Monday, 9 September 2013

Spins, wins and spiders

So I've been uncharacteristically busy the last few days, first thing was getting the beetleweights all ready to hand back over to Shane at the Euro champs at Norwich on Saturday. Friday evening saw me spin up the full body spinner "The Gimp" for the first time. I had not had a real chance to play with it before as one of the battery packs was legit dead. literally no life from it. Nothing. But it seemed to work fine on the one pack, better than it did on two for some reason I'm not clever enough to understand. It had enough juice to power the weapon.. but it dropped a bit and the drive esc went a bit jittery. No limbs were lost and no cockney orphans were harmed in the name of science so it was all gravy good.
You can see the glory of the full body spinner spinning here. That little motor is such a beast, spins up the 500g odd shell in next to no time. There are some amusing dethspiralz when I go too hard on the throttle. Some time near future there will be a single tooth and counterbalance assembly on it.. scary! All the beetles got a bit of attention on the benches, I'm really pumped to be involved right at the start of this totally kick arse weightclass
All the smaller weight classes, beetle and ants

Also what was totally kick arse? Me getting to control one of the heavyweight competitors. The wonderful Air built by Shane Swan no less. I loved it, I was sharing control with Dave Weston. He was driving and I was operating the flipper. In our heat we faced Storm 2 and cherub and with Dave's rather swish driving skillz we won. However an on-the-spot weight check showed that Air was over weight and we were "disqualified" so the victory went to Storm 2. Later on, in a whiteboard out positions were reversed and I was driving. Against Turbulence and Tilly?..something I forget, apologies.  This could only go all the well ever. Well, I wasn't totally crap. Weston's sharper reflexes helped with the flipper and we were able to get under the other two pretty easily even if I did forget how to forwards occasionally. We somehow won this on a Judges decision.
Me at the bench with the stupid haircut, Air is bottom right 

I took home a new pet
Spider bot, Spider bot does what ever a Spider bot does. Can it swing from a web? No. Its about 13kg.
The wiring needs to be totally re done and some new Lithium polymer batteries can replace the shagged NiCads. It sports a very nice walking mechanism. Slightly obsessed with it now. Its also just crying out for steampunk... I mean.. LOOK AT IT.

In other, less interesting news. I started collage today. A 2 year mechanical engineering course. It seems all well and good so far although maths might skullfuck me a  little. See how it goes. I'm fed up being stupid. I want to learn things now. Machiney things.

Ta. Haz

Tuesday, 3 September 2013

Massacre - Combat robot

A little bit of history. Massacre was my first attempt at a vaguely complicated, offensive featherweight i.e. a spinner. Of course due to lack of engineering skill/common sense/budget it didn't go well, in fact I think I might have actually made the worst spinner ever. It did a grand total of about 4rpm for a period of about 0.4 of a femtosecond. But regardless of this it won a couple of fights and qualified for the second stage.. where it promptly lost but hey ho, still better than my previous one win to two losses last year.
This was Massacre V1.0 The design is basically a copy of the very successful robot Hazard, except with all the functionality and destruction removed and replaced wheels and a stainless steel bar.
I still love the overhead concept and I still believe that they can be an awesome force if properly constructed. I'm just having major problems with that part. I'm starting a 2 year mechanical engineering course next week at collage so that should be able to, if nothing else teach me some nice useful practical skills and some nice bits of maths and physics.
Lack of planning and no real world experience with gears lead to the weapons failure. To combat this I've been planning the setup much more in-depth than before and will be leaving enough time to test that it works in reality. Here's hoping for >5rpm this time! General robot practice is to KISS, you know, Keep It Simple Stupid. That's all well and good if you want to build a boring winning robot, but I want cool shit.
6wd? Check. Overhead bar? Check. Hardox wedge? Double check. Now personally, I think this looks right smegging cool, over complicated maybe and it won't be a world beater, in fact it would not surprise me if this did worse than V1.0.

Parts for this are all major upgrades to the parts used on the V1.0 as I shall now compare.

drive: 4x GR01 550 motor gearboxes (drill motors in a slightly nicer casing) and 4x 73mm Banebots wheels
Power: 1x 18.5v 4000mah Lipo
Weapon: 2kg 10mm 304 stainless steel bar powered by a pair of speed 900 brushed motors
Electrics: 2x 30a electronize (model railway controllers?) (clunky as buggery) and 70a relays for the weapon
Frame: 20mm HDPE bulkheads, 6mm HDPE armour,4mm HDPE lid, 2mm titanium base plate and wedge.

Drive: 2x Magnum 775 motor gearboxes (650watt each), plus belting for 6wd and 6x 73mm Banebots
Power: 2x 18.5v 4000mah Lipos
Weapon: 3kg Hardox/similar bar powered by a  4020 scorpion brushless
Electrics: 2x 85a TZ85 botbitz esc and a 100a or so brushless esc for the weapon.
Frame: 10mm 7075 aluminium, 5mm 6086 aluminium, 10mm HDPE, 4mm Hardox wedge.

Since having 6 separate motors for the wheels would make the world implode with awesome  put me overweight I elected to have a series of belts and pulleys that would  give me the 6wd. Now when using pulleys you have to work out distances (lots of calculators and things available online) between the centres so you don't end up with too much slack or the belt being to tight. I first used this on the Beetleweight to see if it was reliable, and it was so not I put it to use on a featherweight (using larger belts and pulleys obviously) Now the pannels that make up the frame are high grade aluminium and they need holes drilled actually, which then need to be bored out to a large diameter to accommodate bearings. Now precision isn't exactly my forte so I would some assistance. I could get myself a hole saw and a costly sheet of alu to butcher or...
Enter waterjet stage left.
I have wanted to play with a waterjet FOREVER and now I get the chance. Now people knowledgeable in such areas mentioned to me that all the cuts and blow outs (holes, etc) really ramp up the cost so I came up with.. Ze Great Uberlump. Its one long cut around the outside, and only 10 holes so its not totally bank busting allowing me to be able to afford a better material. I do have to put a bit more effort into assembly, popping the panels out airfix style and filing them down myself. Not quite the jigsaw puzzle some people like.. but then again this is just a boring box. That just about covers it for now, when I get my act together and start the build Massacre will feature quite prominently here.

Monday, 2 September 2013

Or at least I try to.

This is not exactly designed to have any pleasure derived from it, its almost purely for my benefit, so if you are reading this, I assume you are me, in which case you probably need to buy milk and walk the dog. I find writing things down is an excellent way of problem solving, gaining inspiration and generally sorting things out outside the headbrain. My memory is extremely patchy at the best of times, and having a "public" place where my design and thought spam can be deposited may stop me solving the same problem over and over again and keep a vague order of my builds.

All right, onto my projects of late. The Beetleweight combat robot was going well until today, and even then it still had some problems. Main problem so far is the god awful weight distribution making the damn thing drive like some kind of horrifically impotent one legged puppy. Not good. having a 500g lump of titanium spinning 4000rpm may seem like a good idea for a weapon, and for a weapon it probably is. Its just that the 500g (probably closer to 7-800g once the motor/gearing are counted) is at one end of the robot.. and the motors are at the other. This of course leads to the drive not being all that great to say the least. Also adding to my drive related woes are the fact that one of the wheels is a couple of millimetres higher than the other! What the arse? How on earth did this happen; I put in extra super special effort to make sure the holes on both pieces were in the same place and I still got fucked over. If only I could CNC mill the bloody thing. Gradually filing down one of the front supports seems to be the only way to fix it, a weight on the back seems to push it down enough to drive okayish but that can't be done as I'm already on the limit. (a limit which has already been increased once... can haz 1.6kg now pls?)
Anyway, today's disaster was in me trying to weight reduce when tired. Using a large forstner bit I tried to hack out some grams from the HDPE front brace in a sort of ill fated mill emulation manoeuvre. To say this didn't work would be an understatement; it left the panel looking like the aftermath of some bizarre and deranged plastic surgery (sadly more or less what happened) But no big deal if it was ugly as all sin right, it didn't have to be seen by anybody? Wrong. Some complete tit had managed to mutilate the wrong side of the part, which would leave the horrible mess on the outside. I managed to bodge it and hope and it turned out okay.. its a little wonky and hole had to be re-drilled for its mounting but its more or less fine. This little bit of wonk however was enough to misalign my "carefully" drilled mounting holes for the rear armour of 3mm polycarbonate, so that had to be readjusted as well. I'm beginning to see why my drive might not be the best there ever was in spite of my care.
A bit of visual aid. You get how it fits together now, you can see the 10mm black HDPE part just behind the very nicely machined beater (17mm Ti) and the 3mm polycarbonate arse plate at the back. The wheel closest to you, the left hand side one is the one that is ever so slightly higher. Which makes me approximately all of the sad ever.
Well that will do for now, will probably post another thing fairly soon on this if there are any changes or developments.
Cheers, Haz.