I mentioned last time during the Great Project Purge that RazEr rEVolution was due for a rebuild very soon. I don’t actually plan on calling it RazEr Repackaged, but that’s pretty much what’s going on here. Like the rebuild of Kitmotter, it’s intended as a literal repackaging of parts I already have – a case mod, I suppose. The goals of this rebuild would be to update the frame to a new construction style that I’m favoring more, as well as to clean up some other design loose ends like adding a brake (mixed-up priorities, anyone?) and building in support for the Jasontroller.
The new frame is of roughly the same dimension as RazEr Rev(1?), but it is no longer made of 1/4″ plate for the sidewalls with exposed T-nuts. Instead, the whole structure is 1/8″ aluminum now. Not only does it save weight by reducing unnecessary material use in the side walls, but it opens up the interior volume a little more. The “cavity” for controller and battery is also about half an inch longer. The 1/8″ plates will be attached together with corner blocks similar to those I used in NK.
Additionally, there’s no more structural vs. nonstructural top plate. The black Garolite deck of Revolution is gone in favor of a single top plate and the silvery metal look (changeable with selective application of grip tape or paint).
The first subassembly I put details in is the thing that RazEr Rev never had: a fender brake. By that, I mean it neither had a rear fender (until I appended one crudely) nor a mechanical brake. This being the revision that I hope to address shortcomings, it’s going to get a brake.
I finally spent some time to figure out the way that Inventor processes sheet metal geometries so I could make properly mating sheet metal parts. The side of the sheet metal that you make features on really matters, as does the role of sketched bend lines (start-of-bend, centroid of bend, etc.). Yes, I’ve used Inventor for like 7 years without really touching sheet metal features in depth.
Not shown in the above image (but in the one below) is the spring for the fender – it uses a simple bending plate of spring steel instead of a torsion spring due to the limited space under the fender.
There’s other trimmings to be added too. Instead of a Deans shaped hole in the side plate, I’ve just opened up a big rectangle and will be using 3d-printed electrical panels. Right now, the configuration is for two Deans and a switch. One connector is a battery connection and the other goes to the controller – this way I can easily jack in a Wattmeter or similar. Should I decide to change wiring arrangements, the electrical panel is reprintable.
The motor wiring will be hidden behind a 3d printed cover. While not Apple-like, this at least cleans up the exterior wiring of the vehicle substantially. I’ve been entertaining the idea of a “kit-class” scooter based off RREV for a while, so maybe this rework will move towards that a little more.
The front fork remains the same from the old frame, since it is a solid design. Here’s the front posed roughly where it should be. One of these days, I sweeeeaaaar I’ll model up a handlebar from a Razor scooter.
I cut the frame out of 1/8″ 5052 aluminum. One of the main reasons for moving to all 1/8″ on the frame was the fact that I could get the sheets for much less – they tend to show up more on the surplus channel for one reason or another, 5052 even more so. 5052 is about 2/3rds as strong as 6061-T6, but the vertical height of the material is still more than sufficient to carry the loads I need. 1/4″ 6061 just didn’t make sense any more in the side plates.
This time around, the attachment for the front folding joint is done through a “clip” which makes a material-to-material interface. This opens up space underneath the folding joint which would normally be taken up by a giant nutplate, but this time I can scoot the batteries forward under it. The method is decidedly less stiff, so a “backup plate” of another 1/8″ thickness is also clamped underneath.
1/8″ is too narrow to hold T-nuts directly, so I’m using some 1/4″ to make corner blocks. I probably didn’t need to use this many either, but it was an easy linear pattern to make. The backup plate is seen at the lower right.
Another Classy Thing I’m putting on this version is a 3d-printed “endcap”, similar to the ones found on stock Razor scooters. For this version, I just used the theoretical outline of the corner blocks and internal plates, which means it doesn’t actually fit if the frame is fully tightened and assembled since these dimensions are compressed a little. It’s not supposed to be waterproof; just a splash guard.
Once the frame is done, I should be able to throw it all back together in a day.
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-legoverfeatured 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.
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 canbuyeverywhere. 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).
Really? The bot that made it to real-deal-Battlebots-IQ, then Motorama 2008 and back? The first thing I ever worked on atMITERS? 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!
