One of the things we really wanted in both Intrusive Interloper 2.0 and Steel Stiletto for the Franklin Cup competition was a working gyro to help with the driveablility of both 'bots, but after playing with them during the build process, we just couldn't get them working, so we left them out. This morning we spent a fair bit of time Googling "how to use a gyro in a RC car" and found quite a bit of information on how to mount and use a gyro, so we decided to test our cheapie gyros again. Hit Back after viewing an image.
Here you can clearly see the gyro, temporarily mounted to the baseplate with some electrical tape. The key thing we had done wrong in our earlier attempts was to install the gyro in the wrong orientation! Typically there is a line on the gyro showing you which way should be forward, but this one doesn't have one, and we had been assuming the gyro should be lined up with the cables running front-to-back, but in fact it should have been side-to-side. With the gyro in and powered up, and the 'bot up off its wheels, when we wiggle the 'bot the motors did indeed fire up, and attempt to resist the movement - score!
We wanted to try the 'bot actually running around, but because the wheels had worn down so badly at the Franklin Cup, we didn't have enough clearance from the mashed up corners where Tetanus had chewed on us in the featherweight finals. To fix this we decided to rotate the rear wall so the gouged corners were on top, and spent some time disassembling the 'bot. The fact that both lower bolts were also mashed up meant we had to take the entire chassis apart to be able to snap off the side walls and bolts, then extract the remainder of the bolt.
In order to get the 'bot to stop wiggling, we had to change the end points on the third channel (gyro gain) from 100%-100% to 15%-7%, as suggested by some of the posts we had read on R/C forums, and eventually the 'bot ran well in normal mode. When we flicked the switch to heading hold mode, however, the 'bot would keep going nuts, so we decided that normal mode would suit us just fine, and in the test driving we did, it actually ran remarkably straight, especially condsidering the mis-matched wheel sizes from where some had worn down more than others. We're happy! :-)
Having gotten the 30lb'er working, we wanted to see if we could get the 12lb pushy-bot working too, but again we had work to do. This is the state the 'bot was in after Franklin - you can see the snapped inner rail, and one side of the drive train wouldn't turn.
Here's the offending motor. Nothing looked obviously wrong, so we were a bit nervous that maybe we'd broken a gear in the gearbox, which would be quite a problem, as we don't know where the gears originally came from, so we wouldn't be able to replace them.
Thankfully we found it was the $5 motor that was damaged. The brushes had popped out and jammed the motor up, presumably following the hit from Fiasco that snapped the inner rail. Fortunately we have quite a large stock of these motors, and it took no time to pop the pinion gear off, press it onto a new motor, and solder leads on.
As the current version of Steel Stiletto's chassis is broken, and we had no spares, we pulled out the old chassis, and began reinstalling components into it. The only internal difference between now and the last time we used this chassis is the swap on the drive speed controllers from Victor 883s to 25A BotBitz-hacked brushless controllers, and they fitted nicely.
After repairing the broken drive chain, we hooked up all the internals, installed a gyro with some double-sided foam tape, and prepared for a test drive, having pre-configured the model settings in the radio with the same settings that worked for us with Intrusive Interloper 2.0.
Aaaaand ... nothing. We had charged the batteries already, but there was no power light on the receiver. After dinking around a bit, and re-watching videos from our Franklin Cup event report, we came to the conclusion that one of the speed controllers must have blown (remember the jammed motor above), but we didn't know what was up with the other one. Guess we're going to be doing an autopsy later this week ...
Tags: build, ii2, ss, equipment
We need to stuff a bunch of things into cases and head to the airport, but before we do that, here's a quick shot of the fleet for Franklin. Hit Back after viewing an image.
Here's the fleet as it stands right now (clockwise-ish from the top: Formidable Fustigator 2.0 - 30lb Featherweight, Malicious Mule - 1lb Antweight, Steel Stiletto - 12lb Hobbyweight, Nihilistic Naysayer 2.5 - 12lb Hobbyweight, and Belligerent Battler 1.0 - 3lb Beetleweight in the middle.
Tags: Franklin, done, ii2, nn2, ss, mm, bb1
Okay - we need to "Make it work!" as Tim Gunn would say. On the agenda for today, we want to get Intrusive Interloper 2.0 running reliably; get Steel Stiletto running reliably; try to finish Malicious Mule; and try to finish Belligerent Battler 0.9. Sounds like a lot to do, so we'd better get started! Hit Back after viewing an image.
Having picked up some Y-cables from the local hobby store we set about re-wiring Intrusive Interloper 2.0 with four Victor 883 speed controllers, one per DeWalt. The wiring was a [messy] piece of cake, but it turns out two of the Victors were bad. Here we're swapping in spares.
Argh! Of our two spare Victors, one of those was also bad, so now we're in a bind. We have three of the four motors hooked up, and one lame duck.
Ouch - $600 of blown electronics sitting right there. We were stumped. We scoured all our parts bins, and even tried wiring in one of the hacked TZ85As, but that didn't work either. We weren't convinced we could get a speed controller in time even if we ordered one. This was not a pleasant feeling.
Suddenly inspiration struck - and we pulled out the pile o' parts for the Sportsman we began building for Motorama 2012, and struck gold! There was a Victor 883 mounted to the baseplate! Fingers crossed it works ...
And it did! Hurrah! We now have Intrusive Interloper 2.0 running like a champ. Shame we never got the gyro to work properly, but no matter, we actually feel like we have a 'bot that's working properly. Even if we accomplish nothing else between now and next weekend we have a featherweight and a hobbyweight - more than enough reason to fly to Philly :-)
Steel Stiletto is working fairly well on the new battery pack, but certainly has some control issues, predominantly due to the kludged-together drive train. With a bit more time we'd re-make the hubs for the wheels, but for now we're going to just try 'breaking them in' and see if we can get the 'bot to be a little more controllable. Again, another instance where having a working gyro would be useful, but oh well.
Moving on, we go from the largest 'bot to the smallest: Malicious Mule. Here we've pressed bushings into the outer rails, and we're about to fix the wheels to the axles.
A quick weight check shows that there's no worries in terms of weight - the scale reads 14.6 ounces, so we don't have to sweat that aspect of the 'bot - we just need to finish assembling it.
Here we've bored the wheel hubs out to a quarter inch and pressed in aluminium spacers which will be our axles. The hubs will be pinned to the spacers, and the spacers have been drilled and tapped for a screw to hold them to the Pololu motor shafts.
Here we have the first two axle/hub combos installed. We currently only have three of the four wheels we need for the 'bot, and we're waiting on the Robot Marketplace to make good on the last one. Hopefully the wheel will show up before we get on a plane on Friday ...
All in all we're in pretty good shape with this antweight. All we need to do is tame the wiring and put the fourth wheel on. We did take it for a quick test drive, and the speed is markedly improved over the previous version!
That's practically three 'bots running, so let's go for a fourth. Here's our To Do list for the beetleweight Beligerent Battler 0.9, and although it seems like a fair bit, there's not really that much to do, so we hop to it!
Here's a pair of top and bottom plates quickly cut out on the table saw. We're going to use the jigsaw to cut the wheel holes, give them a lick of paint, and then we can install them.
We've also trimmed down the front wall to allow the timing belts to pass from the weapon motors to the beater. We basically cut 3/8" off each end and installed spacers. We've also installed the weapon motor mounts.
As it's getting late we want to get all the noisy work out of the way quickly, lest we incur the wrath of the HOA, so we quickly cut and sand the wheel holes in the top and bottom plates.
We ground a flat on the weapon motor shafts, and installed the timing pulleys with screws and a dab of Loctite. Hopefully they'll spin - we're not worried about them coming off, because there's nowhere for them to go in the 'bot, it's more making sure they stay engaged on the motors.
And here they are installed! We're contemplating milling a shallow pocket in the side walls, as the pulleys do rub a tiny bit, but we'll see how it goes when we hook everything up and give the weapon a test run.
Here we've installed the baseplate, and right now we'd have to say things are looking pretty good! We're not going to get this 'bot finished tonight, but hopefully tomorrow evening we can do the wiring, and barring any major issues, ought to be able to wrap up the three-pounder tomorrow.
So then the decision will be what do we do next? Both the antweight Persistent Pugilist 0.9 and hobbyweight Nihilistic Naysayer 2.0 have a bunch of work to be done to get them ready. We're thinking we forego the antweight and concentrate on the 12lb'er, because that weight class at Franklin only has five entrants, which could help our chances of winning something, versus the dozen or so antweight entries. Sounds like a plan!
Tags: build, bb1, beetleweight, antweight, mm, featherweight, ii2
We got a late start today, having to spend the morning and first part of the afternoon sorting out a client, but we quickly got into the swing of it, desperately wanting to get at least one "Presenting" post out today, as we're short four working 'bots with exactly one week to go. Hit Back after viewing an image.
After running the 'bot with the second new 9.9V A123 battery pack we're happy with the current state of the rebuilt Steel Stiletto, so we're going to call this 'bot done! Presenting the rebuilt Steel Stiletto!
Moving on, we're done with the re-wire of our 30-pounder Intrusive Interloper 2.0, having wired in four Victor 883s but we're short a couple of Y-cables for the drive ESCs, so we can't test-drive this configuration just yet - we've made a note to hit our local hobby shop tomorrow so we can scratch this 'bot off the list.
It's not stretching the truth to say we had some "issues" tapping the 1/4" 6061 aluminium rails for Malicious Mule, so here's a fresh set from Team Whyachi which have been drilled and tapped without incident, ready for a fresh coat of paint and installation.
Here we've begun assembly for Malicious Mule, with the 10:1 HP Pololu drive motors mounted to the inner rails, and the base plate attached so we can start looking at the internal components.
Here's a test layout for the battery pack, receiver, and gyro, for the 'bot Malicious Mule. Two things strike us imediately after taking this photo:
1) There's not as much space inside this 'bot as our CAD suggested; and
2)We've had zero luck thus far in the build season for gyros, so we're not expecting this to go well.
It's very rare that we feel good about soldering something, but we think we did a pretty good job putting leads on the 10:1 HP Pololu motors, and so the next task is to connect the ESCs.
To reiterate: our soldering skils are not that good. It took over an hour to go from the previous photo of leads on motors to this pic of motors connected to speed controllers, but eventually we got there.
The final challenge of the night we wanted to take on, was getting the receiver to bind with the radio. We plugged things in, unpluged them, plugged half of them in, and eventually got the receiver to bind. Next was calibratintg the ESCs, which also took a while, including swaping the V-tail mixer. But finally we had it done. Tomorrow all we have to do is sort out the drive axles, and we have another "Presenting"' post on our hands, assuming we don't try to use the gyro ...
Tags: build, hobbyweight, ss, featherweight, ii2, antweight, mm
This time next week we'll be in Philadelphia, but as things stand right now we'll be there mainly as spectators to the Franklin Cup. We have two 'bots that are running, but with issues, and the other four are still piles of parts. We don't usually build on Friday nights, preferring to relax from the week, but we don't have that luxury tonight. We're going to do what we can to get Steel Stiletto underweight, and exorcise the gremlins from Intrusive Interloper 2.0. Hit Back after viewing an image.
Earlier today we took a lunch trip over to see Chris, and throw some parts on the lathe. Chris mentioned he hasn't used it since the last time we were here, which was before Motorama 2012, so it was in exactly the same state as when we left.
We wanted to core the drive axles for Steel Stiletto to save some weight after realizing that the original axles were aluminium, and we had replaced them with steel. We calaculated that a quarter-inch bore would save about an ounce, which helps.
Meanwhile, back at the Hall of Justice ...
First on the To Do list is figuring out why the featherweight drives so poorly. We disassembled the drive train, and found a DeWalt that had siezed up. Not sure if it's the motor or the gearbox, but we swapped it out, and everything seemed to spin nicely.
We hunted around a bit, and found four Victor 883 ESCs that seemed to be in good shape, so if the 'bot is still acting wierd with the replacement motor, we're going to see if we can swap in these in place of the hacked ESCs.
With the 'bot mostly reassembled we took it for another test run, and although all the motors now drive nicely, power to them does cut out from time to time, and the gyro is not working at all.
As things currently stand, we're at 29.2lb, so we do have a little leeway to be able to fiddle with the internals.
Taking a short break from the 30lb-er, here's a test assembly of the beetleweight chassis, with the drive train installed. It doesn't look perfectly square, but no matter, the wheels turn, and that's really what counts.
We trimmed the drive axles on Steel Stiletto in addition to coring them, and our efforts have paid off. The scale reads 11.8lb! Success ... now we have to re-wire a little bit to fit the new 3S A123 pack.
We switched the #6-32 nuts and bolts for the ring terminals to #4-40, and shortened the wires as much as we possibly could. After neatening up the wiring, everything fits nicely, so we took the 'bot for a quick test run.
We had an audience - normally critters are not permitted in the Build Space, but this guy was cute, and kept following us around the worktable, so he got to stay and watch.
Well ... that didn't go so well - one side of the drive train bound on a screw that had come out from one of the broken motor supports, which caused the battery pack to overheat. Hopefully the pack is okay - we'll try putting it on the charger and see if it's still juice-able.
After a decent test run for Steel Stiletto (barring the screw-chain-battery issue) we turned our attention to the thirty-pounder. After a couple more test runs, we decided to eliminate the gyro - we tried two of them, and they both caused the 'bot to act squirrelly, so we've decided to ditch them. We've also decided that the ESCs we hacked are not up to snuff - they keep shutting down - so we're going to switch in some trusty Victor 883s and see if that makes the 'bot more reliable.
With the four Victors in place of the two TZ85As the scale reads 29.4lb, so we can keep the four packs in the 'bot, and hopefully get it running smoothly tomorrow. It's getting late, and although we've put in a good few hours of work, it's time to wrap up for the night, in anticipation of a big build weekend - our last before Franklin - to determine just how many of the 'bots will be up and running for the event.
Tags: build, beetleweight, bb1, featherweight, ii2, hobbyweight, ss
Turns out we have a few hours to build tonight, so we're going to capitalize on that time and see what we can cross off the To Do lists. We want to troubleshoot the featherweight, and hopefully get some assembly done on the beetle too. Hit Back after viewing an image.
The last time we ran Intrusive Interloper 2.0 it was pretty screwy, so we've popped the top to try and find out what's going on. First thing we tried was eliminating the gyro, but we still had issues. The 'bot would simply cut out after a few seconds of driving, then come back to life sputtering, and cut out again. We were wondering whether we weren't giving it enough juice with four motors and just one battery, so we put another pair on the chargers and turned our attention to the beetleweight while they charged up.
Here we've milled some slots in the side walls of Belligerent Battler 0.9, and are trying a test-fit of the front and rear walls. So far so good, but the right wall's slot was slightly off, which warps the frame a little bit. Hopefully when we put the top and bottom plates on they will help to re-align the chassis.
Here we've drilled the weapon shaft holes out to 31/64" and pressed in a pair of bearings. After judiciously applying a file to the ends of the weapon shaft, the beater fits nicely and spins freely - bonus!
Here's a quick test layout of the internals. We have a pair of weapon motors up front, along with a battery and receiver. Next in line are the two weapon ESCs and power switch, lastly we have the two drive motors, motor mounts, wheels, and drive ESCs. Hopefully by the end of Wednesday night we have the whole chassis assembled and we can be dealing with installing these components.
With the extra battery packs charged up, we installed them into Intrusive Interloper 2.0, but still the 'bot was acting squirrelly. At this point we have four possible suspects: the receiver, the V-tail mixer, the hacked ESCs, or the DeWalt motors themselves. Frankly, the ESCs and the motors are the most likely suspects - the ESCs because they're an unknown commodity, and the motors because they've been around the block quite a few times. According to the Tentacle Calculator, each ESC should be pulling up to 20A to spin the wheels. These ESCs are supposed to be able to handle 85A continuously, but of course they were hacked with our own dodgy soldering skills, so that could be the culprit. The motors have been in various 'bots through their lifespan, so maybe the brushes are starting to give out. We'll start eliminating components the next time we work on the 'bot ...
Tags: beetleweight, featherweight, build, ii2, bb1
We've resolved today to finish a 'bot. We have today, one more weekend, and up to seven evenings between now and NERC's Franklin Cup, and at the moment we only have one finished 'bot, so we need to hustle! Today's focus will be on the hobbyweight Steel Stiletto. Hit Back after viewing an image.
First from the To Do list: cutting, drilling, and counter-sinking the top and bottom plates, from eighth-inch polycarbonate. We had originally planned on using 6061 aluminium, but don't have any to hand, so hey! Weight savings.
After Motorama back in February Steel Stiletto was limping a bit. We don't know whether this was due to a blown motor or speed controller, but as we've switched the Victors to hacked brushless TZ85A controllers, and we have literally a dozen spare motors, we decided to swap in fresh motors too. We've done this a few times, and we're fairly proficient with the gear puller at this point.
Next step is to solder on new leads to the motors - again, we've done this a few times, so we've gotten the hang of it. Still not pretty, but functional.
At last we can begin assembling the 'bot! First to go in are the motors and their supports. We've also installed the power switch. We left the motor leads long, as we want to cut them to the exact length once we get the speed controllers in place.
After the motors are installed, we put the rear wall on, with the aid of a rubber mallet, and installed the baseplate (currently unpainted) so we could throw some internals in there. We're quietly pleased at being able to put all ten screws in the baseplate!
The first speed controller is installed. We're using ring terminals for the connections, to make it easy to swap spares, should we buy any. The ESC fits just perfectly between the rear wall and the motor.
And the second speed controller is installed also. As we moved on to the drive train, this is where we hit today's snag - can you spot it from the photo?
The geometry of the 'bot is different from the previous versions, and so now the drive train doesn't fit, as it's designed for a wider 'bot - oops! We're going to have to brainstorm this, and see how we can adapt the components to make them fit the new, narrower 'bot.
So the plan is to switch the existing 3.5" diameter wheels for 3" wheels, as the larger ones are too big for the distance between the axle and the front/rear wall. We also need narrower wheels. We had a set of fresh 3" x 1.5" Colsons, but what would be the most efficient way of trimming them down to 1" wide? Answer: buy a new tool! :-) We picked up this little bandsaw from Home Despot, and it actually made short work of the Colsons right out of the box! Hurrah!
This is where we hit the next issue, which is that the bore on these Colsons is considerably larger than that on the previous ones, so the current hubs are not usable. This one had us stumped for a little while, until we remembered making Colson hubs quite some time ago for the Sportsman we almost took to Motorama 2012. We were pleased that the bandsaw was able to cut them down to size without too much hassle too.
So now we had a plan and some parts! This is actually the first time ever that we've needed to disassemble the wheels/hubs/axles from what, a long time ago, was Team Cosmos's Neutrino. Ted was pretty ingenious in how he made these - the sprockets had been lathed down and pinned to the shaft, becoming part of the hubs, with some aluminium round on the drive axles, whereas the driven axles were turned from a whole piece of aluminium round, and the sprocket was pinned to it. Well, let's see how badly we can butcher these :-)
A lot of drilling and pinning later, and we have modified axles that will fit our new wheels! The sprocket has been pinned an eighth of an inch closer to the end, and the aluminium hub has been pinned for the other side of the wheel.
The tires were then pinned to the aluminium rounds, and hey presto! Drive axles! For the driven axles, we cut two lengths of half-inch keyed round, pinned the sprocket and hub to it, and then again pinned the tire to the aluminium hub, and finally we had a drive train that fit the 'bot!
Phew! With a usable drive train once again, we went back to wiring the 'bot up, connecting speed controllers, power switch, and battery packs. This was relatively painless, and spirits were rising!
We needed to trim down the custom "Nut Strip" we were using to attach the titanium side rails, and the bandsaw protested too much - remember it hasn't been tuned - so we went old-school, managing to break one hacksaw blade while cutting these parts down, but we made it eventually, and after a quick run on the belt sander we were ready for the last phase of assembly.
Ta-daa! With the inclusion of a receiver (no gyro yet) we were about ready to take the 'bot for a test drive!
Well. That was exciting! And it's an excellent demonstration both of why wire comes in different thicknesses, and why the Franklin Institute wants LiFePO4 batteries in larger 'bots! The piddly wires on these packs could not carry the current the mini-EVs were drawing, which meant they heated up, burned off the plastic covering, and shorted. If these had been regular Lithium Polymer batteries, they would have gone up in flames, wrecking the 'bot most likely. These packs didn't burn up, which is very neat. In hindsight, we shouldn't have even contemplated using these packs, but hey: they said they could put out 40 amps, and we're betting with thicker wires they'd be able to just fine.
We borrowed a couple of 2S packs from Nihilistic Naysayer 2.0 and swapped them in for another test run. We threw a ~15lb box of old parts on the ground, to see whether Steel Stiletto could push it around.
Not bad at all - plenty of power in those mini-EV motors, and the points on the titanium end rails sank straight into the box. That'll work. Now all we need to do is rethink the battery, and we'll be done with another 'bot.
So close to a "Presenting ..." post, but we can't in good faith say the 'bot is done, because we've got to go back to the drawing board for juice for it. There's not a lot of space inside the 'bot to cram 6S of LiFePO4 cells, so we're going to have to shop around for something that will fit.
Having run out of options for Steel Stiletto for tonight, but feeling good at having seen the rebuilt 'bot run, we decided to likewise take our recently completed featherweight Intrusive Interloper 2.0 for a test run too.
Crazy! The 'bot was uncontrollable, and figuring out what was going wrong was definitely a "three-pipe problem" but finally it dawned on us - the gyro inside the 'bot was plugged in to the throttle channel, not the steering channel - duh! With that realization, we decided it was time to call it a night. All in all, not a bad day's work!
Tags: build, hobbyweight, ss, featherweight, ii2
We're sooooo close to wrapping up our featherweight, so we're going to push on tonight and wrap this 'bot up. We only have a few things left on the To Do List, so let's see how we do. Hit Back after viewing an image.
Not a great picture, but this shoto was taken after we had finally bolted the wedge on to the front wall using ten #10-24 bolts and locknuts. It took a little time to get around the wheels and get those locknuts cranked down, but now that it's in place, it's pretty solid.
Internally we've neated up the R/C wiring with a few judiciously applied zip ties, and need to make three retainers - one for the gyro, which has been squared off against the side wall; one for the ESCs; and one for the batteries. Unfortunately we're out of appropriately-sized spacers, so we'll add them to the next McMaster shopping list and move on. We've also installed a power light, and drilled holes for the light and access to the power switch.
Ta-daa! Weighing in at 28.4lb (without the afore-mentioned retainers nor DeWalt strengtheners), we have a working featherweight: presenting Intrusive Interloper 2.0! The wheels look a little undersized, but the grip is pretty good (40A hardness versus 65A hardness), so we're happy.
Tags: build, done, featherweight, ii2
Hot on the heels of yesterday's efforts, we spent another long day in the Build Space, shooting to get as much fabrication done as possible for our six-'bot fleet for NERC's Franklin Cup. We made good progress yesterday, and was hoping to keep the momentum going today. Hit Back after viewing an image.
Lauren's getting in on the action, putting a revised colour scheme on her 'bots.
Steel Stiletto and Malicious Mule will be returning with more power, more driveability, and more armour. They did a good job breaking oponents weapons at NERC 2012 but you ain't seen nothin' yet! Note the hot pink colour scheme after comments by onlookers that pure pink looked like Mary Kay (barf).
First up for Toni this morning, some drilling and tapping. It doesn't take much time to have the front and rear walls reasy for a test fit for the antweight Persistent Pugilist 0.9.
And the another run, albeit with a slightly larger tap, to be able to put the chassis for beetleweight Belligerent Battler 0.9 together for a test fit. Both 'bots have some slotting needing doing on Milly, but one thing at a time.
Speaking of Milly, we ran and endmill down the UHMW tube that will be the antweight's drum, and were able to put two pieces of 1/4" keystock in the channels without a lot of effort, so that works.
On the other hand, after drilling and tapping the keystock for the #6-32 botls that will pass through the drum and attach the two teeth to each other, this was a pain in the behind! Despite the effort, it came together well, and we're pretty pleased with how the drum is shaping up!
We next turned our attention to our thirty-pounder and, having finished the wiring harness, decided to power it up, and figure out the R/C wiring. After a minute or so of running, the drive motors were faltering, and things did not sound right. The photo didn't capture it, but this drive motor was smoking slightly, and you'll see in the photo that the two LiFePO4 battery packs are in series - they weren't when we first started working, so there's a pretty good chance that in addition to replacing the back two motors - neither of which were working - we're going to have to ditch these battery packs too - darn!
After some time and effort the two rear motors were switched out, and we fired up the 'bot again. This time three of the four motors sounded fine, with the fourth not spinning at low speeds. As all four were showing some signs of life, we decided to figure out what was connected where. We're not doing transmitter-side mixing, as we have a gyro in the 'bot, and it took a little time to determine which receiver port was steering, which was throttle, and which channels to reverse on the transmitter, but eventually we had everything plugged in properly.
We also decided to play a bit with the gyro. Here it is plugged in, and of course it pretty much went nuts, as we would send the 'bot a turn command, and it wouldn't turn as it had no wheels, so the gyro sent the motors into overdrive. On the plus side, we know which way to flip the third channel switch on the transmitter to disable it :-)
Time for a weight check, and something's not quite right here. We've switched from 1/4"-20 bolts for the front wedge to #10-24, yet the scale is suddenly showing a full 30lb! Eek! We decide to ignore it for now, and soldier on, hoping it was an abberation.
Here we've trimmed the drive axles to length with the Dremel-ish, and cleaned the ends up with the belt sander, so we're pleased to see them fit right in to the bearing we had so much trouble with in the past.
Here we're figuring out where the wheels need to be pinned to the shafts. We've put 1/2" bushings between the wheels and the inner rails, and that seems to leave them in the right spot, so we can go from here to actually pinning them.
We've kept it simple, and put a 1.5" long 1/8" roll pin through the shaft into the wheel. Fingers crossed the wheels survive at least a couple of matches, because these pins are going to be bears to get out if we need to replace them, but these wheels don't have a lot of surface area to play with.
Here's a quick shot following the first test run! The 'bot went bezerk, running into a shelving unit in the 'build space, but we suspect that was something gyro-related. Otherwise the 'bot is pretty zippy, and we need to seriously dial down the turning so it's not so extreme.
To wrap up for the night, we decided to check the scale one more time. As you can see, the scale is saying 31lb 5.4oz, which doesn't make any sense, as we've cut parts, not added them, and it was underweight the last time we played with the 'bot.
Frankly, we're suspecting the scale, so we break out the 150lb-capacity Pelouze, and sanity is restored: 28.4lb. It doesn't have the resolution the 40lb scale has, but we trust it. When all is said and done, we can always to hit the mailroom scale at work, and see which one is right.
Wrapping up for the night, we reflect it's been a very productive weekend. Hopefully we'll have our first "Presenting ..."" post for a Franklin-bound 'bot, and we're planning on making at least as much progress again during the week, leading up to another major build weekend next weekend!
Tags: build, antweight, beetleweight, featherweight, ii2, ss, mm, bb1, pepu1
We're another weekend closer to NERC's Franklin Cup competition! We have flights, hotel, and car, but at the moment we don't have any 'bots ... so we'd better keep working! Today more to do on our featherweight Intrusive Interloper 2.0, including figuring out how to get Milly to produce a circular circle. Hit Back after viewing an image.
The first task today is to extract the bearing that wouldn't spin after being pressed into Milly's last attempt at pocketing a circular hole. The bearing definitely put up a fight, as we tried screwdrivers, hammers, and pliers to extract the darn thing.
Finally it came out - pretty mangled - and this is what we were left with. We decided to give Milly another shot at the pocket, and also to take a few thousandths of an inch off the surface to try and neaten it up so the bearing flange would be able to lay flat.
Ouch!! Turns out when Intrusive Interloper 2.0 is standing on end with end walls removed, the inner rails are at exactly the right height to hit you bang in the center of the kneecap! There was much swearing and cursing before things calmed down enough to go find some wound cleanser and the camera.
After a lot of trial and error, we finally came up with a way to get Milly to make a circular pocket we could use, and ta-daa! One side of the outer wall is done. Two more bearing holes to go, and we can think about maybe a lick of paint and getting on with some assembly.
After finishing the outer walls, we needed to enlarge the axle hole in the inner walls, and as we don't have a 5/8" drill bit, we handed this task over to Milly too. We didn't care so much whether this hole was perfectly round or not, as long as there was sufficient clearance for the axle shaft.
While Milly was working on one inner rail, we took the other and drilled and tapped mounting holes for the Whyachi power switch. By the time we were done tapping, Milly was done with the first rail, so we fed her this one.
At this point, we were almost done with fabrication! So to celebrate we broke out the primer, and coated the 6061 rails, in anticipation of putting on top coats later in the afternoon.
While the paint was drying, we began the final assembly. The DeWalts have power leads that are basically the two ends of 6' lengths of silicone-coated flexible wire. We're taking this approach as we don't want to waste wire, but we don't know how much we need, so as we begin wiring we can cut the leads to the appropriate length.
We also tried out all the axles, to ensure there was sufficient clearance, and there is. We do still need to cut the axles to length and pin the wheels to the axles, but we don't have enough Dremel-ish discs for cutting steel, so that will have to wait for the next build session.
Meanwhile, the front and rear rails have dried, so with the help of a rubber mallet we get those reassembled.
Here's where we're at, as the evening dwindles away - we can begin installing some of the internals!
First up, we put the power switch in, then started deciding where to mount the speed controllers. We're initially going to mount them with double-sided foam tape, and once we know how much weight we have left over once the 'bot is totally assembled, we can make some retainers to bolt in.
With the ESCs stuck down we can now begin hooking up the ring terminals on the outputs to the drive motors. We're keeping the leads as short as possible, not just to save weight, but to keep the layout very simple too.
With the motors done, we make a start on putting in the wiring harness for the batteries. They, too, will need some kind of retainer fabricated once we know how much weight there is to play with. It's getting late, though, and it's a school night, so we're going to wrap it up for now and see if we can't get this 'bot driving around by next weekend!
Tags: build, featherweight, ii2, mill
We went on a little bit of a spending spree at the end of last week, thanks to a bit of a bonus at work, and ordered a whole slew of parts for various 'bots we're taking to NERC's Franklin Cup in a month. While we wait for those parts to be delivered, we spent some time this weekend reorganizing the Build Space, and also got some more work done on the featherweight Intrusive Interloper 2.0. Hit Back after viewing an image.
First up, having already received a USB AVR programming controller from Pololu - speedy shipping! - we decided to take another stab at flashing our TZ85A brushless controllers, turning them into brushed controllers. Here's where we left them last time, and one of the leads needs to be resoldered before we can get going.
After inspecting the Pololu board, we found one mistake right off the bat - we had mixed up the MISO and MOSI leads, so we decided to cut off the 10-pin cable, and attach the ends from the 6-pin cable that came with the Pololu programmer. Our poor soldering skills notwithstanding, it didn't take too long to get everything hooked up.
Figuring out the Atmel Studio was relatively simple. Once the drivers for the Pololu programmer were installed, plugging in the device caused to virtual COM ports to be created. In this version of the Atmel Studio, you add them from the tools menu, then open the Device Programming option. It was exciting to see the software actually detect the board, and from there flashing the unit was fast and straight-forward. We tested the ESC with a battery, receiver (it retained its Battery Eliminator Circuit, which is cool) and a spare motor - SUCCESS!
Emboldened by our initial success we decided to try again with the second TX85A. This time we left the heatsink attached, cut off Output C, and also removed the on/off switch leads.
You know, we might be getting the hang of this soldering thing after all - it only took ten minutes to connect the 6-pin cable to the board this time! In a matter of moments the ESC had been flashed - successfully, according to the software, but again we decided to hook it up and try it with a motor.
Hooray - it works! HUGE thanks go to Steve Martin, an Australian robot builder, who figured out how to reverse engineer the ESC and created the hex code. He was also good enough to put up instructions on how to do this. Thanks Steve!
Happy with the speed controllers, we switch the connectors on them from powerpoles to ring terminals, and decided to see where we stood on weight. The only things missing from the photo are some wires, ring terminals, and tie-downs, so as we're currently at 29lb 3.4oz we don't have any worries about this 'bot coming in under weight. You can also see in the photo four wheels we picked up from McMaster. Unlike typical Colson wheels which have a hardness of 65A, these wheels are 40A - the same as we were going to cast for ourselves, but we don't have time to figure that out before Franklin, so we'll play with casting urethane for Motorama instead.
Feeling pretty pleased, we decided to fire Milly up and pocket some holes for the axle bearings. We used Rhino3D and CamBam to produce the G-code, then set her off to work.
While Milly was working, we enlarged the bore on the wheels from 5/16" to half an inch on the drill press, and pushed in the axles. We do still need to pin them, and also the axles need trimming down slightly, but things are coming together.
"Shaka - When the wall fell." Hmm ... Milly didn't do a particularly good job of creating a circle ... we've had this issue before, and fellow builders have suggested checking on the amount of backlash on the X and Y axes. We had it set to 0.002" in the Mach3 CNC software, but checking online shows that other people with units like Milly are more typically in the 0.020" range, so we edited the settings, and re-ran the G-code, and saw that the pocket was becoming more circular. We reset it again to 0.030" and once again the pocket looked better after re-running the code. At this point we could fit a bearing in there, so we turned the wall around and set Milly off on the other side.
Argh! There was a loud crunch as the program got underway - the cutter had impacted the vise, as I had left the part at 0,0 but the G-code goes to a start depth of 0.5" above the surface of the piece, so that was not good. After resetting and letting the code run again, the pocket was pretty ragged - we're guessing that the endmill had become blunt after being rammed into the steel vise at high speed. We tried fitting a bearing, but it wouldn't seat properly, and we also couldn't get it out again! Rats.
We decided it was time to call it a day, and go see a movie. We'll tackle the stuck bearing tomorrow, and replace the blunt endmill, then try the other wall. We're getting pretty close to having this 'bot finished - we're hoping to have it done by the time all the rest of the parts show up, so we can concentrate on the other 'bots we're taking to Franklin.
We have a little work to do today, but it shouldn't take long, so we sneaked in a couple more build hours for the featherweight to see what more we could get done on the chassis, seeing as though our ESC hacking didn't go so well yesterday. If we can get the chassis finished up we can temporarily wire up the frame with Victor 883s and see how it runs. Hit Back after viewing an image.
First up is drilling some 13/64" wholes in the front wedge so we can tap them for 1/4"-20 bolts, which semed to go well enough, although the clearance for the countersink bit was a bit tight.
After the drilling, countersinking, and tapping, thing look pretty good, so it's time to let Milly lose on the front wall to slot it for the bolts to hold the front wedge on.
We'll skip ahead a bit, because we left Milly working while we took care of some work items, and came back to a finished front wall, which we then installed, and fitted the front wedge too - the black marks you see are from the rubber mallet we used to "encourage" the wedge to fit. All told, it's a pretty beefy frame!
Time to wrap up for the day, and so we throw everything in the scale. Chassis, batteries, and some of the electronics come out to 27lb 2.2oz. Missing from this photo are speed controllers, wheels, axles, bearings, and we have a bit of work left to do on the wedge to put an edge on it, so all in all, we're going to get quite close to the 30lb limit, but really shouldn't go over it. Hurrah!
Hooray! Another free Saturday we don't have to work, so time to build! We've loaded Milly up with a few G-code programs, and while that's running, we're going to try programming the TZ85A speed controllers for brushed motors. Hit Back after viewing an image.
Milly's off and running with a program to slot the front wall, and we're looking forward to having the chassis assembled today, to see some progress on this 'bot.
While the slotting's running, we're taking some time to work on these speed controllers using a tutorial from the Australian Robot Wars forum. The cable will be soldered to the speed controller, so we need to label the cables, based on how they were pinned in the connector.
Our soldering skills are still poor, but after some effort we were able to get the cable hooked up. The ground pin was a bear to solder, but in the video tutorial there was a note that the builder hooked the ground pin to the ground wire of the receiver cable, so we used that trick too, and now we're ready to hook it up.
The speed controller will need to be powered, so we put some PowerPole connectors on these Lithium Iron Phosphate batteries - we can't use the regular Lithium Ion batteries at the Franklin Institute.
With the controller hooked up to the laptop, we're having troubles with programming tool (Atmel Studio 6) seeing the controller using the Hobby King AVR programmer. In the tutorial, the builder used a Pololu dongle, so maybe that's the problem. Time to pur our troubleshooting hat on ...
After what looked like a successful programming, we decided to hook up a receiver and motor, and see whether it did actually work - but no go. The receiver was receiving a signal, but the motor didn't turn, so drat!
While we paused to contemplate what to do next, we slathered hot glue over the circuit boards of the cheap-o gyro, as many people had indicated to do, to help it stand up better to being used in high-stress applications, and robot battles certainly count!
"Meanwhile, back at the Hall of Justice"
Milly is still working on the slots in the front wall - we're supplying occasional compressed air and cutting fluid while she's doing her thing.
Et voila! With some gentle persuasion from a rubber mallet, we have the two slotted walls in place, and the top and bottom panels also fit just right. Of course there's more work to be done, for the axle bearings, and bolt slots for the front wedge, but it's nice to see the chassis assembled.
To wrap up for today, we put the wedge in the clamp on Milly and started cutting it down to size. We're probably not going to have time to put the bolt holes in it, but at least we can get it started.
And here's our parting shot of the day - the wedge has been cut down to size. Still to do, we need to mill an angle on the front, and drill and countersink bolt holes in it, in order to mount it to the chassis.
Tags: build, featherweight, ii2
Having mowed the yard this morning, we have the rest of the afternoon free, so it's time for a bit more work on the chassis for our featherweight. After finishing the drillig and tapping yesterday, today we're moving on to milling slots in the chassis and hopefuly having another big chunk of fabrication finished, leaving the wedge, drive train, and wiring to worry about. Hit Back after viewing an image.
It's been a while since we fired Milly up, and it took a little bit before we remembered all the right speeds and feeds to run her at, which is why this first cut is somewhat ragged, but eventually it came back to us, and we set Milly off autonomously.
One of the best things about a CNC-equipped mill is that you can load the G-code and go off and do other things, and just check in from time to time to blow away chips or apply lubricant.
While Milly was doing her thing, we spent some time trying to digest the instructions for hacking the TX85A brushless speed controllers to make them run brushed motors. There's a great page on the Australian RoboWars forum with steps, but we had a devil of a time trying to follow them. As a result, we registered an account, and will ask a couple of questions to try and get going with this.
As we puzzled out the Atmel Studio and USB dongle for attaching to the speed controller, Milly was getting close to finishing the rear wall, so we put down the speed controller and turned our attention back to the frame.
Et voila! The rear wall is finished, and we gently hammered it into place. Everything lined up nicely, so in the next installment we'll spend some time on the front of the 'bot, and finish the front wall and wedge.
After waiting what felt like an eternity for a Saturday to roll around, we finally had some time today to hit the Build Space and do some work on our relaunched featherweight Intrusive Interloper 2.0. Hit Back after viewing an image.
We realized that this 'bot is too darned large to comfortably end-drill the side rails on the drill press, so we had to switch to the vice and hand-drill to get these pieces fabricated.
It wasn't exactly plain sailing, but we worked at it, with most of the holes ending up about where we wanted them, which was a bonus. One of these days we'll have to invest in a floor-standing drill press so we have the depth to be able to work on pieces like this.
Not too shabby - we have two ends of the outer rails done, and all the bolt holes match up, so that's a good thing. Now to the other side.
Et voila! Despite drilling these holes with a hand drill we've managed to be fairly precise, and all the 1/4"-20 bolts slide into place without a whole lot of effort, so that's a good thing.
The inner rails, however, so not go as smoothly - here we've managed to break an 1/8" drill bit in the second whole of this piece. We decide to carry on, as we don't have the material to hand to re-make this piece right now.
After drilling an additinal center whole in the end and tapping it, we're doing okay, so we've mounted the DeWalt motors on this side, along with the baseplate, and everything seems to be fitting okay.
The other side has roughly the same issue - broken drill bit in one hole - but otherwise things drill and tap as expected, and all of a sudden we have a chassis almost ready to roll. We still need to mill grooves in the front and rear walls for the inner and outer rails, but we'll worry about that tomorrow. For now we're happy to have a good chunk of the chassis done!
Time to wrap up for today - we're heading out for Thai food in a short while - so we've thrown the chassis on the scale to see where we're at, and the scale says just under 23lb, out of our allotment of 30lb, so we're in pretty good shape! This version already weighs more than version one, and it's not done, so we're going to be getting close to the weight limit this time. Hopefully more tomorrow!
We have a few hours free this afternoon, and despite the ludicrously high humidity, it's time to head out to the Build Space and get a little more done on our thirty-pounder Intrusive Interloper 2.0. We have relatively simple design, but we want the execution to be spot-on, to be able to take on the heavy hitters at Franklin and Motorama. Hit Back after viewing an image.
Here's an investment we've made for a few of the 'bots we have - a three-channel pistol-style transmitter. The idea is that with the throttle on it's own control, box-rushes ought to be much straighter, especially as we're going to be putting a gyro into the 'bot.
Here's another investment - 85A brushless speed controllers - that we're going to follow a tutorial from a chap in Australia who converted these to run brushless motors. This will be our first hack, so we'll keep our fingers crossed it goes okay.
Here's where we spent a fair amount of time today, reassembling the DeWalt motors to get them all locked in to high gear - disassembling and reassembling those gearboxes is a fiddly, messy job!
And after some cleaning up and trimming down, all four motors have their strengthening kits installed and these motors are ready to go.
Here's a test layout, and everything seems to be square, which is good. We haven't tapped the sides yet - that fun is still to come.
With a bit more time available today, we decided to do a bit more drilling, so we've marked up the rails for drilling the connection points.
Here we've drilled the front and rear walls, and thrown in a little countersinking for fun too.
Just to prove to ourselves that we were able to drill those fairly accurately, we've lined up the front and rear walls and put bolts in - they line up great! Next we have to end-drill and tap the side rails - hopefully we can maintain our accuracy there too.
Tags: build, ii2, featherweight
NERC's Franklin Cup is about three months away, and we're intending going, so that means we need to start putting some 'bots together. As we had the table saw out today for miscellaneous odds and ends about the house, we decided to chop up some aluminium for Intrusive Interloper 2.0 too. This 'bot is a (hopefully) simple brick, so the build should be fairly straightforward. Hit Back after viewing an image.
Here are the raw materials: a bunch of 6061 bar, of various widths and thicknesses, some 1/4" polycarboncate, and misc stuff to stick inside the 'bot. We also have some 40A urethane mix, for the wheels.
The trusty tablesaw - equally happy cutting MDF for shelving as it is cutting aluminium for 'botting.
Once the parts were cut we laid them out: 3/4"-thick 6061 rear and outer walls, 1/2"-thick 6061 inner and front walls, and a 3/8"-thick 6061 angle to bolt to the front wall, plus 12"x12"x1/4" polycarbonate top and bottom plates.
Here's a test fit of the insides, with four DeWalt motors, two 3S Lithium Iron Phosphate batteries, two 85A brushless speed controllers that will be hacked to run brushed motors, a gyro and mixer, and power switch.
Without axles, wheels, tires, or fasteners, the whole kit comes in at 28 pounds and one ounce, so there's going to have to be a small amount of pocketing of the frame, but that's not going to be a problem!
We've pretty much spent the weekend on the couch, knocking back Alka Seltzer Cold and Flu, suffering from the "Motorama Plague" or "Motorama Flu", as it's diversely known. Heck, we haven't even unloaded the 'BotMobile yet, but sitting here with not much to do except avoid infecting other people has meant idle hands - hands which decided to do some CAD work! After thinking about our last two failed attempts to build a weaponed 'bot in the thirty pound weight category, and thinking about all the huge weapons that were in the weight class at Motorama last weekend, we've dusted off an old 'bot design we used to have fun with and decided it was due a revision. Hit Back after viewing an image.
In the first version of Intrusive Interloper we had a three-quarter inch thick rear wall, and half-inch think sides and front angle. Given the damage we've seen dished out at the last couple of Motoramas, that may not be sufficient these days. We initially wanted one inch 6061 on all four sides, but didn't have the weight, so we're going with 2.5" tall by 0.75" thick 6061 aluminium on the rear and sides, then a half-inch thick front wall.
Attached to the half-inch thick front wall is some three-eighths thick 6061 aluminium angle. The bolts are threaded into the angle, pass through slots in the front wall so the height is adjustable, and then we'll use grade 8 washers and lock-nuts to secure the wedge. Fingers crossed that's enough to hold it! The inner walls are 2" tall by 0.5" 6061 aluminium.
Here's the drive train: four 18V DeWalt gearmotors to 3" Colson wheels. In the previous version we had our two "Mini-Walts" but those are currently in use in Steel Stiletto, so we'll re-use the DeWalts from the defunct Formidable Fustigator 2.0 and one of our spares. Not shown are the strengthener kits for the DeWalts which will be installed.
Because we want to take this 'bot to NERC's Franklin Institute competition this year, we can't use Lithium Polymer batteries, so instead we have Lithium Iron Phosphate. These batteries have a slightly different cell voltage than LiPo (3.3V/cell instead of 4.7V) so we'll use two 2.1Ah 3S packs in series to give the DeWalts 19.8 volts of power. The 2.1Ah capacity should just be sufficient for a rumble. The two red bricks are hacked TZ85A brushless speed controllers converted to run brushed motors. The white block is the MS1 power switch, and the purple block is a Hobby King HK401B gyro, which we want to try out, and see if it helps our driving.
Here we have the chassis assembled, and the quarter-inch thick top and bottom plates have been installed. The 'bot was designed so the top and bottom plates are simply 12"x12" to make fabrication nice and easy, and depending on weight, they'll either be polycarbonate or UHMW.
Here's a final render of the 'bot with team colours applied. We have the motors and un-hacked speed controllers for this 'bot, and that's about it right now, so we'll be placing an order for some extra parts like wheels, chassis components, and batteries, once we've had a think about other 'bots for the Franklin Institute competition and see whether we need other components for those.
According to the Killerbotics/Tentacle Torque Calculator we ought to have plenty of oomph from those four DeWalts:
And with judiciously applied pocketing to the chassis parts we ought to just squeak in underweight - completely different than version one, which used to run around 23lb fully loaded:
Tags: design, featherweight, ii2
This site contains records of our trials and tribulations in building combat robots. So much to learn, and so little time!