Harry Makes Ants

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MarkR
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Re: Harry Makes Ants

Post by MarkR »

That pneumatic flipper is great!

Sorry about your skin getting glued. We've all been there.
Robots: Betsie - RaspberryPi controlled flipper bot with gyro stablisation - too clever for her own good?
Stacie - tidy flipper; 4wd driven by hair bands
haz
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Re: Harry Makes Ants

Post by haz »

Thanks! I get glued a lot, dangers of the job.

As is traditional I am working on the V2 before the V1 is shipped and fought but hey, why not!

I end up chopping most of the Lego cylinder away before it is combat ready so I figured - why make life harder modifying when I can build it in the way I want. I copied the geometry I needed and improvised slightly where appropriate. 3d printed material feels shady the first time you think about it but once you take some time on it, it isn't holding pressure (I have a dedicated air tank) the walls are thicker than the standard ram and the endcap is retained with M2 bolts not hopes and dreams. Nobody bats an eye at printed adaptors for spinners!

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That's the V1 and I got really lucky that the ram was functional! Obviously had to ream out the bore to make it A: the right size and B: actually round so it would seal and actuate.

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Oh and the air tank is a weird little experiment using a keychain wallet. You're supposed to roll up an emergency fiver and keep it on your keys. I bunged it in the lathe and poked a hole in it, then added a m3 barb. It was sealed with my traditional gob of epoxy and it's worked remarkably well since.

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This is a tweaked version, you'll notice it printed a bit cleaner too. The fill valve has a proper mount and its the most well laid out I have ever built a pneumatic system. Thanks to the wonderful Joey McConnell-Farber It has a parker valve which is a change from my traditional 'pneumatic microswitch' approach. The flow rate isn't quite there yet but I might go to dual valves or try and optimise the ram around the flow rate I'm getting. I have some really pleasing rams from hobbyking which are much smaller bore but seem to have enough grunt to tip 150g easily.

https://www.youtube.com/watch?v=Oi1MZRMURcw

https://www.youtube.com/watch?v=8a1p-cx2GbE

Spot the difference! Watch this space.

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Oh and I also got a brimming glass of N20's for very little money to help standardise my robots and keep me stocked up.
haz
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Re: Harry Makes Ants

Post by haz »

I stuck some of those new N20's into the tracked lifter and was impressed with the performance even on 2 cell

https://www.youtube.com/watch?v=-LC44jtsA6M

Also took the time to try out making some side panels whilst I had a spare moment at work. They are 2mm carbon fibre.

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Looks quite smart and doesn't rub on the tracks noticeably. I am still tossing up if I am going 2 or 3 cells for this so they may have to go to 1mm or polycarbonate for weight.

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Speaking of batteries I dug out my stock of sadly neglected lipos and elected to do some spring cleaning.

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Cleaned up I have a lot of 120mah 2s packs, three 180mah 2s packs and one slightly suspect 260mah 2s. I have a couple of 180mah 3s packs and loose cells which are still in rotation. Annoyingly my 150mah cells from AliExpress have been delayed at least another month. I'm almost writing them off now.

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I have been working more on integrating the ram assembly into a useful frame where the valves can lay down flat and have some sensible routing of the pneumatic tubes.

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The new flipper chassis is coming along quite well. I have the drive mounted up now and the lego tracks are working well in terms of scale and stability. I am liking how it all fits together currently and all the components seem to be in a sensible place.

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I was feeling more and more disappointed with the performance of a single parker valve so I decided to see if two would be more suitable and the answer is "yeah, kinda!" it's still not at the level of a manually actuated valve but it doesn't feel like its about to break anything either, which could be an unexpected bonus. I am currently restricted on flow by the lego T joints. I will be drilling those out a bit soon to see if that helps, else I have some metal ones coming from china.

https://www.youtube.com/watch?v=md8Zsp4M8SU

it currently sits at 104g with all the pneumatics, battery but no esc or rx or flipper arm & armour. I think its going to be quite easy to not have to compromise too much on armour this time!

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Picked up a 4 channel esc for very little money on AliExpress and it came remarkably quickly! It is also high voltage which means it fits in well with some of my current nefarious plans.

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19g is a little heavy for an esc, so to save weight I added a receiver - yeah, work that one out! Just a quick tidy up of a some of the wires has saved a huge amount. The ESC output is still untouched and has 150mm long wires with jst plugs on the end so there is at least a couple grams still to go once those are trimmed down to the 30mm or so they will be for the bot. The chassis this will be going into is printing right now (in more lurid orange ABS) I don't need the 4th channel but it was cheaper to buy this and only use 3.
haz
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Re: Harry Makes Ants

Post by haz »

The multi channel esc was for this:

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Which is a tracked (okay maybe I should ease up on the tracks) hardcore gripper! it is powered from a standard size metal gear servo with the board and potentiometer removed to make it rotate more and take higher voltages. My aim was to go 4s using a pair of 7.4v 120mah packs but I am fighting to keep it in weight with enough armour to be useful. The claw geometry is rubbish and is just a placeholder and the dustpan/base is missing still.

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Pin removed - all it took! though all the gears are mystery meat brass and are worryingly fine pitch, however this was £1.60 so I am not losing sleep.

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Careful hacksawing and filing of the case removed all that wasn't needed anymore. I didn't save much weight because all the really heavy bits are still there. This was buttoned up with m2 bolts to replace the long screws that went through the case

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This was the V1 frame where it was all too solid and blocky. It was mostly done as a quick geometry check to make sure everything translated ok to reality. I was surprisingly all right with this and with just a couple tweaks I had a really decent starting to V. You can see the bearing which supports the output of the servo, I drew the gear to have an 8mm plain portion which would let me sit a cheap bearing on it to stop it deflecting. I'm now not stripping gears out of misalignment, more pure torque failure - nice problem to have?


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Here it sat around the 153 gram mark missing two plates of polycarbonate and a cell below intended operating voltage. Since this point I have trimmed the wiring down and saved 5 grams and tweaked the chassis to find another 9 grams in other places. I can eek out another 1.5g with a micro rx which I have on order. It is an uphill battle but it is doable

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I took the tracked flipper into work today to remake the printed links out of carbon fibre. They are much stiffer now and there is no bending or wobbling. I also bent the scoop back a tad so it sits on the floor. This is fairly important for a flipper!

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The 6wd flipper had a little work. My retract spring and the general violence of the flip being greater forces than Lego was ever really meant to deal with means the piston seal has deflected past the point of usefulness and has been mashed into a pulp. I just bodged the issue, quickly printing some new piston parts which take some O rings. I drew 5 in 0.5mm increments to get the best fit. It's back on form now but I have found it is really sensitive to lubrication - dry it will fire but stick on the retract.

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Waiting on a lasercut 4" cube so I can test armour. I have a sneaking suspicion I can get away with more in the way of armour than I thought!
haz
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Re: Harry Makes Ants

Post by haz »

Okay with the addition of a single washer and a decent amount of anti seize grease (perhaps not the best choice but it was in reach) I have cured the retract sticking - touch wood. The only downside is a small amount of copper grease getting smeared out the ram from time to time. Cracking the ram open has lost its novelty for the time being so now its working somewhat consistently I am buttoning it up and calling it done for now.

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In a rare spurt of compliance I have actually put a switch on and it was only a slight afterthought. I have hardwired the battery in to the robot so that when the switch is off it is able to be charged via a JST which is mounted to the fill valve.

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If you'll forgive the slightly dodgy charging setup (I should really wise up and make that adaptor before I go to an event) But it is buttoned up with armour. Well, I suppose it's only technically armour, it is just some 0.75mm polycarbonate but this is the price you pay for having a weapon like this. I think I have to win with a couple of flips or just run away from the spinners!

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148.5g - enough weight left for a couple of stickers and some paint! See it in action here:

https://www.youtube.com/watch?v=5q1liggmvTY
haz
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Re: Harry Makes Ants

Post by haz »

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Mean and green it's pretty much done now! I have decided to name it Johnny Mnematic (in reference to the excellent 1994 slice of cyberpunk schlock "Johnny Mnemonic" where Keanu Reeves plays a USB stick, Henry Rollins is a computer expert slash doctor and Ice T has a silly hat)

Warning: do not exceed storage capacity. Advice for life there.

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The armour is just trimmed and folded 0.75mm polycarbonate as before it has just been finished with some green vinyl to help it look a bit neater. I'm not calling it completely done as I still have a couple of grams to find somewhere before its comfortably in the limit.

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The flipper arm needs to be redone as it is still carrying over the old geometry for the elastic band retract, from before I went with the internal spring.

The BBB webstore had a bank holiday sale so I made the most of it, picking up another Malenki Nano esc and a HV servo. I raided a parts box and found some claws from Joey McConnell-Farber and it sort of designed itself from there!

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A quick chassis was drawn up and printed and I got it fairly close first time. I need a little bit more clearance for things like the wires coming out of the servo but it worked remarkably well.

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The gears are mod1 and have 3x6 ball bearings in them. The claws are held on with m2 bolts.

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The electronics are remarkably compact, the battery is built onto the ESC/RX and just has a normal charge circuit and switch

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It then came together really rather well as everything mounts from the top and it all just falls in place. The tires are lego and the motors are the same 300rpm I am running in most of my new builds.

https://www.youtube.com/watch?v=xjy3jqmOXCo Video for reference.
haz
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Re: Harry Makes Ants

Post by haz »

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Finished off the pincher. The chassis now has a little more clearance and is fractionally wider to better guard the wheels. It has a cut out to gently cup the switch and the charge point too, though I may rejig these in future but it all squeezes in for now.

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Lid printed, it's broadly structural as it supports the claw mechanism so it is thicker than I would normally go. It's 4mm with 2mm pockets for the electronics but the overall chassis height is 20mm which is pretty standard. The gaping hole in the middle isn't going to stay like that, well it is but I'll be having some sheet metal cut out in some funky fresh patterns to go on top as I still have about 20g to play with. Wheel guards will take up some of that. Oh, and I'll have to come up with a name at some point.

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With bonus polycarbonate outriggers to stop it faceplanting

I found a suitably sized (90mm) HSS slitting saw somewhere in my piles of junk and I thought wouldn't that make a lovely dreadful robot. A quick and dirty frame was drawn up based around components I had on hand. The powerplant in this is a 21mm SK3 outrunner which is almost comically long compared to diameter. I have a few of these and have had them rattling around since at least 2015. However 60g of sawblade, quite a large motor and needing a respectable battery to get it all spinning well pushed weight up to 155g without a lid or a switch or any armour. Since I'd already made all the compromises I was comfortable making I returned to the drawing board and made it a walker.

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Super simple cam based hobbling mechanism, nothing special at all really. I had a big greasy bag of very thin 8mm bearings that I got for a pittance overseas. The traction surface is some of the foam strips I used for wheels and tracks on my other robots just superglued to the bottom.

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It mounts exactly the same as the wheel, just with added geometry for the slider portion of the leg. The leg rides on little top hat shaped flanged nylon bushings I found in a box. this keeps the legs in line.

https://www.youtube.com/watch?v=WDtBuCZarcY

I went for really slow n20's because I think a lot of the cam based walkers are much too fast and end up putting more energy into frantically jiggling up and down than they do going forward. To be fair I think the more legs you can have the less prevalent this is. I overshot the mark and made it too stable and too slow the first time. I also think the motors are 3v winds because they sounded like servos on 2s. I changed them out for more standard ones which are a little too fast but it's not quite as yawn inducing.

https://www.youtube.com/watch?v=SyxpF4WvyqA

Much better I think we can all agree.

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It awkwardly hobbles in at an alarming 149.5 grams with the bare essentials. This gives me an awful lot to play with. My main goals are armour, ballast and battery. I plan to stick to 2 cells because I don't think the weapon or the drive benefits from the extra gyro or frantic wiggling respectively but I think any extra discharge or capacity will be welcome. It looks like I'll be running two FULL teams with my partner next AWS so the ability to go a few rounds without charging is a billy bonus. So far the name winning out the race is SHAKMA because who doesn't like a dreadful old horror movie about a killer baboon.

In existing robot updates I printed the finalised version of the Slight Force chassis in the right colour and started to put it all together.

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The way I've designed this is pretty great for working on, the whole guts of the robot just lift out with some careful prying and it's all in one hardwired lump.

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The ESC is a fantastically cheap (albeit bulky) unit I get from china in bulk because they are so simple and are excellent at handling the higher current often required by my friction inducing nightmare track systems. I couple this up with a flysky 4ch RX which I also tend to buy in lots of 4 or 5 at a time because they're wonderfully small and easy to work with. The ESC is a kingkong 12a because I had a really quite impressive amount of them "in stock" I believe we used to buy them in fairly substantial quantities where I used to work. They are remarkably robust and come with Blheli preloaded so you can monkey around with their brains quite easily. Whatever past Harry had loaded onto them worked well so I just kept it. Please don't laugh too hard if it detonates in combat.

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For anyone curious, I generally thread all my holes in ABS. While it may potentially be weaker due to being able to be stripped or pulled out I feel its nicer because I don't have any strange stress points from jamming self tappers everywhere. It has worked thus far - though I feel a big bag of heat press inserts are in my future.

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The track wheels are driven purely by friction as there is no tooth profile on the technobots track. I have fiddled with the PCD and the roller size so that I am pretty confident that this will not slip too easily. The technobots track is incredibly poor with regards to traction anyway so I feel the average n20 will just wheel (track) spin in place before anything else gives. These ride on 3x6 bearings and I can bias them axially by jamming more washers in - totally legitimate engineering!

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I'm honestly super proud of this one despite being a total, unashamed rip off of both versions of Bite Force. It drives great and is super stable. The scorpion 2204 motors are beautifully made and are like silk. Let's see how they are after a few rounds of combat. Here they have the 2 tooth disc on them while they're mounted (hey, it's the right colour at least) but I'll be going to a single tooth when I next do a lasercutting order

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printed prototype of the disc. The colour of the filament probably dates it!

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Little bit of decoration on the side armour just hammering it home! Yes its a BF clone.
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