trying to fit all the spaghetti within the bot and actually got everything to fit. Went for a testdrive, and all was well - I had even hooked up the lifter to see how that behaved, even though the lifter couldn't close fully yet (it's quite fiddly to make an accurate prong which both extends the lifter blade as far as possible, but also makes it close fully).

    After about 5 minutes though, disaster struck. Smoke. More and more smoke started pouring out of it, so I carried it outside and prayed the lipo would be fine.

    IMG_20171017_122944.jpg

    And it was. The rest most decidedly wasn't though. Apparently the left drive ESC couldn't take it anymore and chose to go the way of self immolation, taking its two compadres with it. Oh yeah, that was why in Mk1 the two ESCs were not on top of one another.

    IMG_20171017_133859.jpg

    The bundle of ESC was now fused together, so I cut it out, and started to do a post mortem to see how bad things were.

    Surprisingly enough, except for the stench and a scorch mark on the base plate, everything was rather fine. The light circuitry still functioned without problem, but still I ran though the motions of checking the leads.

    IMG_20171018_100420.jpg

    The power plug was mildly scorched and still fine, but I chose to do the sensible thing of changing it out entirely - if anything, I needed to make the power leads longer anyway.

    Now, I have registered Mk2 to compete at the coming Bright Day event the weekend of the 18th of November, so I realized this left me with 4 weeks to rebuild the internals.

    This was also when I realized that now, I could make the entire inside how I actually wanted it to be. With the first setup some wires were too long, others were too short and the placement of some stuff was also less than ideal (like the ESCs, AMIRITE?)

    IMG_20171018_105756.jpg

    I also noticed the blessing of the design of Mk2 - the removable lifter module made the repairs a whole lot easier than they otherwise would've been. Now, I just had to disconnect it and take it out and voila, tons of room to work in.

    An added bonus is that part of the lifter module also gives the lipo its own separated compartment. Simply put, had this not been the case, the ESCs would've also taken the lipo with it and the entire thing would've been a puddle of molten plastic. All clouds have a silver lining I guess.

    Speaking of the lipo, I think it's prudent if I maintain 3S for Mk2. I don't feel comfortable using the Botbitz beyond its rating (even though people do use it with 4S) and since I need the weight, I'll be switching back. I'm also going to downgrade the battery's amperage to save weight - I reckon 1300mAh for a lifter is more than overkill.

    Anyways, with the insides cleaned up and ready for new ESCs, I set my sights to the outside. I wasn't happy yet with how it looked - the titanium wedgelets from Mk1 left quite a gap to the side because the wedges have been moved forward slightly. In a spinner-laden environment as the beetleworld I thought it to be necessary to address this.

    IMG_20171019_134515.jpg

    So I chose to play around with some HDPE. I gawked at how good it actually looked from the side. I assure you though, this is an accident. It won't happen again, honestly.

    IMG_20171019_134401.jpg

    Now, I know that 3mm HDPE is not going to be enough to upend all those balls-to-the-wall RPM guzzlers that roam these lands, but there's a catch. Together, these two HDPE wedgelets weigh in at 44g, which is considerably less than the 107g from the two titanium ones fitted before.

    This leaves me some weight to put wedgelets on my wedgelets - I aim to carve up some of the 1mm Titanium I used in Mk1 and use it to provide the bottom half with some proper shielding. 3mm HDPE + 1mm Titanium ought to do the trick, I reckon (FAMOUS LAST WORDS).

    To be continued when I lay my hands on new ESCs, which is the coming week.

    IMG_20171019_134535.jpg

    Until then, here's a bonus pic showing the front angles of Mk2 as they currently are. I was rather pleased how well it all seemed to fit together... hopefully it stays that way.
    Last edited by Zenith; 19th October 2017 at 20:12.

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