Harry Makes Ants

All things antweight

Moderators: BeligerAnt, petec, administrator

Matt
Posts: 37
Joined: Sun Jul 01, 2018 6:18 am

Re: Harry Makes Ants

Post by Matt »

I think the rule is that if the power cord/ JST lead is easily accessible then it is allowed. To clarify would a lid of duct tape with the lead underneath be allowed?
User avatar
Spaceman
Posts: 182
Joined: Wed May 14, 2014 3:16 pm
Location: Oxfordshire

Re: Harry Makes Ants

Post by Spaceman »

haz wrote: Tue Jul 17, 2018 2:05 pm Thanks guys!

I'd been having some problems with stiff retracts. What used to be a snap shut was a slow pained series of events. Everything mechanically seemed free and the silicone bands still had spring. Ended up stripping and re greasing the ram and it seems much better since.
Image

^^ the setup out of the robot for anyone interested!

After a couple of attempts at armouring it was going to be way too flimsy for combat, even for a sacrificial first attempt. I ended up swapping out the 35ml tank for a 20ml one. I'll take the hit on flips for the benefit of actual armour not just pish and hope - also lets me chop the frame by 20mm! An updated one is printing as I type :)

The smaller tanks are ones I had ordered for my second go at pneumatics so it is maybe a good thing to trial them in this bot. I have also found a much nicer servo to actuate the valve, physically smaller and with metal gears. Bonus!
Image

haha Voorsk, then I feel I must apologise to your son for my naff performance! If you're interested files to make your own Hobgoblin can be found here
What is the green bit in the pneumatic set up in this picture? how does the exhaust of gas from the cylinder work?

Thanks
Team 1202

Robototron (Flipper)
Crabulon (Walker)
haz
Posts: 1855
Joined: Thu Apr 15, 2010 11:20 am
Location: Underwater Lair
Contact:

Re: Harry Makes Ants

Post by haz »

Hi,

The green part is the fill valve. The gas vents through the main valve when it stops being depressed by the servo, then the silicone bands pull the ram down.


Quick test of the hypnodisc disc (disc) I'm quite impressed with the balance of it - plus it sounds jolly cool too :)

https://www.youtube.com/watch?v=s7rssb0 ... e=youtu.be
haz
Posts: 1855
Joined: Thu Apr 15, 2010 11:20 am
Location: Underwater Lair
Contact:

Re: Harry Makes Ants

Post by haz »

A bad idea got rather out of hand and now my hypnodisc-alike is yellow with tracks and wings. Because of course it is.

Image

Image

Now it drives a lot nicer and its much more stable. The stickiness of the tracks counteracts the torque reaction of the disc. It does look a bit oddball however, but then again so do I.
haz
Posts: 1855
Joined: Thu Apr 15, 2010 11:20 am
Location: Underwater Lair
Contact:

Re: Harry Makes Ants

Post by haz »

Thread necromancy alert.

Been fairly productive though.

Image

This was the first version of a tracked lifter idea I had. The tracks are the staple of antweights, Tamiya but these have foam strips painstakingly glued on for traction. The idler and drive wheel are 3d printed also, I just borrowed the existing geometry from the Tamiya parts as I wanted them it to sit over the gearbox of an N20.

Image

The lifter geometry for the front hinge was pretty poor and I wasn't able to get the speed or travel I wanted out of the servo I was using. Plus robots tended to just get fed right into the tracks and shot off the top of the robot - key design flaw here. Because I really liked the chassis shape I kept that and just tried to go for a more traditional lifter

Image

This worked a lot better But I wasn't too happy with the look so I chopped and changed the arm with the aim of making it more a bulldozer bucket style. Main inspiration were the heavyweights Ripper and Behemoth and Oliver Steeple's antweights Private Iron and General Mayhem.

Image

Going back to the old faithful method of a bit of cereal box I made myself a card prototemplate for a polycarbonate version which was skinned with some 0.5mm titanium

Image

Image

I am quite happy with the look of it, my first bit of metal bending in a few years. I thought I might get away with forming it all cold as the angles were fairly shallow and I almost got away with it. There is the beginning of a fracture in one of the corners of the longest bend which is a pain. I think I'll try and get it through a competition and then change it. It is backed by 0.75mm polycarbonate too but I'm pretty sure that's not really strong enough for modern ants.

Image

The linkage isn't great still but it has decent throw and will nicely flip another antweight from the tip of the blade. I am currently waiting on some 150mah cells to make up a better shaped battery for it, and then I will be putting the remaining weight into side armour and a switch and lid. I think I have about 30 grams to play with.


Also on the slab is another pneumatic effort using basically the same components as my previous attempts in a less bulbous form. I also wanted to try and have my cake and eat it - with electronics being smaller and cheaper its now really easy to have cool features and strong drive alongside a weapon too.

Image

My first version was like this, this was a super rough draft that was more just a way to test the drive before I started fitting the pneumatic side of things in and getting the geometry not to suck. It runs lego tires which are actually fairly grippy when you have six of them. The gears are all printed and run on small ball bearings (which I ended up buying a big greasy sack off from china for remarkably little money)

https://www.youtube.com/watch?v=sXuS3i393fs

Image

It worked pretty well too so I splashed out on a Malenki Nano from the BBB store which works with my years old Turnigy i6 and weighs absolutely nothing. Three connections later and I'm driving around - great stuff.

Image

I also neatened up the cells I was using as solid 2s pack so they sat better in the little slot cut out for them in the chassis. Because I don't really have the space or weight for a regulator and the ESC/RX combo runs on full bore 7.4v I just decided to make my life easier and picked up a high voltage micro servo from component shop. Generally I'd do an aliexpress special for half the price but I just wanted to get it flipping under power and it turned up the very next day for a tenner. I can swallow that massive expenditure I'm sure.

Image

Image

It mounts deep in the guts, and the Malenki sits on top of it with all of the pneumatic components basically on top of them. Now it was in more of a working state began checking how I am on weight and seeing where I could claw some back. The first place I looked was the wheels. Sad as I am to see the lego tires go 3 grams is unacceptable!

Image

Also I felt they were fractionally too large so the robot stood too high off the ground. I had some of the foam strip left over from improving the Tamiya tracks and it was a fairly perfect fit. I carefully glued these round the hubs and meticulously glued the whole assembly to my fingertips. It wasn't a great experience but it saved me a respectable chunk of weight, but lost me a respectable chunk of skin.

Image

Image

The grip is excellent too, for foam. I may brush on some latex or cut a pattern into the tread (or both!) to increase traction, but that's not a priority for now.

Image

And I got to keep the 6wd! Very happy and it drives much nicer with the smaller wheels. I think having softer more compliant tires means that its less sensitive to one wheel being fractionally higher or lower and its all a lot smoother.

Image

Here it is as it stands! without the armour and with the lightening it stands around the 136g mark. Might be just enough to wrap something thin around the vitals!

https://www.youtube.com/watch?v=hf7iqor_G2s

^^ self righting test

Till next time friends!
User avatar
MarkR
Posts: 375
Joined: Mon Dec 18, 2017 12:46 pm
Location: Reading Hackspace
Contact:

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
Posts: 1855
Joined: Thu Apr 15, 2010 11:20 am
Location: Underwater Lair
Contact:

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!

Image

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.

Image

Image

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.

Image

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.

Image

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
Posts: 1855
Joined: Thu Apr 15, 2010 11:20 am
Location: Underwater Lair
Contact:

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.

Image

Image

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.

Image

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

Image

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.

Image

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.

Image

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.

Image

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!

Image

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.

Image

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
Posts: 1855
Joined: Thu Apr 15, 2010 11:20 am
Location: Underwater Lair
Contact:

Re: Harry Makes Ants

Post by haz »

The multi channel esc was for this:

Image

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.

Image

Image

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.

Image

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

Image

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?


Image

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

Image

Image

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!

Image

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.

Image

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
Posts: 1855
Joined: Thu Apr 15, 2010 11:20 am
Location: Underwater Lair
Contact:

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.

Image

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.

Image

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!

Image

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
Post Reply