Archive for the 'Done!' Category

 

Operation Bad Timing II: The Soundtrack – Pistons and Valves and Seals, Oh My (God Everything Sucks)

Jul 23, 2018 in mikuvan

Here we go! With the head  now off, it was time to extract the pistons and either repair or replace them while the Chinesium head was on its way. This post covers roughly the week of July 1st. The plan was to pull pistons #2, 3, and 4 out and appraise them for damage. Pistons 3 and 4 were part of the knocking-induced head gasket explosion, so they were the most suspect to me. Cylinder 2 merely showed less-than-factory compression (around 90 PSI), so I wanted to see what problems it had, and to practice my piston-replacement operations on it if need be.

The first step to being about to get to them is to remove the oil pan. Gee, this thing was stuck on a lot harder than I remember… granted, I haven’t personally opened it myself since the Great Accidental Partial Engine Rebuild ceremony, and it seems like they slathered the whole thing in silicone and slammed it on there hard. I ended up having to bend up a corner of the pan to get enough leverage to pry the rest of it off.

This corner was later hammered back into shape, but whether it’ll seal again is another question!

Ahh, we meet again. I removed the connecting rod cap of piston #2 and shoved it out the top while inspecting the crankshaft journal for any damage or abrasion.

Here’s piston #2 in all of its oil-grunged glory. I know for a fact that Mikuvan has been burning oil through the valve stem seals (at least) for the past roughly 10,000 miles, and it shows.

I decided at this point to just use all 3 of the remaining pistons in the original kit that I bought – the original piston which was replaced in the GAPER (still a very unfortunate acronym) was #3, which was one of the now-untrusted ones. Since #1 showed nearly factory compression, I was just going to leave it alone.

This meant making….

Big Chuck’s Automotive Special Tool #BCA-9001-3939-A, Mikuvan Piston Pusher. The factory manual showed an object not unlike this, which led me to conclude it was just two tubes. Well guess what, I also have two tubes and a hydraulic press. The larger tube is a 1.25″ OD thick-wall tube, whose bore I enlarged to 15/16″ to clear the 22mm piston rod, and with two notches machined out to accommodate the piston’s flat face. The tube was in fact originally bought for either creating the hubs of Chibikart or Chibi-Mikuvan’s steering uprights.

It was then easy to push the piston pin out and free it up. Part of my rage-ordering of every component I might need was a new set of crank and connecting rod bearings, and I decided to just go ahead and put them on anyway because why not, I already had this stuff out.

Essentially I was working with the assumption that everything which has touched a pre-ignition event is immediately suspect out to like 2 layers of the network away. In a way, it’s like how I repair my motor controllers: if one FET lets go, its friend on the same half-bridge is replaced, the gate driver is replaced, and all power supply components that are semiconductors nearby are replaced; after all, if you already are heating up the board for reflow, you MIGHT AS WELL.

With my post-facto knowledge, I now understand that this is a better assumption for higher-strung newer engines, or ones built for high performance and racing, in which the stakes are much higher if something goes wrong. Mikuvan’s engine is rather the opposite, an understressed low-revving truck engine which only ever made 107HP out of 2.4 liters new and had an incredible 8.5:1 compression.

My adventures consulting my vanstylists, “car guy” friends, and the Internet at large including Mitsubishi Delica owner forums/groups and reading in general about engine explosion scenarios, has forced me to conclude this: All Internet car advice is horrible and irrelevant.

You need to decide what is best for your application by Kalman filtering your own experiences in with all the differing advice you’ll get, mostly from “car guys” who insist that things must be done a specific way or it’s not worth doing at all.

I luckily have the upside of having a lot of mechanical system intuition that made me question “car guy” advice – do I REEEEEEEALLY need this? Is this the ONLY way things happen? Maybe if I actually did have the turbo Evo engine… And then some from my trusted mechanics who have in the past advised me on what I could conceivably get away with versus what would fail right away, which I was more trying to gauge. I know I’m not doing anything truly correctly, so how topologically-correct can I remain?

Anyways, in conclusion, I could have probably run Piston #2 just fine after replacing the rings, but again, Might as Well if I have the parts handy. So on a new piston and rings go. I learned a great deal about the neckeardry that goes into piston rings doing research on them; these are one of the Insta-Fail scenarios, if you put in the rings upside down or inside-out, they will not seal properly or prevent oil burning. If you don’t install them in a certain rotation (phasing, clocking) according to the factory manual, you could get compression issues right away and uneven wear in the cylinder long term.

There are just so many small details to get “right” that all affect long term operation, yet are presented to you as life-or-death scenarios, which you have to distill out for applicability.

I suppose the advice is all bent towards people who would rather not jiggle with their engine internals on a regular basis.  But hey you know what an electric motor is? It’s one round thing that spins inside of another round thing. I heard the kids are into them these days.

My “car guy” friends absolutely begged me to hone the cylinder bores before installing the pistons again. Another one of my mulling conclusions is that everyone seems to think Mikuvan is more fucked than it actually is, with talks of cylinder wall scoring damage as if I ran the thing without oil up a mountain.

I do rather think the cylinder walls were all fine, but again doing my Kalman Filter research it seems like putting in new piston rings on a previously worn-in surface wouldn’t do me much good in the long run, and buying a simple flexible hone and sticking it on a drill is not hard. So that’s what I did!

I alternated pushing the hone with spraying the area down with WD-40 (you’re apparently supposed to use a dedicated honing oil for Best Results™) while the crankshaft below was covered by a few shop towels to prevent the metal particles and abrasive dust from falling on the journals. I cleaned the journals afterwards with some brake cleaner regardless.

Using “Irritating 1-purpose dedicated automotive tool #21892″, a piston ring compressor, I loaded the new #2 piston in with a healthy dousing of motor oil (you’re supposed to use dedicated assembly oil for  Best Results™). There are SO. MANY. stupid irritating one-purpose tools to do things expediently.

I have to wonder if all this is just entrenched through generations of automotive engineering and service or if there is an actual reason there’s a squiggley-shaped object called a Distributor Hold-Down Wrench. Boy that would have sure saved me a lot of time when I was dismantling most of vantruck’s accessory belt drives off to assembly a specific order of socket universal joints and extensions to loosen its distributor hold-down bolt.

And here I thought the world of drones and 3D printers were a horrifying mess of tribal knowledge – I clearly have never actually worked on cars up until this point. That is a hundred and twenty years of tribal knowledge.

After feeling pretty good about piston 2, it was time to do the same thing to #3 and #4. I was expecting more gore here for sure.

Here they are extracted. #3 on the right was replaced during the GAPER, but it and #4 show some pretty serious signs of oil burning.

They also both had stuck piston rings, #4 moreso than #3. Grunge filled nearly the entire volume of the oil control rings, which were probably doing dubious controlling at this point. So something was bound to fail sooner or later. The further back in the engine, the more it butts up against the firewall (which is actually behind me) and presumably the hotter they get. I’d like to think this is why cylinder #1 has barely shown any problems – it’s first in line to get water, cooling air, and oil pressure.

Control-C Control-V the whole procedure – cylinder honing and cleaning, piston swap, rings, and bearings… to pistons 3 and 4 and back in they go. I figured I did it mostly right if it still turned by breaker bar as easily as it used to.

For now, I put a few towels over the whole thing and went back inside to inspect and work on the cylinder head itself.

The intake manifold is seperated from the head by a few mix-and-match nuts and bolts. This was a little weird to me, since I was expecting all studs and nuts versus half of them being hex-head screws – maybe that was factory, or maybe someone’s been in here before.

Nevertheless, this was when I discovered that this thing DOES have an EGR system. As I mentioned before, the EGR valve was always drawn in isolation with little context of where it actually was. By my guess, I thought it sat behind the cylinder head, and when I didn’t feel it there, I assumed that it was a CA-spec emissions versus REAL AMERICA spec difference. It turns out the damn thing is nested in the U-turn that the intake runners make from the throttle body. The small center tube between the four larger intake runners is the EGR passage, and it mates up with a similar passage which dives through the head and pops out near exhaust valve #4.

What?! Well, either way, this passage was very clogged – not all the way closed, but significantly. Given that I’d never had any EGR-associated idling problems, I decided to leave it alone – I just filled the whole cavity with brake cleaner and came back a few hours later to blow it out with shop air, whatever I could get was it!

The cylinder head itself was fairly caked with oil grunge, with cylinders 3 and 4 being the worst as expected.

My goal with this head was to replace the front oil seal, the eight hydraulic valve lifters (the round bumpies poking out of the upside-down camshaft on the top left), and the eight valve stem seams, which cause the oil burning and vape cloud on startup behavior. While I had the valves dismantled, I was just going to casually clean them and the chambers they sit in – casually meaning yes, I know I’m supposed to take everything off and chuck this thing in some ultrasonic cleaner filled with teratogens, but I think the application is not strenuous enough to warrant it.

This…. is where I got to use “Irritating 1-purpose dedicated automotive tool #37985″, a valve spring compressor. It also ranks as the most terrifying tool I’ve used yet, since it’s literally stamped sheet metal holding onto an angry die spring, and that’s supposed to be an okay thing. I’ve witnessed a suspension spring/strut compressor tool being used before. That is something I will never voluntarily stand next to if I can help it.

It turns out all that holds the valve springs on are these two little taper-lock bushings, literally called “valve spring retainer locks” and similar. I’m frankly amazed they don’t just shear off all the time. Once you compress the valve spring, you bean it downwards to unseat the taper lock, upon which these little halves fall out. Whatever, I’ve already suspended my belief that combustion engines are actually things that work okay for long enough, let’s continue!

 

Yes, the valve stem seams were all very crispy. On the left, a new one. On the right, the hardened and bloated lump that was in it. Sure as hell not doing any sealing, as all of the valves came out with very oil-covered stems and backsides.

I’d also noticed some mild leaks on the camshaft, which is explained by its own hard-as-a-rock seal on the right.

In dismantling and cleaning the valves – mostly wire brushing with some brake cleaner love – I found the reason for cylinder #2 showing slightly low compression: I had a cracked exhaust valve. Very unfortunate, as this means I can no longer just put this head back together. I immediately jumped on eBay and searched down some new-old-stock valves. No matter what, it means a delay in putting things back together.

I was otherwise going to replace ONLY this exhaust valve – I figure all the other ones have already met their own valve seats for a long time, and redoing all 8 would involve having to clean and re-grind the valve seats also. By this point, too, I was also getting tired of the dozens of minute small manufacturing processes that all have to be done and special tools that have to be used, to make things work “correctly” – I wasn’t planning on performing the valve seat grinding/polishing operation at all on the replacement exhaust valve either, just a quick cleanup of the existing valve seat and making them be friends by thermo-mechanical coercion.

Natural technological progression is really an evolutionary process unto itself – you end up with systems that have thousands of micro-optimizations in different places for different things, instead of clean-sheet designing something with the knowledge of the system you now have. That takes a lot of time and money, I suppose. Having researched obsolete combustion engine technologies in the past, it makes me wonder if one or the other design was just invented at a bad time when metallurgy and manufacturing couldn’t support it existing yet and they really were fundamentally better concepts which could do away with much of the “every page in the engineering textbook” experience so far.

It also made me appreciate, and maybe mildly envy, the people who got their engineering career starts working on vehicles, the “car guy” friend in high school everyone probably had, including me. Frustrating folk knowledge aside, you really do get a sampling of every engineering industry in making a working automobile, a huge head start on the pratical side of things. I like to think I gained some of this edge by working on my robots and silly e-vehicles, which perhaps lends me to criticizing the combustion engine industrial complex now.

Waiting on the valves meant I put a temporary stop to work on this head for a little while, enough that on the following Monday morning, I awoke to a pleasant gift from the Chinesium Fairy….

Well, it’s cylinder head shaped, so we’re off to a good start. Stay tuned for more!!?

 

Operation Bad Timing II: The Soundtrack; or Zen and the Art of Van Maintenance

Jul 17, 2018 in mikuvan

It all started with a timing belt inspection.

With almost 230,000 miles on the clock now starting from its 151,000 mile humble beginnings, Mikuvan is essentially a cultural institution in my sphere of influence. It’s just assumed to always be around, and it really has been a relatively (emphasis on relatively) pain-free experience. Originally a hare-brained experiment in what if I built myself an electric car, which I swear to all of the gods who made themselves known these past 2 weeks will still happen, it means I’m physically coming up on service internals I never imagined I’d have to deal with again, because… .and I quote myself out of context from 5 years ago, “It’ll probably last like 10,000 miles if that”.

I can’t find the damn figure on this website, but I know I said something like it.

Well, almost 80,000 miles later, here I am. Since the “Great Accidental Partial Engine Rebuild of 2015“, I’ve actually barely gone inside except to feed its increasingly untenable thirst for motor oil. That, believe it or not, was itself over 50,000 miles ago too (I have the service papers from that still – 178K!). The past abonormally-cold winter finally pushed a number of wear components over the edge, it seems, and I wound up after the cold season with an almost two-stroke-esque oil consumption level of < 400 miles per quart and a complementary vape cloud per start.  So you know something like this was coming anyway, just a matter of when and how.

(Oh yeah – I made a number of other deferred-maintenance level repairs when it got warmer, but those will need to be handled separately now!)

We begin on the night of June 28th.

I was to leave for a weeklong southern-fried van adventure covering most of the Blue Ridge Parkway and Skyline Drive, and diving back to Atlanta through the Smoky Mountains forest roads, part of which I ran after Dragon Con 2016. Essentially wandering down in a casual manner for no good reason besides to be not in Boston, because every opportunity I have, fuck this place. The startup’s hardware status was finally to the point where I felt comfortable leaving it to the other members of the company (a story still building up which I owe everyone… put it on my I swear to God list); I’d already punted, up to this point, several of my usual trips because you don’t leave your hardware before it launches, like the opposite of a ship’s captain but with equal amounts of dodging icebergs.

So naturally, having experienced basically no van trouble in 2.5 Dragon Cons (my benchmark for “It Has Been ____ Days Since an Injury” of vans), it was almost a given that I’d make trouble for myself! Gee, I haven’t looked at the timing belt in a whole bunch of miles – let’s see how it’s doing.

Yup, that there’s a timing belt. Hmm, it looks physically in good shape, but the tension is a little out since it’s worn down. So, how do I tension this thing again? Let’s not go back home to bring out the manual, or go upstairs to read my own damn blog post, and instead just take my best memory-stab at it.

You may be wondering How I ended up in this position why I chose to perform what to normal people and sensible mechanics is highly invasive, expensive, and complex engine surgery the day I was to leave for a multi-thousand mile road trip. Don’t question me – and if you did, I wouldn’t have a good answer. All I can say is since we did it the first time, I was confident I could get in and out in around an hour.

That was only a little wrong – there were a few stuck bolts in the way, which caused the procedure to take until after nightfall. Uh oh.

Alright, let’s see, how do you retension this thing? A quick gander at the online Ukranian-hosted rebuild manual gives me…

Cool, I’ll just loosen the tensioner and breaker-bar the crank pulley to move the timing belt 2 tee…. oh, shit, there’s no spring, that’s right. Mikuvan didn’t come with a tensioner spring – we always set the tension manually, and this was relayed to my van salon when they did the Great Accidental Partial Engine Rebuild. So they didn’t unbend some Smart Car’s front suspension to wind me a new spring either.

I immediately skipped several teeth on the belt.  It was then that I realized I was probably not going on my trip.

A sensible person would probably just Uberlyft home and try again during daylight, but I was already invested deeply into this rapidly sinking venture. Nope, I was gonna drive home tonight. I know this damn thing inside and out. I built it. I summoned it back into existence. So I stuffed the belt back on!

 

 

….and, in the dark, proceeded to misalign the timing belt by 2 teeth. Great! Non-interference engine, let me just pop it back over, right? An afternoon’s work to dig back in, right? Looks like I just aligned the mark we made a long time ago instead of the (impossible to see in the dark) factory-stamped timing dimple, right?

Sadly, the damage was done. The timing was artificially advanced by the belt misalignment, causing massive and horrible pinging (pre-ignition) as soon as I gave it any load; which only happened when I goosed it to get onto the main road.  It idled and crawled slowly out of the side roads fine, which gave me a false sense of security. I tried to limp it back as gently as possible, sounding like a diesel school bus the entire way. It’s interesting to think that if I had gotten it a tooth off the other direction, the timing would have been artificially retarded, yielding just horrible gas mileage and less power…..which I might have just wrote off as “eh, it always does that I guess”.

That’s it; I cooked my own goose. Until a lot of money was spent or time was used up, Mikuvan was down, possibly for good. With compression lost between two cylinders, it was clear that at least the head gasket was gone in that area, with possible piston and cylinder wall damage which often follows bad pre-ignition under load.

Let’s summarize the failure chain:

  1. I insisted on pressing forward with a complex and involved repair in the dark
  2. I checked neither my own documentation on the repair, nor the factory service manual for the entire service procedure, relying on memory of something I did over 5 years ago.
  3. I then proceeded to mis-remember the hardware configuration and performed a service procedure incompatible with the state I had left the engine in.
  4. Not stopping there, I tried to remedy it also in the dark, mis-recognizing an alignment feature.
  5. I also didn’t use a timing light or tool to verify that the timing was still correct – doing so would have immediately shown me that the timing was too far out of line.

The God-King had betrayed a fatal flaw, hubris; easy to taunt, easy to trick.

And so, on the morning of June 30th, when I was supposed to be carving up the Shenandoah Valley, Operation BAD TIMING II: THE SOUNDTRACK began. This was going to be deep.

It took me a while to decide to take on the task myself – I had an entire spreadsheet of options, from trying to source a junkyard engine, to buying an entire parts van (I had been stalking this Craigslist post for a non-running but good body condition Mitsubishi cargo van – the seller had sent me photos of it previously but I declined due to the price at the time), to just asking my van salon for an estimate “Make it Happen™”.

It was a hard decision, but performing this operation was to be a soul-searching mission for myself.

  • If I was so bad at paying attention to detail and glossing over important information to get myself into this position, what does that say about my leadership role at a company I co-founded to the people working for it?
  • Could I reasonably scope my work each day, seeing as how I can no longer just rail on a project until it’s done because of the need to ensure the continued operation of the company and development of our hardware? This might be the newest thing for me, honestly, having to adhere to a regular schedule not just for myself, but for other people. I wanted to limit myself to only thinking and working on it during weekends and after the business day – vaguely defined for us, but still a block of time when everyone’s around – was over.
  • Will I be thorough in all the operations I needed to do to bring the engine back from an unknown damaged state, not skip steps unnecessarily and take shortcuts which will bite me in the ass? Will our hardware be subject to similar requirements!? How would I even know what thorough engineering and design is if I never do it myself?

Okay, enough mangsty philosophy. Time to mark all the connectors of the ECU harness and little hoses and start stripping things down. My goal was to get to the head gasket itself by the end of the weekend.

By the way, if you ever need to rebuild a Mitsubishi 4G64 SOHC 8-valve engine in a truck/van application, here it is in all its gory, bloody detail. There’s quite a lot of English-language information for the JDM/international Delicas, but actually not much information for those who own the USDM vans since they are substantially different. Since I’ve been saved by my own blog posts a few times, consider this also an entry into the annals of “how to unfuck your van” for the owner community.

I marked literally everything. I had watched some of the action when the guys at Smooth Automotive were taking the head apart, and they said to me that really if you look at it, everything goes together in one way only. Yeah, sure, all the connectors are unique and they have logical wire lengths which can put them only in a few spots. But there’s a lot of them. That’s scary. I never touched Mikuvan’s engine harness for this reason, because at the root of things I’m still not a car guy by historical experience. Honestly, it took a year of wrenching on vantruck to get me to this point where I just sighed and said yeah, it’s just like the FiTech rig but spread out over a few cables.

Really, it wasn’t so bad after that.

It was in doing a lot of this that I finally recognized where a lot of the EFI-related parts on Mikuvan were, which I learned on Vantruck performing the EFI conversion. I had only otherwise inklings that yeah there’s a throttle position sensor and idle air control servo and breather tube and manifold absolute pressure sensor and eeeeeeeeeeeeeeeehhhhhhhhhhhhhhhhhh. As it turns out, too, it does actually have a EGR valve – I had assumed the California emissions versions did but Federal did not, because the EGR valve was always shown in the manual in isolation, and when I felt around the area of the head I thought it was in, it wasn’t there, so I wrote it off as nonexistent. You’ll love where it actually was.

It actually only took an hour to get to this point. after pushing the connectors aside, disconnecting the throttle and transmission cables, and removing the multi-purpose brackety thing on top of the valve cover. A real mechanic would laugh, but remember, I erred on the side of cautiously labelling and marking (and taking photos!) for reconstruction ease later.

I also went ahead and removed the exhaust manifold, which was 1. cracked severely, and 2. took another half-hour of gently massaging and milking stuck nuts and bolts. Any antiseize lube I put on those threads has long evaporated.

The valve cover comes off after its two bolts are loosened. Most of the gear up here looks relatively new (since Great Accidental Partial Engine Rebuild, or GAPER….what an unfortunate acronym…  involved a head rebuild) despite the operating condition of the engine since I pretty diligently perform oil changes and whatnot.

How do you change oil on an engine which eats a quart of it every few hundred miles? Well, you keep it topped off and after 5000 or so miles, you do it anyway. Just adding more oil all the time doesn’t make existing grunge go away .

 

Ten giant socket cap screws later, and the head is ready to come off! This is the only place I’ve found on the whole powertrain which uses socket hardware. I wonder why? They’re M12 fine-thread screws with a 10mm socket drive.

 

Actually, wait up. There is a Bracket of Irritation directly under the intake manifold, seemingly there to give it more support, which is NOT DOCUMENTED in the USDM factory manual, as far as I can tell!

It took 10 minutes of gently prying at the head before I finally figured out that something was causing it to spring back each time. This 14mm-drive, M10 bolt is accessed from underneath and behind the suspension/engine mounting member. Just stick your arm behind the driver’s side wheel and poke it upwards past the fuel filter.

(Remember: I have no lift or hoist system, or even a garage. I’m on the ground in a gravelly, disintegrating parking lot with jackstands only as a means to lift the whole thing. This is literally “How to un-fuck your van in the most painful, laborious fashion possible”)

Alright, now the Bracket of Irritation is free. It’s time to yank the head assembly off and…

Yup, that’s a head-gasket alright. As I suspected, it blew out between cylinders 3 and 4, most likely as a consequence of severe pre-iginiton under load.

I’m not just out to stuff a new one on and call it a day. I’m told that once an engine fails due to pre-ignition, everything inside is suspect, from pistons to rings to bearings. It was on the docket while I was deep, brah to go ahead and pull the #3 and #4 pistons associated with the failure plus #2 which showed low compression and inspect them thoroughly. The worst thing would be to bodge it back together then have pistons implode later.

#1 still showed factory-spec compression, so I decided from the get-go to leave it alone. This actually means I can use my leftover 3 pistons from the GAPER (…what an unfortunate acronym again).  I ordered a new set of both crankshaft and connecting rod bearings just in case.

It seems that cylinders 2-4 have also been burning oil for a while, with #2 being the worst. I suspect it began in earnest late last fall into winter (which was a fairly unprecendented cold one) when I really started noticing smoking on cold starts. Yet this damned thing took me to Atlanta and back in January, and regularly got hooned around town thereafter and I didn’t even notice any power loss.

Call me silly for going back on my EV conversion word this many times and digging this deep in to ewwww, internal combustion, but something this hard for me to kill kind of deserves my best shot at getting it working again, eh?

So on the docket for this guy was cleaning the valves and seats (no regrinding or re-lapping, which I declared out of neckbearding scope unless I found serious damage) and new valve stem seals, which were clearly not very seal-y any more. I don’t know what a typical “old car rebuild” service interval is, but for the wear parts to let go after 50K is a little disappointing. However, I also don’t know what the gold standard of the time period was – maybe 50K per comprehensive service was actually phenomenal in the 1980s?

Nevertheless, it was time to clean everything up, scrape the old chunks of gasket off, and put the patient on the operating table.

Around this time, I found a resource which, if true, could be a boon to USDM van-mongers.

A complete Chinesium head assembly for the 4G64 8-valve SOHC? Sure, why not! These engines’ bloodlines made it all the way up to like, last year in a few Chinese car models, and still live on otherwise as industrial engines for forklifts and generators.

I was now determined to do my usual exploration of resources for the greater good of the community. It also offered me a backup solution (if true) in case my head repair failed or I discovered some kind of terminal damage that is beyond my skill and resource to fix correctly.

I hit the button on this order on Sunday afternoon, and soon, the thing was due in on Friday after July 4th. What’s actually going to be in the box!? Hell if I know – if I received a Chinese junkyard head that got run through a dishwasher, I was gonna be happy.

Coming up next: Diving even deeper into the valves and pistons themselves.

 

 

 

The Overhaul Design and Build Series, Part 5: “Don’t you have to ship this on Wednesday, dude?”

May 31, 2018 in BattleBots 2018, Bots, Events, Overhaul 2

Yes, yes I do. STOP REMINDING ME OR YOU’RE HELPING MACHINE THINGS.

Well here we are, after the airing of the Overhaul vs. Sawblaze fight which will be on Science Channel’s website and other streaming service soon! I have a full writeup I need to do on the lead-in and post-match analysis for that one! That will come after the conclusion of the build series in this post.

We rejoin our heroe…. dumbasses in the 2nd-into-3rd week of March. March 21st was the latest ship date available for east coast teams in order for everything to make it there on time (or so we were told!?). Luckily, Overhaul was actually not in a bad position, at least compared to Season 2 when the extra long days really started kicking in. All I really had to do at this point was a final assembly, then work on remaining spare assemblies.

After the Week of #WeldingGoneWild, it was actually very easy to do a fitting of the whole front of the bot.

That’s about it. The only thing which wasn’t added in this photo was the clamp actuator itself.

I’m much more a fan of this design already. Once the whole thing is loosely assembled, there is a degree of “elastic averaging” *ahem* that goes on as all the bolts get tightened down, but after that, the arms are rock solid.

The drivetrain is being assembled more now. Check out the Markforged nylon engine timing chain style guides! The front chain was still a bit loose after this so (at the event) I ended up making a different set, to be shown.

The one on the right between the two motors is a little ridiculous. We were running so tight on time that I wasn’t going to get the #35 half-links of chain in on time, or at least too close to risk not being able to drive test. So I invented the stupidest possible chain -pincher for the intermediate drive chain – it was gonna wear out very fast with its profile, but would at least let me get some test driving in.

Closing up the other drive side. The design for serviceability that I did 2 years ago is really coming back to help me here. Remember, my team this year is scattered – Paige is working a real job across the country, Cynthia is occupied full-time and could only help on a limited basis with set-up operations, and I only had Allen’s help briefly with welding too. Most of the photos taken in this build series was work done by myself solely.

Here’s the first test-fitment of the entire bot with all hardware installed. I’m really liking all the design changes to the steel parts. In person, the new clamp and forks look better proportioned to the bot. At least to me, way better than OH2 for 2016.

(Fun game: See how many dumb project artifacts you can spot in the background of this and other photos. Chibi-Mikuvan currently resides under my desk.)

 

I spent an evening just pounding out spare parts for the incipient shipment. For one, I was short on drive motors now, but with a shipment of new HobbyKing Sk3 6374-192s waiting, I needed to key the shafts and secure the hardware. It was easier to pop the shafts out en masse and set up the mill properly.

This and more! I went through….. zero 2mm endmills, somehow. Still a harrowing operation.

It was now the weekend before, and I realized that I wasn’t going to be able to get my last round of waterjet-cut parts in time. These days, I get to be in the back of the line for MIT shop waterjetting – which I think is a very reasonable voluntary position to be in, as I have no official involvement any more with the institute. But dangit Sawblaze, you guys still do!

The electrical deck could conceivably just be drilled from a plate of aluminum, so that is what I ended up having to do. Out comes the TERRORISM. I just cut a chunk of 1/4″ aluminum plate out and started marking holes like high school Charles would have done, and he is always right.

Please do not ever, ever, ever do this. This is how you die. This photo is for illustrative purposes only and should never be attempted, building a robot is dangerous, etc. If you do, use the finest tooth blade you can get and have someone else pump WD-40 or cutting fluid constantly. Or you will die.

 

In the middle of the process. All the small holes are #4-40 tapped for Brushless Rages. Notice how I put six holes in some positions? This will be important later.

 

I’m loading up the bot with electrical deck hardware and wiring now. The shock mounts are in (and secured from the bottom) and some of the battery harness is visible.

The wiring for Overhaul this time was…… ad hoc, to say the least. I said I would dispense with the carefully cultivated greenhouse of busbars. The fanout occurs at the master switch terminals this time, with 8 gauge main leads splitting into multiple 12-gauge intermediate cables to the Brushless Rages. Single 6-AWG conductors handle the “fan-in” from the 4 batteries to the master switches.

The octopus taking shape, with ESCs installed.

Remember those 6-hole patterns? I had to temporarily use the 6-FET models for drive, keeping the 12-FETs for lifting and clamping.

What, are they magic or something? In actuality far underrated from their published specs?!

No, but I accidentally sold my entire product line – which is great – leaving ME with no remaining 12-FET units – which isn’t great. I had to dig into all my pre-production units here to even complete Overhaul at all. What is stock tracking even??

I wasn’t running off a cliff without a drone backpack, by the way. A month earlier, I had placed the assembly order for a new batch of Brushless Rages, but they wouldn’t get in until the Monday of the ship week and I was not taking any chances.

With the octopus wired in, the drive base is live for the first time. Check out the motor-on-a-stick I used to simulate having a clamp motor.

 

Overhaul prior to its first indoor test drive! At this point, I’d fight in 20 minutes if I had to. I think I was actually ahead of the curve here by a distressing amount.

 

I cleaned up and routed more wires into loom in order to un-nest the wiring some. This is inconceivably ugly to me, like a steaming fresh pile of partly-regurgitated dog squeeze smeared across a sidewalk by multiple unassuming passerby. I would never ship this in a consulting project. Yet some of y’all at the event said this was the cleanest wiring in a bot ever? What the actual hell is wrong with you?

(After seeing inside everyone’s bots, I’m not inclined to disagree. Sorry not sorry.)

 

Monday came, and hey! Look what’s here! More Brushless RageBridge units for all! I’d end up assembling 25 12-FET units and packing them with me to the event (not including my own spares, which were 4x for drive plus another 4x for spare overhead)

One of the put-off things was welding the wedges together beyond just tacking, so I spent much of Tuesday doing this. The plan was to take the tacked units to MIT to use one of the MIG welders I have access to and really smash them out quickly.  Using the bot itself as a welding jig made for expedient alignment of all my wooden dinosaur puzzle pieces.

DETHPLOW ™ was tacked together in the same fashion, by actually mounting all the pieces to the bot and locally squeezing with clamps.

For completion purposes, I fully TIG welded one set of pointy-wedges and mounted them on the bot in their final positions. TIG welding is truly the wrong technique to use for bitey pointy robot parts, in my opinion, since it takes so much time compared to MIG in an application where the sensitivity is not really reflected in the end product.

As I mentioned previously, it ended up pissing us off so much we immediately bought a MIG welder after we all got back from the event.

This, for instance, is DETHPLOW all MIG-welded together, a process which took only 15 minutes or so once it was jigged up. I designed all these pieces to be MIG-filled anyway. Here I am doing some TIG touchup on areas which I fell a little short with the wirefeed or missed, or had a gap that I couldn’t bridge as the fitup wasn’t 100% perfect. This is a fine state of affairs for me – blitzing and then fine tuning if needed.

One thing which occurred over the weekend was crate setup. I decided to just spent money this time to get an elegant and reusable SINGLE. PALLET. solution. As someone who’s had two double-pallet crates wrecked over two BattleBots seasons for reasons unknown, I decided I was much better off with a tall single pallet. U-Line came to the rescue with this 4′ x 4′ x 6′ tall snap-together crate,which I modified by adding some removable side-in shelving levels. The bot with its lift table and large tool chests/boxes was to fill the bottom floor, and more containerized accessory suitcases in the middle, along with the pictured Markforged gear – Markforged went ahead and lent me a 2nd printer for the event.

The top level would contain the loose large parts such as the frame rails and spare welded assemblies.

You know all those spare-everythings I was cutting and machining? They ended up in a tote which contained all the important mechanical bits of the bot. I’d prepped a full set of drive and lift motor spares, along with a few mor prepared motors. There was also enough cut tube sections to weld up a new clamp at the event if it came to be.

 

And here it is, Overhaul and all of its support equipment and tools plus spare parts, all ready to load up into….

 

Vantruck??????????????

 

THE PLOT THICKENS! During the week prior to shipment, a few of us NE builders came together to ally ourselves against the forces of time.

You see, Team Forge & Farm was planning to road trip across the country with their bot in tow. For a nominal fee of a few spare RageBridges, they were willing to also bring Overhaul along.

This effectively bought me an extra 4 days to work on the bot – in fact, the electrical work and spare welding photos you see were done after the 21st. On the Monday following shipdate, I picked up HUGE along the way and ended up in southern New Jersey.

 

…where, under the cover of darkness, we packed Earl’s truck up with our bots and his alike.

So… what’s in the crate? Well, there was still the lift cart and all of the already-completed spares, the printer, the mechanical tote, and other support equipment like the battery chargers and power supplies, and a few doen Ragebridges of various flavors. I handed off the radio suitcase and both of my event toolboxes off with the robot.

 

There were still a few kibbles I had to take care of after the bot went out but before I did. So, how do you jig up pieces for welding with you don’t have a robot???

You 3D print an imitation of the robot! This is an Onyx print with the same hole spacings and offsets as an Overhaul front frame rail. I used it to tack the pieces together quickly (as to not melt anything) before removing them.

And with that, the build of Overhaul 2 for the new BattleBots concludes. To be entirely honest, I found this build season pretty stress-free, largely because I didn’t have to build a new bot from scratch and was making only well-scoped changes I had anticipated in advance. In the position I am in now working on a new company with my friends, I don’t think I could have pulled off the record build of OH2 for Season 2 in 2016. My (and my friends’) experiences in this build and competition season of BB – without going into NDA details of the show – has really shown me that I have to move back to a “When it’s ready” format like I had to do during my busiest times at MIT trying to vaguely graduate on time. I have a lot of thoughts on the show as a whole and the direction I’d like to move in (and the show should/shouldn’t move in) that are much better reserved until after the entire show airs.

But for now, hang out here a bit for the event report and a SawBlaze vs. Overhaul post-match!

And now a word from our sponsors!

HobbyKing – Somehow still loves me and enthusiastically supportive of my efforts to abuse R/C model parts for unintended applications! I’m running a HobbyKing radio (9XR Pro) and batteries (Graphene 6000 65C 6S packs, times 4), motors (SK3 63-series), BECs, and a whole lot of wiring and connectors. Not to mention the Reaktor battery chargers and who knows what other HK kibbles have made it into my tools and accessories. I like to think that I had a large role to play in the commoditization of silly electric vehicles using R/C parts also.

MarkForged – from the days when I knew 50% of the company to today when half the new marketing and sales staff go “Who is…. Professor Charles?”, they’ve provided me with high-strength printed parts for a lot of different projects, both on this site and off. Introducing them to the robot fighting community via Jamison’s and my efforts pretty much made MarkForged printed-unibodies the competitive standard in the 1 and 3lb classes, and trying to find new niches in the bigger weight classes is one of my goals. This time, Overhaul’s drive wheel hubs and casting molds are printed from Onyx, and there are also plenty of smaller chain glides and tensioners and accessory parts.

SSAB – I find it interesting that the company’s full name is SSAB AB – Svenskt Stål AB AB, or Swedish Steel Company Company, but these days the lettering is the whole company name so that’s actually not true. This year, I’m working with one of their North America regional distributors and all of the armor steel on Overhaul – including the entire clamp arm, top plates, and new wedgelets and DETHPLOW™ are Hardox 450. Hardox is the easily-obtained ARx00 of Europe and other regions worldwide, and bots overseas have used it for years, but it’s not really had a foothold here in our scene compared to the number of AR-spec steel products in the US. So hopefully I can help with advancing that brand too!

BaneBots – I was called an edgelord for even thinking about using P80 gearboxes in a modern Battlebot. I always thought they were under-loved after the FIRST Robotics Competition quality issues of the late noughties, and had used them otherwise in several projects including consulting projects before shoving shorty Ampflow motors into them for Overhaul 1 in 2015. And you know what!? They’re great! Overhaul 2 ran them exclusively for Season 2, and now for Season 3, OH is sporting the new BB220 series with much stronger planetary output stages for the lifter.

Equals Zero Designs – Yeah, umm, I don’t know much about those assclowns.

The Overhaul Design & Build Series, Part 4: Do You Want to be Gooey?

May 13, 2018 in BattleBots 2018, Bots, Events, Overhaul 2

Wasn’t that an insane season premier episode!? If you missed it, it even seems like they’re distributing the episodes in more creative ways this time, up and including Prime Video. That’s good news, including for me, who can’t be buttsed to TV like 99.5% of people near my age group and lower, and so can barely watch his own damn TV show. I’m fairly confident Overhaul will first be on the 3rd episode, so I think it will time well with the conclusion of this series.

The bulk of the physical construction took place around the first and second weeks of March. Actually, let me rewind the clocker just a little bit, back to the last weekend of February.

I got another shipment of stuff from Markforged, which is returning this season as one of the team sponsors. First, a bunch of Onyx filament to print wheel hubs with, as well as two large molds made on the Mark X series machines which have a bigger build volume. The Mark Two is limited to around 5″ in the width dimension, and guess what has 5″ wheels?! I printed a pair of 3″ front wheel molds in-house from Nylon, since that’s much smaller than the build volume limit.

Printing each pair of large wheel cores actually takes an entire day (22 hours, anyway) so it’s kind of a long process to make a dozen wheels. However, it was easy to pipeline everything once I got the prints going, as the polyurethane also happens to want about a day before demolding.

The resin of choice was Smooth-On Reoflex 60. I had plenty of good experiences with Reoflex 50 in Überclocker, but thought it wore a little fast and that Overhaul’s overpowered drivetrain would make that worse. So I elected to move up on the durometer rating, and 60A is similar to Colson wheels.  I got a small pack from the local distributor around here, Reynolds, to test my process and also the amount of liquid pigment needed. See, the native color of the Reoflex resin is a pleasant poop brown color, which is actually too dark to turn MIKU BLUE. So whatever, black wheels it is.

I’ve gotten a lot of questions on how the hell these wheels are supposed to demold. The molds are one-piece with zero draft, so it should be some kind of physical impossibility…. but then you realize that is what the screwy tread profile does!

I went light on the mold release here, and subsequent wheels actually popped out easier than that. Have I mentioned it’s also awkward trying to hold a camera at the same time as keeping yourself upright AND applying several Torques to something? At least a few torques.

They didn’t all work out though. The first center wheel mold I got from Markforged seemed to have some extrusion problems for the exposed surfaces, leaving them porous. We figured I’d just try slathering on the mold release as they reprinted it.

Nah, this one was stuck for good. Later on, I actually cut this mold open and discovered the resin had seeped entirely down through the floor of the mold and even through the inner walls due to its porosity… Yup, not unscrewing this one.

The reprinted mold was fine.

The problem with a robot with much larger wheels…. is that little sample pack pretty much only lasted those three initial wheels. So guess who now owns an entire gallon of goo? There is no intemediate size between the small trial-size and the full gallon.

These buckets are kind of crappy to use without dispensing equipment setup, but luckily I managed to get the workflow down for pouring them, and only got everything slightly gooey.

All of the frame rails now have brace plate holes-to-be-tapped drilled into them, so frame reassembly can begin in parallel with the remaining operations on new drivetrain and clamp/fork parts.

The first things to go back together are the liftgear and new lift motors.

One assembled front 3″ wheel… I’m liking these already.  The tread adhesion is outstanding – I can’t begin to tear the sidewall away from the face of the wheel. That and the mechanical over-molded interface means short of getting these things cut off, I’m not going to lose the tread.

A little bit more progress on reassembly, now with added drive motors.

Going on in parallel with the wheel casting and reassembly was lots and lots of welding. This damn thing almost has too much welding on it. I also know that I only say that because during this build, we didn’t have a MIG welder, only a TIG.

Here’s why – TIG welding is a very slow, methodical process which gives the welder maximum control over the weld composition. For the things we’ve been doing for “work” and consulting projects, this has been great! What it’s not good at is making large amounts of obnoxious fat welds quickly, for things which are only meant to run into each other over and over. Really, a lot of what you’ll see in the arms was designed for MIG welding, but I couldn’t gain access to my usual one back at MIT until nearly the very end of the build season. Putting Overhaul’s arms together, and Brutus’ wedges and plows, were processes which took up an entire day, or days.

The combined builds of Brutus and Overhaul made us go out and buy a MIG welder because of how bad it was. So that obviously won’t be a problem again, since now we have a Millermatic 211 in the arsenal.

However, I will begin with pointing out that a TIG welder is great for performing an act of terror I learned during my MIT career: TIG bending. Hey, it creates a highly localized heat region! By gliding the torch over a line scribed into some metal, you can very easily get it up to formability temperature. The upside is also a smaller HAZ than (in my experience) with an oxy-acetylene torch.

To make these bends in Overhaul’s future ears, I simply dumped 200 amps of TIG into them for a minute or so and then quickly threw them in the brake press. The welded-like appearance is actually very superficial and was a result of the metal surface liquefying somewhat.

The clamp side plates required some cleaning and standoff tubes machined. I actually didn’t have to buy any new tubing for this clamp design – all of it was either from some other tubular object on Overhaul, or could be slightly machined to the needed diameter. The machined tubes were advantageous since I could control the width of the assembly precisely using the turned shoulder.

SSAB’s Hardox comes with a paint-like coating instead of the heavy hot-rolled mill scale that I see a lot on generic AR grade steel. It comes off very quickly with a flap disc, whereas last season involved several hours of grinding with a solid wheel to get the material to clean weldable state.

Other weld prep included fitting the new lift hub pieces together – some diameters had to be cleaned up and shoulders turned once again.

I had to do a rather hilarious setup on the ears which connect to the clamp actuator in order to clean up the internal bore. Yep, that’s 4 out of 6 jaws.

Here I am doing the first assembly tacks on the lift hub. I have a very strange welding habit: I like doing my setup with the TIG welder, then switching to MIG to finish out. This is solely because I have no patience whatsoever for TIG.

Remember those little flats that were cut into the actuator ears and endcaps? Check out the parallels on the bottom – they help align everything so there is no complex fixturing needed.

Blah blah blah… welder and paint, grinder I ain’t, etc.

Because the clamp arm’s aluminum pivot rings still need to go over these, I had to clean the endcap welds up on the lathe afterwards.

A finished lift hub with endcaps threaded and with bearings made of oil impregnated nylon. I actually found a blank that I had machined most of to the correct dimensions, so making more was easy. I had more unfinished blanks which I machined new arm bushings for from also.

It was now Pi day, and New England greeted us with like the 3rd winter storm in 3 weeks. But the build must go on! Never give up, never surrender (seriously kids, don’t ever move up here. it’s not worth it. it’s expensive, shitty, and cold). I set out to Mid-City Steel which was able to quickly supply plasma-cut Hardox 450 parts on short notice and for very low ruble. Combined in this order are more parts for Brutus.

With this order came the first DETHPLOW (out of 2 – I entered a 2nd supplementary order for more spares) and all the arm parts too.

Plot twist: The arms are mild steel.

Yes, yes, finally obtain mythical Hardox sponsorship, end up making lifter forks from goopy mild. I was ready to design the arms to be made from HX450 also, but couldn’t help thinking if the arms were extremely rigid, that something happening to them would just take out everything upstream – the lift hub, main shaft, etc. which are decided not very Hardy or Ox-y.

Therefore, mild steel arms it is. Depending on how they perform in the season, this might be changed down the line.

Setting up the arms for welding was a similar process to everything else – chop and turn some tubes, and clamp it all together. I for one don’t mind if we bought a CNC plasma cutter. Before these industrial processes (which themselves are rather “old school” and established) were “discovered” by the robot community, welding a frame together was a much bigger deal and required much more setup and skill. This was the environment I grew up in, so that’s why it took me so long to learn and appreciate welding.

Here I am putting the arms together with our Miller 200 amp TIG in the foreground.

Hey, wait… That’s not actually me! That’s…

Allen, a new team mate for this season, who is a ‘graduated duckling’ of my involvement with New York Maker Faire and the Power Racing Series. These days, he’s a mechanical engineering student at Stony Brook. I stole him for their spring break and basically trained him from-scratch on TIG welding, upon which he somehow dumped the entire tank of argon over the course of the week.

First of all, it was a lot of welding, if I haven’t made myself clear on this front. But I do think the regulator was set up for too much gas in general, since at one point the flowmeter had something heavy run into it and did not work properly, and we set it up by listening to it. Sigmas! We have none!

(We do now have a new flowmeter)

 

Allen put together essentially everything you see in this build report that wasn’t the lift hub. This is a photo of the two Overhaul heads under construction. It was jigged up using the lift hub on one end and the spacers for the tooth on the other.

Your Godfather horse-head moment for this build.

Connecting all of the welded bits together was actually very painless this time. Think this means I’m getting better at design-for-welding! This is a test-fitted complete lifter assembly. Not pictured are the spare set of long arms and pair of finished short T-Rex arms. And the other lift hub. And D E T H P L O W.

Mechanical re-integration of the bot progressed quickly from this point. Check back in next week for more original content!

The Overhaul 2018 Design and Build Series, Part 3: When Your Supply Chain is Missing a Half-Link

May 04, 2018 in BattleBots 2018, Bots, Events, Overhaul 2

It’s fab time! The following story takes place in the last week of February to the first week of March – yep, that’s just over 3 weeks, reaching into 2 weeks, until the bot had to be in the crate! In fact, a lot of the earlier photos here were concurrent with finishing out the drivetrain changes and electronics module, since the mechanical modifications were first priority.

Alright, the first thing to do after two years of stagnation and one entire shop move is to take inventory. Some of Overhaul’s parts had wandered off into other projects or been repurposed, and others had been sold to needy builders elsewhere. Oh, and some things instead were to be deprecated and thrown out.

I was first out to ascertain how many good drive motors I had remaining. I originally built a whole bunch of spares and only ended up using two or three. But the lift motors at the time were low on stock at Hobbyking, so I only had four lift motors total – one of which was burnt out and the other had a severely damaged gearbox from (likely) the rumble and post-season shenanigans.

There were also other parts being counted – sprockets and drive hubs, and hardware relevant to the liftgear which I only had a few of to begin with.

By the end of the day, I had a good idea of what needed to be ordered from McMaster the following Monday, as well as what parts to ask HobbyKing for!

 

I began the stripping down of the bot during this process. Poor Overhaul – it’s mostly been living on a lift cart behind my work area, usually causing me to run into it in some way on a regular basis, causing a pattern of injuries on my leg which would have been highly suspicious during high school.

Breaking the bot down was important since I would want to start over with all new fasteners and ascertain the status of all of the parts, such as where a frame rail might need to get cleaned up or if this or that drive hub was about to let go anyway. There were also quite a few parts which were going to receive lightening in my efforts to make weight for DETHPLOW. Basically everything above in blue is being replaced completely, and a lot of parts which went into the now-previous design head will have to be deprecated.

 

Ah, the sad electrical box. Overhaul hasn’t been operational since a year and a half ago when I sold the DLUX 250 reflashed ESCs to Ellis for Robot Wars. To my surprise, this damn thing still powered on. There is a single brushed RageBridge inside to run the former clamp motor, an A23-150 sized Ampflow motor, as well as a BEC module.

Oh well – everything which caught fire is considered automatically sketchy in my book, and this box had an entire unassembled spare if I somehow needed another one – so I salvaged the bus bars and some intact wiring harness parts and unceremoniously chucked the rest.

Overhaul is probably my current masterpiece in terms of design-for-assembly and design-for-service. I put more thought into how things go in and out into this bot than probably every other project I’ve ever made, combined. It’s actually very easy to knock down as one person, since the majority of the bot is supposed to be serviceable by 2 people in under 5 minutes. It takes on average only 2 minutes to release a set of drive motors and under 60 seconds to separate the upper and lower halves of the bot at the arm towers, after which the set of lift motors comes out with only 4 bolts.

The revisions will see some of this go away – for instance, the frame rail brace plate would add a dozen bolts and a different tool to the process. However, I was fine with this – at BattleBots with the current format, you usually have several hours of notice before fighting, if not days. It gets tighter around the playoffs and finals obviously, but the quickest turnaround I’ve witnessed was still on the order of 2-3 hours. If I was scrambling to replace frame rails that hard, it means I’m doing pretty damn well.

On the plus side, the actuator and upper clamp retainment strategies have been changed to be more easy to service.

Well, when you get down to the basics, Overhaul is just a series of gears.

 

All said and done – this is what my table and bench area looks like. I sorted the remaining spare frame rails by type, since each type needed a different kind of surgery or modification.

Chibikart makes a cameo in this photo.

There was about 8 pounds to lose in the frame, spread across a few parts. Overhaul weighed in at 247.0 on the event scale during Season 2, so I used that as a cross-reference to the CAD weight of 240 pounds. To make sure DETHPLOW took me up to the same physical end weight in replacing the separate heavy wedges, and also taking into account the new frame brace plates, I had to get the bot down to around 230 pounds. The rest of the ‘missing weight’ was to be made up in the battery and ESC assembly being smaller and lighter.

Above, I use an annular cutter (also some times called trepanning cutters) to empty out some of the interior of the Epic Lift Gear. If you’ve never used these before, they’re like specialized high-precision hole saws for metal, and can cut a large hole very cleanly and quickly. They used to be very expensive and specialized, but you can find Chinesium sets now that work fine for under $100.  This one was driven in low-gear on Bridget.

The arm towers themselves also lose a bit of meat, with each side getting 1/4″ removed. In a mild perversion of their use, I actually used the same 2″ diameter annular cutter to make the circular boss by simply leaving the interior portion and machining the rest away.

It was now the first week of March, and life suddenly got much more exciting.

I had been scouring the country for a more consistent source of the 4mm AR400 steel that makes up Overhaul’s clamp and fork profiles. Basically, the material seems to come and go at McMaster, who also seems to source it from the depths of a tropical rainforest as all of the AR grade steel I’ve ever gotten from them has been covered in rust and not a single one has really been straight.

Through a lot of calling around local steel companies, I was given an inside sales contact at SSAB – the international manufacturer of the UK/Europe robot fighting circle’s preferred armor steel, Hardox. The gist of the conversation was essentially “Hold on, what did you say you guys were building? Let me talk to the sales manager and we will see what we can do”.

Only afterwards did I do some research and found that SSAB was essentially the U.S. Steel of Sweden. To be fair, I’m not sure what I was expecting, since it’s not like some small mom-and-pop operation produces 8 million tons of high strength steel alloys a year.

So there we go – I’d like to formally welcome SSAB Americas as a sponsor of Overhaul this season! This explains the big Hardox logo on the Equals Zero Robotics Facebook page now.

They not only straight up sent me a diced up 4′ x 8′ plate of 4mm Hardox 450, but also helped find a local steel distributor who had a fast-turnaround plasma cutting service for even more Hardox. This will come into play just a little later.

Alright, presented with several hundred pounds of steel, I will obviously go waterjet. I paid some hush money to the MIT Edgerton Center and popped out a few parts on the Omax 5555 in an evening. I started with 2 full “heads” for Overhaul and basically all of the kibbles which go into the new lift hub design, as well as one set of titanium brace plates.

Here’s the finished parts in the middle of some post-machining.

Back at my shop, I cleaned up the actuator-mounting bore on the clamp side plates. The actuator trunions will ride directly in these holes, so I wanted a not-sandpaper finish here. I didn’t have a carbide boring bar that fit my old boring head, so I reground the old HSS lathe rool I used in there and just ran it very slowly and gently to scrape the little bit of Hardox off.

Harder steels might be horrifying to machine, but they do leave wonderful finishes if you know their weaknesses.

I made a design change to the lift clutch which entailed cutting out some new parts. I wanted to increase the clamping pressure significantly because Overhaul had a lot of trouble actually hauling stuff over during Season 2. To do this, I made new thicker pressure plates such that the tightening nut could exert a lot more force without causing bowing and decreasing of the contact area. I also switched to a higher-friction clutch material (what McMaster calls their high-coefficient of friction), from a medium one.

Additionally, I made over a half pound back here by machining down the Epic Lift Pinion and clutch gear! Technically, that shaft also never ever had to be made of steel – 7075 aluminum would have been highly reasonabel… but I already had slugs of steel sitting around in the right size back then…

Just a couple of days later, the new actuator bodies arrived from my Chinese CM.

Oh. My. Baby robot Jesus.

Probably the most gorgeous assemblies I myself have ever designed and carried to fruition (if I do say so myself). The story of the gear-nut is a tragedy upon itself. I originally threw it at my Chinese shop along with the billet halves, expecting them to basically tell me to quit it with my English Acme thread in the middle of a gear nonsense.  I was fully expecting to just buy two bronze nuts and shove machined stock catalog gears around them.

The problem is then they asked me for a sample of the 1″-4 leadscrew, which is obviously not easy to get in China, as an assembly fitment. They already made one. What?

Absent the ability to mail a chunk of leadscrew (which I didn’t even order yet) in a timely fashion, we settled on the next best thing: I would send them a 3D model of the leadscrew, and they will SLA resin print it and use it as a fitment test. These gearnuts have less slop in the Acme thread than my Bridgeport does.

In the end, it was worth it! The gearnuts are probably the highlight of this whole operation – on almost every project and bot, I have something I call the “penising piece”, referencing the unfortunate tendency for us guys to put a lot of effort into something very showy and impractical for the sake of one-upping each other.

You know what I’m talking about. Don’t deny it. Think about what sport this is.

Too many parts and assemblies like that and your whole project becomes very out-of-scope quickly. Trust me on this, I used to do entire projects that way.

That is not industry terminology. Do not dare try to make it standardized.

There was only one “quality control” problem, and it wasn’t the Chinese’s fault. You see, the thrust bearings I specified on McMaster had a nominal outer diameter, which I designed the pocket for. It in fact was a full 0.02″ larger in real life.

I’m technically not even mad – it’s a thrust bearing. What kind of dumbass tries to make a radially tight-tolerenced fit on something like that?!

The outer shell of those bearings is just a stamped piece of steel – it doesn’t acually Bearing anything, it just vaguely holds the upper and lower races together so you don’t sprinkle the rollers everywhere.

Sadly, I had to bore out my beautiful Chinesium to accommodate the ingrates.

Here is how things fit together. The big thrust bearings sit directly on the face of the gear. The pinion shaft is retained via snap ring and has another bearing that carries it, located in the half not shown here.

And this is how it fits together. I’m quite thrilled with this unit! It ended up weighing about 1lb less than the fiasco I designed last time around, is much smaller and also capable of much heavier loads due to the large trunnion diameter and thicker leadscrew.  The rod end is threaded into the leadscrew and retained with two cross-drilled 1/8″ roll pins each.

Next time on Overhaulin‘ – lots of welding. so much welding.