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Ondray
Joined: 06 Jul 2015
Posts: 142
Location: Newcastle
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I've repaired Hellamax so now for the post Vivid Report:
Great event! I was super happy with how the bots went and all the fights were bifftastic. Won 3/6 and all went for the full 3 min. The thing I was most happy about was getting over the electrical gremlins I had last year (Hellamax did have an overheating ESC and smoked up in it's last fight, but that was me pushing it too hard rather than random issues). Funniest part was the bot that I put on the reserves list ended up winning more fights.
First fight was People Eater vs. Citizen Flips. This was my first time fighting a CO2 flipper, but People Eater was built for the 'open' featherweight so I knew it'd take the beating. I was a bit worried about getting the saw spun up, the new brushless motor has a lot of power but struggles to get started with the meager 2:1 reduction. But, it got spinning and it drove straight for Flip's wheels. The saw wasn't quite low enough to get under, so it was just hitting the armor. People Eater got flipped a lot. Like, heaps. The pot came off on the first flip, it was a bit of cosmetic fun. The invert-ability was great, and put the saw blade up high where it was able to do some cosmetic damage The problem came when one of the wheel 'pods' came off, and it landed on the wheel loosening it which caused the wheel to come off near the end of the match. I simply over tightened the bolts holding the pods on the day before and stripped the tiny bit of thread. For the rest of the night this was fixed by using tape to hold the bolts in lol, as a more permanent fix I'll weld nuts on the inside of the bot. Win went to Flips, but not before it ran out of gas and got a few chunks taken out its kevlar armor.
Second fight was Hellamax vs. Zhenghario (mispelt?), the was one I've been looking forward to because Steve and myself have been doing robowars about the same amount of time, so are pretty evenly matched. Hellamax had the different weapon attachments, a long arm with a spike for max damage, a middle range axe for versatility and a lifter for dangerous opponents. I nearly went with the spike, but went with the axe for quicker self-righting against the lifter on Zhenghario. As it turned out Hellamax flipped itself more then it got flipped, as Zhenghario's lifter wasn't lifting as hard as it used to. This fight was also a perfect test to see the improvement with the new wheels - holy moley, huge improvement! Hellamax was shoving Zhenghario all around the arena, while swinging it's axe. The ESC that was having issues before did overheat again during the end of match countdown, causing the wheels on one side to stop. But win went to Hellamax
Third fight was People Eater vs. Strange Young Man. SYM's lifter didn't have enough torque to flip Eater, so Eater had the upper hand at the start. Then the nut holding the pulley onto the weapon motor came off. No more saw From here it was a shoving match, but a fun one. SYM had the upper hand with 4WD drive and grippy tires. But Eater was able to get some hits in by 'boxing' with the wheel pods Somewhere along the line SYM knocked off Eater's Pot-head and it's own head lol. Surprisingly, Eater was given the win. I thought SYM had the upper hand in most of the shoving part of the match, but the enchanted saw blade must have swayed the judges. I wasn't the only one surprised, one of the youngn's in the pits came over and told me all about how he thought SYM should have won, not realizing I was People Eaters driver lol.
Fourth fight was Hellamax vs. Polaris. This was the most intense fight I've had so far, trying to avoid the flipping arm while trying to get around the side of Polaris. I knew Hellamax would be especially weak against CO2 flippers. It's wide front and high clearance make it easy to get under and I don't fully trust my Aluminum square section held together with angle build strategy. Plus, the potential torque on the weapon system if it landed on the weapon was worrying. I went with the lifter hoping to put Polaris on it's back most of the match. Turns out it didn't quite have enough strength with the long forks. It did allow me to play defensibly, and Hellamax was fast and maneuverable enough to get around the sides of Polaris, avoiding the flip most of the time. But the flips happened, Hellamax survived better than I thought it would, it got thrown hard into the wall a couple of times. The frame held up fine, and none of the weak-looking RC wheels broke despite landing on them a few times. It was the weapon system that took damage. Landing on the axe sent the force back through to the motor shafts, bending them in - see below. But somehow they still worked! Volvo quality! They were noticeably weaker though, and power wasn't getting through on one side. The problem is the worm-gear motors won't rotate from an external force, causing the shaft to bend instead. I figured that out on the 2 hour drive home after the event. Polaris often landed on it's back after flipping Hellamax, with quicker (or more consistent) self-righting Hellamax was able to get some quick advantages in while Polaris was upside down. Polaris even ended up on top of Hellamax at one point, leading me to promptly send Polaris into Deathrolls corner. My brain was like "you're Deathrolls problem now". 3min done and win Polaris, but I was stoked that Hellamax survived the whole tank of CO2.
Fifth fight was People Eater vs. Ice Pick Of Doom. IPOD (only just noticed that acronym lol) had a rather hard hitting axe, I was a little worried about it getting through the 6mm polycarb and hitting the battery or electronics. But the saw was working again First hit of the fight saw the pick knock Eater's head off lol. I don't think it lasted more than 30s in any of it's fights. I thought IPODs wheels were steel so I wasn't running the saw blade at full speed (or at least the speed it was going in the previous fights, the whole night it was limited to 15% throttle to protect the weapon motor from the saw). It was a good fight with Eater running exactly to my battle plan of 'spin weapon up, hit them, reverse to spin weapon up, hit them again'. My concerns about the pick were gone when I realized it had too much reach to hit Eater when they were 'touching noses' (this is G-rated). So I stopped trying to go for the side and just went full frontal assault. IPOD got some drive/electrical trouble. Looking back at the video, it may have been due to a tire that got cut up by the saw jamming up the rest of that side's drive. I'll chock that up was a win for design intent. From there IPOD was limping, but enough to not get counted out. So I started having some fun, attacking the Eater's decapitated head with the saw and picking a fight with Deathroll (with the saw off because Deathrolls wheels are expensive lol). Win People Eater
Last fight was Hellamax vs. Flipper. I knew then would be a close fight with their solid well driven little lifter. So I used a higher C-rating battery than I was using previously to give maximum shoving and axe power. At the start of the match Flipper got a couple of good lifts in, with Hellamax struggling to self-right with the damage to the weapon system from the Polaris fight. But I figured out Hellamax was able to reverse off their lifter before it was able to flip Hellamax. While the lifter was coming back down Hellamax had the advantage and was able to get some good hits and shoves in. But that new battery had twice the current output of the previous ones, and in the last minute Hellamax smoked up. #420. At the time I thought it was the speed controller I had been having issues with, as moments before it smoked it lost power on that side, turns out it was the main power wires overheating. Win Flipper, and the audience got to see some smoke
Burnt out power wires:
So, great event. People Eater went great! It's going to get re-modified for the nationals, I don't like the belt and pulley being on the same side of the bot as the weapon, as much as I liked having a dead shaft, it's too great a risk of hitting itself. So that will get flipped, which will also make more space for a thicker weapon bar. It'll also get some tire armor on the wheel pods because I don't think that 3mm steel will survive a big spinner hit.
Hellamax also went great, just not as great. The new wheels were awesome and the weapon swapping system was nice and quick. The axe didn't hit very hard though and the lifter didn't lift (it might have with the shorter forks). It needed some repairs, new wiring and new weapon motors. I stripped it down this weekend and replaced all the supercheap "12gauge" speaker wire with pretty pink and blue RC grade 12G wire. On the strip down I noticed another potential cause of the smoke out - and maybe even the ESC overheating issue. The front right wheel motor had come loose and had twisted it's wires up, possibly causing a short. That's also been fixed. Hellamax is also now covered in condensed plastic gunk from the wires that smoked up
Fortunately, my old Volvo had four electric windows so I had two spare weapon motors sitting there. I stripped the broken ones down to see if I could fix them for spares and was just impressed with the number of things those Scandinavians think of. The insert that drives the sprocket is connected to the worm gear with rubber padding to adsorb shock:
I also noticed something I suspected the motors had, a little current limiting resistor:
It's that grey box, about 0.15 ohm from testing with my lab supply. More power is always better, so I've shorted across that resistor in the 'new' motors. Testing this evening shows a noticeable increase in hitting speed and torque (measured via push-up speed) - hopefully now the lifting fork with be able to lift other bots! The broken motors have been bent straight, but the cast aluminum is a little cracked around where the shaft is supported. So they will keep their resistors and be my spares for future events. With Hellamax all fixed now it's time to convert People Eater back to Pothead
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Sun Jul 09, 2017 8:31 pm |
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Ondray
Joined: 06 Jul 2015
Posts: 142
Location: Newcastle
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So the upgrades to pothead are progressing, the tire armor has been added to the wheel pods. Turns out car tire is *$^%ing hard to cut! I tried the angle grinder at first with a cutting disc, but it just clogged up. Then I was using a hand saw, which was too slow and caught on the metal re-enforcement. A jigsaw with a metal cutting blade ended up working, slowly. I had to clamp the tire down hard to stop it moving with the jigsaw. But it bolted on easy enough, should help defend the wheels against spinners and saws:
That was last weekend, this weekend saw me move to the weapon bar. Of coarse everything was harder than I planned it would be. I got some bushings for the 20mm stainless rod, with the plan for the rod to go through the bot, welded to the bar on the bottom and bolted to the pulley on the top...The 20mm rod is 19.2mm, so the bushings have a little more play than I'm happy with. The outer diameter of the bushings is 23mm, a size all my stepped bits skip, which meant drilling the holes to 22mm then working them out with the dremel...which died, now is off for the repair warranty. I also blunted some more stepped bits drilling through the 10mm bar...
How do you make big (>13mm) round holes in steel without a plasma or waterjet cutter?
...The first piece of stainless rod I used for Vivid drilled and tapped easy, but I think I must have blunted my bit and my tap on it, because the new pieces were butts to drill and tap. But with a 4pm to the hardware store and a cobalt drill bit, that's done. Then the new weapon bars had to be welded together and the shaft welded in. Most of my welding prior to this was on 2-3mm thick stuff with my Grandads old 2.5mm welding rods, which I finished off this weekend. So I had to buy welding rods for the first time, I knew I'd want 3.2mm rods for the 10mm to 10mm thick bits (I also got a big pack of ones similar to what I've been using). So, the old welder is 3-phase, which will work on single phase on low settings. The 3.2mm rods didn't like the low settings. I turned the welder up and tripped the fuse on the power board a few times (which I was using because I knew I'd be pushing the max amps and didn't want to black-out the house) before going back to the 2.5mm rods. Which means there's not as mush penetration as I'd like, but welding two 10x50mm bars together to make a 20x50mm bar wasn't ideal to start with, I'm just working with what I've got. The first bar is welded up, I'll make a spare, or two, next weekend.
I'm almost ready for assembly and testing, two weeks out I have to make a little adapter to mount the pulley onto the weapon shaft. I'm a little worried the setup may have too much friction and mass for the brushless motor to startup. The bushings should be ok, but all I've got is some chopping board to support it vertically...I might make a quick and dirty bolt on wedge in case this whole setup fails, probably worth anyway as a backup for when it gets broken at the event I also got some hard-facing rods, so I can make the weapon tips a bit harder. I don't know how much of a difference it'll make, but a small pack for $16 is worth a go.
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Sun Aug 06, 2017 9:40 pm |
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