I think my new life mission is to collect the 3 legendary birds derpy Japanese 80s vans. Here’s an interesting review of the 3 competing Japanese marques in the November 1987 issue of Popular Science! As an enthusiast of things which go quicker than they need to, I’m glad to see the Mitsubishi Van win the most sporty award. All of these models were discontinued by 1990, and I think the Nissan in particular is the rarest since there was an active mass recall for them. Definitely next on my list…

Anyways, as previously announced, Operation: BAD TIMING went down Saturday, and I am proud to say that it was a resounding success; the sound you hear is a hilariously lawn-mower-sounding 4 cylinder Mitsubishi 4G64 powering a vehicle which resembles a normal American minivan, just with the nose belt-sanded off and a few corners hit with a deburring tool.

Here’s the story of what all came together on a bright, sunny Saturday afternoon in (a basement in) Cambridge.

The scene of the crime. A few days before, I went to the neighborhood Harbor Freight and invested a very low 3-digit sum in a 3-ton hydraulic jack and 3-ton jackstands (among other handy accessories). As someone who has used HF equipment for years, I’m fully aware of the need to de-rate everything Harbor Freight tries to sell you by 50+% in order to use it safely. Especially on a matter which would probably reduce me non-consensually a few inches in thickness if the equipment fails. The van weighs 2910lb (1.5 tons, basically) empty, so 3-ton everything it is. Jackstands were placed according to The Official Derpy Van Strategy Guide – there’s a convenient round frame rail on the underside that fit the stand cradles exactly, almost like they anticipated people doing this or something.

The jackstands enabled free access to the underside of the vehicle in order to release several engine cover/timing belt cover bolts, and to release the lower transmission cooler and radiator coolant feed lines.

To get to the timing belt, the radiator and all accessory belts and pulleys needed to come off. This stage was basically done by Official Strategy Guide and some finger-feeling. The service manual doesn’t show some steps, figuring you know this stuff already.

For instance, the only step in radiator removal was “RADIATOR”, not “Remove these 2 bolts, this hose, and this other hose but from the underside of the car, and drain the transmission first so you can also get these two other hoses. Oh, by the way, the radiator shroud doesn’t clear the main cooling fan, but it will if you yank hard enough so you don’t have to take these 4 other bolts out.”

Yeah. That’s how you do it. “RADIATOR”. We decided that yanking was the best way.

After the radiator was wrestled out, I started attacking the fan and fan clutch. This right angle T-handle drive ratchet came in handy immensely for many of these tasks – among others being a makeshift impact wrench and hammer.

Leverage was used to break the fan bolts hold, then the T-handle used to quickly extract the bolt. There was no space to actually put the electric impact wrench I bought in there.

One of the fan nuts needed some Vise Grip Assist to untighten. It didn’t make it back onto the fan hub afterwards. Surely 3 bolts out of 4 is enough…

About midway into the disassembly process, and all the accessory belts have been removed.  The next stage was to remove the crankshaft accessory pulley, which was another 4-bolts torqued way too tight. I actually had to have Adam counter-torque me through the camshaft pulley (holding a socket wrench locked the other direction from my torquing) and rock my own wrench back and forth to break it loose!

After the accessory pulley came off, a few bolts later and the timing belt cover could be removed.

…and this what fell out as soon as we did that. A ball bearing.

Not a good sign.

As the cover was removed further, several more ball bearings fell out. This was not looking good.

A shot of the front of the engine with timing belt components exposed.  The lower left, short timing belt is the balance shaft belt, to be replaced along with the main timing belt. Its tensioner was actually pretty intact. The main timing belt, however, was a different story.

The tensioner is a “offset cam roller” kind of thing mounted on a swinging, lockable mechanism. The mechanism, a single steel stamping, was just fine. But where the hell is my tensioner?

Oh, there is is! At least, that’s the inner race. The actual tensioner roller itself was freely jiggling around inside the timing belt case. It seems that the bearing disintegrated long ago, scattering balls everywhere inside and causing instantaneous and likely fatal timing loss for the engine.

I purchased a full timing belt components kit, so it came with the 2 tension roller assemblies and belts. This is the new balancer belt assembly.

Bear in mind I was not the person taking the pictures, or you’d likely have gotten a picture of the main tensioner roller with every ball bearing recovered and piled on top of it. Others are not so OCD about photos as me, so for now, enjoy this picture of the lettering on the timing belt.

And this photo of nothing in particular. You can kind of see the new (green shielded) tension roller for the main timing belt installed. Much carb cleaner was used to make sure the mating surfaces and pulley faces were clean, then the new timing belt was installed. We didn’t go to extraordinary steps to clean everything, nor was the water pump replaced.

We had thought that “line up the timing marks” was going to be an arduous process of HERE, HOLD MY EVERYTHING WHILE I PLUG IT IN, but rather found that all the engine parts just sort of rolled into place. The cam shaft has 4 big springy detents from valve actuation, one of which was just the correct timing. The balancer shaft naturally rotated from gravity to the right timing.

It’s almost like it was designed this way or something.

After the timing belts were installed, we plugged the (newly replaced) distributor and rotor in, connected the spark plug cables, and tried a test run. This was the make-or-break here – if something was terribly amiss, it would show itself upon cranking. If the engine still didn’t start, I was prepared to keep removing things on the spot.

The video is of the second test run. On the first, we were all taken by surprise as to how quickly and smoothly it started up. I was honestly expecting explosions or jets of flame or something.

The engine idled smoothly and revved up smoothly. I blipped the throttle to about 2500 RPM briefly before we remembered that it had no cooling whatesoever and decided to end the test. Success for now.

After the test run, everything is getting reinstalled and refilled.

Your pretend-mechanic hoodrats of the day are Adam, Dane, and yours truly.

Buttoning up everything and rerouting all the cables. The passenger engine everything compartment hasn’t been this together since I got the thing.

Finally, after about 5 hours of work, Mikuvan is back together again. We finished at around 7PM Saturday, still early enough for the sun to be out!

Naturally, a high-stakes all-hands test drive was in order.

The total mileage of the first ever test run was about three or so. Not very much, but enough for me to observe that everything was in good working order (up to 3rd gear), that nothing was overheating or making weird noises, or that for some reason it really wanted to turn left. Hell, I’ve ridden in friends’ cars which were consistently less reliable.

The evening resulted in one discovery: the source of the coolant leak. First, a major leak from a misplaced hose clamp on the radiator from our servicing. But second, a persistent but lower flow leak which left me puzzled as to why I was leaving a bread crumb trail of coolant droplets everywhere. It turns out that someone in the van’s 23 year history had sheared a bolt on the thermometer to radiator hose connection, so the gasket was completely uncompressed and leaking.

Well, I sure fixed that.

mission 1

The conclusion of the test drive was the N52 parking lot:

That evening, I topped off the brake fluid and also refilled the gas (with 93 octane premium for sheer kicks) and cleaned off some of the bird shit stains and tree droppings.

Sunday has been filled with gratuitous driving (to places I would normally scooter to or even walk and stuff… amazing, right? It’s the weekend, I can park anywhere!) to double check and recheck reliability in starting and fluid leakage. At this point, I haven’t stalled out once, nor had any more issues with dripping fluids with the exception of some small oil dots that appear after a long period of parking. This tells me that there’s probably a very small but consistent oil leak somewhere. I’d like to get this thing on a lift, still, to fully clean the engine and transmission so I can watch oil leaks form.

Other things I have noticed include a pretty rumbly ride, which could indicate bad bearings. At 151,000+ miles, it’s about time for them to let go. However, during the time on jackstands, I did not notice any wobble or looseness in the front at all. It could just be a natural noise from sitting right over the front suspension.

I have yet to take Mikuvan on any highway cruising to obtain true steady state operation; this is on deck for this coming week. At this point, it only has a pile of minor issues to redress:

• The body panel rust holes on the underside, and the bumper
• The swivelly chairs can’t lock in place – the mechanism is obviously broken on both of them.
• The broken coolant gasket bolt can be resolved by buying a new thermometer unit
• The idle is still erratic, though I have yet to stall out. It varies between over 1000 RPM and what appears to be 450 or less (expected: 750rpm). The idle air control servo is known to get sticky over time.
• The front blower is broken! I don’t mind not having air conditioning, but some moving air would be nice. The blower assembly does not seem to be accessible short of an entire-dash teardown, however. I may get desperate enough to do so.
• Rims
• Subs

This week, my intention is to maybe take it to a detailing shop to clean the rest of the superficial imperfections out (stuff I can’t attack with a towel and kitchen counter cleaner) and to actually register it. I’m already having immense amounts of fun trolling drivers of more conventional modern cars with its Zeerust-future look and 27 foot turn circle. My ultimate fear is not that I have to learn to handle its peculiarities, but that I’ll forget that everyone else has wheels in front of them. I don’t have front wheels, just middle ones.

In the intervening week and a half between the last update and now, a few things have happened. First, I untorqued the oil filter, and bought a set of torque wrenches. I hope you guys are satisfied.

Next, I tweaked and diddled enough things to get Mikuvan driving – tenuously, and only for a little while.

We… err, muscled that one back home.

This video was taken before the arrival of my new mass air flow sensor. The engine was easy to keep running when cold, but difficult otherwise after it warmed up, to the point where it would stall quickly if I let the throttle pedal go. The reason for this was yet unknown to me, but a few friends thought it might have something to do with the engine temperature sensor or intake air temp sensor, neither of which I’ve inspected with a voltmeter.  The missing MAF couldn’t have helped either.

But it showed that it could move under its own power! There was hope. I didn’t get up to a speed to shift into second, however, so the transmission remains untested.

After that, still waiting on the MAF replacement, I decided to give the underbody a much more thorough car syphilis rust inspection.

The matching rust holes in the front step got much bigger with some scab picking. Oh boy.

I chiseled each rust patch to the point where the metal became ductile, so some of these holes were growing distressingly large. But these are the full extents picture.

The left side which has seemingly met another vehicle in a somewhat amicable fashion has a large through-hole on the bottom. There is a matching set of holes on the right, which are smaller.

The bumper, though, was in horrible shape. Not the frame where the bumper attaches, fortunately, but just the bumper metal. Above is a picture of the right side bumper attachment point, and this thing was so bad that it was crunchy when I stepped on the rear tailgate. Clearly no longer structural. Replacements for the bumper stamping seem to average $600+, so I might start asking on derpy van owner forums for cars being parted out soon. Worst case, I’m gonna weld a mockup from something ridiculous like 1/8″ waterjet-cut steel plate later.

The deterioriation of the other side was also significant, but much lesser – the metal was still ductile.

I didn’t check extensively for this when I bought it in PA, so I suppose it’s also my fault. I can’t help but think Mikuvan is a little “lemon flavored”. However, given the talks I had with the seller, I ‘m not sure if he knew of the extent of the rust either.

What I can take solace in is that the trouble spots are on the body sheet metal (patchable) and on a “consumable” item, the bumper. They must make the bumper from a lower quality steel on purpose – the frame around it is in fine shape. There is basically no frame rust, which is the important part.

I don’t intend on addressing these body problems yet. It would be nice to get it running before making it pretty – the summer months also have no threat of wet road salt, so if anything, this is a great season to find this out.

The day after, my new MAF arrives. It’s a pull from a ’91 Eclipse.

The MAF unit was the same, but the “can” it came in was much smaller. So, some screwdriver work later and I had the MAF unit swapped into my intake canister. I also got a new air filter during this time, on the left.

After replacing the MAF and resetting the ECU, I managed to get the engine going again enough for a new error code to appear (if the MAF was fixed or I bought a lemon-flavored unit). The ECU read “all clear” this time, but the problems were still present. Inconsistent starting, and this weird cycling behavior:

As I understood it, this might have been the ECU trying different fuel-air mixtures for starting, none of which were quite right. I’m not sure of the actual cause, since I’ve literally never heard an engine make this kind of sound.

One issue I had not yet resolved was checking fuel pressure or changing the fuel filter. I got a Harbor Freight fuel pressure meter, but it clearly required me to cut the fuel line and splice it in to use, something I was not keen on doing yet.

I could definitely try the filter in case it was clogged through:

Cue 2 hours of gentle hammering later, and the “original” filter is out. My goodness, it must have been actually original. The thing was almost rusted through, and when I took it out and shook it over the oil drain pan, rust colored pasty chunks fell out of it.

The replacement filter was a few ounces lighter, and I can’t imagine it being a newer or better design, so I’m gonna say there was a ton of shit inside the old filter.

Remounting the new filter was a relatively painless process. It was in an incredibly awkward location, but at least it was accessible directly from under the vehicle, without dropping anything else, and with only one universal joint ratchet involved!

With the filter hopefully no longer depressing fuel pressure, I tried cranking the engine again. It still cycled as before. This time, I basically couldn’t get it to fire any more, or for it to “catch on” and start idling.

At this point, I decided to move onto the last “0.5″ point of the 3.5 things that constitute spark, fuel, compression, and spark timing: the timing. The thing to do was to remove the timing belt cover, crank over the engine manually to the point where the camshaft pulley lines up with its timing mark, then check the position of the distributor rotor. The rotor should be pointing basically at the #1 spark plug.

So with some trepidation, I removed the distributor cap and and upper timing belt cover.

First, that timing belt is in bad shape. Like worn down to the cords bad. This indicated to me the tensioner roller was probably seized, or the belt was just dragging on something else.

I put a socket on the big camshaft pulley nut and began pulling.

The timing belt jumps several teeth in response and I almost fly out of the driver’s side perch. There was basically zero tension on the belt – see the ‘convexity’ on the right side. I could push this thing in a good inch and a half. I’m amazed the engine ran at all. Perhaps the first few good starts were with the timing belt in a serendipitous position, and something I did caused it to skip teeth thereafter – now, there is no timing the engine can possibly be on which would let it run.

Well, shit just got complicated.

Speaking of the distributor, the points were also in seriously bad, corroded shape. I’m further amazed that it somehow ran now. Luckily, I have a new OEM rotor and cap.

cue Operation: BAD TIMING

I was clearly not going to skip the timing belt back to the right place, and at any rate, it needed to be replaced.

I was at a decision point here. Now, the Official Derpy Van Service Strategy Guide said nothing about what needed to happen before the timing belt was replaced – it just showed every part of the front of the engine in the clear, as if I could access it or something. I basically accepted this was an implicit “Drop engine”. At the very beginning, I said that if I had to drop anything to solve a problem, everything was coming out and I was going electric right away.

Before I did anything else, I decided to seek professional advice – by which I mean ask the Canadian Mitsubishi Delica forum. After getting some reassurance that I would only have to remove the radiator to do this, it became a more palatable task.

I basically declared #YOLO #SWAG: If the operation was completed successfully, then hurray. If not, or I badly fucked over the engine doing so, then more things will just be removed until I am left with a glider frame.

With this in mind, I ordered a new timing belt and tensioner kit:

I got the part from Rock Auto, which seems to be the McMaster-Carr of random car parts. It was even the kit recommended by the forum!

Time to remove more things to get the radiator out. I busted out the masking tape to label wires and tape fasteners to their respective holes so I didn’t end up with like 30 extra bolts after all was said and done.

Hang on a sec – you mean the transmission is also connected to this radiator?

Fuck integrated systems, man. I had to drain the transmission first. Luckily, I disposed of the 20 tankerloads of black used oil last weekend at an Advance Auto Parts locally, so my filth container was available for the task.

The manual indicated that if the transmission fluid smelled burnt, it was a bad sign. Well, what if it smelled both burnt and rancid? I couldn’t describe the smell as anything other than a very sketchy Chinese restaurant. DEXRON-II tranny fluid apparently contains jojoba oil, a natural oil. (Here was when I learned that transmission fluid at some point was made of whale oil.)  Actually, given the history of neglect of this vehicle, it might as well have had used McDonalds frying oil added to the transmission.

(I also totally did not intend to capture the single droplet of transmission fluid in midair, but that’s pretty awesome.)

Also, speaking of automatic transmissions, what is this shit? How can anyone have thought this was a good idea?!

Fuck this noise so incredibly hard. my only previous car and every car i have driven was automatic.

The bleedout of weirdly neon fluids continues with the radiator. This thing has clearly been corroding internally for a while, as the first few seconds of coolant was a bit brown. It cleared up, however.

At the same Advance Auto Parts I made the oil drop at, I learned that coolant could not be collected. Apparently it has to go (in MA) straight to the local public works department or hazardous waste collection site for disposal. That, or through some unscrupulous egging by friends, poured into the toilet so it goes through the wastewater system (as opposed to a storm drain, which around here goes straight to the Charles River, which is itself bad symbolism).

As I learned, the reason is because used oil can be recycled readily, whereas coolant (ethylene glycol) must be disposed of.

Maybe I’ll just polymerize it into polyethylene-glycol and then have a year’s worth of very smooth bowel movements.

After the radiator drain and transmission bleed, I decided to hold off on removing anything else until I have some  backup. Steps from hereon require working under the vehicle while on jackstands, something I am not comfortable with on my own – crawling around under this thing while supported by 4 little spindly steel triangles sound incredi-sketch.

Operation: BAD TIMING is scheduled to occur on Saturday. Here goes nothing in particular! Any peanut gallery advice before I dive in?

Nope, it’s not Miku colored yet. Quit asking.

It’s hard to believe that I only went on the Great Van Escapade a week and some ago. Between then and now, I’ve done many hours of disassembly, testing, and debugging. I think I’ve finally rooted out the problem, but am waiting on some more advice and recommendations before proceeding. Why am I even buggering with fixing the ICE engine, with all its attendant pre-OBD-but-post-CARB Mitsubishi-only oddities, when I’m just going to unbolt it all and drop in an electric power system? Not quite sure, but some of it has to do with curiosity in figuring out exactly how much of a complexity nightmare ICE vehicles are, and others because I have 20 more days of temp plates left. Getting in some driving feel would be immensely helpful too.

Mikuvan lives in the enclosed underground parking garage under my apartment block, next to a Honda CR-V, a Volkswagen Golf, a Prius, and (among other cars) a 1963 Mercury Comet. Good, I’m not the only project car sitting in a pile of its own parts. Looking down the row of parked cars is amusing – all you see is hoods and headlights…and then there’s this.

At least it’s not on-street or outside. But the downsides of this arrangement include the total lack of AC outlet power nearby, poor lighting, and a lack of Wifi or cell reception. The nearest outlet is 75 feet away, necessitating some extension cord creativity. I have a 500W halogen work light to relieve the lighting issue, but it is still only one source. The latter issue means I often neglected to bring cameras or camera-enabled things with me into wrenching sessions. Hence, even though there were plenty of cool photo ops, this post will sadly be mostly text.

Hey, so is my air filter supposed to be furry?

The story of digging in around in the drivers seat engine bay is centered around consulting with people who know a thing or two about what cars are, then vaguely following their suggestions but ultimately falling back to the Official Strategy Guide / Shop Manual to figure out through its well-drawn but extremely narrow view diagrams where the parts in questions actually were.

It’s often said that you need 3.5 things to get an engine to work. Spark, fuel, compression, and when-does-the-spark-fire (i.e. timing the spark, the 0.5 part). I basically began by checking the ones that were easy: spark and compression. To check the timing properly would have involved exposing the timing pulleys, which, as far as I could tell necessitated removing the radiator and cooling fan shroud, then also removing the distributor cap which was more accessible. I did not feel like attempting this in the dark with limited tools. In Pennsylvania, we already verified compression, so I started by checking the spark plug lines.

I bought 2 of these in-line plug checker lights from Harbor Freight (not sure why I just didn’t go ahead and get 4). The firing order of the engine is 1 – 3 – 4 – 2, so I started by putting the lights on 1 and 3 to verify the order, then 3 and 4, and so on. Basically to make sure that 1) there was spark even if it may not be the correct timing, and that 2) the  cables weren’t switched around or something.

The sparking order checked out fine, so I began reading up on fuel injector testing and cleaning. My suspicion at this point moved to the injectors, since they were really the only element left. I highly doubted it was a timing issue in that somehow the timing belt (which is in great condition as far as I can see – it must have been replaced fairly recently) skipped 1 tooth or the distributor cap rotated enough such that I got completely inconclusive cranking – even a late spark would give me some kind of ‘puff’ and an early spark would cause premature detonation and horrible noises.

But I couldn’t help but think that all 4 injectors failing or clogging at once was extremely unlikely. In my experiences with watching friends tell stories of problem cars and from a few trouble vehicles my family has owned, engines don’t just suddenly stop working unless either something

1. catastophically failed on the mechanical side, which I would certainly know by now, or
2. a single electrical point of failure such as a sensor is preventing the ECU from running the engine properly

My money was moving towards some stupid sensor failure. For instance, if the crankshaft position sensor, used for fuel injection timing and electronic spark timing (the ECU fires the ignition coil when it feels like) is out, then the ECU won’t know when to do either of those things. If the throttle position sensor, which is potentiometer based, was broken or worn, it could be reporting a completely nonsensical value, though this seemed less likely since you’re never supposed to step on the throttle while starting, unless you know exactly why you have to. There’s other sensors involved too, like the mass air flow sensor which the ECU uses to determine how much fuel is metered into the cylinder.

With all of these things having to work in synchrony, I’m amazed cars function at all.

Here’s the scene of the crime, lit up by the aforementioned 500 watt halogen light. It kept the area reasonably warm, as the rest of the garage is unheated and basically settles to its own temperature by thermal inertia alone (surely it will get unbearably hot during the summer).  At this point, to access the fuel injectors and high pressure fuel rail, I have the passenger seat slung up, the driver seat removed, and the underframe of the driver seat also detached but just shuffled out of the way a bit since it has the parking brake lever, fuel door lever, seat belt anchor, and a host of other stuff on it I don’t feel like dropping into the engine.

Here’s the whole mess from the other side. The shop manual has been my reading material of choice for the past week. It’s extremely informative, but at the same time I can tell it was written by mechanics for other mechanics. I assume that the unlabeled detail shots require some background in wrenching to understand where to insert the thingimadoodle and how many degrees to turn the whatchamadoosit. There’s other info missing such as sensor pinouts right after it tells me what voltage this or that sensor should read…

…While the engine is running. How about a little help for the other case here, guys?

Before taking even more things apart to get to the injectors, I decided to see if it could tell me what was wrong.

Okay, now I’m seeing something familiar. My van debugs like a Kelly controller or Hobbyking controller!

It predates OBD (“OBD-1″), so it has multiple means of debugging available. You could buy the $500+ “multi-use tool” which is like a form of proto-OBD scanner, or you can debug with a voltmeter. Not a digital one – an analog one. It puts out little pulses of voltage so you can see the needle move (digital meters do too much time-averaging to see this effect). If I added an LED to the circuit, I literally could have watched it blink. It probably would have said “FREQUENT RESET” or something, knowing the average Kelly controller.

So an analog voltmeter it is. It took me a while of digging in MITERS to even find one of our crufty analog voltmeters, and I ended up having to make hardwire leads for it anyway.

But it worked! The key has to be turned to ON (not start) for a few seconds for the ECU to start putting out pulses. The result is:

Normal State!

Oh, come on.

My guess is that since the vehicle has not been started since my new battery was connected, the ECU doesn’t know what’s good or bad. The engine must run, no matter how crappily, for a while before the ECU can recognize something is out of range or nonresponsive. My mission now was to try and get the thing started no matter what. If the injectors were clogged, then I’d have to unclog them.

One thing I was told to try was to drop carb/throttle body cleaner (i.e. vicious, surely carcinogenic,  and highly volatile solvent cleaner) directly into the fuel rail, mixed in with the gasoline, to try and dissolve anything which might be causing injector blockage on the spot. Basically you cycle the injectors bathed in disgusting solvents and let it sit for a while, then try again. Rinse and repeat. I bought a little can of Seafoam on recommendation from friends, which appears to the most disgusting of the disgusting solvents since it claims to clean everything. Seems legit, right?

The procedure was to disconnect the high pressure fuel line from the rail, get most of the fuel in there out, and replace the rest with Disgusting Solvent #81289. I wicked fuel using a few shop towels, which were promptly lit on fire for my own amusement (this process does not have photos associated), and mixed in Seafoam about 50/50 into the rail. Next, I gave the engine about 10 seconds of crank to get the new mixed drink into the injectors. During this time, the engine sputtered a few times.

Promising.

An hour later, I came back to give the engine another spin. 10 more seconds of excited cranking and sputtering later, it took off.

It was shaking like crazy and white smoke was everywhere (allegedly a sign of the cleaner doing its thing), and the revs were unsteady for the first few seconds of run. It seemed to settle into an idle, though I was both too excited and scared shitless to check the tachometer for functionality. Something was happening.

I was under the impression based on checking the dipstick in Pennsylvania that the engine was very low on oil. It was also running with zero coolant. Fearing causing damage due to lack of lubrication, I shut the engine off after about 20(ish) seconds of running.

it did something

Unfortunately, that was the only run I got out of it that night. I regrouped thoughts for a bit to formulate the plan of attack if it started and ran more than once. On the next shot, there was some more sputtering, but no consistent behavior. I gave the air intake a dose of starting fluid to no avail. By the next few tries, the battery was wearing down too low to crank effectively. I’d have to bring in my charger and top it off before trying again, so I cleaned up for the night.

That was when I noticed that the air flow sensor wasn’t connected at all.  Remember the air filter shot? I opened the air cleaner box to remove and replace it with a fresh one, but neglected to reconnect the airflow sensor.  So, the engine running must have been pure luck – or the cleaner/solvent making for such a volatile mixture that any small amount was sufficient for it to keep turning over. The air flow sensor is a “hot grid” type sensor (looks like this) used for air mass calculations. If “disconnected” also means “off scale low”, it means the ECU would think that there was no airflow. No airflow means no air mass to calculate fuel injection quantity with. And no fuel means no combustion except if you’re basically mainlining Seafoam. My exhaust system is probably really clean right now.

Yesterday evening, I tried re-adding some cleaner to the fuel rail (in lesser quantity) to try and confirm this theory. I got the engine to sputter some times, but no starting and running was observed.  I also noticed that the ECU code had finally changed to:

Air flow sensor.

It was definitely connected. I even abraded the pins a little and recrimped the socket to increase contact pressure just to make sure it had connectivity. I couldn’t tell if the element was damaged (it looked good, even clean) or the entire sensor had just stopped working or what. I cleaned the grid element with some rubbing alcohol and let it dry under the halogen lamp for a while. No obvious changes were noted, nor were any starts effected. Maybe “disconnected” is a totally different signal from “porked”.

A new-used MAF sensor costs about $120 on eBay, so I went ahead and ordered one. Even if it’s not the problem, I now have a debugging chain to follow instead of shooting in the dark.  The airflow sensor being problematic would corroborate my theory that some critical sensor failing is causing the ECU to not control air, fuel, or spark properly. We’ll see how this goes.

With these new developments, I decided to do some staging and preparation. First, I wanted to get the disgusting sludge oil leftovers out of the engine and put in something fresh. On the same Harbor Freight trip earlier in the week, I anticipated needing to do this eventually so I got an oil filter strap wrench and a waste oil container, the kind with the integrated drip pan. I ordered a new oil filter off eBay (the best auto parts store!) last week already.

The oil drain plug and filter were clearly designed to be accessed from an auto lift. I didn’t have this, so luckily the thing has a massive front nose cavity…

The plug and filter aren’t visible in this picture, but they’re right behind the front suspension arms. The radiator to the left is the A/C condenser – it’s the first thing to hit if you drive over a tall curb or something.

I also noticed while I was under there that the transmission oil pan is basically the first thing to hit the ground if I go over an enthusiastic speed bump. I’m not sure how they expected this to navigate the rough streets of the U.S. while loaded with seven U.S. sized adults. Maybe everything was smaller back in 1989…

It was black. ALL BLACK.

Around 5 quarts of entirely black oil poured out of the crankcase. Like, this stuff was basically the color of the filter. So it did have oil after all! “Oil”, anyway. I think we must have read the dipstick wrong in PA, since we swore it had very low oil.

Always a good thing to find in the drip pan – little metal particles. And chunks of sludge.

I let both filter and drain plug ports drip for over an hour (while waiting for the battery to charge) before refilling it with some new 5W-30 from the gas station. I didn’t bust money on premium oil since I figure it wasn’t going to stay in the car for too long anyway.

Oh, also, the oil filter had basically no torque on it. I didn’t even need the strap wrench – just the torque of my hand trying to engage the strap loosened it. No wonder there is a thin sheen of oil all over the underside – it must have just been leaking forever. I made sure to crank it down when I installed the new filter.

The game right now is to wait for the new airflow sensor and see what happens from there. I’ve pledged to give an honest debugging effort to this thing even if I’m not keeping the engine for long, and I’m willing to spend some money on it.  I’ll make sure to take more pictures of everything in the future.

This is also the first post in the new Mikuvan build thread. Oh boy, I’m in deep now…

I’ve been in hiding for the past few days out of fear for my life EVERYBODY IS IN FINAL PROJECT DOOMSDAY MODE!!!! PANIC!!! since I’m a TA/lab instructor for the Media Lab’s famed MAS.863 How to Make (a Huge Mess) out of (Almost) Anything class as well as 16.842, a systems design class based on the DARPA Model Based Amphibious Racing competition (MBARC). I have rants prepared summarizing my experiences in both of those, but that’s for another day.

What’s on deck right now is a brand new version of Überclocker, my ‘flagship’ combat robot (flagbot?), which has been out for retirement since at least 2010 or something. It’s what I have been slowly hammering away at for said past few days, stretching sporadically into the last two weeks or so. I’ve realized that it’s rare to see a explain-the-CAD-image on this site any more, which makes me a little disappointed since so much of the idea synthesis that ultimately determines the fate of a build is contained in the design period, and perhaps my thought processes can help in the design work of others. So in an attempt to go Back to My Roots, I’m going to have an explain-the-CAD picture post summarizing the status of this Überclocker build, now entitled Überclocker ADVANCE! for reasons that are difficult to explain using words.

Let’s face it – Clocker has been a little slow-moving compared to most of my past robots and current vehicle-like things. In 2008, it was completely terrible because I basically square-wave stepped into infinite machining and fabrication resources from almost none, without the attendant knowledge and theoretical foundations to use them. In 2009, I rebuilt it using “every trick in the engineering textbook”, and t-nuts, to wholly unsurprising consequences. 2010 and 2011 were marked by dismal failures brought on mostly from a lack of true concern, since at the time I was well-distracted by the aforementioned vehicle projects, and didn’t really take upgrading and repairing the bot seriously. Finally, in 2012, I stepped back and really upgraded the robot, and it did well consider how terribly I ended up operating the damn thing.

The design of this bot actually has a year and a half of history, at least. My first inklings of a desire to totally start from scratch basically started after Dragon*Con 2011 with this concept solid model, made in a few hours.

It got the basic point across – I was tired of having low ground clearance and tiny wheels with their traction limitations (hence the big wheels). Clocker’s broadside attack weakness (since it’s so damned long, at 27″) was fresh in my mind, so I wanted to make the sides rounded in order to give me some complementary leverage in a pushing match. The legs, while they worked reasonably well, were bulky and some times caught on the stage edges and elements, so I wanted to replace the rollers with a ball shape. All of these things were on track for  addressing in version three. But, that model lasted about as long as I spent designing it.

The next burst of inspiration built off this sketch-model in later 2011. It was on the flight back from my most recent Singapore trip that I went through like all 3 of my spare laptop batteries on the plane and followed up on the sketch-model’s selling points. The end result was this.

My god, it’s round. It’s so round. And it was even mostly circular! Did I mention round? Curvilinear?

This was a very strong candidate for the design at the time. It would still involve a fair bit of waterjetting magic, but the frame was out to become much simpler than Überclocker Remix’s original 2009 frame. I actually spent some serious time making the circular edges as … well, circular as I could.

Sadly, I just straight up forgot about this for a long time after landing. Some part of me still said that the shape was impractical, that I wouldn’t have far to tilt before I lost traction, or that the waterjet puzzle was too complicated to be robust. But damn does it look good.

Fast forward another year, and I’ve basically had enough of this thing. Yeah, it was round. But my reservations were correct in every way I cared about. Überclocker original (2008) and Überclocker Remix (2009) both had very distinct and unique shapes – very flat and sleek, with angular elements everywhere that were neither positively contributory nor very easy to make. My recent Great Awakening with Null Hypothesis, a desire to return to the ugly square drivetrain-dominant bot that just worked more than anything else, pushed me strongly towards ditching the desire to be circular. In the modern Battlebot match, the giant brushless spinning weapon staying alive and driving is, in my opinion, something like 75% of the game. So long as you keep rushing at the other guy, strategically or haphazardly, you’re more likely to curry favor from the judges if you last. In the recent past, Clocker has had… well known issues… with that.

The new idea floating in my head was to make the thing bone simple, at least a simple as a 4-actuator 4-wheel drive bot can get. The frame needed to be just big straight rails. The dual-motor setup for the lifter had to go (because ultimately, one motor jamming or stopping will cause the whole thing to quit functioning), the whole thing needed to get smaller or at least get no bigger, and I really needed more ground clearance.

Images in my mind began forming of basically shoving the fork and clamp assembly onto Null Hypothesis. That bot was fast, had infinite traction from it’s 40A durometer 2″ wide “McMasterBots” wheels, and almost unlimited traction-positive angles because of the big overhung wheels. What it translated into in real life was a bunch of bad whiteboard sketches, including…

Yeah, what?

That looks like a combination of Omegaforce, the Wubba-wubba-Bot that never was, and some agricultural implement. It lasted as long as it took for me to sketch it out.

With the final project blitz happening to every lab class on campus including the two I was involved with, I hunkered down in my stuffnest and began creating geometry in Autodesk Inventor, for realsies (but interrupted roughly every 5 minutes with a different variant of “Do you think using a ____ on my _____ is a good idea? Is there one in the shop?”).

Yup, that it’s. That’s the whole robot.

I’ll admit that my reasons for creating DeWut!? were mostly self-serving. I needed to get away from two things:

1. Using sketchy-ass 18 volt Chinese cordless drills in anything. Null Hypothesis basically ditches a motor every match. While these drills may have been better in the past, modern product design committees have cut so many corners out of them that they’re pretty well rounded off … literally. The cases have gotten curvier and prettier, but the material quality has really been shat out and redigested. I think they’re still fine for 12lbers, and 30s if they are not overdriven at all, but NH clearly pushed them too far.
2. Repacking the guts of non-sketchy 18 volt American cordless drills (the DeWalts, which are made in China anyway) into my very sketchily-made aluminum gearcases. You can buy this for $200 already, it’s better than my version, but they’re never in stock.

Hence, if I could get the DeWuts made as a stock solution, then I can design everything around them. And soon, everybody can!

With that model in mind, I quickly started jotting down the geometric outline:

It’s still round.

I just can’t let that go. Cold Arbor was kind of round, and it looked great (but that saw is something I will be ashamed of forever), so I threw it in. The base form is that of Clocker as it exists now – two “pods” on the sides and a simple box frame in the middle, and the fork out front. In this picture, I was trying out Null Hypothesis’ 2″ wide giant caster wheels for looks. While I liked it, it would have caused the bot to be almost 2 feet wide, so they were not the final choice.

The hardest part about starting a new build is usually anchoring the design. Where the hell do you start, and what part do you start with? I found that making the outline made the choice much easier since it was then easy to see right in front of you what is holding the bot together.

After Clocker’s 2012 adventures, I tacked on some more items onto my list of grand design intents. The full rundown was now:

1. More practical and easy to build, as previously described
2. Higher ground clearance and increased maneuverability, as previously described
3. The ability to resist or defend against broadside attacks, because round
4. Making the legs actually useful.
5. Making the clamping action much quicker

Here’s what I mean by all that.

Making the legs actually useful

Clocker’s “reactive outriggers’ are probably its best feature. The idea is when a 30lb opponent is lifted, the weight shifts forward and the robot gets up on two wheels and the rollers at the end of the outriggers. Hence, the robot still maintains traction and can move while carrying an opponent without hoisting it up all the way. Many historical clamp type weapons like Darkangel and Complete Control (both Clocker inspirations!) have static outriggers that function only to prevent tipping.

Here’s a picture all the way back from clocker 1 in 2008 that shows the principle.

That’s where the fun begins. The idea is basically to spin the opponent in a circle and then let go – not causing damage per se, but it looks intense. Some times it backfires. Other times it’s a big hit at the event.

The problem is that it really only works for a limited range of opponents because of how short the legs on the original Clocker and Remix (2009-current version) were. A little too chunky and Clocker would just faceplant. If they were too small or compact, then I don’t really get enough displacement to break rear traction. If the ratio of leg length to wheelbase were higher, then the range of spinnable opponents would also increase because it would both let me tilt forward with less weight and be more stable in that configuration.

Next, the “doubly supported” legs of the original bot, and Remix as a consequence, were a severe pain to remove if the drivetrain needed servicing (and my goodness did it need servicing…). It used a different hex wrench diameter than the rest of the stuff on the side, and there were 2 screws and 2 washers to line up correctly to remount them.

Some times, a single big chunk of metal is warranted over a creatively sculpted series of smaller chunks. I wanted this build to use a single, thicker ‘leg’ per side that could easily be removed and swapped if needed, from one side of the bot.

Making the clamping action quicker

Unlike many clampbots of smaller weight classes that use R/C servos or larger weight classes that use pneumatics, Clocker has an electric linear actuator to reduce complexity while still offering good grip strength – an R/C servo of this size class exists, but all I know about it is that it’sreally expensive. So, the clamping action is admittedly a little slow. This has resulted in a quite a few missed grip chances in the past.

This particular grievance isn’t a major design element, since Clocker’s clamp actuator was pulled from Cold Arbor and can be customized in several ways. I’m thinking of either switching up the leadscrew from a 10 TPI to an 8tpi fast-travel screw (with 2 starts, so effectively 4 TPI), which would make for a 2.5x increase in tip speed. Else, I can remove a whole stage of gearing from the chopped 36:1 drill gearbox that runs the actuator in order to effect a 6x increase in speed.

It’s a little hard to decide, since I’d have to weight the costs and benefits – namely, how much clamping pressure do I really need? If I could get 6x more speed and not really sacrifice how hard I can hang onto the opponent, then it’s worthwhile. Alternatively, I’ve used the clamp as an emergency lifting arm in the past, so maybe I don’t want to sacrifice so much torque.

Oh, wait, I forgot one thing…

Not needing 3 different sizes of hex wrench, 2 of which must be ball ended, and 20 minutes in order to fix anything.

Probably the worst thing about Clocker is how hard it was to pull anything. At D*C2012, I had to take out the lifter gearbox in order to remove one gear stage from it that had stripped out and binded up the whole thing. It took pretty much exactly 20 minutes to take the robot apart and put it back together, just as I had experienced in the shop. This design goal kind of goes with the simpler and more practical frame design.

Now, where was I? Onto the actual evolution of the design.

I very rarely use an outline of the bot as a design guide, but this time I founded it immensely helpful to visualize how all the parts will interact, roughly, before committing a part file to it. Above is shown an arrangement of the parts as conceived fairly early on, including the Third DeWut that will run the big fork. That’s right – no more weird dual-motor gearbox.

I was fighting back and forth about whether to do direct-drive to one wheel and chain/belt to the other (per side) or an indirect drive to both wheels with the motor in the middle somewhere. It was primarily finding a balance between 3 variables – whether or not the bot needed more ground clearance, the kind of speeds I could get with either method, and where I had to stuff everything else.

If the rear drive wheel were mounted in-line with the motors, then I would be limited to a maximum theoretical ground clearance (i.e. without any type of bottom armor) of 0.75″ with 4″ wheels. If I designed Clocker solely for smooth-arena combat, the ground clearance would be only 0.25″ at most using 3″ wheels, but this is not the case, so 4″ is pretty much required. 0.75″ clearance is what Null Hypothesis and the latest Überclocker all run with, and it seems to be fine for the stage combat scenario of Robot Battles. It would limit me to three speed ranges dictated by which gear I put the DeWalt geaboxes in – they have a 450, 1450, and 2000 RPM ranges (at stock voltage, rated by the company).

Now, I’m dead set on overvolting 18v motors to 24v at least (or rather, 25.6v for 8S A123 cells), because it’s a glaring sign of n00b to run motors at their rated voltage. At the very least, 7S must be used to be comparable in drive power to the current version of Clocker. This depended on how creative I could get with placing the battery itself. At 8S, I would see a (theoretical) top speed of 24mph in the middle gear. Yikes… that’s pretty high. But the alternative, 8mph, in low gear, is really really slow. At 18 volts or 6S A123 cells, the top speed would be a more tame 17mph, more to my liking but a little on the high side. So, wheel-on-motor would be a good choice if I was satisfied with 18 volt electrical systems and 0.75″ ground clearance.

However, if the wheels were not directly in line, I have more options. I could run 3″ wheels at below motor center line to retain the same level of ground clearance , but more manageable speeds. The motor location would be significantly more flexible. It’s wholly possible to run a 1:1 using chain or belts and with the motor not directly connected to either wheel – in this arrangement, my speed at 24v would be still 18mph, which is excellent.

The next variable to consider is how much tractive authority I wanted. By this, I mean how far can the robot be tilted or rolled without losing tractive authority? This would dictate my ability to escape from bad situations – the speed might be enough to avoid them, but if I ever got in one with a low clearance bot with little stubby wheels, it could be worse. Bigger wheels will always help with this problem.

I decided it was worth trying a 1″ ground clearance experiment using 4″ wheels. It would be a new design direction for me, since I have classically favored flat robots. Ideally this would make Clocker virtually impossible to wedge under because it would take incredible effort to break its traction fully. I wanted to leave space for the option of 8S packs, even though it meant a mid-20s top speed, because I could always back down from there and save some weight if that was warranted. A greater tractive authority combined with high speeds makes a bot much harder to catch.

The culmination of all this reasoning and pulling tradeoffs back and forth is many hours of positioning components and thinking of what parts go with the configuration, and roughly how fast it would go. Some times, a good arrangement existed for battery and motor placement, but there was not really space left for the Ragebridges. I made configurations with one Ragebridge per side (instead of 2 stacked on top), the battery in the front (not optimal for center of gravity), and even offset motors.

Ultimately, here’s what it came down to:

I had to release one constraint to settle upon this, and that’s the bot’s width. Clocker is already huge for a 30lber, covering a 18 x 27″ footprint. That’s bigger than some former 60lb Battlebots lightweights. Part of it’s unavoidable with this kind of design, where I have to contain a majority of another opponent.

Only by letting myself build a 19″ wide bot could I fit an up-to-8S pack in the rear along with the ragebridges. The motors and battery pack were now all rear-biased, which was favorable for CG reasons.

The observant would notice that I went back to the 1″ wide wheels after the previous shot. There were 2 primary reasons for that move. First, I really wanted doubly-supported wheels with static (standoff-like) axles. This increases the rigidity of the frame over a single supported wheel, and also lets the outer frame rails act as wheel armor. And second, those 2″ wide wheels would have pushed the bot width dangerously close to 2 feet.

After this part of the design was roughed out, everything else began falling in place. There’s really only one place to put the clamp and fork, really.

The next big challenge was how to mount the fork assembly. Clocker’s current configuration is a little “torsionally unsound” in that the force of a 30lb opponent capture in the fork is reacted entirely by the front frame cross-members twisting. Said front cross-members are also just flat plates, which are known to be very poor in torsional loads. Without the top and bottom plating to support them, the whole thing just lurches back and forth if any load is applied to the fork. While the latter configuration is acceptable (loaded top and bottom armor), I don’t like it as much because it depends on a material much less stiff than the aluminum (i.e. sketchy McMaster FR4 garolite plates) to handle the loads – I’d rather have a more “atomic” structure.

In the above image I’ve whipped up a pretty simple first-pass attempt at the clamp motor and pivot mounting structure. At this point, I was still relatively unsure about how to attach the whole thing to the frame.  The two big top-level choices were a CRJW style standoff tower (preloaded like mad) or just two crossing trussed-out 2.5″ tall aluminum flat plate members, separated a few inches. CRJW’s build style worked out very well with respect to overall stiffness, so I initially favored it.

I was also split between chains or gears for the main lifting drive. The first Clocker used #25 chain, the second used giant custom spur gears. At first, I figured chain would be easier to make an assembly with  because it was narrower yet more flexible (in terms of positioning the components). Hence, at this point, I still had a narrow assembly set up for a #35 chain (for more durability over #25) assuming I’d drop a sprocket in there.

However, what I eventually realized is that chains need space to exist, and I’d need to cut huge gaps out of the frame to pass the chain through. A sprocket combination that got me the needed external reduction in other to not make the fork a fucking hammer meant the large sprocket was almost approaching 6″ across!

I could more easily get 5 or 6:1 in a set of spur gears, whereas the same ratio in a chain necessitated a 9 or 10 tooth sprocket, known to be extremely weak and highly stressing on the chain. So with my brief excursion into the dreamland of chain drive complete, I returned to modeling the assembly to favor a set of big custom 12 pitch spur gears. The assembly would have to get much wider, of course, but this was a minor adjustment.

Here’s a random picture of a gear.

Needing a bit of mental break, I decided to get really creative with a spur gear and embedded the “overclocked” Doomsday Clock motif that appears in every Überclocker. About 3 people will ever get it, and it doesn’t actually make sense to put on the bot. But hey, it’ll look pretty in the model!

I went through an entire round of parts arrangement with the standoffs-style structure that involved lots of shifting the motor and gear around. I wanted the ability to use all 4 corner holes for fastening, else the continuous structural loop would be sacrificed, reducing stiffness. But this generally involved crossing a spur gear (or a chain sprocket), so the gear had to be moved or the fastening hole had to be moved. Keeping the standoffs spaced as far apart as possible maximizes the stiffness of the assembly, but that was of course in direct conflict with whether or not I could stuff a motor and gearing into the same projected space.

After a while, I began realizing that the conflicting goals were pretty much irreconcilable given my choice of constraints and the desired size and aesthetics of the bot. Taking apart a bunch of standoffs would also be a serious maintenance problem (I’d need a clear, straight-shot space across the bot to pull a threaded rod out of). Maybe some crossing spans weren’t so bad after all?

They weren’t. Making the pivot axis of the fork directly over the motor (as opposed to offset in front of it) meant that I didn’t have to make as large of a cutout in the frame rails as I had expected. This allowed the condensation of the assembly to only 3.5″ wide – basically, just enough to contain the motor itself.

In this arrangement if I torqued the pivot axis hard (like hanging a 30lb opponent a foot away) the twisting load is taken up by shearing 4 2.5″ wide bars across their width, basically. Much better than twisting the same bars about their own center axes. This is incredibly difficult to explain in more detail without a thousand more words dedicated to it, or a cute drawing/diagram.

I’ve closed off the structural loop around the fork motor now, and am pretty satisfied with how this turned out.

I try to not optimize anything too hard until the whole system has materialized to some degree, so I moved on immediately towards filling out the less critical parts of the bot, like the fork tines. These were laid out using the outline as a guide, but not for dimensional accuracy. Check out the fish hooks on the end – I’m gonna keep them in “production” just because they look pretty cool (uh oh…), and I also foresee them aiding in sliding under someone’s side armor and catching them. Worst case, I’ll sand them off, so who cares?!

I added the top clamp from Clocker’s 2012 incarnation, which was a newly built assembly, to see how it looks. I’m going to keep this clamp because it’s already built to work with the geometry of taller robots. The pretend-o-bot is starting to form. At this point, I’ve gone back and diddled with the geometry of the motor mount some more in order to get a more favorable “angle of decent” of the fork. As it turned out, a totally centerline pivot point forced the descending part of the fork to be very shallow, which made the ‘active’ part shorter but also let the fork swing down lower (before it hit the motor mount). Here, there was a tradeoff of “do I really want Clocker to lift it self off the ground?” – while it seemed advantageous for making sure I win the wedge war, it would be a disaster for expedient driving and maneuvering since the bot would be effectively high centering itself.

So, in the end, a steeper angle won out since I could hard-stop the fork just barely above the ground. I’ll deal with wedges as they come.

I’ll be reusing the clamp actuator too. Some time was spent playing the Geometry Game (midway down in this post) trying to maximize the range of travel without having the motor impact anything. This time, the components played out in my favor and made a little corner that the motor could stick into without running into the pivot shaft, as well as being protected on most sides by the bot structure!

A geometric example of a new leg has been added, too. The new design calls for this to be machined from solid 3/4″ aluminum. Chunky? Yeah, definitely. But, I need the stiffness if it’s going to be single-supported and stick out that far.

Here’s a bit of SCIENCE!! which I used to sanity check myself when designing the leg. I basically took a reasonable guess at how much instantaneous force the leg will see if Clocker just ran into a wall for no reason – say 1500 lb-force, applied directly to the big roller screw. Then I assumed the bot was infinitely stiff and could hold the leg still at the rear where it is attached. Then I told Inventor to pull some magic and tell me how much it deforms. Result: Probably about .25″ in compression and bending, and I’m more likely than not going to bend the roller screw.

That’s okay, I’ll make spares. A 0.5″ wide leg made Inventor yell at me for large displacements – that indicated some degree of hopelessness.

Realistically, a static FEA calculation isn’t going to capture the whole picture. The bot is not infinitely stiff – if it dives into a wall, the frame will most likely bend significantly at the mounting point, too, absorbing some of the hit energy. The suspension spring could also take up some of that force. The only question, really, is if the whole thing will just stay bent after it, which could be found out with More Analysis I’m not currently in the mood for. Just ship it.

At this point, I was starting to look at just making small refinements. I’ve taken the liberty of shortening the bot a little closer to original dimensions. This was accomplished by swapping spaces with one of the chain tensioners – before, I was limited in how far back I could move the fork pivot axis by how close I could move the tensioner to the main drive sprocket.

Well why not just swap them then?

I threw the current version of clocker in just for a size comparison. As can be observed, the ratio of robot to fork has decreased somewhat, and the ratio of leg length to wheelbase has increased. The frame itself is a tad shorter, but wider. And much taller. Overall,  Clocker ADVANCE occupies a bigger bounding box, but most of it is pretty spindly and empty.

When I was happy with the placement of parts, I began the t-nutting.

Now, I promised to not t-nut so prolifically any more, but this situation warrants it, I swear! The little gussets and brackets will double both as frame binding elements as well as top and bottom plate mounting points. The difference in this case being the top and bottom plates are made no longer structural – just to hold the guts in, not to take loading (short of direct impacts, which will be guarded from with piles of ablative material). These are far less egregious than Clocker Remix’s frame.

Additionally, the presence of the U-shaped gussets in the motor mount strengths that region from twisting even more.

The best part? The lifter motor pops out after undoing 4 screws accessible from the front. It drops out the bottom and can be immediately replaced. The drive motors will take a little more thought.

One issue I ran into was how to retain the gussets from moving in the Z-axis. The last picture showed pretty well an underconstrained joint – i.e. in the absence of friction, it could still slide out the top or bottom. Only friction retains it in real life.

By insetting the fingers fully into slots, I capture them in the Z direction, too. The downside is making the left and right chassis rails 0.125″ taller per side. I found this inconsequential because INFINITE GROUND CLEARANCE. Now, with these captured slots, there is also a clear assembly order for the bot – everything in the middle first, side plates go on last.

I turned my attention to the legs now, and devising a real mounting solution for them. They pivot directly on the front drive wheel’s axis, on a shoulder screw (which also anchors down the front drive axle standoff itself. I devised entirely new shock absorber things for this build, because I need to go up in spring stiffness to counteract the longer lever arm. The basic principle is still the same, however. Waterjetted from the same chunk of metal I will presumably make the legs from, then secondary machined.

I’m considering making a little extension to the frame to put these parts in “double shear” mode which will once again increase their stiffness. I decided to leave this until after the rest of the bot was modeled, since by this point I was getting close on weight.

Notice the blue string running around the model sprockets? I decided to try out Inventor’s chain drive designer for realsies this time. Prior to this, I’d only used it to generate sprocket profiles for machining. But as it turns out, it will tell you exactly how many links you need and whether or not you have enough tensioner travel to last the life of the chain, because chains stretch a few % with age (The answer for me was no, not for 10,000 hours anyway). You select existing cylindrical axes and tell it how big each sprocket is. You can even say a certain axis has an allowable amount of wobble (to make cam style tensioners) or can move in the XY plane a certain amount (for linear sliding tensioners). Then it will update whenever the sprockets are moved, and yell at you if you move them to an impossible position or you need to adjust your tensioners.

Wow. Computers are pretty damn cool.

In seeking more structure for the outer side plate, I decided to extend said tensioners to become standoffs in their own right. These have off-center holes so I can rotate them and then tighten down the long screw that binds the two plates together.

I added simulated top and bottom plates for the final almost-finished look.

At this point, the bot “weighed” 31.0 pounds. Uh oh… All that solid metal has to go. I want it to weigh 28 pounds or so in order to include overhead from wiring and screws I did not yet model (most of the big bolts were put in already).

Clocker Remix is very much “gothic cathedral’d out”, my term for making structures sparse and spindly to reduce weight, like… gothic cathedrals. I’m sure those guys did it less for weight and more because they were badasses, but whatever. However, it was done rather haphazardly – I have truss elements that really don’t do much and could have been totally absent (Did you know that trusses triangles are ideally all equilateral?)

And that’s it.

After selectively trussing out most of the plates and adjusting the height of others, the bot is now at 28.6 pounds as-modeled (with more big screws added, too). The side plates have gotten much lower (and name-emblazoned), which saved a ton of weight. I added one more standoff to raise the stiffness of that outer rail some more. The lowered sides also makes the motor mounting screws that much more easier to access. The only plate not hollowed out right now is the very back, which I’ve decided to keep solid because the bot otherwise has no rear armoring.

And the back shot.

in conclusion,

this is the longest post ever on my website at about 5500 words! I keep upping this number for some reason. It’s been a long time since a pure CAD-based brain-dump post, and I must say it was rather refreshing. Airing out decisions that you have made, makes you think about them more and critique them a little more impartially.

Construction on Clocker will commence as soon as everything opens up again after the Christmas-New-Years-What-Have-You holiday season. The target is Motorama 2013 (more strictly Robot Conflict @ Motorama 2013), an event I haven’t been to since Clocker and Arbor’s collective dismal losses in 2010!

 

With the holiday and end-of-year business shutdowns finally ending, the steady trickle of parts shipments for Landmelonsharkpigbeartankboard is flowing once again. I’ve finally gotten my trippy PCBs in for Make-a-Bot too, but haven’t gotten the chance to make the heat spreading plate and test it yet. Otherwise, I got Segfault running once again, now with its own enormously overkill battery.

Overall not much to say, so let’s just start with the grocery list.

landbearshark

LBS is still a pile of parts that has been steadily increasing in size. The materials needed to start the entire project off are the aluminum plates, which have yet to arrive. Otherwise, I have essentially everything – motors, motor-side sprockets, chains and links, the four shock bodies, a whole mess of stainless steel hardware, most other drive components, and this cute little contactor.

Here’s what the whole mess looks like right now…

Still on the way for whatever reason are three 24″ x 24″ x 1/4″ aluminum slabs. Other frame materials are used in small enough quantities to just be scrounged.

The design has been filled out with the requisite t-nuts needed to hold the panels together.

Some minor touches are missing, including places to mount the rider-sensing switches. The contactor and other major electrical components are also homeless at the moment. I also need to make the “second deck” of electronics which will handle tasks other than motor control. I did collect a model of the Giant Red Key Switch, and it hangs out in the back.

If I’m lucky, the metal will arrive tomorrow and the frame can be cut out by the weekend. That’s really the only hard part.

(Okay, minus the electronics…)

make-a-bot

At last, the trippy PCB heaters!

Trriiiippy.

I made one change from the version I keep linking to – there’s a center hole in the board so I can wedge a thermistor between it and the aluminum heat spreader. You know, so I can actually find out the temperature of the working surface. Otherwise, the trace resistance checks out (the squiggles on the bottom side in the design were put there in case they did not…) I’ll need to cut a single square of aluminum for the heat spreader. The aluminum will then be thermal-epoxied (not bolted or sandwiched) to the top of the board.

I got two boards, but will only prepare one of them for now.

segfault

Poor Segfault.

No, I haven’t completely trashed it yet again. It’s been working, but always became weak after 30 minutes or so because all I had in it were two of Überclocker’s packs. It would usually just fall over after an hour. So after the term ended, I swore I would make a new battery just for it such that I can reliably bring it out for demos. Naturally, with the ennui of the break, I felt unmotivated to do anything. Additionally, during an unfortunate scooter-organizing incident, the cable leading to the control knobs was sheared off, so it was just one more impediment and grunt-work repair job I had to tackle before it could even work again.

So maybe I did completely trash it. Either way, I guess it counts as New Year’s resolution to repair Segfault? I’m not sure.

Here’s where it starts.

Ah, another brick of A123 26650 lithium nanophosphate cells; here, being prepared and tinned.

Segfault’s completely empty right side was just begging for a brutally large battery. I measured everything out and found that I could easily fit a 5 x 7 cell array. Since Segfault already demonstrated operation on 7S (about 23 volts), I’d have to make a pack that had 5 cells in parallel. This is more or less a 146% \m/etalpaKkK. With 5 2.2 amp-hour cells in parallel, the total watthours count of this pack comes out to be around 250. It ought to be enough to keep Segfault running for two hours or more.

The enormous \m/etalbraid makes a return on this pack. Grounding braid is now my staple “battery bar”, as shown by the \m/etalpaxXx themselves and RazEr rEVolution’s pack (and the Clockerpacks, and the monstrosity I made for Cold Arbor). Segfault will never draw enough current to overload these busbars, but hey – maybe one day this thing will be repurposed. Have to plan ahead, you know.

Soldering is discouraged on cells like this because of the risk of melting the polymer separator close to the terminal, which results in bad. If you’re very fast and have a soldering iron with a large tip (high thermal mass, effective thermal bath), it’s definitely possible. I stuck to my 3-second rule here – once the joint starts melting, I count 3 seconds to smash it down and add more solder. Once that time is up, I immediately move on to another cell, and don’t return to that one until I’ve visited the rest of the pack.

It’s probably not very legit, but I haven’t overheated a cell yet…

After the whole pack got busbraided, it was time to add the wires. There’s three heavy-gauge wire pairs coming out of the pack this time. The two off to the right interface with the existing double battery connector in Segfault. There’s no reason to have a double connector in the thing, but it’s the way I originally made it to accept the robot batteries.

The single cable to the left is only used for charging. But I guess it could be a third discharge port if needed.

I ordered JST-XH connectors in several different sizes from Digi-key, so I was actually able to make a legitimate balancing harness.

Now the fun part begins: Packaging the whole thing.

MAGIC!!!!

So there’s no soda bottle big enough in this world (please prove me wrong) to swallow up 5 cell wide rows. The \m/etalpaxXx required a 3-liter soda bottle, and they were only 4-parallel groups. And while I could have planned ahead and ordered wide heatshrink tubing, that just doesn’t work with how I like to build these things – i.e. right now.

I did, however, buy a six inch wide roll of Kapton (Crapton, since it was from a Chinese ebay seller, and doubtlessly not real DuPont polyimide film) for Make-A-Bot’s future build surface. So I decided to just give it a try with finishing the packs up. With some cut up sheets of adhesive-backed foam rubber fitted on the cells for shock isolation, I wrapped the Giant Crapton around the whole pack several times in two separate loops. I think it came out great. The tape doesn’t really stretch, so it doesn’t look as “heat-shrinky”, and I wouldn’t say it’s waterproof. But it got the job done.

After a brief interlude to reconnect six little wires, Segfault is now once again attempting to kill innocent riders.