Archive for the 'Project Build Reports' Category

 

Thank You for Calling Big Chuck’s Lawn and Landscaping: Introducing Crabmower

Sep 25, 2020 in crabmower

This website is now a van.

In my circles, “being a van” refers to something which needs constant upkeep and repair before it can be useful. If you have a certain arcane procedure and checklist for booting something up, or a very prescribed set of operating conditions and limitations, then you have a van. Vans do not have to be van shaped to be considered vans, as the state of van is a radically inclusive and individualistic phenomenon. Mikuvan was, for the longest time, a van. It’s still a van, just less in the van sense. Get it!?

Running on an installation of WordPress now over 10 years old that’s no longer supported and full of security holes, with plenty of my custom-hacked PHP and CSS dating back to 2007, and all plopped on a hosting which Godaddy has called me plenty of times about calling it “Legacy”…. this website is a van. You in fact might have noticed it, in fact. There’s a little annoying spambot that occasionally hijacks and redirects search engine referrals and tries to sell you dick pills on my behalf. I pry this thing off the PHP directories every once in a while, like an advertisement-laden barnacle. It doesn’t affect the site within itself, only search results like from Google hits and the like. Well it turns out everyone just searches ‘charles guan site’ because this site’s name is impossible to spell for normal people!

Anyways, that Van Factor along with my summer mechanical misappropriations is why this site’s been so dead lately. There is plenty of content, I just don’t want to keep updating it and maintaining it, so I walked for a while. But now I figure I’d get in a few more posts, download the database and file structure, then nuke the whole thing from orbit and try again with a modern CMS or something. We’ll see when I actually devote the mental energy and time to Internets again.

I’ve said it often before in various contexts including here, that modern social media just makes it too easy to share stuff to a big audience and so the extra effort of maintaining a static website presence is less rewarding. I’m no social butterfly, but Instagram has certainly made it easy to puke photos onto the Internet. As I am mainly a visual storyteller anyhow, I adopted it more in earnest this year. For the latest candid and disorganized photos, look here at my Instagram page @fakecharlesguan first. This is a deliberate choice in username, as if I get famous enough and someone tries to make a fake me page, they will have to necessarily use @officialcharlesguan or something similar, adding to the confusion and hilarity. Be prepared for many cats and electrical atrocities.

Obviously, a lot of the new not-seen-here content will eventually make it here in a static format, such as the series of posts I want to write called The Summer of Ven. You can guess what that might entail.

Anyways, let’s get back to the #RobotTrapHouse. You know what it has? A lawn. You know what lawns do? They grow, and while I’m technically under no obligation to perform lawn maintenance in my lease, I also don’t want to That Guy too much just yet for the neighborhood. For a few months into the spring and summer, I decided that I was done trimming grass in high school, so I paid for it As A Service. Then I decided that the yard isn’t really that big and maybe this was a chance to get another horrible machine of some kind to tear apart or improve.

I actually was looking first at a current-gen brushless self-propelled electric lawn mower such as the Harbor Freight Special. It was more about the curiosity of what kind of value engineering went into such a power system, in the same vein as my dissections of serial killer equipment. It got to the point where I actually went to Harbor Freight to inspect the goods in person, drawing up plans for using the dual rear drive wheels to make it autonomous. I kept an eye on Facebook Marketplace and Craigslist for used ones – that was my first mistake – but it seems like they’re a bit too new to begin circulating on the informal economy cruft cloud.

Then one morning, I saw this thing.

 

What in the hell? It looked like a walk-behind commercial mower at first, but other photos showed it had a seat. What the absolute, interminable fuck is with that drive belt? The “My granpappy left it to me” quip in the ad made me wonder if it was homemade by Granpappy himself, or so far cut up from a production model that it’s basically the same.

I obviously had to offer the insultingly low price of $200 – figuring it’ll get declined but I was out to spend $200 or so on something anyway. That was my second mistake.

Well, it’s the following Saturday, and my third and final mistake was complete: Renting the trailer.

 

Luckily, this thing was only about 15 minutes away by van. It was exactly as described: Covered in rat shit and lawn detritus, all tires flat, and with random parts everywhere. After looking it over, I decided… why the hell not. Worst case I attach two Overhaul motors to the drive wheels and make it remote controlled.

Vantruck carries my “yard wreckage recovery kit”, so I just busted out the tire filler and proceeded to fill up the drive tires. Sadly, the steer tire was completely destroyed and would not fill.

So the seller towed it out of the building with his truck and helped shove it into mine, which was a fair ways away since I couldn’t get right up to it and turn around.

 

By the time this process was done, the rear wheel was definitely quite sad. Look at those rear forks and bracket it rests against – that’s solid 1/2″ and 5/8″ thick steel bar!

We’ve returned to the #RobotTrapHouse now with my absolutely HOA-terrorizing long unkempt grass. I decided that since it was still bright and early (for me… so, 3PM) and with the summer yielding plenty of sunlight, I’d try to get it running and drive it into the yard for more work and repair later.

(Note: This area doesn’t have an HOA, but again, everyone else does keep their yard nice and clean so I might as well give a superficial attempt)

First order of business was taking the rear wheel off. A nearby tire shop had a selection of lawn tires also, so I asked for them to put on a replacement. I’m used to non-automotive tires being split rims that use inner tubes, but it seems this thing is Pro enough that it actually uses one-piece tubeless wheels, so I couldn’t pry it off myself. Fancy!

As I worked on it, of course, I started doing research on what on earth it was I actually bought. Why didn’t I do this beforehand, you say… well what’s the fun in that?

So this thing is a Yazoo Master Mower, built by the Yazoo Manufacturing company out of Mississippi. Yazoo has now reached semantic saturation for you and just sounds funny. Yazoo.

It seems to be good ol’ redneck ingenuity sent straight to production, which was exciting. The company appears to have made some legendarily durable/serviceable commercial and consumer lawn equipment into the 80s when they merged with another company, and the bloodline today lives on in Husqvarna lawn and garden equipment.

Judging by how many “THIS PRODUCT IS UNSAFE” stickers are on it, it’s right in line with my interests! This is how all products should be made, by the way. The goobermint can set safety bars, but you should be able to voluntarily not abide by them. If I then buy your brightly labeled unsafe product because I think it’s cool, then that’s kind of on me, no?

 

Look at this wild drive belt. Just look at it.

The major innovative feature of this transmission, apparently fully built in-house, is that it contains a set of double clutches with reversing gears. One lever will flip it between forward and reverse not by crashing gears together, but just by engaging the clutches. The rear wheel steered like a forklift and allowed a near-zero turn radius. I know nothing about the lawn care industry at all, mind you, just that this is dope. The only thing they couldn’t do with this transaxle, it seems, was make it take a sideways input shaft. Instead, we have Pretzelbelt here.

Here’s why I like maintaining a real website. I discovered someone else has a website about servicing and modifying this incredibly obscure, niche piece of equipment that I bought without much planning. I get e-mails all the time from people who bought some obscure, niche piece of equipment and then it turns out I dissected it or fixed it up on this very website, whether that’s random scooter motors or the Ryobi chainsaw or even up to the giant Surplus Center gearmotor. I have apparently sold people on getting their own piles of Chinesium because they read about it on this website.  At least one person got a Mitsubishi van project because of all the posts about Mikuvan showing its ins and outs.

This is the kind of thing that is very hard to do with contemporary social media which is very focused on The Now and not The Later. Even Youtube videos are hard to search through since you have to remember what video title contained what content, at what time, and if the user account got hard-canceled by Twitter or not.

Interestingly enough, while looking it over harder, I found a very faded decal from a local lawn equipment service company. They’re not far away, and are still in business. It was very tempting to tow the thing right then up to their door and make it their problem again.


It was getting late in the day now, and I couldn’t get the thing to really stay running. It would happily run if I fed it a steady trip of starting fluid (ether), and did independently run once for a short time. It seemed like it was having fueling issues – fuel was getting to the (oh no) carburetor, but  seemingly not making it out. I figured it was just full of grunge from sitting in Granpappy’s shop forever.

Either way, it was getting later in the day now and I had to return the trailer, and I hate carburetors. I decided to just drop it off in the covered carport for later perusal.

Off the trailer it goes! I just pushed it to the edge of the ramp and let gravity do the heavy dropping. There was enough drag with it in gear and with all of the small idler wheels that it took some more pushing to even get it all the way off the ramp.

This is a carburetor. I hate it.

I was about to see if anyone made retrofit fuel injection systems for tiny engines as I took it apart. Anyways, fuel comes in the top left hose, some magic unicorn thing happens, and it exits in the airflow stream of the intake. The big lever on the horizontal runner is the manual choke, and the little stepped lever behind and under the whole assembly is the engine speed governor, which I learned pulls against your speed setting cable as the engine speeds up and therefore closes the throttle slightly to keep the engine speed steady. The uppermost twirly-gig with the adjustment screw is actually the throttle flap itself.

I began removing screws and separating the components. I couldn’t blow through the fuel inlet, so something’s just not passing…. gas

It took a while of friend consulting and fiddling for me to figure out what was going on. For one reason or another, the carburetor float (the brass soldered donut, which is hollow) and the needle valve it actuates was either out of position, incorrectly reassembled by someone, or was bent out of shape, because in what should have been a fully empty position it was barely letting me blow through the needle valve. Only if I let it hang down to a physically impossible position if assembled was it freely flowing.

Obviously this is going to mean almost no fuel enters the float bowl. I otherwise couldn’t find any “gunk” from it sitting.

I had to bend down the Lever of Needle Valve Actuation a fair bit to achieve a state where it would admit fuel in a physically plausible location.

 

Well it’s all put back together now, everything’s lubed up and resealed and freely working, so let’s just turn the key and see what happens.

And there we have it. I moved the vans far out of the way so I could practice driving a bit. This thing is weird. First, I’m not used to driving a lawn mower/tractor where you set a speed and aren’t really manipulating the throttle all the time. You really do drive it with the forward/reverse clutch lever, and it will reverse hard enough to throw me off the seat. What else throws you off the seat? Doing a hard zero point turn by swinging the rear-steer all the way! Everything you do seems to be ejecting yourself. No wonder they said it’s unsafe!

But fun? Very.

Now with it running and driving, it was time to make some other facility improvements before seeing if it’s good at its One Job.

First of all, like every other thing I’ve bought nth-hand, the wiring is atrocious. I repaired the positive side by cleaning up a lot of the corroded terminals and lugs, and ran a new ground wire to the battery because the existing one was just completely hopeless. It started far more enthusiastically afterwards. There’s not much wiring on this thing save for the starter/dynamo circuit and the ignition circuit.

 

The deck seemed to run fine, so I decided to just untangle and clean it out. While doing so, I pulled out this old ‘murican flag, covered in plant grunge and reeking of rat urine.

Guys. It emitted an American flag at me.

This is how I’m making America great again.

Notice the deck is lifted up by a jack here. I elevated it further with a chunk of 4×4 wood (leftover from workbench construction) so I could get under and inspect the blades and spindles. I couldn’t back off the spindle nuts to put new blades on, so for now, I did an in-place sharpen using an angle grinder.

The two large springs in the front counterbalance the deck and allow you to use a lever on the side to raise it slightly. With one spring broken, lifting the deck was kind of hopeless at my scale of force input. I’m sure a burly 300 pound gardener could do it just fine still, but I ordered replacement springs from McMaster the day before. They’re a bit weaker than needed, since it still takes some serious lunging effort to throw the lever, but at least now it’s plausible.

…and its first cut, one week after the purchase.

Okay, I’m not even. Even what? I dunno. Not mad, not glad, not sad, just d a d.

It’s been clean over a decade since I’ve cut any kind of grass, and I must say this …. device made very short work of it. And this was with crudely angle-ground blades in a position I could barely see what I was grinding!

It was hard to track straight since the forklift wheel had a lot of slop in it. relative to the steering wheel, even after I tightened the connecting #40 chain between them beforehand. Inspection revealed either a mostly stripped keyway or broken weld, so I’ll have to take it apart some day and bang it back together. Once I got going pointed in a direction, it was fine, but the corrections needed every U-turn needed getting used to. The top speed isn’t much more than a brisk walk, which is just fine by me, as I am not yet trying to race someone else’s lawn mower.

So afterwards, I gave it a good wash and blasted all the remaining grass grunge off the rider deck. I think I’m going to get a racing seat for this thing, as it absolutely needs bolstering. I’m not sure if you were supposed to anchor yourself from being obese or throw a ratchet strap on yourself or what, but the hardest part by far was just staying on the damn thing.

As a finishing touch, I was informed by a friend who used to be an actual lawn professional that the two mysterious forks in the front were for a roller to intercept obstacles. Not knowing what model roller would fit on this thing, I decided one round plastic thing was the same as any other and just 3D printed one in approximately the size and shape needed. The ridges aren’t for anything special, just adding more radial stiffness without having to make the thing solid.

And that’s it. With minimal fuss, crab-mower has done the lawn every 2 weeks. With fall and winter now approaching, I’ll probably lube and tune everything and tuck it away fairly soon. It was an interesting little distraction, a week-long dive into yet another obsolete technology. This and much more will come soon in the Summer of Ven post series!

 

Robot Ruckus at Orlando Maker Faire: How to Somewhat Scale-Model Test Your BattleBots

Dec 21, 2019 in Events, Overhaul 3, Überclocker 5.0 - 30Haul

Hello everyone. Here’s a photo of Überclocker 5 experiencing Waffle House for the first time, alongside Earl of Bale Spear team, who makes a better “BIG CHUCK” figure than I ever will.

Let that image never fade from the collective knowledge of mankind.

Anyways, as Robot Ruckus approached, I had to figure out how to get my bots all the way to Florida. Taking a week or so to drive there and back was kind of out of my realm of possibility at the time, so I decided to run a little bit of a relay race with the HUGE team.  They’re in Connecticut , which is either a suburb of New York or Boston depending on who you talk to.

I delivered Sadbot, Clocker, a tote of spare parts, and a toolbox to them one fine Sunday afternoon. They were then going to drive everything – Huge included to Earl in New Jersey (if you recall, Earl also brought Overhaul to Battlebots in 2018!) upon which he will travel to Florida. So after the delivery, I had plenty of time to do Other Stuff before flying down to Orlando.

Upon my arrival, I obviously had to grab a rental car. I figured that I’d get the shittiest econobox possible since I wasn’t going many places, just to the event and a hotel room. Well, when I got the reservation and headed over to the rental car garage, it turns out the company was out of shitty econoboxes.

So what now, do I get a free bicycle instead? Nope. Free upgrade time! The garage handlers throw me a key fob which I assume was to the small dorky crossover nearby.

Nope, behind that:

Thanks, I hate it.

Let me be very clear: I’ve forgotten how to drive. No, not in general, but remember what I’m mentally calibrated and trained to for years: Being high up and on top of the front axle, and having a very short or nonexistent hood.  THIS WAS NEITHER. You cannot see out of these. Not out the sides, not out the back, and barely out the front.  I guess that’s the trade for prioritizing looking cool and edgy. For yours truly, stepping into any modern car requires some zen and meditation, and a constant reminder that I now have a front.

I am always terrified of automatically failing over into “van mode” while driving anything rental, and going full Unintended Acceleration into a store or dumpster or fire hydrant as I try to park 1 foot away from something.

How fast does it go? Greater than Van. I dunno man, I don’t have a good sense for How To Fast. My friends who work at GM (who had to listen to me complain about it in real-time) said it likely has the rental-car spec turbocharged 4-cylinder Ecotec engine, which may explain why I was experience what I swore was turbo lag, but more likely might be several inter-related drive feel variables like any economy modes it was stuck in.

2019 Chevrolet Camaro: Faster than a 1986 Ford Econoline.

 

Also, this interior panel fell off while I was heading back from the event at one point. It snapped back in, of course, but seriously?

The trip from the airport to my hotel was made in complete darkness, in the rain. Great. So I’m sitting 2 inches off the floor behind 8 feet of snout, unable to see anything, trying to figure out why every new car is a forsaken spaceship simulator inside, and mingling with other equally lost tourists trying to figure out their own rental cars on the fly. Through several construction zones, to boot. I guess I’m glad I went ahead and got the full-plausible-deniability add-on.

When I arrived at the event the next morning, I found Uberclocker like this.

 

Aaaaaaaaaaaaaawwwwwwwwwwwww. Earl took it in a South of the Border restaurant apparently, and they had these convenient accessories available.

 

I unloaded totes and began setting the bots and infrastructure up for safety inspections.

Sadbot

Sadbot was up first against the multibot Crash and Burn, built by Fingertech Robotics (incidentally, a Ragebridge dealer!) and which has done very well at Robogames events. They were running in kind of a reduced functionality state for this event, so it was more or less a pushing match. Sadbot is obviously a great shape to get pushed around, so it went about as expected with the exception of me getting a few good shoves in. At one point, I took a huge gouge out of the railroad tie side bumpers with the log splitter tip. It definitely did its job.

In the first 30 seconds of the match, the lifter controller popped. Uh oh!

 

It was a pre-production 12-FET brushless Rage board that I pulled out of a bucket labeled “SAD RAGEBRIDGES” and wired up. I probably deserved this.

It would appear I neglected to solder some of the pins on the MOSFET packge. Quality control! That probably popped as soon as it saw any heavy load. I replaced it with a “production model” I brought along in the pile of Equals Zero wares.

What’s more important, though, was the powertrain holding up great for that entire match of me running around and into things. The C80/100 drive motors were lukewarm, and so was the aluminum heat spreader plate in the electronics deck. And even better? I loved driving the damn thing. I mean, saying it handled like Overhaul 1 would be cheeky. Obviously from the video, I took a while to get re-engaged with bot dynamics. But afterwards, it felt like driving a big 30lber, which is my desired effect. Big wheels and conservative gearing seems to be holding up so far.

Sadbot’s next match wasn’t going to be until Sunday at this point, so I decided to take the opportunity to go to Home Depot and grab some….

…masking tape, a big wire brush, and some spraypaint.

This thing has always needed a paint job, and I wanted to paint the frame pastel purple to match the Miku blue and pink attachment aesthetics. Well what better time than now? It was a bright and only somewhat windy day outside and around 70-something degrees. I brushed off the accumulated rust and grunge on the outside and had at it. Paint+Primer, you say? I dare you.

So there you have it. Sadbot will be purple from now on.

My next match was against the other multibot, Macaroni and Cheese. The matchups are “DETERMINED RANDOMLY”, or so I am told. Maybe the random quantum computer just really likes seeing multibots get thrown around.

I went a little more hard-headed in this match with the added confidence of the previous fight, more actively chasing as well as trying to back off from engagements. I stayed to a “I weigh more than thee” strategy instead of trying to capture with the pokey dingle, and managed to drive both halves in the wall a good few times, including propping them both up by the end.

One of these power charges had the unfortunate side effect of making Sadbot somewhat droopy.

Ah well. This match was a much more aggressive one from the stick perspective. I purposefully drove like the maniac I should be driving like, to see if I could get anything to upset itself. The motors got warmer, but not concerningly warm, and I unfortunately neglected to take a controller temperature.

I asked Earl to use Farmer Force™ to straighten out the pokey dingle a little – the upside of it being slightly bent was it at least touched the floor.

 

Sadbot’s final matchup was against Kraken, the actual BattleBots entry. This was finally a chance to drive a match against an opponent of equal weight, and what an intense driving match it was – I went full hard as if it the Giant Nut depended on it. This thing also perfectly fit in Kraken’s trap, as I found out. I kept the pokey dingle at a height to engage Kraken “in the jaws”, and did it once and drove it into the corner. However, once we recovered, Kraken got a better bite on the lid, which led to…

Oops. That’s the outrunner’s wires getting squashed into the rotor. One of the downsides of using external rotor’d motors is you have to pay a lot of attention to where your wires are going. It would have been better to make this a side-exit mounting instead of top-exit. Overhaul, if I keep this drive setup, will definitely have an external shield over the rotor to prevent this.

The wires took a little while to get chewed through, during which it was shooting sparks out the side of the bot which I thought was the controller exploding. I lost this side of drive around 75% of the way through the match, so had to play defense and pivot to keep facing Kraken. Anyhow, I couldn’t find any explosion signs on that Brushless Rage, but I also didn’t feel like repairing this at the event after the Heavyweight bracket ran out of time – originally, each bot was supposed to get 4 matchups, but only we had three in the end. This will be a forensic investigation for later!

Überclocker

Clocker got off to a …. great? Memeful? start by fighting “Marty”.

I’m going to let the video explain itself. Well, I found out it’s definitely front heavy, but it’s also compounded by the fact that Marty is enormous. I also found out this match that Clocker gets stuck on the floors very easily here – they’re plate steel laid on wood foundation, and definitely were shifting around as the event wore on. That’s one of the foils to having a super low wedge in BattleBots – the arena floor will only get shittier, and you’ll definitely regret missing your charges. It’s a tradeoff – possibly get stuck or bounce off a seam, but have weight on the ground.

After I parked the bot at the end of the match, I noticed when picking it up that the lifter was actually seized. What on earth?

It would seem that I #HardParked it maybe a little too much, and the P61 bent in half.

Uh oh. This is maybe an engineering oversight, but the failure mode is also a little infuriating. See, the P6x series shafts neck down to 10mm no matter what diameter you order them as, to pass through the bearings which are of limited size to support the mounting hole pattern. They’re also made of stainless steel.

 

This last part I don’t really get, but basically the shafts are rather soft. So once the preload on the screws is overcome, the whole thing will buckle. Maybe I should have secured them with a 2nd plane or backup plate of some sort. Or maybe I should have used a face-mount technique instead so there’s no “gear climbing” force. Or maybe…

Okay, whatever. I didn’t need the full torque that the 45:1 ratio was going to give – I more did it for a limited lifter speed, but I suppose that’s why I took the care of engineering clutches into Overhaul, and Clockers Past, so it didn’t consume itself.

That’s why you might have noticed the bot split in two for service during Sadbot’s segment. I managed to get a P60 from another team that was the 16:1, two stage ratio, so I had to fiddle it into the bot. This involved cutting the height spacer down in length because the mounting pattern changed. Luckily, I anticipated something dumb like this happening, and the bottom rail has both the 2:1 and 3:1 pattern.

The only downside of going 16:1 is the lifter will be almost hammer-speed. But this could be entertaining in its own right!

Clocker’s next fight was against Ascend, a very powerful 30lb pneumatic flipper. This was going to be a durability test!

It was hard to get under using conventional means, so I mostly had to drive around it and hope to catch it vulnerable post-flip. I also spent an infuriating amount of time trying to get out of a floor seam.  Clocker went flying several times in the fight, which was the shakedown test I wanted.

Near the end, it got stuck upside down because the retaining bolt for the lift axle on the left (gear) side actually backed out and fell out somewhere!  So the gear just skipped as I tried to put it back upright. I managed to get one good grab-and-lift and a couple of other pushes, but didn’t prevail in the decision.

What was cool was I actually got a wheel nibbled off from a direct flipper shot in the first 30 seconds, then drove the entire rest of the match on 3 wheels. Just fine.

This was very exciting. To me, this means if I can keep the chain and inner hubs on, I can treat the wheels very disposably. Not that I’d do it as an explicit tactic, but as get out of jail cards if the situation forced it.

In Overhaul, I’d likely keep the inner wheel tightly retained while the outers are left to float on plastic/shear-rated hardware. I have a few ideas of how to do this for Clocker itself come Motorama.

Another downside of just coupling your actuator to the bot lazily: When your actuator suddenly has 3 times the power, it’s gonna start consuming itself! Remember I put a 42mm brushless on the leadscrew drive instead of the usual 500-class drill motor.  Overhaul has a dedicated trunnion on the lift hub, this is just me not wanting to bother redesigning everything after the lift gear to use a 30lb-scaled one.

The lift motor didn’t blow itself up this time, and in a way I found the lessened torque to be more tolerable. I still clearly had grab and lift ability, but now with the weight of the bot having more leverage against the motor, I noticed I could “trim” the bot better in that match. I’d stick-down just a bit, and gradually the thing finds its self-levelling point. I could then periodically stick-down to refresh it, in a way.

All patched up after wheel service.

Clocker’s 3rd and last fight was against BEEESS???!! (You must only say its name with the upward questioning inflection). I found it hard to get a grab on with his defensive tines sticking out everywhere, so this match was just a lot of driving practice.

And that’s it. Sadbot came away 1/2, and Clocker ended up 2/1! After the event was packed up, I sent the bots back up north with Earl and picked them up from Connecticut again the week after.

Well, not before getting up to some shenanigans in the dark behind the building.

Sadbot, being “Extremely robot shaped” as we termed it, was used as a test dummy by a few teams with lifters/grabbers. Here is a future possible BattleBots entry, Claw Viper, tuning lift motor settings using Sadbot as a dead weight.

The Real Giant Nut was the Lessons We Learned Along The Way

So I’ll do a  more in-depth discussion of the implications for Overhaul separately as its own design series. But here were my two biggest takeaways from this event:

  • If I can make the equation “Overhaul 3 drives like Sadbot drives like Overhaul 1″ work, then I feel far more confident bringing sexy back in the arena. I’m satisfied with this powertrain setup, consisting of the single 80mm brushless motor on a Brushless Rage, geared conservatively for about 13mph, and back riding on big blobby wheels.  What I’d probably do is use this as an initial design path, but have a failover ESC solution (VESC controllers have grown up a lot in the past 2 years) as well as a failover brush DC solution. I have some candidates in mind for the latter which I tested over these few months and think are a good idea. More on that later!
  • Clocker was a great architectural test beyond what I intended to accomplish. I definitely wasn’t counting on losing a wheel here! The bot was vastly easier to maintain, even replacing the lift gearbox with a different ratio. I now know that the frame should get longer to better grab and lift – part of the issues stemmed from having to move the front wheels so far back. The small poker wedge legs worked out reasonably, but I’d probably want to make several kinds because of the arena floor. There’s only minor changes and mods I want to make before Motorama. For one, it needs to test the DETHPLOW architecture for Overhaul, and maybe implement my 2-stage breakaway wheels.

One thing to note about Clocker is that I should have dropped the Angerbox clamp drive system to a single stage. I’ve basically done away with the requirement that either Clocker or Overhaul can crush stuff. The clamp should therefore be fast to close, something it wasn’t really at this event. Clocker and Overhaul will likely run single-stage gearing into their clamps for future events.

Between these two major differential tests, I think I have a good handle on what Overhaul 3 has to be.

Namely, it should be Sadbot, but with a grabber and lif….. wait a minute. #holup I swear I’ve built this bot before.

 

Überclocker 5: Finishing Up The Everything Else

Dec 16, 2019 in Überclocker 5.0 - 30Haul

Last episode, I had just finished machining and assembling the frame. As I said then, it felt a little wrong. Almost too simple compared to my usual. Well given that’s one of the major directives of this build, and for Overhaul 3, I’d better get used to the feeling. So with the aluminum machining taken care of, it was time to do some welding and final assembly.

The new leg design is almost 1 for 1 what I want to build for Overhaul. Its armored pontoons were a good idea for some forms of kinetic energy weapon dispersal, but weren’t very good at wedging otherwise. Last season I made the “stiletto” versions for matches where having broad surfaces against the ground would be a liability, but the way it mounted to the bot was still predicated by the angled wubbies. I could adjust their ‘preload’ into the floor with washers, but this was permanent (for the match duration) and they actually would impede the bot’s motion by slightly lifting the front small wheels off the ground. There’s really no substitute for a good set of hinged wedges that will always conform to the floor under gravity. I’d eventually want to redo these plates from an alloy steel like Hardox or good ol’ AR400, but for now, a surplus piece of on-hand 1/8″ cold roll steel works too.

Initial tack welds were laid down the parts as-fixtured, then I’d remove the leg itself and add a dab more weld bead. The design was specified for approximately 4mm gauge AR steel, but using 1/8″ cold roll meant there was a lot of placement slop, so I’d rather fixture as the parts were going to be used.

Top side in progress, mostly done.

And then backfilled from the underside. I then ground all four undersides smooth, and painted over the legs and mounts in black.

While the various painted parts are all drying, onto assembly work.  There’s a series of little spacers that have to be installed for the wheels to attach at the right distance to clear the drive chains. Not the most elegant approach, perhaps, but one that was workable given the commercial nature of the parts. For Overhaul I’d have custom hubs with the correct spacing already designed in.

On the inside, a series of washers to hold the hub face on. Another slight point of tack is to put the wheels on, you really need to remove the outer “hubcap” plastic Versahub because otherwise there’s no easy way to line everything up looking through the 1/2″ hex bore. A minor complaint, and really I could just put a plastic circle piece here instead of the Versahub.

Well, it has wheels now!

The lifter motor is suspended off the lower plate by a large gearbox-shaped spacer. It’s a bit of an overconstraint with a fixed bearing in the frame rail; same with the external bearings on the drive motors. Overhaul will have these be isolated systems with flexible couplings like I have on the existing lifter design.

 

The lifter fork and clamp parts all slide onto the main shaft one by one. The dead shaft does allow this thing to be far more serviceable than Clockers Past.

Once the three crossing tie rods and spacers are tightened, the assembly is rock solid. Unlike Clockers Past, the only method of force transmission  from the lift gear side to the “drive” side (right hand) is through those three interspersed tie rods. With the live drive shaft, both forks directly received motor torque. Now, My Calculations Show™ that the rigidity is adequate even picking up a 30lb opponent entirely on the right fork.

Overhaul already has a method of through-transmitting lift motor torque in the form of the big hollow hub the arms sit on, so the considerations there are much different.

Support legs all installed and tightened. A shoulder screw whose shoulder is the length between the hinge sides gets tightened down, and that’s all.

As I expected, this thing is really front heavy. The CAD model doesn’t quiet show it all, even, because it’s a static representation. With nothing in the back, the bot tips forward on its two front wheels immediately.

There will be things in the back, of course, and the final design showed I could possibly have a 3 pound counterweight spanning the back frame rail.  We’ll see how it ends up. I also suspected that the bot will drive very differently depending on how squished the front wheels are (i.e. how much downforce is placed on the arms).

One minor “oh yeah, I modeled that” as I mounted the drive chains: I specified flat-head screws for most of these frame connections, but to do waterjet layout when I wasn’t the one using the machine, I had to make a configuration of each part with the countersink diameters suppressed.

Then I promptly forgot I was supposed to use flathead screws, so installed button heads. This works fine for every place that doesn’t have a chain run next to it, of course, so I didn’t even notice until now.

Ah, that’s much better.

Electronics installation goes quickly, but first, I needed to throw things inside to get wire run distances.

Another “PM Charles” habit I learned and now don’t feel right without: I even created a wiring diagram for this thing with gauges, connections, and lengths before I cut a single piece of sumptuous silicone-insulated ultra-flexible noodle wire. And labeled every cable as I made them.

(As wires get into the multiple-0 gauge, they and their connectors begin getting more and more sumptuous as well as expensive if you fuck it up)

I avoided making something intelligent like Super DEANSBUS and instead just went for the good ol’ Hong Kong Soldered-Shrunken Squid. I only needed four ESCs and an auxiliary connection (for receiver power).

Prepped and ready after a couple more hours of soldering. I’m very much now used to crimp tooling and contact systems used in commercial/industrial connectors. The R/C world really needs a “crimpable bullet connector” of some sort (And I don’t mean these trash-tier things), because solder cup filling for dozens of wires just takes so much manpower.

And here it is!

I was very much right when I said it would drive differently depending on if I had the arms down or up. If the arms are raised, the back two wheels basically aren’t there – it drives like a 2WD bot and is almost too squirrely. Overhaul 1 had similar issues, but the long triangular pontoons damped it a lot.

However, if I drop the arms down and preload them into the ground even a little, it will transfer some weight to the back wheels, unsquishing the front wheels just a little. It gains 4WD-like traction, but still puts substantial weight down on the forks. I actually managed to accidentally sand a good mount of the forks off on the bottom driving around in the rough concrete area of the shop.

This is a desired result. If I make sure Overhaul can sink down a good half inch or so in the front when the arms are raised, it means I have a fairly large band where the arms can be down and the bot still retain full traction. OH2.x wasn’t capable of this – the small wheels deformed so little that it propped the front 4 off the ground, making it act like a front-dragging 2WD bot.

On my mind now is a good way to make an easily adjustable travel limiter so I can, if need be, just slam the arms down without having to modulate them carefully. On this bot, if I drive them down too far, I can get it to start behaving like OH2.X – turns become more difficult and less predictable as the rear of the bot is trying to pivot around a drag point in the front.

The final weigh-in is pretty much on the money minus the weight of the wires, which I didn’t put in a simulated blob of copper for. The CAD weight was 26.7lb. Looks like either way I’ll have around that 3 pounds to play with to install a counterweight on the back plate!

Stay tuned for some exciting Orlando Maker Faire coverage, where I’ll get to find out if everything is wrong.

Überclocker 5.0: In Which I Actually Have to Build the Bot, Not Just Talk About It

Dec 11, 2019 in Überclocker 5.0 - 30Haul

Here, have an Überclocker kit. That’s it. My job is done and I’m going home.

Hah – funny story though. The past 3 generations of Uberclocker were actually ALL sold in the end to other builders. That’s right – before this build, I didn’t possess a single one of them. They were sold in various states of disrepair, of course. But sadly, I have yet to see any of them back in the arena, or face my own follies.

By the last week of September, this was the pile that I’d collected. The last head assembly is just for show – it was a spare made for the previous bot (Uberclocker 4.0) and is damaged in a couple of places. I’d gotten orders in for motors and pulled a couple of other Clocker 4.0 parts out of the organizer. A lot of this will see reuse intentionally.

Putting together a wheel assembly revealed that the Vex aluminum Versahub downloadable model is WRONG! It shows up as a flat face on the oberse, but in reality, has a shoulder that is larger than the 1.125″ on the other side. Vex uses 1-1/8″ as the standard because it also happens to be the outer diameter of a Type R8 or FR8 bearing, a very common bearing size.

So I had to turn the short shoulder down to 1.125″ in order for it to actually fit the plate sprocket. No biggie, but hey, update your damn CAD model.

Notice how the wheels are mated together – they have the previously mentioned #8-32 standoffs crammed into them. If I trusted friction enough, there isn’t even a need to have something on the other side. These were rather tough to press through!

One of the plastic Versahubs caps off the outside here. The whole assembly slips on to the P80 keyed shaft and is retained by the shaft’s end-tap screw hole and spacers.

That’s it. What? I made a drive system that’s one gearbox bolted to one wheel? On purpose? Boy, haven’t done that in a while.

The P61 gearboxes assemble almost directly onto the Sk3-4240 motors using the Mabuchi 775 motor mount kit. The shaft is too long by about 6mm however, so I had to trim all of them with a Dremel disc and cleaned up on the belt sander.

I printed off a couple more of these “Angerboxen” as I call them, which have been a staple of my bots for a few years. They’re based on a design I made all the way back in high school (with less tools) and carried through to bots like 12 O’Clocker, and then a spare motor from that made it into Uberclocker v4.

They’re just repackages of generic single speed drill gearboxes into a 1.5″ square profile, compared with their usual 2″ funny shapes. This will be the first time I cram a brushless motor into them, though. For the sake of convenience and expedience, it’s easier to keep this bot all brushless instead of make room for a brushed Ragebridge. Previously, Uberclocker 4.0 had a DeWut for the lift and a 550 size drill motor for the clamp, so it made sense.

I picked up a 4.95mm reamer to bore out some spare drill pinions (I have a 10 pound bag of loose random cordless drill guts) to turn them into pinions for the SK3 motors.

And here it is ready to close up!

…and a day later, after a quick redesign.

 

You see,  the SK3-42mm motors are bigger in diameter than a 550-size drill motor. Not by much, but by annoyingly enough that I could not feed one of the threaded tie screws in from the motor side.

I ended up changing the design up to have the tie rods enter from the front, basically making this an ersatz P60/61 gearbox. I mean, at this point there’s no real need to have a custom design and I might as well do an “embedded P61″ like Overhaul had the P80 integrated into the clamp motor. But this setup is lighter and already designed in, and it was easy to replicate.

I added a set of 2 smaller holes in the center for a Mabuchi 400 size motor. This faceplate mount is often found in the smaller 28-30mm brushless motors – if weight got out of control, I could quickly drop the motor weight in half by going to one of them. I don’t need the full power of a 42mm brushless on the clamp arm anyway, but it was there and easy.

All of the subassemblies and components are starting to come together now. If there’s one thing that 1. Building Overhauls and 2. Doing Massive Drone Startups have taught me, it’s always just pipeline spares if you have the materials on hand. You will need them sooner or later, whether gust of wind or gust of Tombstone.

The lift arm shaft, unlike Clocker 4.0, is now a dead axle like Overhaul. I wanted to ensure the less complex box frame had more members to tie it together side to side. Pretty much every Clocker Past has had a live axle to let me easily turn a shaft collar into a torque clutch., but for this one I’m doing it dirty! Shown here are a bunch of spacers to keep the arm elements at the right distance apart. The shaft material is McMaster’s “ceramic coated aluminum” shaft material. Easy to machine, but you have to break the ceramic coating which is actually fairly tough. It will eat regular steel tools, but carbide will defeat it.

After the first week of October (Well, there goes Franklin Institute), my waterjet parts arrived from a local vendor. I dropped off material the week prior, so an average turnaround time, plus picked up a handful of company parts while I was at it.

This was enough parts for two bots except the frame, which I figured wasn’t going to get trashed at a Sportsman’s Class competition like Robot Ruckus, so I decided to not incur the extra cost and the having to order additional material.  I’ll do this for Motorama instead, where I plan to enter Clocker into the full combat 30s.

Checking off your own fabrication prints is always satisfying. Maybe just left-over project managment energy in me, but this is definitely my most documented and organized bot in years. Having other people needing to read your thoughts and intentions clearly in mission-critical systems is something I’ve had to get used to in the past 2-3 years, and I most definitely learned a ton from other folks at the company with more extensive industry experience.

(Not to say these are remotely version-trackable and custody-chain verified prints…)

I even back-added the “live edits” into the drawing files and annotated the CAD model. Oh, the horror.

 

Both Uberclocker and Overhaul make extensive use of these 12 pitch, 12 tooth, 20 degrees P/A stock spur gears. I made a point of just ordering a half dozen and broaching them all, because again, I’ll need these again for OH3.

Anyone ever find it funny when company logos and motivational posters show odd numbers of gears in mutual mesh?

It’s really just a Freudian slip into the culture of the organization.

Machined rear axle spindles and a test fit in a hub. The rear hubs are the same Vex aluminum Versahubs, but bored out on both sides and a type R1212 miniature bearing stuffed into the pockets. They’re retained by a big washer at the end of the spindle so will take more effort to peel off than just ripping out a set of tiny bearings. I could have gone for simplicity and done a Delrin bushing too, but a large overhung load onto the relatively short (5/8″ wide) spindles made me leery about added friction under the bending load of the bot.

Next up, frame rails that need channelling and pocketing. I knew this was going to end badly for me if I didn’t mark them very clearly.

 

They also needed the top and bottom plate holes drilled and threaded – I set all of them up at once in the mill with the same reference edge and played a bit of paint-by-numbers on which hole has to go where, making something like the world’s most impractically slow subtractive dot-matrix printer.

Invitably, I had to bum it up somewhere, and that’s being off by one edge-finder radius on an arm tower. Everyone does this eventually, no matter how veteran! So I had to slot one of the arm towers to let it actually sit where it needed to be.

The top and bottom plates are being test fit here. Overall the tolerances were alright, but they do add up, so some of the holes just barely did not align and needed to be step-drilled up a 1/32 in size. I went 1/16″ over as extra future slop insurance.

Next, the frame was set up and clamped to the table to perform the drilling / tapping operation of the front bulkhead which was just going to get line-drilled in place. I didn’t feel like tilting the Bridgeport head 15 degrees and doing those coordinate transforms to get to the hole placements this time! Stabbing straight inwards with a drill was going to be all the grace this frame sees.

And that’s it.

The frame’s now fully assembled. 5 parts for the base and 2 for the arm towers. In some ways, this kind of bulky rail construction is elegant in its own right. Clockers Past have had elaborately puzzled together plate frames with part counts that ranged from 15 to 20 or so, and Overhaul carried that over for version 2. It’s now something I aim to move away from for V3.

Next up: Filling in the other parts of it that make it more robot-shaped.

Überclocker 5.0: The Big Post of Designy-Stuff

Dec 07, 2019 in Überclocker 5.0 - 30Haul

Alright! So previously I established some of the bot’s principal geometry. Now I had to actually import more components and try to flesh it out, and make little edits here and there. Recall this was where I ended before:

I’d already tabled the idea of moving the clamp motor to the arm tower region, and the lift motor has been moved slightly forward and under the lift gear. This had the side effect of pushing the drive motor (and hence the front wheels) rearward a good half inch or so, and I was a little dubious on if the bot would have weight far enough towards the rear to lift anything.

The clamp arm (the “head” as everyone calls it) was going to stay identical to the previous 30Haul version; I already had parts to fit it, and so it didn’t make too much sense to change. This was, after all, an exercise to see if I could keep a lot of Overhaul 2.x parts the same when it comes to the liftgear. So far, I think I can keep the entire top half of the bot using the same parts, so it will save a ton of redesign effort.

I’m now continuing to flesh out geometry and adding more critical (but blank) parts. The lift gear was going to grow some compared to last 30Haul, to give it more of a ratio with the lift gear. I had a plan this time of running a 3-stage P61 gearbox and using a single larger output stage, in order to be a little more commensurate with the old DeWalt-based lifter which was a 52:1 ratio with a roughly 4:1 output stage. The plan here was for a 45:1 P61 with 5:1 on the main lift gears. The motor shaft would stick through the left frame rail some, so the plan was to put an outboard bearing in to greatly reduce the bending burden that the narrow, necked P6x shaft would have to take otherwise; that’s what the large clearance hole where the lifter gear should go is for.

The intermediate vertical bulkhead from before has been turned into a kind of quasi-bottom-plate made of the same thickness material. All 3 motors bolt to this plate with spacers between them and the plate.

I’ve fully fleshed out the drive system here (all…6 parts of it) and given more detail to the lift assembly, including generation of the arm towers which are hidden in this view.

The Wall of Wub positioning was going to be two large groupings on either side to accommodate the legs Uberclocker is known for (which turned into the wedge pontoons on Overhaul). I also made volume claims for the center shock mounts when 30Haul gets its very own DETHPLOW.

I just imported a 30haul old arm in for geometry and visualization purposes. At this point, the bot’s CG was already very close to exceeding the front wheel line (a.k.a it’ll always tip forward). The height change of the main lift axle meant the forks themselves had to be shorter with a more severe curve. I decided to start over instead of trying to change the geometry of the existing arms, because there was something else I wanted to try.

One of my perceived flaws of the Overhaul lifter fork design is they’re still rather wide at the tips. I wanted the lateral rigidity there, but it did mean if the arm tip got bent up it was hard to get under someone with it ever again.

My bright idea for 30Haul, which would be equally reproducible for Overhaul, is to have a main plate member that is extra thick and rigid, but only have its thickness sticking out as the attack interface. Something set a little more inboard can provide the overall side to side rigidity.

For 30haul, this meant I was actually going to make each fork from a solid backbone of 1/2″ aluminum. We start with the basic dropdown shape which will clear the frame. I made some push and pull adjustments as I went, since I wanted the arms to descend down quickly, but shouldn’t cut away too much of the front frame rail.

The upper curve is generated with some tangent arcs.

And the bottom curve just follows the same arc center with some more edgy features. This is actually how Overhaul 2.x forks were all generated too!

I smoothed things out and added some thru-spacer holes as well as bolt circles.

Check out that arc of 5 holes that runs roughly down the length of the arc shape.  This is what they’re for:

Instead of discrete standoffs like last 30Haul, I’m going to be using a single solid plastic spacer between the inner and outer fork. The discrete spacers were fine for 30lb Sportsman’s Class duty. But they just entered Full Dab mode under any significant side impact since the standoff thru-bolts provided bending axes!

The idea of this fork is the thinner reinforcement plate and the thicker main plate are supported full-contact with the rigid plastic insert. Hopefully, this means it will act substantially like a sandwich composite in that side bending regime, and maybe a hard smack from a weapon will introduce a bend or a bow, but it won’t just completely fold up.

I was planning on using the Markforged machines to print the center spacers in Onyx, but they could also be cut from solid plastic.

 

After specifying and adding the inter-arm spacers, the majority of the bot’s mechanical needs are done now. Seriously, there’s so little going on compared to one of my average designs.  It’s kind of a refreshing change, honestly.

I next moved onto making the basic support legs that enable the bot to grab and lift. These front legs had to be Sportsman’s Class rules compliant first, which is why I’m going for a simple fork tine-like projection instead of the crazy angled wedges.

I started with the sketch plane that’s defined off the thickness of the rubber shock mounts, and made a big plate which covers all of them.

I had a change of heart at this stage, and instead of making solid projections that altogether ride on the wubbie mounts, I decided to pursue a hinged design.

I always thought I could preload Overhaul’s wedges into the ground with carefully adjusting spacers/washers on the wubbies. Yes, I technically could, but they then weren’t far from a permanent setting anyway. I found that the previous 30Haul only exhibited a narrow range of satisfactory wedging versus propping its own front wheels off the ground.

Hinged wedges have been on the retreat in the sport for a while (albeit slowly) because of their vulnerability to getting damaged. But a lot of bots still sport them, because having something load itself into the ground with its own gravity beats you carefully applying a pre-determined force trying to do the same in an environment that can throw anything at you, at any time.

The legs themselves will be made from thick aluminum also, for this time. They’ll be allowed to hinge upwards about 10 degrees – something can get under them without consequence as long as I back off in time. Even a fixed-but-compliant  wedge would, in that circumstance, still cause the bot to lose traction in the front if lifted.

I just drew some lines that looked cool first and foremost before making the geometry compatible.

Here’s what that assembly looks like up front. Now, it IS true that having hinged elements that are also on wubbie mounts is superfluous, and I agree. If the wubbies proved to add just too much extra compliance, I was satisfied with running plastic spacers underneath for Franklin and Robot Ruckus.

A size comparison between Clockers 4 and 5 (a.k.a first 30haul and new 30haul). The new bot is shorter by a bit – maaaaaaaaaaaaaaybe even too short on the wheelbase. But it’s not outlandishly compact like I worried about going in.

Before I started on the electronics layout, I decided to put the finishing fastening detail touches on the mechanical end – Every hole got at least one sample fastener as a sanity check, and I also laid out top and bottom plate bolt patterns.

 

Up until this point, I’d actually never designed the rear idler hub. I modeled it as kind of a top-hat shaped spacer with two shoulders, one for the wheel hub bearings and the other to space it out from the frame. It would just get anchored in with an extra-long frame rail screw after the wheel is mounted.  Relatively simple and durable!

I also decided to knock off a few BB entry trends and add “breadboard holes” to the frame. Some on the sides,  as can be seen, but mostly on the back.

The idea of these breadboard holes is to be able to add attachments and defenses in a quick, reasonably strong way. You standardize on your own bolt pattern when designing these accessories. I didn’t have any in mind at the time, but it’s one of those “Boy, it’ll be annoying to drill them later” features.

 

The clamp actuator was imported from Uberclocker v4 and is almost completely unmodified except for a total height trim right next to the three small mounting holes. There was just a lot of unnecessary material here before, and this allows the actuator to be about as compact as I can get  it.

So that’s about it, mechanically, for the bot. I’m definitely not used to something having this few parts, and I really hope the design approach works for Overhaul proper.

With this allowed to rest for a while, I turned my attention to “things which hold electronics”.

I’m reusing the design of the battery tray from Uberclocker 4 with a few small geometry shifts to accommodate the frame shape of this bot. It has slots underneath where hook-and-loop cinching straps get fed through, which hold the battery down.

The “Rage-hutches” as I call them each hold two 6-FET Brushless Rages face to face stacked vertically. I found this was a convenient height – just barely under the thickness of the frame!  They’re made of 2 pieces each. One is a baseplate with mounting ears, and the other is the perimeter “U” shape with holes and reliefs for the heat sinks.

In another deviation from my usual form that I want to point out is the utter lack of small hardware on the bot now. The top and bottom plates are retained by 1/4″-20 thread size, and even the electronics mounts get 1/4″ compatible clearance holes for a nut-and-bolt interface with the bottom plate.

I’ve tended to use #4 screws – or at least very small screws – to hold ancillary parts and electronics in. One of the critical exercises we did for the company products was really trying to standardize on hardware, and after being part of that, I am keeping in mind the number and types of fasteners in use in the bot. A long time ago, most everything I made robot-wise was just using whatever hardware conveniently fit the geometry…which meant I might have needed 4 different hex wrenches to change a motor, for instance.

Working  on deployable products, plus the much higher regimentation requirements of the BattleBots pits if you actually wanted to get things done fast, have made me think of all this from the start. This bot should be serviceable for the most part with a 5/32″ hex wrench. I actually spec’d button head 1/4-20 (frame and top/bottom plate) but regular socket head #10 screws (motor mounts) because they share the 5/32″ drive. I made more use of #8-32 than I ever have before as my “small screw”, because Vex parts are made for 8-32.

And here’s the size comparison again from the top view. I was fully expecting Uberclocker 5 to not be able to drive without the opponent raised very high. Overhaul 2.x and Uberclocker v4 both have substantial front traction in the form of small wheels located nearer the center of lift. Other things of note – the inner frame rails of Uberclocker 4 are about the same width as the “Outer” ones of v5. The attacking cross-section of the bot remains much the same in terms of width and height. Really it’s those big Vex wheels that sort of make the thing look small, in my mind – the body looks visually smaller in comparison to the large wheels that poke out.

From the side, the bot has gained some height, but pretty much solely due to the added chassis height. I was able to keep the curvature of the fork tips not too severe – the taller they are, the harder it will be to grab opponents.

Overhaul 3 itself should still have a somewhat longer wheelbase and better proportions of the wheelbase x track rectangle. Remember, I had to move the front wheels backwards. By the original design, they should be very close to the front transverse frame rail.

I personally felt, too, the bot could have stood to be a bit longer even here. But, it really couldn’t get longer. Why?

If the bot went further back, the thing wouldn’t really be able to self right. I’m sure it can throw itself back over with the momentum of the lifting assembly, but I like being deterministic from the start. This was a length restriction for Overhaul 2.x also – in one swing of the forks, I had to be able to tip the bot onto its wheels again. So this means Overhaul 3 is going to have to gain wheelbase, If I so desired, by moving the front wheels forward again to where I intended them.

Next up, the initial rounds of fabrication begin!