Hey people. Should be a fairly picture/progress heavy update because shit got done in the past month or so.
First on the list is new toy! I paid for/ordered my lathe in mid January and it turned up about 3 weeks ago.
Sufficiently meaty bastard to match its owner. This is a WM 250 from the fantastic Warco. I got it for just over a grand because I got a great trade show deal. The machine itself is fantastic, I love working on it, the restrictive feeling I get when working on my mill.
This was getting the damn thing into my workspace.
Where it lives now. I can use both machines unrestricted which is nice. They don't clash at all.
My RobotMarketplace order finally showed up. Customs decided to charge me one arm and one leg and a few fingers as well but that is to be expected.
2 smallest wheel sizes are for me. Smallest are for beetleweight shenanigans and the 63mm ones are for Massacre. The other ones are for other people's robots.
Random arse end of steel in there for Shaft Simulator 2015. There are 3 7075 standoffs I made in this picture. I felt compelled to pretendobot at this stage. Delrin bushes removed from colsons and they have a plain bore now.
I machined a new faceplate for my brushless inrunner weapon motor. It is also sporting an enlarged shaft and much bigger bearing. The new faceplate is made out of 13mm 6082 aluminum.
The dink in the new part brings shame upon my family but you can see the upgrade. Gonna go for 6 mounting holes instead of 3 and going to go for M5 threads over the M3 for attaching the motor to gearbox
Speaking of gearboxes.. Here is the new rangle setup to drive the weapon. Same basic design as last year; custom U channel made out of 6082 and grinder gears. Some changes though. Ball bearings to replace the bushings and newer less terrible gears with a higher reduction. 3:1 over 2.5:1 of last year. The bearing pocket at the top looks off but only the first mm or so is, I accidentally took to large a cut for my final pass and quickly noticed. I'll fill the gap with epoxy and enjoy my stay in engineer's hell. It needs a clean up and obviously to be bolted to the motor, but thats it mostly done with the minimum of pain.
Hmm mysterious parcel of mystery. I wonder what it is.
Roboparts! amaze! The waterjet place was hella quick. I got the parts next day and they were still wet when I unpacked them. Here are some bars for Mass and some discs for another cooler featherweight.
"Hang on" you may be thinking, "Since when did suddenly watercut hardox, I thought titanium was happening"
Not enough hours in the day for the ti bar right now. I had to come clean with myself and my timeframe and ability that it wasn't going to happen properly. Give me 2 months and it would happen, give me 3 weeks? Fuck that noise.
However, designing a flat single piece bar that wasn't dreadful strength wise and pug ugly looks wise proved too much for me in the late night clusterfuck session in which the bar changes happened.
Thankfully Ellis stepped in with his wonderful design and mad engineering skills. Billybob came up with the shape inspired by the fantastic Secto and Torgr
Here you can see the 7075 lump I have to turn into a pulley. It will be fairly dificult as it will have to have 2 bearing fits. One 32mm bore for the needle roller and one 80mm dia outer section for the SuperBearing.
7075 hubs pressed into the colsons. I made them a hella pressfit but still might have to retain them with a grubscrew or something. A knurled OD would be really good. Maybes next time.
Whoa there Bessy, that jumped to a more complete robot!
A parcel of lovely things awaited me after I finished work, my CNC milled gearbox housings and my lasercut baseplate + lid
It's so damn shiney! Shot with semi cleaned up bar for scale!
Don't judge me. I know it's cliche but damnit I think it looks cool.
I'm ever so slightly flexing with the lid cutting.
Got one gearbox made, got the internals sorted and machined the output shaft, It isn't keyed yet because I'm lacking a 3mm endmill right now.
That is more or less up to date with Massacre at the moment. I'll try and update sooner with more interesting things such as my draw and opponents for the champs etc and hopefully some more complete robots and maybe even spin ups...
Remember everybodies favorite semi useless 30lb overhead bar Massacre?
Well it is a thing again. This is now the third proper version. It should be in a totally different class now, fingers crossed.
This design, build and documentation process is slightly convoluted for a few reasons. For my final year at college I needed to have a project to work on, so naturally I picked robots, something I would be working on anyway. This caused half the design process to be totally backwards and stupid parts covered very in depth just to fall within the project's guidelines. #education
I've tried to kind of keep shit here in a near coherent order. Focusing on one different section and talking through its own evolution at a time. Then probably splitting the actual build and assembly of the robot into a separate post.
Frame.
Last year the frame was made out of 2" by 5/8" aluminum flat bar which was pocketed out to fit motors. Nothing really wrong with this, the frame didn't sustain any damage but I wanted to change it up a little bit. Smaller, tougher, higher tolerance, better designed.
This is the new frame. Looks a lot like the old one, and it pretty much is. Bulkheads are 15mm thick on the side and the cross braces are 12mm. Main difference though is this is alumec 89 which is a very high grade aluminum alloy. It has strength comparable with steel. It ended up getting CNC milled by Ed Wallace of DB5, DB10 and Turbulence fame. He did an incredible job and the parts came out fantastically.
A more fleshed out CAD here. Notice the weapon bearing system. Late night shit talking with Ellis Ware on how to make the weapon system not suck and be so weak.
It used to be just a simple dead shaft bolted to the baseplate which I wasn't particularly happy with. Ellis had the idea of using the biggest bearing known to mankind (100mm OD, 80mm bore) to fit around the pulley while still having a dead shaft and bearings in the centre. Hella strong! The alumec frame for the weapon system added yet more strength.
When in the robot, the shaft is both live and dead. I give you, Schrodinger's Shaft. Or Zombie Shaft If you're that way inclined.
Here you can see the frame after it had been beautifully milled by Ed. I shoved my manually milled box section battery box of shame and some other components in there for a Pretend-O-Bot and just kinda marveled at how fucking shiney it is! Loogadit! Shiney!
Dat finish doe, hnggggg. Seriously its fantastically done. Tolerances are hella tight and parts fit smoothly and perfectly. Close up on my big ass bearing. Can you belive RS components wanted like £90 for one. I ended up ordering German and getting 3 for 40 euro (£30 or so) which arrived quicker than bearings I ordered from the Uk on the same day.
Small robot is small if you hadn't noticed.
Drive
Is more or less the same as last year, the year before, same as every drive I've had. Good old drill gearboxes. In slightly nicer cases however..
Internals are your common or garden cordless drill gearbox inside a CNC milled aluminum housing with dual bearing supports and a beefier output shaft. Gone are the days of shitty 12mm mystery steel with 3/8" external threads and LH M5 internal. Today we welcome the new era of 17mm silver steel with a keyway instead. It will either go badly wrong or it won't. One of the two.
I haven't had quotes for the gearboxes yet so if they are going to be hella money I'll have to get creative.
Motor wise I was planning to run a fairly standard 12v 550. However I didn't actually have any. (Massacre last year ran on 18v motors and promptly broke all of them or donated them to other teams once out of the competition) Trouble was I didn't fancy paying stupid money for a new set. Gimson robotics stopped selling them and they were like £8 anyway. Ebay just turned up a lot of really weak and benign versions that, while cheap were woeful on the power front. Outlook = bleak.
I was at a model engineering exhibition up at ally pally in mid January, I'd crashed at Ellis's with his family who are super super nice people, me and him spent the day wandering around poking interesting tools (I accidentally bought a lathe).
After a while we found this. Thank you robot Jesus!
These looked very weird/interesting indeed. They had a very high speed and theoretically not much power. However they were very nicely made. Close inspection and twiddling of shafts (#moulds) revealed that these had very thick windings and fairly strong magnets.
£4 each or 3 for a tenner, I wasn't going to say no so I got 6 of the buggers. I kind of wish I'd got more but I was already lugging about 35lb worth of crap around at that point and was running low on funds.
Mmmm perdy motors. Same mounting pattern, m3 25mm spaced, same 3.17mm shaft. Just a tad longer than a normal 550
Flux rings on the motors are really thick, which is probably a good sign. They do seem nicely made
Bae motor got a booty. Yeah the endcaps of these motors are a little different. Some kind of dull cast metal. Heavy duty. Brush housings look standard and the taps are very thick.
Now for the more interesting bit. I took some measurements of power, sadly no rpm measurement more accurate than eyes and ears.
The spec sheet (i.e. bit of card taped above the bucket of motors) stated 26000rpm and 2a @12v Normal 550s are close to 20000rpm at their nominal voltage which suggests these aren't 12v native. Using a bit of basic mental maths you can see they run 20800rpm @ 9.6v. That's more like it. Asking the bloke on the stall clarified these were 9.6v motors and that they did in fact come out of drills, cool!
I did some testing of my own. If it was true and the motors were going to run 24w no load then that would be very much on the low end but I'd see what they pushed when stalled. Run through a gearbox on 4s lipo they pushed 75-80w just idling, that jumped up to 90w when the gearbox was stalled by hand. Thats more than powerful enough for my needs. £20 of motors well spent, and I have spares, it's like christmas in February!
Wheelwise I went for a stock solution. No real reason aside from cooler looks and an easier thing to carry spares for. I would have had to mangle my wheels from previous years to use them again. I'd rather keep them useable and try something new.
I went for 2.5" colson caster wheels from Robot Marketplace Getting 60mm ish wheels is a pain in the arse and getting them the right shore for combat is more painful than getting kicked in the face by a powerful horse. Colsons seem good. Americans do robot combat hardcore like, and if they are good enough for them I'm more than happy with them
I got a load of these, so hopefully I should be okay throughout the competition. I will have to machine the wheels to take a hub that will mate with the shaft. They come with a plastic bushing as stock which will removed before I use them
Weapon
As was made painfully clear last year, the bar simply wasn't up to it and the tensioning system was frankly piss poor. To fix this I plan to be less of an idiot.
Oh, and also titanium. The large piece of titanium was given by Dave Moulds, the smaller round is 7075 aluminum for use as standoffs. More on this and its Toolox teeth as they happen.
The ti should be much better at dealing with the forces from combat and its lightness allows me to strengthen it. Overall the bar assembly is about a kilo heavier than last year.
Power comes from the same motor as last year. Running a lower voltage but should still be pushing about 2kw of power. Same style of right angle gearbox, then a pulley reduction. Fast motor and large reduction should cut spin up time for a minimum.
This is just a post to get the ball rolling as it were, more stuff and more pictures will follow when shit actually gets done. When the chips are flying the camera will be snapping.
Some of you may remember eggbeater. It is a comically large beetleweight with an equally obese weapon. 500g of hurty titanium. Going ZOMG MASSIVE WEAPON is abhorrently newbie, but in fairness I was incredibly newbie when I gave the dimensions when it was made about a year ago. It featured a much nicer rebuild in February. Still a long way away from good but it slightly functioned and it actually was able to drive.
I broke the previous version down into what sucked and what didn't. The overall concept was fairly solid, the execution, material and basically everything else was rubbish. Stronger, smaller and more sensible was the goal for the new version.
While hanging out with Ellis we went to his material stockist and I accidentally a half meter length of 80*10mm aluminium flat bar. It seemed like a good idea at the time okay? I started this robot by lopping off a hunk, carving it up and bumming holes in it.
After drilling the pilot hole out to 12mm (largest drill I currently own) I stuck the boring head in and began trying to make bearing pockets. Normally my holes are painfully oversize by about 2 thou or so.
Not this time though. The fit was great. Still getting used to the boring head but both the bearings plopped into place nicely.
Finished bulkhead. Came out very nicely. I decided to quit while I was ahead and finished up for the day. The next day I began by doing the marking out same as the first one, then more holes + boring and doing all the curves and milling work. It came out much better the second time. I changed the cutter from a fairly blunt 3/8" to a sharpened 10mm. Finish was worlds better. Lesson learned.
A little tool doink happened on this part sadly, and the finish was ropey until I changed cutters. But you can see the difference in the last picture. Left hand side was with the new cutter.
The bulkheads then got slotted to fit the 5mm aluminium flat bar that made up some of the frame. Bit overkill I spouse, but that's about the thinnest that can hold a semi decent thread and with the beater spinning to self destructing RPM I would like a substantial metal plate between it and the lipos.
Also at this point I had a Hobbyking order come. Spare brushless ESC's in case of death by cheapness/abuse/hella current draw as well as some small servos and a couple of these.
Daww well isn't this a little cutie. 3800kv and 4s makes this a total beast. Fast motor + high reduction seems to be my choice for weapons. Hope it works okay without exploding itself or detonating my escs. Only bad points so far about this motor are the stepped shaft (booooooo) and the fact it has M2 and M3 mounts. Y u no all M3??
Ellis was a proper lad and machined my dual groove pulleys for eggbeater. They have a 4mm rounded groove instead of a V or a flat which means they grip like buggery and hopefully won't need extreme tensioning.
Worth every penny. All dimensions correct to .02 at least.
To engage on the beater, the boss of the larger pulley was to have a 17mm wide slot milled in it in order to engage with the 17mm flat portion of the beater. This was so much more reliable than setscrews or anything else I could really do.
Machinists/anybody halfway competent avert your eyes. Dodgy machine set-ups are my speciality.
It worked though, so I'm not complaining. It was a pressfit on the beater in the end. Not so extreme it can never come off but it would need a fair amount of persuasion in order to do so.
Putting the set screw into the smaller pinion pulley (NFI what the correct term is) Admire Ellis's amazing grooves while you're here. The screw is large in comparison to the shaft to aid in making setscrews not suck. Should be enough to work at this level. They never entirely unsuck though.
Around this point the belting material arrived for the drive and weapon system. I quickly and I mean real quickly jammed together some belts and dug out the dual ESC for the drive. I had some massive problems with it to start with. One motor would just jitter like hell and cut everything out. At first I though it could be because I was using a DX3R transmitter for the first time over my DX5e. After a bit of head scratching I isolated one of the motors as being at fault. The brushes were totally cattled causing the jittering and were shorting out causing the emergency shut downs. Changed motor and everything was fine!
Ignore the bobbing. It just does that on the paving slabs. Flat surfaces it is fine on. I will try and magnets on the back anyway for more weight on the motors.
I ran it hard after that. Just to see what would break and if it could survive itself. I'm not overly sure on time but I had this on in the background and it took me the first two and a half songs to get it trimmed and mixed okay, so maybe 30 mins or so?
What happened:
Shit broke. Clumsily-welded-with-hope and a lighter belts failed. As expected truth told. Will make a proper welding jig for them out of nylon or HDPE or something me thinks. The other one held great I will be keeping that as a spare or cutting and rejoining properly.
Also everything got hella hella hot. Like Emma Watson levels of hotness. Within about 5 minutes the sabertooth was too hot to touch (but somehow kept functioning fine) and the drive motors were baking. I initially put it down to stupid robot design, the motors having to lug a huge weight around with a mechanical disadvantage. It all became clear when the belts came off. The motors were turning without the belt, but the tension was so high with the belts on it was stalling the motors out. I'd tried to trim them a little bit to get the robot to go straighter. No wonder everything was toasty with an almost constant stall. Sorted this then all was well and robot was happy again.
Start of a new day and I had a chance to have a closer look at the parts that came the day before (I was rushing out the door to work when the post came) Silversteel shafting, bolts of various flavours, and a sheet of carbon fibre. You can see Fakdisc relaxing there too with its shiny new bolts fitted.
Popped my motor apart to get shot of the shitshaft and replace it with a custom length of silversteel. This eliminates the stepped down to 3.175mm nonsense and it stops the MASSIVE STRESS RISER circlip grove from being a problem
Rough cut to length then I faced off the ends. It was less of a bitch to turn than thought/remember. I had some work to do in silversteel back in college and I remember it being a huge pain in the hole. It went totally fine now.
Booped the motor back together with the new shaft. I was expecting it to be a bearing fit out of the box but NOPE chuck testa. Probably because shonky bearings in the motor. Big, small, cheap, expensive, happy, sad I have yet to have a brushless with bearings I would qualify as *good* But yeah. Took the shaft down to size so its a nice fit. Span the motor and it ran beautifully. Sweet.
Began marking out/cutting the carbon fibre. I had planned to do this with an angle grinder but my neighbours were having a barbecue (slightly in the rain) and spraying people who don't complain about late night/very early morning drilling are people you don't want to spray in the face with toxic CF and epoxy dust. Did it by hand with a hacksaw with a fine toothed blade. Went well but a tad wonky. Nothing some sanding can't fix. Because of the wonk I made this piece the base plate. I just Pretend-O'd it on as the lid to see how it looked.
Tapping the mounting holes (M3) into the bulkheads.
Hello scrap of 3mm aluminium. Your destiny is to become a motor mount. Prepare to be milled and Swiss cheesed full of holes.
Excuse the horrible screws. I didn't have any hex countersunk M3 in the right length. I didn't bother with the set of M2 screws because I flat out didn't have any. With loctite these should be enough.
Mounted to the bulkhead with some lovely standoffs from Ellis. Pulley is also attached. Still all spins good. The motor goes like a mad bugger and pumps out a tonne of air. Hopefully that will help with some of the heat in the robot.
Made the rear armour. No pictures of the process as it wasn't that interesting (not like that has stopped me before) but it was just booping 8 holes with the hole-booper and a bit of tapping. The piece is 6mm HDPE.
Internally its pretty spacious. Like, not just room to swing a few cats but the owners of said cats and their significant others too. No excuses for not having neater wiring now. A bit of wiring later and I had stuff ready to go for a spin test this time. Round one:
Result: Disappointing IMO. Naffy belt joins failed again (one did, the other stayed solid) but it span on one belt which is good. Dat flap tho. One thing I stupidly failed to account for was the heat caused by friction in the system to soften the already softer belts causing them to stretch. Like.. really bad, it went from Tyrion Lannister to Michael Jordan.
Bad points:
-belts got warm (unsurprisingly) so stretched. This is why its flapping around in the video
-I'm loosing a several thousand RPM somewhere, probably because of belt tension but very annoying all the same. Hope I can fix that.
-One belt snapped on spin down of the first time. But as the second one was fine throughout all the testing can put it down to dodgy joints.
-30a ESC hella hot so switched to the HK own brand £7 lumptroller. Heavier but it didn't miss a beat.
Good points:
-Nothing exploded
-It span with no tension and one belt
-Motor makes noise to scare opponents
-£7 ESC actually worked.
-Batteries were not hot to the touch
About dat motor noise. The motor is srsly over revving
Belting saw a change for the better and all parts of the weapon system got a bit more attention lavished on it and it was time for round 2.
It sounds better. It feels a lot nicer. I think physics has something to say about the theoretical max speed and air resistance combined with the motor power means I highly doubt it will ever get there.
It then got left alone for a few days because I got asked to do some extra days at work.
Not the neatest wiring job ever, far from it but it works and everything does what it's supposed to.
Cut out the lid from more 2mm carbon fibre and sanded down the edges. A slot for the belts was also cut out.
I had some problems with bearings moving outwards on hits or after extended running. Dave Moulds suggested making some washers that bolt to the beater itself and hold the bearings captive. I got a sheet of .08" brass out.
Many bloody hours later.
Horrorshow. Should be grand. One side is a much better fit, the problem only occurred on one side so for reasons of weight (and that this part was a pain in the arse to machine) I may end up with just one.
Wheel armour. Well "armour" it's 2mm hdpe. It will be bouncy and flexy and stop instant belt death but I'm not going to kid myself into thinking it will be any good. It changed from the CAD because weight reasons. Still. It's mostly accurate.
This is kind of it before the competition. I'm fully expecting it to get totally rekd if it has to fight anything more deadly than a small paper cube. Event rundown coming soon.
