Archive for the 'RazEr rEVolution' Category


All Good (And Poorly-Maintained) Things Must Come To An End: The Great Project Purge of 2012

Jun 26, 2012 in Chuckranoplan, Cold Arbor, Nuclear Kitten 5, Project Build Reports, RazEr rEVolution, Test Bot 4.5 SP1

i swear to god i will fix this later

At some point, I need to stop telling myself that. It’s well known that my stuff isn’t exactly world-class in terms of reliability and Six Sigma class in quality, but even I can get sick enough of it to declare it a loss and start over. Over the past few months (and years) of neglect, quite a few of the robots and silly vehicles have become damaged and non-operational. I kept Swearing That I’ll Fix It Soon, Guys, but my shelf of stuff is long past overflowing with parts and project detritus and some of them contain good parts that I don’t want to keep buying. With my general shift of operations towards the newly opened IDC space just up the Z-axis from MITERS, tearing down some of the old derelicts and returning their parts to the Earth (/my storage bins) became more appealing – especially as I started collecting more stuff, most of it landing on my fresh new corner desk.

So it is with great sadness (and hidden catharsis) that I must announce the decomissioning of…

Cold Arbor

Cold Arbor never really worked – the frame was too flexible to accommodate the huge teeth of the saw. After Motorama 2010 and Dragon*Con’s Robot Battles ’10, CA pretty much only ventured off my shelf for the occasional demo – it illustrated, visually, what a “combat robot” was very well. Pretty much everyone’s first reaction at the word “Battlebot” is “You should put a saw on it to cut through the other robot!”, and CA is…. well, pretty much a saw. It never really stopped driving, but then the saw actuator broke so it couldn’t do the extending thing any more. Arbor, being the biggest lead weight I had on my shelf, was therefore the first to go.

But before I tore it totally down, I decided to use it still-functional and very smooth drive base as a test dummy.

Last year in the Austrailian robot fighting circle (did you know that Australia has a very active robot combat scene too?), one of the builders began to modify Hobbyking brushless controllers to act as H-bridges for DC drive motors, utilizing 2 of the 3 half-bridges available on the average BLDC controller. I’ve been advocating something like this for a while – use the cheap hardware base that is Chinese brushless motor controllers instead of custom-developing an expensive niche robot controller solution. The choices in robot controllers these days are either said niche and expensive but generally reliable controllers, or these one-tiny-FET-per-leg overfeatured doodads that I’ve literally had zero success rate with. Or you straight build your own and have them work, but I’ve also not successfully managed that yet. There’s nothing on the market right now which is just a bucket of large FETs like the old Victor 883s (which you can still buy, but they’re now a design so old it can almost drive).

That aside, I have also never bothered to schematic-trace the brushless ESC boards or learn & put up with enough raw Atmel C to reflash the microcontrollers (though I suppose I could have flashed Arduino onto them…). So, a ton of hot air rage on my end, but lots of action in the 40+page thread over on the Robowars forum, which has seen all of the cheap common ESCs reverse engineered and firmware implemented for – up to and including its own confusing beepy configuration menu.

They’ve now started selling them (when I say ‘they’, I really mean like one dude), and I took the chance to get some modified “85A” units based off this Hobbyking ESC.

First, I had to remove most of Arbor’s existing electronics. Okay, so my success rate with the Sabertooth controllers isn’t zero – Arbor runs two of the closely related SyRen controllers, but $75 for 25 amps is stupid these days, and I’m also royally undersizing their loads – one is running a little Speed 400 class motor and the other is running a drill type 550 motor which sees about a 10% duty cycle on raising and lowering the saw.

Way cleaner wiring and layout with the ESCheap85 in – I could easily see a robot with a whole rack of these next to eachother. The massive spam of SMT FETs technique used to great success by cheap Chinese controllers is an acceptable compromise, in  my opinion, between one-tiny-SMT-FET per leg used by the Sabertooth and Roboclaw and other most-likely-designed-by-newly-graduated-college-students controllers, and the one-huge-nice-FET approach I usually take. It keeps the board size down, too.

After hooking this up, Arbor was taken on several somewhat strenuous (and absurd) test drives.

None of it was very scientific, nor was there really enough space to seriously stress the bot out. I’m going to have to use these in battle myself before I’m fully sold on the idea, but based on the reports of the substantial number of Australian users, they’re pretty bulletproof, and a few American users have already run 18v DeWalt drills in drivetrains using them (the same motors that Clocker uses). The 85A type has been praised as a “Victor replacement”, but its more limited voltage range (30V fets and 35v capacitors) doesn’t quite convince me it can be swapped directly into a native 24v (up to 28v fully charged and more during dynamic braking) system. I fully agree with the concept, though, and for about $1 per amp I don’t have any complaints past my own reservations.

That doesn’t mean I’m no longer going to attempt my own controllers – I have yet to successfully execute a small current-controlled vehicle H-bridge, of which robot controller is a simpler subset. But that’s for another post.

At the end of it all, here’s Arbor mid-scrapping:

Scrapping is such a negative word. It took me a while to crack open that weapon drive gearbox, since I sealed it up so well at the start – and some of the bolts were bent.

Here’s everything I ended up keeping from Arbor. All of the motors, pretty much all of the drive mechanics (especially those delicious custom gearboxes, which were one of my first good ones), and of course the saw and worm drive in case I rebuild it all. The VictorHVs and Sabertooth controllers were also kept and filed in my robot controllers bin.

prospect for rebuilding: slim

Arbor was a very complicated robot with lots of moving parts – it’s something which is more difficult to get right, and it’s usually more disappointing (to watch as well as to operate) when it doesn’t work. Arbor’s build was rather rushed and many details weren’t completely thought out. I’m more likely to build a 30lb bot that is either more plainly functional or spend alot more time to build a complex but well-designed and tested robot before trying to compete with it.

Going down the line, next I pulled out…

nuclear kitten 5

NK5 was heavily damaged last Robot Battles, and ever since then has been sitting on the shelf. However, the disc motor still works great – and I can make spare discs, so that’s definitely being reused on something. The controllers and motors were also potential salvage items.

NK5 was the last robot I built before I converted fully over to “T-nut” style construction, visible in pretty much all my stuff from 2009 onwards. The design actually dates from late 2008 – my first major t-nutted endeavor was the ill-fated 2.007 robot. The frame has these wonderful corner bars that I machined for this application, but it seems like now you can buy everywhere. I really liked these, so I went ahead and saved them. Tapping into real metal is way better than t-nuts at any rate.

Here’s NK’s remnants pile. The frame materials were just not worth keeping, but I kept the motors – the gearboxes are not stripped, but one of the pinions fell off (but is intact). They might become donor parts for future gearboxes. I am a fan of these little 25mm metal gearboxen: while they are not planetary, they’re big and chunky inside to make up for it, and fairly cheap at $10-15 each.

prospect for rebuilding: hell yeah

I can’t guarantee when, but D*C 2012 is likely because I pretty much have everything-minus-frame. The disc is up for some revision, though. Big tall vertical disc spinners are no longer in vogue, being replaced by small, low bricky drum things with built-in motors (of which there are now like 50).

Next up is my pride and joy,

test bot 4.5 MCE

Really? The bot that made it to real-deal-Battlebots-IQ, then Motorama 2008 and back? The first thing I ever worked on at MITERS? Yep, since its default parking spot since Moto 2008 has been in Clocker’s lifter when it’s not doing other things.

TB certainly has the most grime of any of the bots, and the lifter was pretty much utterly trashed – it took a direct from the vertical disc bot Igoo at Motorama 2008 (that video is slightly painful to watch).

This is one of my first drill motor hacks. I did a few in 2006 for the original TB version 4, but they were either terrible or dismantled very quickly. This thing predates my entire website, pretty much. The extension shaft with the pinion was added when I redesigned the lifter for Moto 2008. It had an additional outboard support, but since it was made of UHMW, the whole gearbox still flexed too much to keep the gears in mesh, and so the pinion stripped very quickly in battle.

After I took the damaged arm parts off, I realized that TB’s drive base was actually in very good mechanical shape. I still love those gearboxes, too: they are super special 12:1 drill box hacks that I made with mating the salvaged 18 tooth planet gear and 9 tooth pinion gear of the first stage of a drill motor with an intact output stage. Coupled with the extremely overvolted 9.6v drill motors, this made the bot have a rather zippy top speed of 14mph. The first version of this gearbox predates the website (again) – this version at least had the luck of being milled, so things actually lined up!

I briefly entertained throwing the BotBitz ESCs in the frame just to drive it around again, but decided against it for the time being. It’s sure been a long time since I’ve had a 4WD drill-powered box.

So I closed it right back up again. Only the damaged arm and wedge parts were scrapped – otherwise, I think I can put something interesting in this bot again, or at least give it a better sendoff at a serious combat event later on, as the most honorable fate for a combat bot is still, in my opinion, being thoroughly vaporized into a cloud of small particles.

prospect for rebuilding: not for Robot Battles

TB4′s design was optimized for “arena” combat which has more guaranteed smooth floors and a more pressing need for huge, thick angled armor. The RB stage is purposefully left fallow to discourage pure wedges – a passive aggressive attempt at encouraging more robot creativity, which I contend has been successful in the past few years even though it kind of locks me out from competing in 12lbers again there with this design. Maybe Motorama 2013….

Finally, a project that I hate to see get tossed so early, but…

razer revolution

It’s lived a decadent life of being a demo attention whore as well as occasionally coming in handy when Melonscooter was on blocks, and has seen 4 different motor controllers (Double DEC’er, Melontroller, Tinytroller, and Jasontroller!), but recently RazEr Rev has become kind of a wreck.

I donated the front end to another MITERS scooter effort after the new battery got 2 dead cells after only a few weeks – definitely a case of bad initial conditions. Since then, it’s been sort of chilling in a corner, slowly being eroded away by the tides of cruft and dead power supplies that ebbs and floes around the shop.

The Jasontroller works great, the battery can be surgically corrected (I’m literally going to scalpel/X-acto knife the dead cells out and make it into a 10S pack), and the Dual Non-Interleaved Razermotor is a little rattly in the bearings but otherwise functional.

So that’s pretty much all I kept. Oh, and the extra heavy duty generation 2 Razor handlebar, after they moved away from welded-to-frame folding joint but before cost cutting made the joint like 24 gauge steel. This front hinge is massive – the steel is something like 0.13″ thick.

The reason I decided to scrap RREV now is because I’ve become dissatisfied with the frame design. It uses a design which I now consider inferior to other similar scooters in the way it’s put together. Starting over with the frame will be a great way to optimize the design towards less material use (like giant plates of 1/4″ aluminum) and make it simpler to assemble in addition to making dedicated space for the battery and Jasontroller, both of which were “aftermarket” additions. It should end up lighter for the same performance, but I don’t see it getting any smaller. Sorry Jamo, but Razor Wind is a little on the small side for my tastes now.

All this talk of what I’m gonna do means the

prospect for rebuilding: immediate

I already ordered some more giant aluminum plates (…sigh) and will probably be redesigning the frame this week. I’ve already got the changes planned out – they’ll just need execution. Like NK5, it will just be a matter of moving old parts over to a new chassis – there’s otherwise not much about RREV that I’m unhappy about. It’s definitely going to get a stock fender.

other stuff

I didn’t take any pictures, but all the Chuckranoplans have been parted out and recycled too. I’m probably not going to be touching this for a while until I stop being afraid of foam so I can build meaningful scale models. 3D printer models were fun for design practice, but are too heavy to work.

Alright, now that I’ve eaten half my offspring, I can start considering rebirthing them again!

A Bunch of Waterjetted Things

Dec 17, 2011 in Project Build Reports, RazEr rEVolution, The Next 3D Printer

Quick update on a few things as I manage to momentarily surface from intensive planning and building for next year’s 2.007 contest – which, given the whole point of the thing is to issue a challenge to students, I’m actually going to not say anything about until the spring semester begins in February. I promise it will be either a riot, a circus, or a shitshow… possibly some combination of the three.

I got a chance to finally cut out Tinystruder’s structure:

I found enough useful scrap plate to make 2 Tinystruders’ worth of structure. However, the second faceplate didn’t cut correctly since it turned out to be routed over a missing chunk of the scrap… oops.

All of the hardware that I need to finish Tinystruder has arrived from McMaster and others, including the tiny 693 bearings and the correct tube fittings that have a normal 10-32 thread on the end instead of some weird tapered NPT bullshit.

Also, steppers! I got the Polo(lololololololololo)lu 35 x 28mm steppers – they’re a bit shorter than I expected, but I most likely had the 35 x 36 size in mind. If they can crank the filament, then all is good. For convenience, I also got one of the Allegro A4988 driver chip breakout boards, which is incidently the same type that the Reprap RAMPS boards use as axis drivers.

I received my order from Makerbot that consisted of the custom 0.4mm nozzle (boy is it tiny) and the drive rollers. I also purchased one roll of 1.75mm ABS on a reel from, which seems to be about the sketchiest place you can possibly get plastic filament from since there’s no business information, contact information, shipping information past a flat charge, etc… which would help you distinguish a legitimate vendor from some shady Eastern European place that steals your credit card information to fund organized crime. Well, I’m so far glad to say that the place is legitimate, and way cheaper than most 3d printer supply sites.

The only ingredient I’m now missing in this whole affair is the pair of cartridge heaters which Makerbot is still out of stock on – and nobody else seems to make 12 volt cartridge heaters.

No problem, I simply ordered some heaters of the same size (1/4″ diameter x 1″ long) off eBay, where they’re like 8 bucks each. Downside? They operate at 120 or 240 volts. I got a 120 volt variety and plan to just plug it into the wall through a variac for testing purposes. Not very scientific, but who cares? It either melts and extrudes or it doesn’t – I’m fairly confident those smaller steppers can crank the filament at 230 to 240 deg C.

scooter utensils

While I maintain that 3d printed scooter wheel forks are totally fine for average use – both RazErs use a 3d printed fork and fly over railroad crossings, cobblestone, and those blind people curb things with no problem – they are definitely less durable than equivalent metal ones. Case in point, I managed to totally shatter RRev’s fork by trying to mount a rough step curb cut. I totally forgot that I wasn’t on melon-scooter (which can handle a 1″ curb just fine, with its giant regularly-underinflated pneumatic tires), and the next thing I knew, I was riding on top of the front wheel.


With Make-a-Bot out of 3mm ABS filament, it was time to retire the printed fork and just make something metal. Of course I elect to take the utterly lazy bum way out instead of making all of, or even part of, the scooter fork from machined aluminum stock.


Maybe I should have added more t-nuts. But, the majority of the loads that this will see are upwards from the ends of the fork, supported by the Razor A2/3′s rubber block thing. Rearward bending moments are transferred into the steering fork through the crossing piece in the back.

These were last-minute shoehorned into the same batch that Tinystruder parts were being cut on.

I have yet to make the little spacers – this assembly was mostly forgotten in the rush of MEETERS. I’ll finish it off tomorrow and try it out on RazEr rEVolution – if it’s workable, I’ll probably make a pile in varying widths for future scooters.


RazEr rEvolution Repaired… with Sensorless Jasontroller

Nov 13, 2011 in Project Build Reports, RazEr rEVolution

I’m sort of in love with these Jasontroller things lately, honest. I guess it’s because it temporarily relieves me from buggy controller duty and it’s already better than anything I foresee myself building in the near future.

The last time RazEr was mentioned, it was rolling on nice new wheels but with a miniature house brick stuck to the back half of the deck. That’s the sensored shady e-bike controller that I picked up in Singapore. For a while, I had bounced around the idea of just mounting the thing inside. The board in those controllers isn’t that large – it’s the aluminum case that comprises most of the volume. But I ultimately took the controller off, tossing it in the box of EV parts, and RazEr was left a dummy for a while…again. This being the semester I have devoted to making sure more of my projects were working instead of starting endless new ones, I decided to dig it out and investigate everything again.

Embedding the controller was only possible if I switched batteries to something with better packing density. The A123 26650 cells are nice, but they’re not the best if I need more volumetric energy density since there are huge gaps between the cells, even in the “close pack” configuration.

I started playing around with various arrangements in CAD and in real life. I used some spare surplus 18650 type Li-ion types to gauge just how many cells I can stuff into RazEr while either maintaining or improving my pack capacity. I could, in fact, fit a 3rd “row” of 18650 cells in the center of the frame where there is a cutout in the aluminum structure. With 16 cells per row, I could maintain a 12-series (38.4v) pack.

Testing with the Sensorless Jasontroller revealed that it handled RazEr’s hub motor extraordinarily well. It was significantly quieter and smoother without sensors, which boggled me for a while – but the sensors in the DNIR are known to be placed with some angular alignment error. Sensorless commutation also seems to let the motor run at the speed it “wants to” instead of forcing it to be hard-switched by changing sensor states, especially if those sensors are mistimed. So the decision was made to drop a 350w type Jasontroller into RazEr instead, and keep the sensored controller around for other, more mundane tasks, like Kitmotter.

The actual cells to be used are A123 18650 cells, each of 1.1 amp hours. While it’s not like one of those brand spanking new Panasonic 3Ah 18650 cells, these are much less likely to set on fire and are more tolerant of abuse, because A123 . The actual pack is roughly 1.5 inches shorter than the 26650 pack and with 4 cells in parallel, I don’t really lose any capacity.

I really like these cells, because not only do they pack better, they respond better to Angry Soldering Iron. They’re definitely much easier to solder, and I really had to exercise my touch-and-go battery soldering. The upside of making a ‘strip pack’ is the fact that I get to drop a single piece of braid across 8 cells and have a 2-cell, 4-paralle string in the end. This pack went very quickly – in fact I spent more time making those damned balance connectors.

The linear arrangement also lent itself well to routing the cell balancing taps between conductive things in order to avoid accidental balance wire deflagration syndrome.

After finishing, padding, and heat shrinking the whole thing, I got to see how well the new pack fit into the frame. The cell parallelogram is arranged such that the bottom layer is furthest forward, which gained me another half an inch or so to play with on the lower half of the frame.

A gutted and cleaned Jasontroller is also shown in its quasi-final location. I’m just going to seal the board and then mount it to the frame via the MOSFET heat spreaders.

I used the heat spreader bar as a template to drill holes into the frame such that the board was out of the way of the battery and also did not contact anything it wasn’t supposed to. 12mm long M3 socket head cap screws were used to attach the controller to the frame.

And the controller is mounted (but not sealed in Goop or anything yet). I ended up making new leads for the phase outputs since the existing ones weren’t long enough to reach under the board and out of the Hole of Wire Clearing. I laid some silicone heat transfer compound between the heat spreader and the frame, so it should have the entire frame now to warm up.

I elected to leave this 350W Jasontroller unmodified power semiconductor-wise, but jumped the shunt to 1 milliohm in order to bring the power output up to par with the DNIR’s capabilities. On a Wattmetered run, I managed to pull 1200 watts from the thing – so close enough to 1milliohm it is.

RazEr now pulls hard enough that it will almost wheelie if I’m not careful. Right now, it is almost on par with melonscooter for speed – which admittedly is a little frightening.

And the final ‘press shot’. Maybe I can even install a real switch again!

RazEr rEVolution: Concrete-wheel-be-gone

Oct 19, 2011 in Project Build Reports, RazEr rEVolution

Continued from last time, I’ve finished installing the 5″ Colson wheels onto RazEr rEVolution.

This was how RazEr was meant to be. Seriously, why didn’t I just start it off with Colsons initially? While it’s still not as smooth over the average sidewalk seam as, say, a pneumatic tire, it is a marked improvement over my surplus forklift tires.

The story continues…

The first order of business after the can was completed was to install the magnets. Foreseeing another potential stray magnet spacer herding episode like the first build of the motor, I went ahead and cheated by 3d-printing a small magnet spacer thing. This must have saved at least an hour or two of diddling with little wooden sticks.

The magnets were first located using rubberized CA glue wicked into the gaps.

Next, I mixed up my favorite concoction of West System 105 epoxy with 109 hardener and a ton of phenolic fluff filler. The filler adds volume and thickness to the epoxy and prevents it from running everywhere.

Make-a-Bot has actually been instrumental in the creation of RazEr. Not only did it 3d print the entire front fork, but now it’s serving as a convenient epoxy curing oven. I set the head and platform temperature to about 50 celsius each, and left the can on it overnight. This temperature isn’t enough to damage the magnets, but ensures that the epoxy sets thoroughly.

Seriously, what did I do before this thing? It’s really in need of an update.

The next day, it was time to pop back over to the Edgerton Student Shop (where Nice Things exist) to make the internally threaded wheel locking ring. They had the only internal threading bar that I knew of…and that wasn’t broken.

This recent build should probably be entitled “Charles samples a different lathe on every part”: The machine of choice of the shop is the revered Monarch 10EE, the later type without the big round knob. It’s nice.

Maybe next time I’ll pop over to the CSAIL Machine Shop for their Hardinge HLV-H.

The internal threaded Ring of Wheel-Retaining.

I actually had to make this twice, too. For one reason or another, my motor can was turned on 22 threads per inch, not 24 like I thought. I might have just been off by one gear after looking at the selection grid from the wrong angle. Regardless, my x24 thread did not fit, so I had to cut off a chunk and start over with a x22.

And this is how it goes on.

This is actually the wrong direction – the correct direction is with the chamfer facing outwards away from the wheel. What I discovered, though, is that it will thread on just fine in this orientation, but can only make it 3 or 4 threads facing the other way before it just locks up solid. The threads are definitely not crossing, since the initial engagement is smooth and there’ no resistance for several turns. But then it suddenly becomes very high friction – not even thread lubrication helps, and I’ve definitely cleaned this thing 5 times over.

I made a thread diode. What the hell?

Oh well – another engineering pass in the form of “let’s just keep it this way” is pulled.

While reinstalling the stator, I lost control of it under the magnets’ massive pull and it ended up slamming into the far endcap, shearing 4 of 5 sensor wires. Fortunately, this happened at a point which was outside the motor, so I was able to quickly repair the broken wires.

Instead of fixing the can in a drill press vise and slowly lowering the stator into it using the quill, I just held the two. Maybe it worked for tiny motors, but it definitely does not work for a motor like this, and I could have sheared off a fingernail or broken a bone.

tl;dr don’t beast large motors by hand.

And the wheel reinstalled. Black and gray wheels coordinate with the color of the scooter better, IMO.

Pursuant to this, I stole the front wheel and fork off the temporarily defunct Straight RazEr. So here is the finished conversion, except still with its shady-e-bike-troller tumor since I have not gotten around to repairing the melontroller yet.


Revisiting RazEr: Finally getting rid of those concrete wheels

Oct 14, 2011 in Project Build Reports, RazEr rEVolution

Let’s return to a scooter which is not made of wood.

For the longest time, the only thing that’s prevented RazEr rEVolution from being an actual useful vehicle has been the rock-hard wheels I selected for some reason last year. Both were surplus finds and very cheap, and the rear wheel especially was selected at the time for its low tread profile. Being industrial casters, though, they were hard, a fact that I didn’t really think about being a possibility before I got them. The front wheel is 95A Durometer (pretty damn hard) and the rear wheel was 90D Durometer (might as well be plastic).

So basically every time I rode RazEr around, there was a loud rumbling sound on top of the earsplitting 4kHz PWM sound, and afterwards I could not feel my ankles. RazEr rides were limited to indoor, smooth environments. This isn’t to say I didn’t try riding it back and forth across campus a few times, but the numbness in my joints afterwards threatened early arthritis and I was constantly afraid of shaking apart the components inside the motor and destroying the melontroller. Ultimately, though, the vehicle prevailed over my willingness to ride it…until I accidentally detonated the controller in Singapore. With RazEr out of service anyway, I got a little more motivation to replace the wheels. The other portion of the motivation came from discovering how well Straight RazEr handled with the 5″ 65A durometer Colson Caster wheels (a staple of combat robotics in the past). Straight Razer rode very well as just a regular scooter, but it just had too much horsepower to safely handle day to day.

I never thought you could machine a Colson wheel all the way out to the tire, however. My impression of them was that the plastic ended very close to where the rubber began. Therefore, coring them out would not end well as the ring lost integrity while being machined. But while visiting the GT Invention Studio, I watched Colson wheels being machined for A Certain Other Hub Motor Scooter (no, not that one…. the other one). It was indeed possible -the Colsons had a plastic ribbing that the tire was molded over, so even the clamping pressure of a lathe chuck wasn’t enough to deform them for light and moderate cutting passes.

Well, could have had me fooled. It was time to change tires.

There was a problem, though. The 5″ Colson wheel can only be bored out to about 3.3 inches, and the Dual Non-Interleaved Razermotor had that big aluminum outer case which measured at 3.5 inches. This would have required alot of machining of rubber, which was suboptimal.

However, the original Razermotor V1 (dear god that’s an old post) had an outer can diameter of 3.25 inches, the maximum diameter a 125mm scooter wheel can be bored to. Its successor, Razermotor V2, had the same dimensions. Conveniently enough, a 5″ Colson can be bored to 3.25 inches with no issue. So the solution was to make a longer can version of Razermotor V2 to fit the existing stator of the DNIR.

This is a 5″ black Colson wheel. It is in fact the 100th build picture of RazEr rEVolution, continuing my streak of photographing utterly boring subjects for the centenary build picture. To bore this wheel out, I needed a lathe big enough to grip the entire outside of the tire.

Luckily, one existed in the form of a recent addition to the vehicle teams shop: a late model 19″ LeBlond Regal . This thing is the size of a car, and before I hopped on it to start messing around with the controls, I have in fact not seen it ever run. But run it does, and it’s probably now my favorite heavy metal mayhem machine on campus (no less because I have access to it 24/7 and it has all the nice features… minus a DRO). The installed chuck is a 10 inch type which opens wide enough to shove the whole Colson in.

Even more luckily, the only accessory it came with was a boring bar. There were other tool blocks to fit the toolpost, but I would have to “borrow” the tooling of the other machines to use them.

A few minutes later, a centerless Colson. The cores of these things are made of polypropylene, so they’re exceptionally easy to machine.

I ordered my usual Giant Steel Pipe from Speedy Metals to build the new rotor.

This is where the horsepower and mass of this thing really shined. By this time, I had already assembled some basic tooling, and was having fun making 3/8″ inch wide bright blue steel curls that were several feet long. Technically that’s a bad thing to come off a lathe during operation, but it’s a welcome change from the slightly anemic Old Mercedes (I haven’t thought of a snappy nickname for this one yet, but nothing short of Leviathan or Behemoth or Kraken or something would suffice).

I also spent a little while reading about how the Servo Shift worked. This was LeBlond’s “thing”, and it was pretty much an automatic transmission for a lathe driven by hydraulic cylinders and controlled by electrically actuated valves with switches as feedback (Turning the big dial selects which set of switches the gears have to move in place to trigger). The spindle literally jiggles back and forth while the shift is occurring (in a manual transmission lathe, you jiggle the spindle yourself to mesh the gears together). This machine completes the cycle in a second or two, which apparently means the Servo Shift is working exceptionally well – it sounds like an utter pain in the ass if it ever breaks.

I love overly complex mechanical solutions to a simple problem. The rest of the variable-speed machines here use belt-based CVTs, which are far less parts but less heavy metal.

Okay, enough diddling. Time to make a motor can.

The protoform can emerges. This is actually the second attempt. On try number 1, I was still getting used to where the threading controls were and how they functioned specifically to the machine, so after almost finishing the part I accidentally started the carriage incorrectly and instantly plowed off all of my threads.


The thread is a 3.25″-24, which is not in any standard catalog of threaded objects. It just means I have to make my own matching nut again.

I borrowed a Nice Carbide Threading Tool from the Edgerton Center Student Shop, and its niceness shows. These were cleaned up a bit with a pass of Scotch Brite.

Unfortunately, hugelathe didn’t have a parting tool yet, and other tools couldn’t be used on it again because of toolpost incompatibility. I therefore had to transfer the part over to another machine to perform the cutoff. In this case, it’s the second largest machine in the shop, a Clausing 4900 type.

After the cutoff was complete, I transferred it back in order to finish the stepped bore for the endcaps. Tossing a part between machines like this is risky for concentricity unless the workholding implements are exceptionally well-made and precise. The old American machinery did not disappoint.

The finished product.

The next day, I returned to remake the endcaps. These now mount directly inside the steel rotor, so they’re smaller in diameter.

I finally took apart the DNIR to recover the stator and center shaft. I’m glad to see that even after being stuffed into a rock tumbler posing as a wheel, the stator, windings, and sensors are all intact. However, the winding potting epoxy, which I used a cellulose filler (read: paper fluff) for, seems to have charred from the heat. That was quite interesting to see – at first I thought the windings were burnt, but it’s just the paper fluff not handling high temperatures very well.

With the “protoform” can and endcaps done, it was time to drill the radial mounting holes using my trusty indexing fixture.

I still have to glue the magnets inside the new can, but after that, I should be able to just put everything back together and have it work. This takes care of the back wheel of RazEr – the front wheel is less of a priority, but given that I have another Colson, I will probably go ahead and finish that too.

Oh, yeah, and fix the controller. Hmm, this might take longer than anticipated…