After running some errands this morning - including picking up some metric hardware - we're ready to get to it, and see if we can't finish up the drumbot build. We need to install the new drive motors/wheels and finish up the wiring. Once this 'bot is done, all we'll have left is the walker. Let's see if we can get ourselves down to just one 'bot left ... Hit Back after viewing an image.
Using the M4 screws we picked up from Home Despot this morning the drive motors mount okay - we were out of alignment in drilling one hole, but we'll blame that on it being metric :-) Now we can assemble and move on to wiring.
The side rails are back on, and so is the curved rear wall. We're finally settled on the placement of the electronics, so we can move on to hooking everything up.
There's just enough room for the power switch, which has been mounted in the rear compartment. We've tied all the ground wires together, and hooked the battery and weapon speed controller to the switch, along with a jumper wire for the two drive ESCs, so things don't get too crowded around the switch.
We've spent so much time in the build space recently that we're now on to the third season of Stargate SG-1! We'll likely finish this boxed set too before we hit the road for Harrisburg.
The first motor has been wired to the speed controller, after spending a little time with jump leads to determine the spin direction, and make sure left is left and right is right. Note that the motor actually isn't spinning in this shot - it's from where the motor rubbed a wire when it was in the featherweight, but it looks like it's constantly in motion now.
And on to the second motor, again with the jump leads to ensure we have the proper spin direction. This doesn't take too long, and we're able to trim the ESC leads to length and make the final connections.
Et voila!We do need to hook up the weapon ESC to the receiver, and drill a hole in the new rear top plate so we can get at the power switch. While we're at it we may throw a lick of paint on the new panel too.
Here's the 'bot all buttoned up, sans paint and power hole. There's one other thing missing too, at this point ...
A quick weight check shows us at 11.8lb out of the twelve allowed with everything accounted for but one thing: what we're going to stick to the motors for traction. We're debating the use of the grip tape, based on what it did to the Build Space floor with the previous motors. We're wondering whether we should switch to a layer of adhesive-backed neoprene for traction instead, and so we've put some on order from McMaster. Unfortunately it won't arrive until Wednesday, after Toni leaves in the BotMobile, but Lauren's flying in to Motorama, so she'll throw it in her suitcase before heading to the airport. We're not going to be able to call this a "Presenting" post, as the 'bot isn't 100% done, but it's sure close!
Tomorrow the balance of our metal gear servos show up, so we'll be assembling the combat Hexy kit, and that leaves Tuesday to fabricate the weapon for the walker and pack!
Tags: build, nn2, hobbyweight
After wrapping up our featherweight yesterday we're left with the 12lb drumbot and 3lb walker to work on. As the hobbyweight is closer to completion than the walker we'll start there today. We need to wire up the drive train and take it for a test drive! Hit Back after viewing an image.
We've cranked up the Keurig, and in a caffiene-induced frenzy set about configuring the wiring inside the hobbyweight. Here we're working on finding the right collection of settings so the wheels run in the direction we indicate with the transmitter. After reversing channels, motor connections, and also receiver connections we finally have the right combination - to the test drive!
Hm. That didn't go exactly as planned. You can see the scuff marks on the Build Space floor that the 'bot has left while it was spinning donuts. The original motor is plenty powerful, and is able to move the 'bot. The new motor isn't powerful enough to do the same, and by the end of the test run all we'd managed to make it do is smoke. Note also that the grip tape is not as ideal a tyre coating as we imagined - there are many spots where it simply ground up the concrete floor. It looks like we're going to have to stop and re-think this drive train ...
Before we know what we can do, we need to know where we're starting from. At the moment the 'bot weighs about 10.8 pounds out of a maximum of twelve, give or take a lid and some small screws. That gives us a pound-ish to engineer a solution.
We've disassembled the whole 'bot, near enough, while we scour the Build Space looking for drive train components that might work. Either we need to gear the brushless motors, like we did in the recently completed featherweight, but finding appropriate transmission components is not going well; or we could switch to a brushed setup, but the issue there is space - fitting a brished motor and gearbox is going to mean making a wider chassis, which isn't really an option given the time available.
Option number three: moar power! :-)
This is the 'bot with the two existing drive motors removed and the two G60 weapon motors from our retired featherweight Formidable Fustigator 2.0 switched in. As you can see we're up to 11 pounds, without a revised chassis back end to accomodate the significantly longer motors.
Time for some P.A.D. - paper-aided design. The inside of the 'bot is 9.25" across. The new motors are 2.3125" long, so that leaves 4.625" of space for the chassis components. Subtract two times a quarter inch for the walls, and we have a space 4.125" by 3.5" to work with. We drew a 1:1 scale box, and here we're test fitting the speed controllers and power switch inside that space.
Confident we can make it work, we've cut new top and bottom plates from quarter-inch thick polycarb, and marked, drilled, and countersunk them.
Here's the new rear chassis bolted to the middle wall. The next step is actually fitting the speed controllers, power switch, and all the wire in this small space.
We did sand down the top and bottom plates to match the curve of the rear wall, and it came out nicely. When we're done we may actually be able to drill and tap the aluminium side walls to bolt them to the rear wall for some added stability.
Ugh - already this is looking pretty messy. With the battery and weapon speed controller in the front compartment we need to fit two drive speed controllers and the power switch in the rear component, and then decide the best location for the receiver. Argh - so much wire!
But the good news is that barring a few screws, this configuration will easily make weight, so we're going to press on and see whether we can make it happen!
This blurry shot is where we removed the bronze bushing that was in there for the old motors, as the new ones have larger dimensions so we need to accomodate those.
Here's a test-fit of one of the new motors. One thing we didn't consider is that now the aluminium side walls aren't recessed into the middle wall, so the hole that was there for the old motors is now about a quarter of an inch in the wrong place.
Having marked roughly where there needs to be a clearance hole in the side rails, we handed them over to Milly to cut out those holes.
Much better! The motor fits okay at this point.
Because we've hogged out so much of the inner walls, we need to mount these motors to the outside walls this time around. After using our CAD file to determine the placement of the holes for the 30mm metric bolt pattern we drilled and countersunk a set of mounting holes. They came out pretty accurately as best we can eyeball by holding one of the motors up to them.
Time for assembly! And we came to a screetching halt: the motors use 3.5mm pitch metric screws, and we none. Plus, we're out of ring terminals if you can believe it! Gah ... well, we figured out a shopping list for tomorrow morning, and turned our attention to the last remaining 'bot ...
... The beetleweight walker. All the leg parts are now dry, so we can try assembling one. We have enough parts to make seven legs, plus a spare set of foot parts, as we imagine those will be the ones taking the most dings as our opponents crash into us. Here we've pressed together a thigh, using the arbor press to ensure things are snug. Note to selves: next time we have slot and tab parts cut, underside the tabs a bit. Still, with the arbor press, and given that this stuff is 6061 aluminium, we can make it work.
Here we're in the midst of attaching a foot. The foot servo is connected to the controller board to ensure it stays stationary while the foot is being attached. Our only niggling doubt about this design is that we're using the plastic servo horns that came with the servos for this build - hope that doesn't prove to be a major weak point later on down the road ...
Oops. Further note to selves: pre-drill holes before installing components - do not attempt to drill hole with part in place. We've accidentally drilled through a servo. Well, we have a spare, so we can carry on for tonight, but we need to make a decision: do we pull all the metal gear servos from the plastic kit for this build, or do we wait for our second shipment to show up? USPS shows it cleared customs in Illinois today, so there's a good chance it'll show up Monday, or worst case Tuesday. We have the day to build and pack Tuesday, but will a day be enough? On the other hand, keeping the plastic kit intact will allow us to work on sizing the weapon properly and ensuring our wireless control scheme works. While we try to make an executive decision we continue with the leg assembly.
Here we have the foot installed, and it moves surprisingly cleanly for being heavier than the plastic one, and a much tighter [press-]fit together. Additional note to selves: press all the captive nuts in before continuing with build.
After not too much longer we have a finished leg! All the servos turn freely, so that's a plus, and we haven;t damaged any more during the completion of the leg, which weighs in at 5.86 ounces. Therefore six of them will weigh a grand total of two pounds and 3.16 ounces, give or take. This is one hefty beast - beetleweight-wise anyway!
We still haven't reached a decision on whether to disassemble the plastic kit - we're going to sleep on it and see how much time we have tomorrow after we finish the drumbot and fabricate the weapon for the walker. It may be that we wait until Monday anyhow, and if they don't show up Monday, use the day to test the wireless control on the plastic kit, then salvage the metal gear servos from the plastic kit and continue assembly of the combat Hexy Monday night and Tuesday, then reassemble the plastic kit in the evenings while on the road to Harrisburg, PA, later next week. That sounds like the plan - at least for tonight :-)
Tags: build, beetleweight, hobbyweight, nn2, Hex1
Almost a third of the intended Motorama 2013 fleet is yet to be completed, and we jump in the BotMobile in five days! Fortunately it's not as grim as it sounds - both the featherweight and hobbyweight aren't actually that far from completion, and the beetle walker is essentially a kit, so fingers crossed that one goes according to plan. Today we'll focus on the featherweight Intrusive Interloper 3.0. Hit Back after viewing an image.
First: to the paint shack!Having picked up a fresh can of matte black, the leg parts fo the beetleweight walker get a healthy dose of spray paint, and are left to dry while we turn our attention to the other end of the weight class spectrum.
We have one drive pod that refuses to run in reverse, so our first task for today is to replace it with the spare. We cut some axle shaft, asembled the gear, wheel, and core, and were ready to wire the pod to match the one being removed.
Here we're in the midst of replacing the defective pod, and it's not as plug'n'play as we were originally intending. Given that this 'bot is about six pounds underweight, the next iteration will have both weight and space for better modularity. Maybe we can come up with a way to use PowerPoles to click a drive pod in for power, rather than have to mess with these ring terminal stacks.
But success!Note the motion blur on the wheels and motors - this pic was taken with the transmitter stick at full throttle; which makes quite a racket too! We didn't notice initially, but the back left wheel is actually rubbing on the cardboard box edge that the 'bot is sitting on - oops!
To help clean up, we pulled out the Dyson mini-vac and got all the shavings out. We also had a drive pod that siezed up at this point - the front right one - turned out the set screw in the collar on the brishless motor had undone itself sufficiently to get embedded in the polycarbonate - oops! Another modification we're going to work into the next iteration is a thin polycarbonate wall seperating the wheel from the gears - this will help keep debris and detritus from the floor getting into the gears.
But all in all it was a success - we could actually run straight, and turn on command. Trushfully, we're not sure how quickly we're going to wear through the 45A durometer wheels, but we have plenty of them, and driving with the left/right on the left stick is weird, but that's what driving practice is for.
With some time left yet this evening we turn our attention to the hobbyweight. This one, too, has a brushless drive train, but the idea was that the motors themselves would be the wheels. One of the motors was damaged at Franklin and we never got around to ordering a spare. Instead we mounted one of the slightly smaller ones we ordered erroneously to go in the wheels. Here we're in the midst of laying out the electronics.
The trick is trying to cram this stuff in in such a way that it makes sense and is easy to maintain. With the smaller LiPo battery versus the LiFePO4 ones we used at Franklin we have more options, but the optimal configuration is eluding us.
Finally we have our final configuration and have started wiring the 'bot up, however time has escaped us, and it's time to wrap up for the evening. Tomorrow morning we'll finish wiring the 'bot, and with any luck get it driving!
Tags: build, beetleweight, Hex1, featherweight, ii3, hobbyweight, nn2
Tonight's efforts were predominantly directed at the twelve pound drumbot Nihilistic Naysayer 2.5, which sustained damage back at the Franklin Cup at the hands of Fiasco, which damaged a drive wheel. Our goal tonight is to swap the dead wheel and make sure the speed controllers work, now that we've got the hang of programming and calibrating them. Hit Back after viewing an image.
Before we get started on the hobbyweight, we had a quick test-fit of some parts that came in from McMaster today. This is the weapon 'hinge' for the hammer that will go on top of the beetle walker. We still haven't quite figured out where the servo will go that will power this setup, but one thing at a time.
The first thing we did was extract the damaged drive motor. You can see here that the can took a hit, which crunched a magnet. Even after cleaning out pieces of broken magnet and roughly tweaking the can back into shape, the motor was jammed, so it went in the Pile o' Used Parts.
Given that the motor had locked up, we were concerned about the speed controllers. A while back we had tried programming them without the card, and it had not gone well. Now we had the card we decided to try again. The first speed controller wouldn't calibrate though, and despite numerous attempts, we assumed that half of the FETs had blown up, as it would work in one direction, but not the other. Another piece of kit is relegated to the PoUP.
After successfully calibrating and programming the second speed controller we had a brain wave! These speed controllers can be programmed to only run in one direction, although obviously we don't want that, so maybe we had inadvertently set that last time we attempted to program them with the transmitter? We grabbed it out of the PoUP and hooked the card to it. Sure enough, that's what happened. After setting the parameters and re-programming it was working fine - hurrah!
These were the replacement motors we had ordered, but had managed to mess up - the diameter is larger than we had wanted, and they won't fit inside the nifty FingerTech wheels like we wanted. We debated ordering different motors, but the likelihood of finding one that would reach us in time was slim, so eventually we decided to go with what we have.
We used the foam tape trick again to build up a tire around the motor. It didn't hold up to Fiasco last time around, but what are the odds we'll fight that 'bot again? 1 in 16 we guess, but last time the 'bot was essentially immobile - this time it will drive! If we can keep the weapon pointed at the opponent, that means the wheels are out of the way.
A fresh layer of grip-tape was applied to both drive motor/wheel combos, and we turned our attention to the insides. Having yanked the drive speed controllers to test and program them, we decided to stop for a moment and reconsider placement of the internals. For Franklin we had to use Lithium Iron Phosphate batteries, which are considerably bulkier than LiPo ones, but there's no such restriction at Motorama, and we're free to use a smaller, lighter, Lithium Polymer one.
Here's where we wrapped up for the night, with a fresh layout in mind, incorporating the 4S LiPo pack, and a properly mounted power switch. Tomorrow we'll reconnect all the wiring, and see if our freshly programmed speed controllers can make the 'bot move. The brushless setup we (almost) have working in the 30lb'er uses the same speed controllers mated to four G25 motors theoretically rated to 600W, albeit with some gearing. The two motors in this 'bot are rated to 800W, but there's no gearing, as the motor is the wheel - fingers crossed it works tomorrow!
Tags: build, beetleweight, Hex1, hobbyweight, nn2
After running a few errands, including a trip to the hardware store for some more #6-32 taps, it's time to get to work - specifically on the drive train for Intrusive Interloper 3.0, and whatever other tasks we want to cross off the lists. Hit Back after viewing an image.
We picked up yesterday's mail, and in it was a box from Amazon with our monthly Subscribe 'n' Save coffee, plus these two items. A 16GB micro-SD card and a very small camera to put it in. This video camera will be mounted to the Sportsman for some action-cam footage at Motorama.
Skip forward a ways, and we're done tapping the FingerTech wheels without any more broken taps. Aside from the one drive pod we still need an axle for, we've bolted the gears to the wheel hubs, and installed the wheels to the axles with keystock and the nylon cores. Next up are the speed controllers, after a brief interlude for some test driving.
A quick shot of the 'victim' Steel Stiletto was sparring with - a 30lb box of junk. Let it be known to all 12lb builders: cardboard would not be a good armour material :-)
Here we've started to install the speed controllers. They're stuck to the side wall with foam tape, and lead 'C' will be connected to the yellow motor wire in all cases. Red and black will be connected depending on which side of the 'bot the pod is installed in.
We happened to have the table saw out to make a couple of supports for a cat tree (we have hefty cats) so we took the opportunity to cut a second piece of aluminium angle down to size for a second wedge for the featherweight. It still needs to be drilled, but that shouldn't take too long.
Here we have all five speed controllers mounted in drive pods, so the next step is to break out the transmitter, receiver, and programming card, and get these things configured.
Here we're in the midst of configuring the speed controllers. We have two per side, but we're missing a V-tail mixer, unfortunately, so we're going to have to hit a local hobby shop tomorrow and pick a couple up before we can really get this 'bot wrapped up. Time flies when you're having fun!
Tags: build, featherweight, ii3, ss, hobbyweight
Finally! Two packages have been dropped off by USPS - both containing servos. One came from Hong Kong, and the other from Washington state. Let's check them out ... Hit Back after viewing an image.
The Hong Kong package contains 22 metal geared servos that we're going to put in our Hexy Kit tonight. Then we're going to load up the kit so it weighs a grand total of six pounds, and then we're going to see if it will walk. The idea here is that if it can move six pounds with these servos (rated for 2.2kg-cm of torque) then we can build the aluminium combat version of the kit with them, and keep the same leg design.
If it turns out that the replacement servos can't cut it, we'll need to trade up to heftier servos. For comparison the original metal gear servo is on the left. Next to it is a larger servo, also with metal gears, rated for 3.0kg-cm of torque - this would be our first choice replacement, as it's the smallest of the three options. Basically what we'll do is, knowing that the little blue servos have 2.2kg-cm of torque, we'll see at what weight they can move the kit, and then factor the needed torque for six pounds from there. For example, if they can move the kit at four pounds, we'll know that to move six pounds we'll need about 3kg-cm of torque, and so the next size up servo will work. If the little blue servos can only move three pounds, we'll need to step up again: the third servo is rated for over 6kg-cm of torque, and the fourth one is rated for 8kg-cm. If we do need to redesign, fingers crossed it's for the first alternative, because the other two are HUGE!
More tonight ...
Tags: hobbyweight, hh1, gearingup
Tonight's goal is to finish up Steel Stiletto and have it in a controlable state. Shouldn't be too hard, considering we did most of the work over the weekend - all we really have left is wiring, and figuring out whether we want to incorporate a gyro or not. Hit Back after viewing an image.
We switched back from BotBiz hacked ESCs to Victor 883s, as we determined over the weekend that they don't play well with the gyro we have. We coupled up all the wires, throwing in a Battery Eliminator and new mixer - the old one was damaged in the spin-out a while back.
We also gave Milly a quick pocketing program to let us recess the bolts that hold the spikes on, as the heads of the bolts were rubbing on the wheels. We want to do everything we can to make the drivetrain run as true as possible, in case we can't get the gyro working.
Ta-daa! All buttoned up, we took some time to give Steel Stiletto a test run. The short version of the report is that the gyro didn't work worth a dime, so we yanked it, and played with radio settings for a while to try and tame the beast. Eventually we worked the 'bot and the radio into a pretty nicely controlled setup, so we're happy.
A quick weight check, and we're at 11.6 pounds, so no worries there. One other change we've made is to switch the Victor speed controllers from Brake to Coast, to reduce the load on them when we change direction. It makes for some neat drifting maneouvers, and hopefully will allow the Victors to make it through a whole competition without blowing up, as our stockpile is pretty lean at this point.
The last shot of the night: our To-Do Lists. There's a reasonable amount to do, but we think it's very doable in the four or so weeks we have until we load up the BotMobile and head north-eastwards towards Pennsylvania. We put in a bunch of orders today for the parts that are still outstanding, and may also have had a breakthrough in how to more easily build the beetleweight walker - more on that another time ...
Tags: build, hobbyweight, ss
Today was one of those days where we got a lot done, but with very few pictures to prove it. The goal was to wrap up three more 'bots, and although we fell a bit short of that mark, we had a very productive day. Hit Back after viewing an image.
The weapon motor on Transcendental Terror 2.0 was not spinning up. We'd already identified one wire that was not connected properly, despite our best soldering efforts, and after pulling off the electrical tape, it was pretty easy to spot the same problem on the other two leads.
We broke out the crimper and PWM pins, and mechanically connected the motor to the speed controller. Finally, all was well. Time to bolt on the top plate and take the 'bot for a test drive.
No video at the moment - sorry - but the 'bot is pretty zippy on it's 3S battery and 30:1 HP Pololu motors. Final weight is 144 grams, out of 150 allowed, so no worries there, and the internal components are very tightly packed, so our worries about the side walls pivoting are essentially unfounded.
At this point we switched our attention to Belligerent Battler 1.0, which needs some upgrading done. We neglected to take any photos, but were able to cross a few things off the To Do List.
Switching focus again, this time to the hobbyweight Steel Stiletto. We used hacked brushless speed controllers in this 'bot at the last competition, and they worked fine, but in testing with the gyro we want to put in the 'bot, the ESCs would rhythmically 'pulse' on. We decided to switch to the configuration that worked in our 30lb'er - using Victor 883 speed controllers instead. We also took the time to update the 'bots paint job.
This is as far as we made it tonight - the 'bot is mostly assembled, but needs some additional wiring and internals installed. Then we'll put it through it's paces with the gyro and see if it's more controllable than last time. More to come tomorrow - same 'Bot Time, same 'Bot Channel.
Tags: build, beetleweight, fairyweight, hobbyweight, bb1, tt2, ss
This time in five weeks we'll be in the midst of the Motorama 2013 competition, yet at the moment we have zero 'bots ready to participate. Losing a week to the 'flu has definitely impacted the build schedule, so we'll just have to see how much we can get back on track. Today we're going to focus on the 'bots that are closest to being done, so we can cross some things off the list. Hit Back after viewing an image.
So here's something new to us - a BotBitz ANTSwitch. We figured out last time how it works, which sounds silly, as it's only a switch, but it wasn't as intuitive as you might think. The battery connector for the fairyweight has been cut to length, and we've soldered it to one side of the switch.
We soldered a random length of wire to the other side, and snipped holes in the polycarbonate casing of the switch for both wires. Due to the sloppy soldering the switch fits extremely snugly in the case, so no tape or bolts required.
More soldering - this time all the ground wires on the fairyweight are being soldered together: two drive ESCs, the weapon ESC, and the negative lead from the battery. Fiddly, but accomplished.
After soldering together all the positives too, we were about ready to give the 'bot it's test drive! There are a couple of minor issues to get out of the way first, such as ...
Trimming down the prop-saver bolts on the weapon motor, to ensure that they don't rub on the top plate. The already had been cut off, but as the top of the motor needs to fit in a hole in the top plate now, we wanted to trim them down entirely.
At this point we were ready for a test drive, and bolted down the lid, with all the components fitting nicely inside - yay! The 'bot was zippy, as you'd expect with Pololu HP 30:1 motors on 3S and 1.5" wheels, but the weapon wouldn't spin up. We had previously tested all the components before assembly, and everything was fine, so we're going to have to tear down the weapon assembly and see what's up.
Disappointed with the fairyweight, we decided to take a break from it, and take a look at the antweight. The issue here is that the weapon ring doesn't want to spin up. We decided to disengage one of the motors and see if that helped. It did. A lot. The ring spun up just fine on one motor, but pretty quickly slipped out of alignment.
So we needed something to keep the ring in alignment. Specifically what we needed was a 9/16" outer diameter washer. Not having any on hand, we took a 3/4" OD bronze thrust bearing and judiciously applied it to the belt sander, to whittle down the outside. Eventually we ended up with something fairly roundish, that fitted nicely.
Having formally decided to ditch the second motor - hey, instant spare! - we decided to upgrade the battery pack. You can see too that we're using a couple of bronze bushings to keep the thrust bushing in place on the standoff. With the original 470mAh battery pack, we're at 15.59 ounces, so we're pretty much good to go, finally, with this 'bot.
Happy that we finally have some progress made, we turned back to the fairyweight, and started disassembling the weapon. You can see the problem here - one of the motor leads did not 'stick' when we soldered it to the speed controller. At this point we spent a good ten to fifteen minutes trying to resolder it, but the solder simply would not 'stick' to the motor wire. Frustrated, we decided to go mechanical, and needed a simple, lightweight way to hook these wires up.
Remembering our experiences with the PWM cables from the other day, we decided to crimp a pin set to the wires, and just plug them together. The pins were a bit fiddly to deal with, as everything was still mounted in the 'bot, but it worked. We taped it up, and put the battery on the charger before testing again.
Meanwhile, back with the antweight, and we finally worked out the best arrangement of motor, idlers, and washers. The battery on top of the 'bot is just a test pack, but with this arrangement of the original two idlers at 3 o'clock and 9 o'clock, and the washers effectively taking the place of the second motor, straddling the 6 o'clock position, the ring remained engaged on the weapon motor, and all was well.
The day was surprisingly warm for a January day, and we took advantage of that to deposit some paint on the chassis of our hobbyweight Steel Stiletto. Unfortunately the photo doesn't do the paint colour justice - it's a pretty loud, neon pink - you'll have to see it in person to get the full effect :-)
One final check on Poor Punctuation and you can see we're cutting it pretty close - 451 grams (forgot to change the setting). One pound is 454 grams, so this is 15.9 ounces - fingers crossed the official NERC scale is in sync with ours.
We didn't have all the bolts in for that test, and so the two that were in unscrewed themselves, which let the weapon ring slip off the motor, hence the sparks you saw at the end, but the weapon did actually spin up, and with that, we can declare we have a working 'bot!
After looking at the field of fairyweights for Motorama 2013, they all have spinning weapons, so Lauren decided to scale down her pushy-'bot design to 150 grams, and gathered up some parts. We'll throw together some CAD designs for it, and make sure it'll make weight before committing to it.
Ta-daa! Presenting Poor Punctuation 2.5! The scrape on the top right, by the way, is from drilling the top plate (titanium) with a relatively dull drill bit to enlarge the hole for the top of the motor - the plate spun at the very end and scraped the paint a bit.
And a second Ta-daa! Presenting the rebuilt Malicious Mule. This time we think we have the right balance of speed and torque, still within a quarter-inch thick 6061 aluminium chassis. With both antweights done, we can get some skirmishing in between now and Motorama. We're wrapping up today with 20% of the fleet ready for Motorama - hurrah!
Tags: antweight, fairyweight, hobbyweight, build, pp2, tt2, mm, teti
We don't usually build on Friday evenings - it's typically pizza-and-a-movie night, but having lost a week of building to the 'flu, we need to regain time, so it's out to the Build Space we go. Hit Back after viewing an image.
After rummaging around in our boxes of bits, we found some PWM pins and housings. We weren't feeling entirely confident, but decided that the best way to reduce some of the cabling would be to cut them and put a new set of pins on the wires.
After a trip to our local Fry's, we had an appropriate crimper, and a few YouTube videos later, we decided to give it shot. As you can see, we did pretty well - hurrah!
A blurry shot of the weapon speed controller wire with it's new PWM connector on [much] shorter wire. We tested at this point, by plugging it in, and doing a quick spin of the weapon - it works! Now on to the drive ESCs.
While the cable editing was going on, we had been attempting to get Steel Stiletto to play nice with a gyro. We did find a gyro that seemed to work, but it also caused the drive wheels to 'pulse' on to a rhythm - not a good feature. It dawned on us that when we had the gyro working in Intrusive Interloper 2.0, it was with Victor speed controllers, rather than the BotBitz ones, so we decided to swap them out and put Victors back in the 'bot.
Back to the fairyweight, and the two drive speed controllers have had their PWM cables shortened and tested - everything is works still!
And things fit much better inside the chassis as a result. We still need to figure out what to do with the electrical wiring though ...
As a result of chopping down those PWM cables we've also chopped three grams out of the 'bot. No weight worries for us with this 'bot.
This shot was taken while we were trying to figure out how we're going to manage the electrical wiring. One thought was to have a removeable link, to allow us to keep the connector on the battery for charging, but there's simply not enough room inside the chassis for it. The soliution is still eluding us at this point ...
Last shot of the night, and we've drilled and tapped the Lite Flite wheel hubs with a #4-40 bolt to act as a retainer on the Pololu motor's D-shaped shaft. We'll add a dab of Shoe Goo too, once the wheels have been assembled.
Tags: build, fairyweight, hobbyweight, ss, tt2
We're having a bit of a cold spell here in Austin, Texas, and the temperature hasn't been getting much above 40°F the past couple of days. Looks like today is going to be a bit chilly too, but none-the-less, it's time to head out to the Build Space and see if we can't make some progress on the fleet. Hit Back after viewing an image.
Here's the current fleet status: lots of boxed parts. The beetleweight Belligerent Battler 1.0 is about the only working 'bot at this point - all the others are in some stage of [re-]construction.
We're starting today with some work on Lauren's antweight Malicious Mule, which is getting a rebuild based around Pololu 30:1 HP motors. Here we're using a (recently) trashed motor to ensure the motor mounts fit the fresh motors, with the aid of the arbor press.
And the first wheel/axle/motor/mount is successfully installed. This ought to be a fairly robust drive train when it's done, based on how solid the 'bot seems already.
Three more installs later, and all four motors are in place. Truthfully we trashed another Pololu motor installing all these, but luckily had some spares lying around.
Next is a test fit of the top plate. With three walls installed, every single bolt has gone in just fine, which is pretty impressive by Team Radicus standards.
Et voila! The chassis is assembled, and everything seems to fit quite well. One bolt missed the mark, but there are enough others to keep this 'bot buttoned up just fine.
After breaking out the soldering iron, we had some electronics installed, including the receiver, mixer, and two FingerTech speed controllers. At this point we took it for a test drive on two LiPo cells, and it was pretty zippy! It'll be interesting to see it on four - definitely going to need to get the gyro installed.
At this point we spent about two hours trying to integrate the HobbyKing gyro but to no avail - no matter how we aligned the gyro, or twiddled with the radio, the antweight would just go nuts. Getting frustrated, we put the 'bot to one side, intending to revisit it tomorrow with a fresh cup of coffee.
With that, we turned our attention to Lauren's other 'bot, Steel Stiletto which had blown up the other night, ripping up the electronics inside the 'bot, which had become displaced to outside the 'bot. You can see here one of the ESC signal cables wrapped around one of the axles. We dug it out, intending to try and repair the ESC.
Here's where we wrapped up for the night, soldering some fresh PWM cable into place to patch up the torn up part. It was getting late enough that we didn't try to run the 'bot following the repair - we'll save that fun for tomorrow!
Tags: build, antweight, hobbyweight, mm, ss
We recently picked up a couple of replacement speed controllers for the hobbyweight Steel Stiletto, and decided this evening to get them installed, so we could try running the 'bot with a gyro in it, to see if it would be more controllable. Hit Back after viewing an image.
The first step is to put some connectors on the ESCs, and in this 'bot we're using ring terminals, so we crimp a set on, which takes no time at all.
Having not run the 'bot in a while, we pause and hook up the batteries to chargers to let them get topped up. The batteries are well wedged into the 'bot, and we don't want to mess with taking the front and back panels off, so we elect to charge the batteries in place. We can't do a balance charge, but the odd standard charge shouldn't hurt them.
While the batteries are charging, we turn our attention to Poor Punctuation 2.0 and drill and tap a pair of new motor mounts, for #4-40 bolts this time, instead of #6-32.
Rather than try and extricate the 30:1 Pololu motors from the current mounts, we dig out a pair of 50:1 HP motors, forgoing a bit of speed, and press the motors into the new mounts.
After pressing on a pair of fresh 1" foam wheels, we install the mounted motors onto the chassis of the antweight. We also spent a little while contemplating the internal layout of the 'bot, trying to minimize the amount of witing we'll need to do, to see how much weight we can save, remembering that we were an ounce over last time.
The underside of the 'bot - that's a lot of screws! We're debating whether we can take half of them out to save some weight.
Meanwhile, the batteries in the twelve pounder have charged up, so we set about installing the new speed controllers.
Eventually everything has been re-installed, so we fiddled a bit to make sure the ESCs were plugged into the right channels on the mixer, and also installed the gyro for it's test run ...
... Which did not go well. The 'bot went into a death spin, ejecting the receiver, gyro, and a speed controller, which sparked as it came out.
Here's where the sparking happened: the PWM control cable on the ESC was sheared, so next time we get to building, we need to replace or repair the cable, and keep our fingers crossed that the gadget is still functional. So much for the gyro test ...
Tags: build, antweight, hobbyweight, ss, pp2
It's been a while since we stepped out into the garage Build Space, but it's coming up on the end of November, which means Motorama 2013 is not that far away and we have 'bots to build! The game plan is to try to finish as many of the fleet upgrades as possible before the end of the year, so we can focus as much of January and February as possible on our beetleweight walker Hexapedal Hitman 0.9. Guess we'd better get a bit of a move on! We've placed orders for parts and materials, so while we wait for those to show up, we decided to see what we had available to work on. Hit Back after viewing an image.
The last time we were out here, we left scratching our heads as to why Steel Stiletto wouldn't power up. After checking all the other parts, we decided to check the power switch. As you can see here, we must have gotten over-enthusiastic turning the 'bot off at some point, and bent the copper bar inside the switch, such that it wouldn't connect - oops! We flattened it back out, and reassembled the switch.
Unfortunately, during the process of wiring the 'bot back up, we somehow managed to short one of the speed controllers by touching a ground connection to the metal heatsink on top of the unit. Drat! This means having to swap it out, and swap a fresh one back in. The only spare we had was one of the ones we hacked ourselves.
Which did not go well. Oh well ... we have a couple of pre-hacked ones on order, and will swap them in once they arrive, and maybe finally we'll get to try out a gyro in this 'bot. Moving on ...
We dusted off the chassis of one of the beetleweights we started a while back, and played a little with mounting some internal components, before realizing that we already have two working beetles, plus we're going to be building the walker, so there's no room at the moment for this 'bot in the fleet, and therefor no need to spend much time on it. Moving on ...
Next up, the Sportsman class Palindrome30. We took the parts with us to Motorama 2012, which was pretty foolish, because there was no way it was going to be completed in the pits. But at the moment we have time, and most of the parts already in hand, so we put some effort into it.
We're using 6061 aluminium round for the weapon shaft, but it's oversized and we can't get a sprocket on it, so we opt for the Poor Man's Lathe, and chuck the round into the drill press, and hit it with some sandpaper. It took a while, but eventually we had the round down sufficiently to be able to work the socket on.
Ta-daa! One end of the 'bot - not quite complete, as the weapon blade hubs have not been pinned to the axle, and we need to drill a couple of holes for the weapon chain, but pretty close!
Here's the end bolted into the chassis, and looking about how we had it in our mind's eye. We're working without CAD for this 'bot, which is unusual, but also somewhat liberating, and it's a fun 'bot to work on.
After repeating the lathe process with the other weapon axle, we were able to bolt together the rest of the chassis, and here it is!
The next step will be to install the drive train, and then move on to the weapon motors, and finally the electronics. Here we're testing drive shaft lengths, and our home-made bearings. Things seem to fit quite nicely, but we've hit a stopping point for today for two reasons - we don't have any wheel hubs for the 6" Colson wheels we're using, and we're headed to the movies to see Skyfall!
Just for fun, this is what the fleet looks like in the Build Space - ants and beetles on the top shelf; beetle, hobby, and sportsman next shelf down; feather and hobby on the next shelf down, and finally misc parts on the bottom.
Tags: build, ss, hobbyweight, sportsman, pal30
This is our last build day before NERC's Franklin Cup 2012, and we have three working 'bots, one that needs tweaking, and one that still has a fair amount to be done. Time to get cracking! Hit Back after viewing an image.
We have a bunch of wiring to do on Nihilistic Naysayer 2.0, and the best place to start is probably with the batteries. This shot reminds us that we actually need to make a rear wall for this 'bot too - better add that to the list.
The new rear top plate unfortunatly doesn't match, as we couldn't find the brand of paint we usually use, and the new can is a bit bluer than the original, but at least it fits.
A quick test weigh-in, and things are looking good - 11lb 10.6oz, and that's without cutting down the rear wall yet, so no worries on weight. We're probably going to have to trim a bunch of wire out of the 'bot too, because it's pretty packed in there.
Speaking of cutting the rear wall, we had a little trepidation with this, as there's only 1.5" between the blade and the fence, and the part is curved, so this seems dicey.
We took a breath and went for it, but this is as brave as we were feeling - we made it about half-way on each side before bottling out, as our fingers were a tad too close to the blade for comfort.
After debating a bit how to finish this part, we decided to wrap up the cutting with the jigsaw, which was much safer!
We left the wall to cool down and went back to wiring. We can feed the battery wires into the front compartment to hook up to the power switch. We can also bring one set of drive motor wires in there, to meet the ESC, but the other motor doesn't quite stretch that far.
Here we've put the drive ESCs and power switch into the front compartment, along with the weapon ESC. It's really crowded in there, and so we're going to need to trim wires some to be able to get the lid on.
Back to the rear wall, and we cleaned up the jigsaw cuts with the belt sander. Again, we had to pause to let the wall cool down, but it came out pretty clean, so we're happy with it.
While the wall cools we turned our attention to the littlest 'bot, Malicious Mule, and fitted the fourth wheel which arrived yesterday. After bolting on the side rails, we took the 'bot for a spin - almost - the friction of the rubber wheels on the side rails meant it hardly moved at all. Uh oh.
After a quick weigh-in (15.0oz) we decided two things: (1) to replace the 2S battery with a 3S one that is only 0.3oz heavier; and (2) to cut new front and rear walls to allow an extra eighth of an inch of space between the wheels and outer walls to eliminate the friction.
Back to the hobbyweight, and we've removed the on/off switch and replaced them with simple jumpers to force the ESCs on. We're going to hot-glue the PWM connectors and power jumpers so they don't come off in combat.
Here we are fitting the rear wall. We're simply going to drill and tap for four bolts, rather than the elaborate curved slot it was supposed to sit in, in order to save time and complexity.
After drilling and counter-sinking the rear wall we were able to finally put some primer on it. This is the last piece of the 'bot - all that's really left is wiring, finally.
We start that by putting our favourite PowerPoles on the batteries. We're pretty sure we can install these in our sleep at this point!
It's a little tough to see what's going on here, but we've hot-glued a pair of LEDs to the middle wall as power light indicators. Much more compact than the dual-blue ones we've used in other 'bots.
To match the new power lights we've drilled view holes in the top panel, and also a new hole for access to the power switch.
Our thoughts habe turned to packing, and although this wasn't a consideration during the design phase, Intrusive Interloper 2.0 fits perfectly in the Pelican case. Unfortunately the 'bot and the case weigh 47lb together, so this is definitely going to be an overweight bag! Oh well.
Here we've fitted the rear wall. It isn't exatly per the original design, but it fits just fine, and we're glad it's done.
Here we've installed the new front and rear walls and the 3S battery into Malicious Mule and taken it for another test drive. The 'bot moves, and is pretty zippy, but is definitely missing the torque it used to have with the old 50:1 Copals. We're thinking the 10:1 reduction on the Pololu motors might be a little too low, so we're contemplating switching the drive motors to 30:1 ones.
Here we're in the midst of wiring the drum-bot, and we're trying to be judicious in how we trim the wires, but truthfully it's getting late and we're losing focus, with packing on our mind too, so we're not entirely convinced this 'bot is going to be complete when it's packed up.
Ouch. Toni walked into an aluminium bar. You're not seeing blood trails here - this gash does in fact run that far down her leg. Well, at least it woke her up a bit!
More wiring, and it's definitely time to call it quits for the night. Tomorrow morning we'll just have time to pack and then run for the airport. Looks like we've fallen back into our bad habit of building in the hotel room - the wiring for this 'bot will have to be completed in Philadelphia. Nursing a cut leg and bleary-eyed, we wrapped up for the night and headed to bed.
Tags: antweight, build, mm, nn2, hobbyweight
We actually took the night off last night, because (a) we were tired, and (b) we have two full build days before we have to pack up and head to Philadelphia. This morning we hit the ground running, to see how close we could get to finishing the rebuild of Nihilistic Naysayer 2.0. Hit Back after viewing an image.
The To Do List has a couple of new entries after finding out on Monday night that the drive motors were longer than we'd designed for. We think we can work with it though, and we're hoping our batteries show up soon! Time to get to building!
We let Milly loose on the remaining side wall slot, so that was something we could cross off the list. It'll also let us paint the chassis components later today.
We need a new drum axle, as this time it'll actually fit into the side rails to decrease the likelihood of snapping the bolts that hold it in place, so it needs to be a little longer than the previous one.
Milly has finished re-slotting the center wall, and as you can see the drive motors fit a lot better now. We were a bit concerned about the screw holes for the right drive motor wall, but we were able to drill the just far enough away from that hole that they're good.
It's not very often we have to tap steel, and we remember this being a pain in the rear end last time around, but truthfully tapping the shaft for 1/4"-20 bolts was pretty easy.
Ta-daa! We drilled the bolt holes out to 3/8" going 1/4" deep into the side rails, and after a touch of sanding the shaft fits nicely. Hurrah!
The drive motor walls/mounts have been drilled and countersunk for the drive motors, and they actually came together fairly easily, despite being metric.
Here we have the drive motors installed, and you can see the spacing to the side rails is spot on this time around. We need to bore a hole for a bearing in the side rails, though, to support the outside of the motors.
Meanwhile, on the business end of the 'bot, we've touched up the positioning of the weapon motor pulley, and drilled and tapped for a #6-32 'set screw', except we don't have any, so we put in a normal screw and Dremelled it down.
Rats! When we cut the new rear top and bottom plates this morning we tripped up, and cut the 3/16" too short. Time to re-cut them and re-paint them, except we're out of paint, so it's also time to make a quick run to the store.
When we got back we set Milly up with the job of milling a circular pocket in the side wall for the drive motor bearing. Two things wrong with this photo: (1) The circular pocket is somewhat less than circular; and (2) the pocket is on the wrong side of the wall! Doh. Okay, so we adjusted the backlash a little and gave it another shot.
Second time we had a respectable pocket, so we pressed in a bronze bushing, drilled to 7/16", and the motor fitted nicely! We will need to trim the shaft on the motor a little, but that's an easy job. The 'bot is finally starting to come together.
Here the front wall was been drilled and tapped, along with the center wall, and next we move on to the middle wall.
After tapping the middle wall and drive motor mounts, we're able to attach the front and rear base plates, and all of a sudden this is beginning to look like a 'bot! Which is good, because it's getting late ...
The side rails are given a coat of primer, and we take a break for something to eat. Steak and salad! :-)
After dinner, we try to figure out where the internal components are going to go, as we've had to re-jig the dimensions of the 'bot somewhat. We think we can just about cram the drive and weapon ESCs in with the power switch, leaving the rear compartment for the A123 battery packs.
We haven't quite made it to wiring things up yet, but we're going to have to take the fans off the drive ESCs in order to make everything fit - hope that doesn't become an issue!
To wrap up the night we put coats of black paint and clear enamel on the side rails and call it a night. Tomorrow ought to be a pretty exciting day! :-)
Tags: build, hobbyweight, nn2
Phew! We have three 'bots ready for NERC's Franklin Cup this coming Saturday, and one more missing a wheel but essentially done. Give that we have two and a half evenings plus one full day of build time left, we need to decide what we want to focus on. We can either work on the antweight, in a field of a dozen competitors, or we can put our time and effort into the hobbyweight, which is up against four other contenders in the weight class, including another of our own 'bots. Frankly, it's been so long since we earned a trophy that we're going to take the route with the numeric advantage, and work on the 12lb'er. Hit Back after viewing an image.
Here's the carcass 'bot we're rebuilding - Nihilistic Naysayer 2.0, which took a few hits at Motorama 2012, breaking the weapon shaft and crippling the drive train. Hopefully the improvements we're putting into the rebuild will beef it up some.
This what we have after taking the 'bot apart - a number of damaged frame pieces, a pretty solid drum, and lots of room for improvement! And so we move forward, keeping the drum, weapon motor and speed controller, and not much else.
Here's a quick test-layout of the new chassis and components. The 4S LiPo battery is being replaced with 5S of LiFePO4 cells; the drive motors are going brushless and will be essentially the hubs of the wheels, and the frame should be somewhat sturdier.
Here we've milled slots in the 1/2" 6061 outer walls. The front and middle walls don't look quite right here as they need to be slotted too.
And indeed, here's Milly working on the polycarbonate middle wall. We like working with polycarbonate and UHMW because things go so much faster than when working with aluminium.
With the middle wall slotted, we realize we've made a mistake. Note that the weapon motor shaft is off-center? We cut the slot 1/4" deep, rather than 1/8" - oops! Luckily this ought to be an easy fix.
This is a quick test fit of the drive walls which have been drilled and tapped. The drive motors should end up bolted directly to them, and also need a slot for them in the center wall.
Originally we were planning on casting 40A durometer urethane onto the drive motors, but we don't have time for the Franklin Cup to figure all that out, so here's our 'brilliant plan' instead: we applied five layers of double-sided sticky foam tape to the motor, and then on top of that we added a round of traction tape. In theory the foam tape ought to have some give, like a tire, and the traction tape should - well - give us traction! The traction tape pretty thin, but we have 60 feet of it, so we can afford to replace it between matches.
And this is right about where we see the fatal flaw in the plan. Somehow we messed up the design, because the motors are half an inch longer in real life than we designed for. Argh! If we move the drive walls a half an inch each, we won't have space for our battery packs. Argh! We really want this to work, so we pause to consider our options ...
We decide to press on. We're going to move the drive walls, and order two 2S A123 packs that will fit in the remaining space and run in series. We're dropping 20% of the voltage, but on the other hand, it'll work! So we painted and counter-sank the top and bottom panels. The rear panels will need to be trimmed once the drive walls are moved.
We're about out of time for tonight, so we decided to throw the parts on the scale and see how things look. 11lb 5.6oz with all the existing parts bar a few screws. Even switching the batteries for heavier A123 cells we can still make this work - it's just going to be a matter of time.
There's a saying that goes "Work expands to fill the time available". We don't believe work can possibly contract to fill the time available so looking at our To Do list, we'd better hope we can make good use of our two evenings and one day of build time remaining!
Tags: build, hobbyweight, nn2, mill
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
After spending a good chunk of time last weekend on the rebuild of Steel Stiletto, including burning up some battery packs, we'd ordered some replacements and today they arrived, so we headed out to the build space with the intention of finishing this 'bot. To paraphrase, the best laid plans of mice and 'bot-builders oft go astray ... Hit Back after viewing an image.
Here are today's new parts, from top-left, clockwise: A couple of female JST pigtails for Belligerent Battler 0.9 and Persistent Pugilist 0.9; 2 A123 3S packs from EP Buddy for Steel Stiletto; a few 2S LiFePO4 2S packs from Hobby King USA, also for Steel Stiletto, a couple of - unfortunately - 3S LiPo packs we can't use in Steel Stiletto for Franklin; replacement 6061 rails for Malicious Mule from Team Whyachi to replace the ones we broke taps in; and a spare 1.25" wheel for Malicious Mule in case the fourth one from Robot Marketplace doesn't show up in time.
As we began wiring Steel Stiletto for the new battery packs, we decided on a whim to check weight. Uh-oh! Currently we're almost a quarter of a pound overweight! Basically this is because the LiFePO4 packs shown here weigh considerably more than the ones we burned up in our last test drive. We need to start thinking about weight reduction measures we can take.
After eliminating the gyro, switching ring terminal connections to #4-40 hardware, and trimming leads we were still showing as overweight, so we had to stop and think where this weight is, and where it can be eliminated. The 'bot is pretty spare, so this will take a fair bit of imagination to work out.
The first thought is to replace the steel driven axles with 6061 aluminium round, so we fitted a fresh hacksaw blade into the saw and went at it, cutting two replacement pieces for the the 'bot's steel axles. We figured this would eliminate half an ounce.
Except the problem here being that there's no easy way to remove the tires from the hubs, as the pins are nigh ungrippable without cutting into the tire, which we don't want to do. On the plus side: they're completely solid; on the negative side: they're completely solid!
So we start doing math. Late at night. With a couple of beers. Stay in school kids! :-)
Here we've calculated that if we switch the 3/8" 6061 front and rear walls with 1/2" polycarbonate we'll save almost half a pound, but we want to check other options too, as we'd prefer aluminium to polycarb in this particular application.
After cleaning up the wiring some more we're about half an ounce over, not counting the gyro - if we use it - and whatever else we need for hooking up the electronics. This is the first time in quite a while that weight has been an issue. We figure that if we can core 1/4" out of the axles, trim the axles, and shorten the bushings, we can probably save about a half a pound, so we don't have to hack up the tires to switch in aluminium shafts, although that's definitely on the cards for Motorama 2013!
So finally we have a new To Do list for Steel Stiletto with our weight-saving measures. If we did all these things we could run 4S LiFePo4 batteries and not worry about weight, but there's also the thought that in a 16' arena 3S (9.9V) might be enough. We'll make the first few changes then take a test-drive and see how things are shaping up, before deciding on the more drastic - and time-consuming - changes.
Tags: build, ss, hobbyweight
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
This site contains records of our trials and tribulations in building combat robots. So much to learn, and so little time!