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The Overhaul 2 Design & Build Series, Part 4: Ramps, Forks and Clamps, the Pointy Things CADpocalypse

Mar 15, 2016 in BattleBots 2016, Bots, Events, Overhaul 2

In this part, I’m moving on from the aluminum parts of the bot and putting in some REAL STEEL. First order of business is designing the front armor, the angled pontoons for which Overhaul 1 was somewhat famous for. Next, I’ll put in the lifting forks, and finally the Razer upper clamp arm which is supposed to Razer come down on opponents and mercilessly crush them like Raz… hey, wait a minute.

Welcome to the Overhaul 2 Design & Build series, episode 4: A New Work Plane. Because that’s what’s going on here. So many work planes

The work planes are where sketches are drawn to make the solid pieces. While Inventor will let you sketch directly on the surface of a part in an assembly, I wanted to keep this part a little more separate from the assembly. Therefore, these work planes are defined from the assembly parts, but will still be around if I delete the part (e.g. to replace it with a new version), or edit/delete a frame part.

I honestly didn’t know what I was aiming for when I started. I knew the general shape of things from the sketch model, so I just started making a basic wireframe. The best term I could probably use to describe these first few versions of the pontoons was “Gundam armor”. Impractically faceted and pointy, and likely very hard to make in real life.

Here’s one completed example. I wanted too many things out of one design – the flat sides for easy attachment to the shock mounts, the sloped outsides to deflect KE weapon blows, and the sloped upper panel to protect the liftgear and better act as a w*dge passive-traction-leverage-implement. (It’s no longer polite to say w*dge in BattleBots!)

That’s how many work planes I got up before I decided to just start over. This was the accumulation of 3 revisions, so it included a lot of angles and facets I ended up ditching.

Here we are, after tossing THAT part in the dumpster of bytes. This shape more approximates the original sketch, with its sloped sides and double-angle front. I initially did not pursue this because I was thinking that modeling the non-straight sides would be a pain. To generate the surfaces, I use the wireframe (made of many sketches on different planes) to generate boundary surfaces in Inventor.

The double-angle front armor was borne of some musing about how to overcome horizontal spinning weapons. You can usually do only two things with big KE weapons – absorb them, or deflect them. The former usually ends quite badly.

We saw in the Bite Force vs. Tombstone final how effective usage of material geometry can bounce KE weapons around, since no matter how  much energy you pack in a weapon, your bot still only weighs 250 pounds. The idea of the double-angle pontoons is similar to that of a Jersey barrier, which is designed to bounce wayward cars back towards the correct side of the road. The lower angle slope guides the weapon upwards, and then the sudden higher angle slope destabilizes the now elevated weapon. The height of the angle change is set just barely above the average blade height of all the big hitters at BB season 1*

Adding to this deflective geometry is the soft rubber mounting points, which on a good connect will squash and cause the pontoon to come into contact with the ground. The hope is that this will basically mean the opponent suddenly reacts against the arena floor, adding to the bounce effect.

That’s the theory – we’ll see how it works in practice. But the effectiveness of even a single angle, solidly mounted deflective plow can be seen in the snippets of Captain Shrederator vs. Stinger (trust me, it was even more awesome in person) as well as the Bite Force final.

*The sound you hear is everyone rushing to build variable height weapons

Adding more of “the details” to the pontoons – now they have vertical panels and bottom plates. These are all still surfaces. The plan is to use this part made of surfaces as a reference to “grow” the final plate models from.

For now, I left this surface as-is since at the least I’ve defined the shape of the pontoons and therefore the shape of the front of the robot. I moved onto the next Most Critical Module, which was the lifting arm assembly.

I burped this out after a few hours of thinking about how best to attach the forks. Fundamentally, it’s a big center hub with an ear attached to it where the lift actuator will eventually mount – dimensions and spacings for this were guessed, since I hadn’t designed that yet and wanted to keep it flexible. A similar structure appears on Uberclocker Remix on its main lift shaft.

For OH2, I wanted the forks to be easily removable in the event of oh god I got owned but somehow won. To do this, the fork arms can’t be made a permanent part of something, and the attachment method also needed to be rigid in bending as well as be able to handle what might end up being thousands of ft-lb of torque if I actually use the full crush force on something.

I decided on a dead shaft system where the fork arms also have bearings (rather, just bushings) in them with the hub a separate piece. Eight 3/8″ threaded studs are anchored into the hub, and the forks are retained by 8 nuts once they are slid onto the hub. The way to quickly remove the forks would be to remove the lift shaft (two bolts), then undo 8 nuts per side, and then slide them out.

The lift hub is therefore a totally indepedent structure, so I could conceivably run OH2 even without arms or without the clamp for some reason.

 

Because this thing will be reacting all of the clamp actuator force through itself, I decided to check in on how the material was going to handle it. Having a 5″ round wad of solid aluminum in the center is great, but not for weight. I wanted to see how far I could hollow it out while retaining rigidity, so it was back to the good ol’ FEA tool.

If you haven’t ever seen FEA before, it basically does all of the stupid bending-twisting-beam calcualtions you had to do in engineering school by hand with a stupid lookup table (IF YOU’RE LUCKY AND HAVE A VERY GENEROUS PROFESSOR), on very finely subdivided elements of the part such that the result is a model of how a very complex geometry reacts to forces and deforms, broken down into simple numerical problems for the computer to crunch through quickly. Quicker than you. No, I’m not bitter about my Mechanical Engineering degree or my classes at all. Why would you even THINK that????

In a typical FEA simulation, you set the constraints (how the part can’t move), set the loads, the materials, and any contact conditions (e.g. between 2 parts, between 2 materials), and let the computer have at it. There’s many ways to do FEA WRONG that I won’t get into detail here.

Here, I’m doing a bending force analysis on the point where the clamp actuator mounts. I wanted to see if this would cause problems with the whole thing deflecting when OH2 mashes down with a few thousand pounds of force. The conclusion is that no, this hub is fine. Double shear for the win!

I usually design to Yield Strength for materials (the point which a material bends). It’s more common to design to Ultimate Tensile Strength – the point when the material breaks. I prefer Yield because if something bends in battle, you’re hosed, but this won’t put any planes in the air…

Having run through the hub once, I started generating the lifting forks. They’re going to be made from some steel tube and some steel plate, cut out into scientific shapes and joined in less than scientific ways by yours truly.

At this point, I was still interested in curved forks. I wasn’t quite sure how I was going to make these yet, but hey, why not try CADing something different? The tube profile was generated with a Sweep of the square tube profile (modeled without fillets).

Now in solid form…

I did something slightly nontraditional here, and made each of those elements you see – the tube, the tube caps, the fork curved square tube, etc. a separate solid body in one single Part file. This let me easily reference the parts off each other. To break this down into things I can cut, I highlight and save each solid body individually.

Modeling the “fish hooks” at the end from what will be waterjet-cut steel plates.

Time to see if this fork can stand up to the maximum force exerted by the upper clamp arm. This is a view of the “finite elements” in “finite element analysis” – the computer solves iteratively how each of those little triangular sides deform based on some relatively simple continuum mechanics rules. I modeled for 2500 pounds-force per side, at the tips. This is basically the full, err, bite force of the upper clamp arm (ideally each fork seeing 1/2 of the load).

First attempt: Dorky mild steel tubing.

Nope. Utter failure. Everywhere.

Second attempt: 4130 steel, normalized (not heat treated). This was assuming I could get 4130 in those needed sizes, which later proved to be a problem. This is “edgy” – the yellow on substantial parts of the tube means that on overload conditions like mashing someone into the wall, it could bend and fail there.

Okay, how about using geometry instead of more hardcore alloys? I modeled a single rib that runs the length of the fork arm on the inside. This is not preferable at all, since I don’t want to have something sticking up right where weapons can reach it, but I was interested in how it changes things.

The rib option is workable. This result is a little deceiving, since I had the force concentrated on a small region of the material (the hook), so it will deflect more than everything else. Really what I’m paying attention to is the green-yelow on the rib itself and the tube being largely blue – the rib has transferred most of the stress out to itself, which is what is expected.

The bolt holes are still a little concerning. They are, however in regions which will be tightly bound next to other parts, which simple FEA modeling doesn’t capture.

Instead of the rib, what if I just went to a thicker steel section? Here’s 1/4″ wall tubing (still using 4130 – not even sure if it existed at this point!). The performance is better than the 1/8″ tube version without the rib, but actually not too much. Since the rib is further away from the imaginary axis which this arm would bend along, it can resist the forces far better than more steel closer to the axis. Geometry!

I stuck with this for now, for the purposes of moving on. All of this analysis was really completed in one evening, by the way, so this wasn’t days and days of running simulations. I was willing to trade the inability to use all of the upper clamp force for some “easy” – roll a tube, weld some plates on, whatever.

I’m going to skip ahead a few weeks here, since I like the continuity of this thread about the forks. You’ll get to see the “final” fork design, even if the photos of OH2 from here until a few posts more will be showing this “old” design. Basically, after finishing the bot in whole, I began revisiting parts which I felt I had left “sketchy”, including the forks. In the intervening weeks, I had called around getting quotes and prices for sourcing the arm tube. I had thought I had a handle on sourcing 2″ square 4130 tubing, but I was either imagining it or they changed the Matrix between the design and my revisit.

Bottom line was that I thought using 4130 was no longer realistic in the (Time * Frustration) factor department. Therefore, I decided to capitalize on known available materials, and good geometry.

This time, I’m using a “tube and side plates” approach where the side plates define the shape of the arm and also carry the majority of the weight. The tube really is there for closing off the top and bottom surfaces (sideways rigidity) at this point, and I could even replace it with a rolled curved plate and have an H-profile beam.

This design kind of looks like the original “rib” design, except the ribs are sort of discretized into the new side plates.

The plan was to cut them from the same material as I was making the upper clamp – AR400 plate.

AR is my new favorite  material after building OH1. It’s just so good and versatile, and is my mental go-to if I need a ~140ksi yield strength material that can remain mostly flat. Usually, stuff with that high tensile strength isn’t easily welded, but they designed this alloy specifically for tacking Iron Man suits together in the oilfields with tin cans as filler material or something, so it’s also easily weldable. You do lose some strength in the weld area, but again – geometry can help overcome, or at least offset that.

Throwing it into the FEA module. I modified the location of the force so it wasn’t causing signficant deflection of a single point (the hook) – instead, it’s centered on the large planar face.

Some geometric changes and lightening holes later, and this is the curved arm design. The holes in the side lost about 2 pounds without substantially raising the stress levels.

The geometry here is modeled as “bonded”, meaning no movement at material boundaries is permitted. Clearly this isn’t true in real life – to approximate it, I’d have to weld substantial portions of the holes to the arm tube, or the movement will cause one or the other part to exerience more stress than designed. FEA is one of those things which is tobe melded into everything other aspect of a design, not the end-all answer to a problem.

Skipping forward again another week or two, I was discovering that the tube rolling process was going to be problematic. First, the sides won’t be flat any more – the tube will bow out. Second, there was no tube roller nearby that could handle the material – not in my network, anyhoo. To get the tubes rolled by a known bot-friendly company would have been 2 weeks of leadtime since they were on the west coast.

So I decided to do the final refactor of the design into something which can be built right now with materials and methods on-hand. This means angles.

The “look” of OH2 had been defined by the curved forks, so I wanted to keep an element of them in the final design while hiding the square tubes. Conveniently, the curved side slats are also excellent gussets. The idea was to approximate the curve as best as I could with regular square 2″ tubing.

The above shape with the “elbow” of square tube sticking out underneath…

…which I hid with an “inverse fish hook” coming from the side slats. Hey, they look intentional now!

Looking at the analysis of this part, the problem areas are where I’d expect them – the areas of the side slats near the elbow primarily. (After this picture, I increased the fillet radii substantially and the narrow neck near the elbow was no longer an issue)

As I had modeled these new AR400 plates with anticipated cutting tolerances, there’s gaps in them which I could not force to be “bonded” contact. As a result, you can see the corners of the front angled plate being “highly stressed” – causing the safety factor minimum to be artificially low in that region. In real life, these are going to be welded securely.

Alright, time to undo the timeskip (this was “roughly week of 3/7″). Now we return to the pontoons and upper clamp arm.

 

I took the surface reference model for the pontoons and literally grew those surfaces into 3/16″ plates…

…and then did my usual “edge stiching” finger joint method on the individual plates. This will make the part very easy to self-fixture for welding.

More details, such as internal gussets, have been added to the pontoons, with more to come.

With the front pontoons done, I brought in some more components as a bit of “work-ahead” – thinking about the next step while I’m working on the current one. I knew what I had to do for the upper clamp arm, so I just had to crank it out while thinking about electronics mounting, the bane of mechanically-minded robot builders everywhere. Can I just cast the whole thing in hot glue and be done with it?

Coming up next: The upper clamp arm geometry and actuator!

The Overhaul 2 Design & Build Series, Part 3: The Drivetrain and Lift System CADnado

Mar 11, 2016 in BattleBots 2016, Events, Overhaul 2

Alright kids! Buckle in, cuz I’m not stopping the CADvan until I have to pee at some point, usually around Stamford, Connecticut.  Oops, sorry – I forgot that this isn’t me piloting Mikuvan on an average trip to New York Maker Faire or Motorama…

This post begins the long journey from the concept sketch model to what will hopefully be the finished design. The primary goal is to show the evolution of the design and my thought processes.

One thing that will be a little slight in these posts is technical content – the hows and whys of selecting a certain component. I already knew much of what I wanted to work with when I began, having built Sadbot as a power system mule before this all started.

What I’ll do is recap the construction of Sadbot and how many of the power system components were picked after this segment of CAD model posts – there is a lot of interesting science to help advance the state of the sport which I was able to distill. What “engineering” content there will be in this series of posts will be more centered on mechanical engineering and materials, since this IS designing the frame and structure.

We begin with the trailer photo in the previous post, the new OH2 frame besides Sadbot:

 

Using the information about component placement from the 3D sketch model, I began making individual part files that represented the frame rails. I tend to start with drivetrains and bases first. Not everyone does it this way, but I figure if the robot can’t move, then I’m in bigger trouble.

The choice of frame rail material is massive 1.5″ by 4″ aluminum bar stock. I went for this extraordinarily beefy material since OH2′s frame was, for the most part, also going to double as its armor. The aluminum rails will be hollowed and machined out (“hogged”) where needed to save weight. One upside of using a large starting section area is that even if much of the material is removed, it is still more rigid than a full smaller section.

Great, first I’m a Bite Force knockoff, now I’m an Icewave knockoff.

The thick rails allow the use of offset bolt patterns to increase the fastening rigidity of the joint (compared to, say, 5 bolts in a line) as well as avoiding the postage-stamp effect where the bolt holes become a neatly placed line of perforations.  But now it looks like an Icewave knockoff.

All of the frame bolts are 3/8″-16 size.

Modeling in more of the structure, including the cross-rails. The initial spacing of the wheels was determined by the sketch model, which had wheels positioned according to the drive motors. This, as you’ll see, will change a lot.

One of the first things I modeled “for real” was the drive wheel hubs. This uses a retaining ring system similar to Überclocker’s final wheel hub interation, and is designed for the 2″ wide Colson series – 5″ x 2″ in the back, 3″ x 1.5″ (with a spacer) up front.

The hub permits sprockets to be mounted on one or both sides, and the center bearing is a needle roller bearing system to minimize friction. To transmit wheel torque, the whole hub is double-keyed with 0.25″ standard keyways.

Modeling in the plate that holds the drive motors now…

One of the issues which plagued OH1 – and really, most of my bots – is serviceability. While we became fast at replacing something on OH1, that doesn’t mean it was good. I aimed to make all top-level components which could break – motors, batteries, controllers in particular – be serviceable without taking apart the frame rails. The wheels would be an exception, as the shafts make up part of the frame.

In particular, since the motors and controllers were going to be highly experimental, I wanted the ability to swap them out quickly. OH2 has four drive motors not just for power, but in part for redundancy.

Shown above is the drive motor area, where I’ve designed them to pop out the bottom. After unbolting the motor mounting plate and disengaging the drive chains, both drive motors on one side just slide out from underneath. There will be a small gap in the baseplate for the rotation space, which will just get covered with some duct tape to discourage the collection of arena grunge.

More motor mounting details get modeled in on the underside. The motor mounting plate is roughly T-shaped.

I originally had the four holes on the outside also facing out the bottom, but it would have required that region of the outer frame rail be made pre-emptively solid to accept the threaded holes for the bolts. To keep the design more flexible for now, I decided to keep the holes in the more space-saving configuration by having the bolts point into the smaller motor mounting plate.

I flipped the design back over and added all the rubber shock mounts to the top. I bought a few different candidates from McMaster-Carr prior to this, in order to appraise the candidates.

The strategy with the shock mounts (or as we kept calling them, wubbies) this time is to use many more smaller ones in a more distributed fashion. Not only will there be these facing upwards and forwards, but also some facing sideways.

When the bot loads the front pontoons this time, the six shock mounts on each side will be put into compression and tension to react the load, instead of just being bent. Twelve ought to be enough to hold the forces – if not, McMaster has harder versions of the same mounts.

I’ve generated the motor mounting plates here and have put in mounting features for the gearboxes. The holes are slotted for chain tensioning adjustment.

The vaguely completed frame so far! Here, I’ve added two of the side shock mounts. These don’t play as much of a role in a lift, but if I get whacked on the side, they help isolate the pontoons from the frame.

With all of the frame rails and critical features in place, I added a baseplate. The school of thought for fastener placement here is “Whatever patterened the easiest”. It’s likely not all of these fastener holes for #10-32 countersunk-head screws will get used.

Now that a box frame with bottom was complete, I started bringing in other parts for sizing verification.

With the shape of the frame basically defined, it was time to start putting up the arm towers.

In keeping with my preference for the “This is a drivetrain. Everything else bolts on here.” design school, I decided to make the arm towers a separate piece each. Here’s pass #1 at the design.

This was also a move for manufacturability. The idea is to make everything from the 1.5″ x 4″ barstock, and then waterjet-cut the arm tower to rough shape, then finish-machine.

Pass #1 got the idea across. I decided to use the arm towers to additionally brace the large cutout in the side rails where the motor pass through, so I extended them past the motors. Furthermore, the long rear slope evokes the arm towers of OH1 more (it had a highly sloped backside).

The arm towers are anchored with five giant 1/2″-13 bolts apiece. Nothing will fail here… if the arm towers get torn out, something very, very bad has already happened and stripped threads are no longer something I need to worry about.

Once the shape of the lift towers was set (for now, anyway), it was time to fill in the details.

HUMONGOUS SPUR GEAR!!!

From Sadbot experimentation and some math, I had a range of gear ratios which would be acceptable for the lifting forks. The goal was to get an arrangement of some combo of gears and sprockets to get into tha range.  The ratio to hit was approximately 180:1, with 16:1 of that taken care of by the P80 gearbox on each motor. This would permit the Sk3 6374/149 motors to lift a 250lb opponent at the very end of the roughly 24″ long arm at roughly 42″ per second.

Almost 4 feet per second, up or preferrably also down. Überclocker was well known for smashing opponents on the arena floor over and over, and this was a move I wanted to duplicate with OH2. That’s literally 10 times the speed of OH1′s linear actuator lifting arm.

Why gears? Remember that in the initial sketches I had a big sprocket modeled. Well, after thinking aout it during the arm tower designs, if I was going to have unboltable arm towers, then what good is it if I have to find and remove a chain master link to service the liftgear? A HUMONGOUS SPUR GEAR will permit me to unbolt the arm towers and just lift everything off for independent service, and furthermore, just smash it on and tightened the bolts down when done.

The liftgear must be then beefy enough not only to stand the static force of holding an opponent – already 500+ft-lb of torque at the lift shaft, but also the forces of me slamming the transmitter stick in the opposite direction of travel and the impacts with the floor. For now though, ratio was more important than tooth size.

The idea was to have the big gear be part of the removably top assembly. So to start off, the little gear (“pinion”) must be mounted in the frame. This first attempt was with a 3:1 output stage, which kept the intermediate stage requirements also reasonable – it’s difficult to get more than 4 or 5:1 in a single stage without making one gear tiny.

The gears shown are 6 Diametrical Pitch, 36 tooth and 12 tooth.

But that design left the pinion directly in the line between the frame and lift towers. Attempt #2 is a 4:1 output stage with a 48 tooth 6 DP gear and a 12 tooth pinion.

For those keeping track, a 48 tooth 6DP pinion is 8.3″ across. It’s the size of your face.

While the 48/12 arrangement put the pinion at a good location on the vertical axis, gear calculations showed that the tooth forces were going to be too great. The smaller the gear, the more tooth force is needed to transmit torque. I was going to have to make the gear from hardened tool steel for it to have a chance. Therefore, I downgraded the output stage to 3:1 and decided to use a 15 tooth pinion (Alright, so it’s 3.2:1. Bite me.)

To retain the ratio, the lift towers had to be increased in height slightly, which was something I was willing to accept.

By the way, these gear tooth numbers aren’t being magically summoned. I was thumbing through various gear manufacturer’s catalogs and industrial suppliers which carried those products in stock. I wasn’t going to start specifying custom-machined gears just now…

One of the difficult “real life engineering” things I tried to teach in the 2.00gokart course for the freshmen and sophomore students was that you had to be able to buy or source the thing you designed, so don’t spend too much time optimizing for the peeeeeeerrrrrrrrrfect system. Chances are, the supplier won’t have it, and your beautiful numbers will crumble to dust in front of you like a timeless story of fairy tale justice.

Since both 48 and 15 tooth gears existed in real life, I settled on that for the time being. Now it’s time to design the intermediate stage. The input ratio – 16:1 – and the out ratio – 3.2:1  – were both anchored. To hit the target ratio, I needed a 3.75:1 intermediate ratio.

I had to play some geometry games. Shown above are the two lift motors, each with a 12 tooth pinion – the smallest available pinion in that Diametrical Pitch with a 1/2″ keyed bore. And really, the smallest gear I was comfortable fitting on the motor shaft due to the bore size. Any smaller and the distance between the keyway in the gear and the bottom of the tooth become very small, risking it failing there.

With a 12 tooth pinion, to get a 3.75:1 ratio I would have needed a 45-tooth gear. Unfortunately, I couldn’t quite find a geometric solution here. The diameter I would have needed to fit the 45 tooth gear meant pushing the lift motors further apart and further down. The baseplate is one constraint, but the shaft axes impinging on the drive motor area was another one. Plus, nobody seemed to have 45-tooth gears in stock. It’s a bit of a weird tooth count.

A 42 tooth gear made for a near-perfect arrangement where the motor were seated on the baseplate and also spaced closely together. This meant I could only get 3.5:1 in the space, leading to a total ratio of 179.2:1 from the motor.

Okay, whatever. That’s 180 enough. 2 plus 2 equals 5 for large values of 2, and sufficiently small deviations about a designed optimal point will generally go unnoticed for the majority of loads. I was honestly happy I could get close to 180 at all. The best part? Everything was in stock!

I moved forward with the 42-tooth intermediate gear. At this point, I also began to think about how to clutch the output shaft. Having such a high gear ratio makes your system prone to inertial damage. The very act of suddenly stopping – like slamming an opponent on the ground – causes the motor’s inertia to be magnified many times through the gear ratio, adding more stress to the gear teeth in a very short amount of time.

Plan A of clutch design was using a Trantorque keyless bushing. These things are cool. When you stuff it into the bore of your gear or sprocket and tighten the nut, the outside collar expands and inside collar contracts, causing immense friction. That’s how it transmits torque. Transmits. Torque. TranTorque. Hey, I think I get product marketing, guys!

My plan was to purposefully half-assedly tighten it onto a hardened and polished shaft such that it could slip at some hopefully pre-determined load. Hardened and polished is critical so the surface does not gall up and destroy itself – both the smoothness and hardness are important.

How do you size gears? Well, you could pick up a mechanical engineering textbook and do it OLD SCHOOL COOL, or use the gear generators and analyzers now built into many modern CAD packages. These are the equations and tables in those textbooks packaged in a way a lazy millenial* can understand.

That’s how I found out the 12 tooth pinion was going to be very unhappy. The key number for my purposes is the Sf value to the right. That’s the Tooth Breakage Safety Factor. That’s what you DON’T WANT TO HAPPEN. For the 12 tooth pinion, it was getting awfully close to 1 – and by that I mean like, 2 or 3. In robot-smashing duty, you never, ever design anything for a low safety factor. I’m sorry, aerospace & rocket folks. Your robots always lose for this reason.

Gear 2 is the larger gear, and notice how its safety factor is something like 7.6. This tells me the gear material is very much overkill for strength. In fact, it might be fine being made from aluminum. I decided to keep modeling it as steel for now for weight purposes. When I need it, I’ll hopefully be able to shed a few pounds by moving to aluminum – this would entail, for example, waterjetting an epic gear from 7075 plate or similar.

The other very red and concerning looking numbers are not of interest to me here. One is the Tooth Pitting safety factor, and the other is the Static Contact safety factor. These are important if your gears are running for a long time and you’re looking for longer term tooth wear reliability. All modern gear design methods factor in many different little environmental conditions as well as the desired running lifetime.

For me, that’s like, 5 minutes – so I really only care about teeth breaking.

*Note: I am probably on the very trailing edge of who’s usually considered millenials these days, being a product of the late 1980s like my van. I use the term both to express indignant outrage and to disparage my peers’ achievements depending on what is politically advantageous at the moment.

Using the Trantorque GT clutch-bushing idea, I continued to build up the infrastructure of the liftgear. Here, I’m putting in downloadable models of bearings and shaft couplings to see how much space I have.

One design evolution was in the length of the bot at this point. I wanted the liftgear to be double-supported, meaning they were surrounded by frame rails on both sides. This enhances the rigidity of the area immensely, since the gear loads were no longer being supported by twisting the front frame rail.

But already, there was no space to put a secondary frame rail here. The lift motors and drive motors were too close together.

Solution: Make the bot an inch longer. The 3 vertical holes are for a 0.75″ thick transverse frame rail to help bolster the motors.

As seen here!

Alright, a few days after this design session, I received a Trantorque GT bushing I had ordered in the mail. Conclusion: no

Not because the idea was flawed, but that the bushing is made from a soft steel. After all, it’s supposed to be mushed into the bore of a large fan pulley or something and stay there for decades. I became concerned about controlling what slips on what using this bushing. Bushing slips on hardened, polished shaft? Sure. Bushing slips against bore of unhardened, similar-alloy steel gear? Bad. I’d be machining the bushing out after that.

So I threw that idea on the ground and decided to make my own. Shown above is a very drastic torque limiting clutch.

Here is a cross section of the clutch. I just took an industrial torque-limiting hub for sprockets and made it longer.

Those things are really simple. A big nut pushes a (usually) Belville Spring onto a pressure plate which is keyed into the shaft, and the pressure plate is what transmits the torque. The brown material is clutch pad, which McMaster-Carr sells in VERY EXPENSIVE sheets.  Some quick calcs show that this clutch should be able to hold up to around 500 ft-lb of torque with that big Belville spring I picked out from McMaster-Carr (which sells it in VERY EXPENSIVE packs of………… 1). There might be a pattern forming here, I think.

Dropping the new torque limiter in the CAD and continuing to build up infrastructure by air-placing parts.

A set of spider couplings join the gearbox output shafts to the intermediate gear stage.

This is here for 2 reasons. First, for springy compliance: While the big torque clutch gives frictional compliance, a single high-energy impact, such as getting tapped by the Pulverizers or an opponent bot’s hammer or being run into a wall with the arm up, etc. could still put enough energy past the intermediate gear stage before the clutch even starts slipping to damage the gearboxes. The springy compliance absorbs this brief input of kinetic energy by deforming the rubber/urethane core of the spider coupling.

So the liftgear has two protection mechanisms. The torque clutch prevents the motors from driving and overloading the mechanism, while it and the spider couplings work together to prevent external driving forces from being shoved back into the motor with a vengeance.

Once I was happy with the air-placement of everything, I began wrapping frame rails around them.

Here, reason #2 of the spider coupling’s role is revealed. I’m also using them a bit as dog clutches in conjunction with a motor mounting block that can be unbolted and slide out quickly should something bad happen to the lift motors and they need to be replaced. Another design for serviceability factor!

This basically concludes all the design work on the liftgear. From here, after letting the design bake for a little while, it’s time to move onto designing the front armor pontoons.

We begin with a bunch of reference planes…

The Overhaul 2 Design & Build Series, Part 2: How to Design an Overhaul!

Mar 08, 2016 in BattleBots 2016, Events, Overhaul 2

In the previous post, I presented a summary of why overhaul1 sucked the various shortcomings of the Overhaul 1 design. This will be the first of two (or more…) posts which heavily dive into the details of CAD modeling, and SOON! you’ll get to see the Overhaul 2 design in its entirety. The idea of these posts is to show how the design evolves incrementally from the crude sketch to complete model…. and also the little changes made to it even after it’s “complete”, because that happens every time. Always.

My software of choice is Autodesk Inventor. Yup, I’m a child of the Autodex. They got to me first in 2005 when I was a wee lad high school sophomore, with handing out Inventor Professional to FIRST Robotics teams. MIT largely ran off Solidworks, and during my time as an instructor I also taught intermediate to advanced Solidwanking (that’s a technical term) for the design classes, but whenever I do something for my own projects, Inventor is still my go-to.  These days, Autodesk tends to push Fusion 360 to the maker crowd and it’s generally free with limitations. Even just a few years ago, if someone asked me how to start using CAD programs, it was hard to give an answer that was accessible. That’s changed now with Fusion, 123D, Onshape, and other platforms, which is great. If you’re a student or have .edu affiliations, you can get students’ and instructors’ licenses for Free (as in Beer) from Autodesk Educational Community for a few years at a time.

So anyways, all the screenshots you’ll see will be out of Inventor Professional 2016. My opinion is that on the average non-commercial (or even light commercial) usage level, the difference between Inventor and Solidworks is largely like Ford and Chevy – largely the same features, same commands, and same structure are seen in both, with some nitpicky differences such as I’ve never successfully turned on a headlight in a Ford car, I’m pretty sure. “Solidworks vs. Inventor” is like the vim & emacs debate of CAD students, so I’ll just say that I’ll have none of it here.

Let’s begin with the sketch from July 2015.

 

This sketch was actually the last in line of several I was playing with, which sadly were not saved. It originated from the desire to push the “dustpan” front end of the robot into the drivetrain a little, such that I could have front wheels almost directly under the center of lift. This was something that we played with for Overhaul 1, as shown in this CAD party photo from last year.

As can be seen, the bot was a lot more sloped, and the earliest designs of the shuffler modules reflected that. We were going to make the front armor heavily sloped and stuff the front of the drivetrain under it. But that evolved away for reasons which I do not remember well – possibly ease of fabrication focused.

The rest of the shape of the sketch followed the thread of putting wheels under the new dustpan region. Those wheels had to be smaller than the others, which was fine. I originally had the design as 4 wheels instead of the 6 shown (3 per side), and I think that would have been passable. However, I decided to explore 6 wheels to give me more options for wheel placement – basically, tuning the “front” and “rear” wheelbases independently as needed. 6 wheel drivetrains also have the benefit of being able to place the center wheel very slightly lower (“drop center”, for you FIRST kiddos) such that the bot is basically 4wd at any point in time on a shorter wheelbase, preserving turning speed while affording a large stable base.

Beyond that, the sketch was simply “what looks kind of okay” on the dustpan profile and body length I drew. There was no science behind the other dimensions – I just wanted something on screen to stare at. I liked the idea of a multi-faceted dustpan for cool looks, but wasn’t entirely set on it.

Fast forward to October. Season 2 was supposed to have been announced 3 months ago and I was in the middle of RageBridge 2 development, when suddenly, applications for #season2 opened up! Uh oh, now I actually have to put things in the frame sketch. It became obvious very fast that this bot was too small – nothing useful could fit inside the space as-drawn, even though it looked nice and compact!

So I made it longer.

As you can see, I literally made every dimension a bit longer, and put some sketch boxes in to represent motors and stuff. Also shown in this sketch is an imported side profile of Overhaul 1. Yes, even after stretching the new design (“Holy crap, 3 feet?!”) it was still shorter than Overhaul 1.

This sketch was reasonable to start making “3D” so I could start playing with placing part models.

So I did just that! I took this sketch, stuffed it in an Assembly file, made it a reference drawing, and started extruding parts off it. Just solid blocks.

INTROUUUUUUUCIIIIIIIIIIIIIING

 

OVERBITE!!!!!!!

Sigh.

Everyone who saw this sketch model said it looked like Bite Force. Well gee, I’m sorry not sorry if some times in engineering there is an optimal geometry to get something done. That’s going to start biting BattleBots in future seasons, I think, when more of the design space is “claimed” by certain successful designs. But we’ll burn that bridge when we come to it, as I always say.

Noticeable additions to the sketch include little side strakes on the lifting arms. I put these there for looks largely, but Überclocker’s “fish hooks” have been wildly successful in snaring bots that the fork gets under, so I was planning on including similar entrapment devices. Did I mention pointy bots look cool? They do, right!?

Another side profile shot with OH1 in the background as a halo.

Whoa… quite a jump from the last picture here. Actually not so much. I just hid the square arm and replaced with with 1/8th of a circle that intersected the lift axis and was tangent to the ground, and then extruded a bunch of shapes off it. I think this looks cooler – the curved arm works well with the upper arm (which has been separated into individual pieces, but still all driven off the big assembly master sketch). Not only that, but the constant curvature is stronger than a sharp angle joint with faced with the bending forces imparted into it by the top arm.

I was playing more with the top and back sides of the bot at this point, trying to emulate the sloped-back look of OH1. I made a simple Sheet Metal part with 2 bends in it to give some more non-square shape to the sides. And the cherry on top was of course the now-classic Overhaul Ears, also a Sheet Metal part that was referenced from the top center hole in the arm.

Nothing in this assembly can move – it’s all just sketches and extrudes. It’s a visual clay-model for me to think about the shape and size of the bot.

This is the previous sketch model with the top plate removed. The arm towers just grow out of the big solid rectangular extrude feature that is the body, so my next step was to hollow it out a little bit to add part models inside.

Now it’s starting to look a bit like a robot. I stuffed some sprockets in to get an idea of plausible drivetrain scenarios. How much chain/gear/belt ratio you can use is largely dictated by things like wheel size, and that’s influence by robot shape. I grew this design from “robot shape” downwards – many people grow designs from “I have this motor” upwards. In this case, since it’s a bot which is trying to take after a previous design, I wanted to establish the form first.

Notice also that the bent-style top plate is gone, in favor of a single flat plate that forms the sloped back of the bot. Again, just playing with shapes – I decided to let component placement dictate where I put top armor and back armor. So long as things fit inside, we’re chill.

Look! It’s Sadbot! I have a whole build report on this thing that some builders in the community will find very interesting.

Especially after this next image.

Here I am trying out a few test components. Keep in mind that these were all part models I had on hand, or extracted from manufacturer websites. The blue bricks are batteries – the same 8.0Ah, 18.5V lithium packs we used in OH1, just a flatter configuration. The purple things are motor controllers, and the gray cylinders are motors themselves. These are quite different from what I’m used using in bots, especially big ones.

I can hear jaws dropping, the “I KNEW IT”s, and the finger snapping from some of you already. Again, explanations in due time, I promise.

Also shown in the photo – on the right upper corner, two Whyachi MS2 switches, since the new rules required separating drivetrain and weapon power, and some more big sprockets and gear models downloaded from McMaster-Carr to, once again, get a rough idea of how much gearing I can put into this frame. Less than 2 hours of clicking around separate the last two images, so no magic is being exercised here.

Here is a different configuration of the interior. Motors and controllers are often the biggest-ticket items in a bot design, so you kind of wrap the thing around them because they ultimately dictate how your robot drives and behaves. They’re also the juiciest and most prone to damage from abuse, so it’s good that everything is kept in the center.

Instead of a “2 x 3 stack” like previously, this arrangement is just all the motor controllers in a row, laid out flat. I liked this arrangement more, because it lets all controllers be accessed equally for replacement or service if needed. I imagined just having a huge bus rail attached to the battery pack that the controllers plug into, so I can rip one out easily if need be. Their heat sink fins being vertical also helps for heat dissipation, which if you’ve read enough RageBridge development posts, is the number 1 enemy of motor controllers.

The 7-in-a-line arrangement was very tight on space though. I could have made the bot wider – and did, briefly. But on one side of the bot, I played around with pushing the drive motors further out. The gearboxes shown in the design are Banebots P80 gearboxes, which proved themselves well on OH1′s lifter and clamper/crusher gearboxes, so I contemplated using them for drive. Part of Sadbot’s mission was to see if a few of them could handle a 250lb-class drivetrain. In this sketch model, I had the bright idea that I’d basically use the P80′s longitudinal structural bolts to mount them to the frame – just use longer ones, so they poke out the back of the gearbox.

Pushing the drive motors further out enabled me to free up almost 5″ of interior space across the width. That was plenty to put the controllers in, separated comfortably, with room for future mounting hardware, since you don’t just throw things inside a bot frame and hot glue them in…. Okay, fine, some of you do.

It was in this state that I submitted the application to BattleBots for Season 2 in late November. Everything KIND OF makes sense, everything OUGHT TO fit, and SHOULD work on a good day. Seemed legit to them!

As for how this region ended up – here’s how it looks in the finished design.

well that escalated quickly

Some things changed. Some things are gone. Some are still there! The next few posts will tell the story of how everything got to that point. You know how I said “oh, not much work separated these two images”. Well, a whole lot of damn work separated these last two!

It was now late November. Time to stop CADing for giggles, and start CADing for real. This is where it begins….

s

The Overhaul 2 Design & Build Series, Part 1: How to Overhaul a Design

Mar 07, 2016 in BattleBots 2016, Overhaul 2

Here we go! The very first (real) post in the Overhaul 2 Design & Build saga, which will set the stage for the future posts. What I’d like to do with this post is give a little more story on how Overhaul 1 was designed and built, its shortcomings in the competition, and then move onto how I think the new build should address those issues. Then, from here on, the posts will be exclusively design and build oriented. My anticipation is that Parts 2 and 3 will be very long, showing the evolution of the CAD model, and from there, the posts will be more scattered with build updates and interspersed with CAD updates.

The first step in evolving a new design is always to appraise the functionality of the old, and to do that, it’s time to review what made Overhaul 1 into what it was for Season 1. In the first portion of this post, I basically summarize the build process for Overhaul 1, so that’s worth a read. What you never got to see in that post, since it was made prior to the airing of Season 2 episodes, was the competed design and the near-completion bot. We weren’t supposed to reveal anything yet, much like how you’re not “supposed to” be doing now.

So here’s some never-before-seen pictures of the build of Overhaul 1. First, the finished CAD model:

There’s the beast in its entirety, designed using Solidworks 2014. Trying to twiddle this model a year after the fact has caused me to forget much of its hacked-together behavior, and additionally made me wonder what the hell “midline axis of fancy thing” was (it was the central axis of the leadscrew nut on the top clamp arm…)

Documentation. We has one.

Recall the photograph in the “Life of Charles” post which shows megatRON mated to Uberclocker.

You can basically break down OH1 into three components. The front (leftmost part of the CAD model), which is the dustpan/corral of Ron, the upper arm and clamp which is heavily Überclocker, and the shuffler modules inspired from Fission Product. It was largely designed in this manner, with the four of the principals (J, A, me, and D) moving from ‘station to station’ with the design.

We basically knew from the start that nothing about this design would be ‘optimal’ due to the genetic confluence and conflicting design requirements. So the design was kept very modular on purpose. The drivetrain was one box, the dustpan was another, and the arm stuck on top. The positioning of everything ended up being dependent largely on where internal components had to go, which is a theme which will return for version 2. This ended up giving Overhaul 1 it’s very characteristic “hunchback” look in the arena.

Not only that, but the wheeled drivetrain seen in the tournament matches in Season 1 had to be made to fit entirely in the space previously occupied by the shuffle modules, resulting in the wheelbase being very short – only 10″ on a bot which was 41″ from end to end. It might as well have been 2WD!

 

While this made for quick turns, it meant the bot had no front traction centered under the massive front dustpan, and furthermore, was already very front heavy with the lifting arm and its 2 actuators (plus the top clamp arm) hanging off it. The little black and white ball below shows the center of gravity – as you can see, it started past the front wheels.

When we got anyone on the forks, it was often at the expense of being able to, you know move. And then there’s this embarrassing shot:

This, coming from someone whose bot was known to do the “robocopter” was borderline shameful. This goof was a result of putting the large rubber shock isolators (“wubbies”) in a straight line at the dustpan’s interface. We just kept it to the height of the bot frame for convenience.

Contributing additionally to traction issues was the large overhangs of the drivetrain caused by the switch to wheels. The shuffle legs could reach well past the “wheelbase”, but wheels, obviously, were limited to the contact directly under them. This meant that there were plenty of moments where OH1 was lifted up backwards – either by opponent attack or counter-torquing the lifting arm, such as the first Lockjaw match below, where I couldn’t get out of it without lowering (or being lowered) back down.

OH1 could really only be tilted back about 15 degrees before losing rear traction, and this was a key issue in why we lost the Bite Force match (besides my too-aggressive tactics, which is not really a design problem so much as a firmware issue with me). Any time Bite Force got under me with some energy, it was enough to prop OH1 off the ground.

Besides driving, the arm itself was too slow – watch OH1′s matches again and you’ll see quite a few missed lifts. I’m used to the very fast lift of Überclocker, and the linear actuator driven arm was a great deal slower than that, and lack of practice really hurt my timing.

The reasons why we went linear actuator over rotary (e.g. Bite Force and some other lifters like Stinger) was partly due to available parts and partly due to lack of experience. It was our belief at the time that you couldn’t get a gearbox heavy duty enough to handle the torques – many hundreds of ft-lb – without it being massively heavy or requiring another stage or two of torque amplification to use, which also increases weight. A linear actuator is a cheap way to get immense force at the expense of speed. In fact, Overhaul’s lower lifting fork could lift well over 2500 pounds at the maximum current of the motor, accounting for the 85-90% efficiency of ball screws. That was basically unnecessary, and should have been traded for speed somehow. Another factor was convenience – the clamp actuator and lift actuator were fundamentally the same parts, just one with a bigger gearbox.

There’s another detail which influenced the ability to grab and lift effectively. Look at where the forks end - well inside the tips of the triangular pontoons. They’re tucked in largely in the interest of anti-spinner protection – we didn’t want the forks to be the first thing a horizontal kinetic weapon hit. This also led us to make the “backboard” for the portion of the arm which dropped down into the dustpan.

It was kept that length also due to an unimplemented feature:

The crossbar at the front of the dustpan was going to be 1/4″ AR400 grade steel bars with some 1/4″-wall steel tubing and ribs backing it up. Not only would it have greatly increased the rigidity of the dustpan, but it would also have visually completed the bot, giving it more of a reason to occupy its nutty 42″ total length. One guess as to why we left if off…

By the way, after the tournament, I realized it was much better that it got left out. The triangular pontoons allowed OH1 to get a proverbial foot in the door in most of its  matches, where the broad surface of the crossbar might have prevented it, and also prevented more of the opponent from reaching the arm.

Can you guess the reason yet?!

In the end, besides “fundamental design flaws”, we never really had any major problems with the build or the tournament, and we frankly had a reasonable time with maintenance.  We got skilled to the point where we could pull a drive motor in under 5 minutes with tools ready, or the entire clamp arm assembly in the same time to get to the actuators, which was what we were doing when I was interviewed for the 2nd Lockjaw match; they had a penchant for bugging us for interviews and talks exactly when we needed to do something. It was definitely not “designed for service” in many ways, but we got good at it to make up for the part access deficiencies. It helped that OH1 was not very dense – a lot of it was air….

….but someow it STILL weighted 253 pounds out of 250 when done. Yup, no front crossbar for us.

So let’s summarize.

  • Overall, the completely unoptimized design, prioritized for a fast build and ‘unique combination’ of predecessor bots, led to a number of inherent flaws. When you glue 3 robots together in CAD, and have that be the point of the build, there will be parts of each bot which won’t work well with the others.
  • The lack of front traction under the dustpan section hurt maneuverability with an oppnent under control. Either I could try to push against someone or I could lift, but not both; at least, not very well.
  • The wheel were not pushed far enough towards the edge of the body to grant the bot sigificant rear traction. We tried to work with the existing spacing of the shuffler axles and used large wheels, both contributing to the short wheelbase.
  • The rubber shock mounts were used in bending instead of tension and compression like they were designed for. The result was an overly flexible dustpan that folded when the bot attempted a lift
  • The lifting forks were too slow because of the use of linear actuators. The lifting forks had superfluous force that could never have been used effectively.
  • The lifting forks did not project out of the dustpan, meaning the bot could not initiate a lift first. I could only drive under someone and try to maneuver them towards the arm.

Therefore, we can now designate a set of goals for Overhaul 2 that will resolve these problems.

  • Overall, the design must flow together and each part must have a reason to be in the place it is.
  • The chassis must either extend under the dustpan, or the dustpan must be affixed to the chassis in a way that allows a drive wheel to bear the lifting load; at least, the center of gravity should be between a drive wheel and a stationary contact with the ground, or best, between two drive wheels, as seen from the side.
  • The wheels must be made smaller to be pushed towards the corners, or the frame must have cut angles to permit tilting back; preferably 30 or 45 degrees or more. (Überclocker has wheels that ‘poke out the back’ for near universal traction)
  • The rubber shock mounts should be used in compression and tension as much as possible to mount the dustpan.
  • The lift system will be driven by a rotational actuator like a geared motor instead of a linear actuator; speed of lift is critical in being able to control opponent traction.
  • The lifting forks shall protrude from the dustpan profile, or better yet, be modular to be swappable to a short or long configuration as needed.

With these factors in mind, it was time to begin playing with concepts. We begin with the first concept of Overhaul 2, drawn some time in July 2015:

I’ll explain myself, don’t worry.

Presenting the Overhaul 2 Design and Build Series

Mar 03, 2016 in BattleBots 2016, Overhaul 2

FARUQ TAUHEED MODE

LAAAAAADIIIIIIIIIIIIIIIIIIES AND GENTLEMEEEEEEEEEEEEEEEEEEEEEEN, IT’S ROBOT…

END FARUQ TAUHEED MODE

…blogging time.

Greetings everyone, cat ear guy Charles here with an exciting new muscle-building, fat-burning workout pl…. wait, wrong commercial script. You know, I’ve just been drowning in fame and commercial endorsements and guest appearances since Battlebots season 1 ended and all. Yeah – don’t even get me started on the Great Hot-Dog-Bounded-Pizza Debacle of 2015 – I’m gonna NEED a workout plan after that one. Conveniently enough, #season2 is just around the corner, and you know what that means! Accelerating the deterioration of my lumbar vertebrae by another 25 years!

Sardonics aside, welcome to the Overhaul 2 build report series. If you’ve been a consistent reader or browser of my website since 2007, you’d know that I really enjoy documenting every part of my project builds as they happen, week by week, or even day by day. If you haven’t been a consistent reeader or browser of my website since 2007…. well, I really enjoy documenting every part of my project builds as they happen, week by week, or even day by day. Hello. I do not enjoy long walks on the beach.

And I really mean it; not only do I highlight the successes of my projects, but also the failures, the mistakes, and the could-have-beens. Nothing is hidden, glossed over, or excused. That’s because over the past roughly 10 years of etotheipiplusone.net (wow…), I’ve helped create a culture of project documentation and build blogging amongst my peers, first through the MIT student club MITERS where weird project people like me flourished, then later on as an instructor for the MIT electric-vehicle-building classes of my own design. This website, and by these indirect extensions and influences, has helped formed the core of a small network of  well-documented projects in the electromechanical realm, and have served as resources to many hundreds, if not even more, projects; I’ve only heard of or been told of via e-mail a few hundred of them, anyway.

By its very existence, it shows that making things isn’t all praying and summoning spells – it’s a dirty, involved, some times convoluted and counterintuitive process that you have to go through to make your project work. Nothing is magic and everything is machinable™ .The fact that problems are dissected on this (and others’) websites are what differentiates them from project galleries or “selected works” pages.  This is not a pretty portfolio site, and that’s by intent.

Which is why I’m taking significant time out of the activity of actually building the robot to tell you all about it. The truth is, this runs directly contrary to what the big shots at ABC, who fund the production of BattleBots and give it air time, want me to do. For months now, builders have been under a veil of secrecy which is just now being lifted in controlled ways. They want exclusivity and popcorn-spilling movie trailer structured hype. Well, if I had it my way, I’d have been posting about Season 2 since last November, each step of the bot’s design evolution and each one of the changes. I held off because the process would necessarily have entailed exposing the final robot design prior to the loosening of the leashes, and I didn’t want to fuck over the BattleBots producers.

My sole mission and agenda for #season2 is to make Overhaul 2 the first open-source BattleBot (with a capital B) and to inspire throw head-first onlookers into pursuing careers or hobbies in the engineering & making fields. Sole. I don’t care about huge multinational media conglomerates, and I don’t care about toy deals or book deals… though let’s face it – this build series will be a very well-sized book. I care about telling the world that the glamorous, sparkling mechanical violence they’re watching is not beyond their reach, and that each and every bot in the series was built by real people who all started somewhere, some not very long ago.

Engineering and science in pop culture is constantly presented with a little dog-shit of whipped cream on top and a wave of the hand, and my goal is to throw that right back into the money-greasy line kitchen that made it, in the only way that I know how – by not holding back when I fuck up. Overhaul 2 will be the most involved and complex engineering work I’ve embarked on to date, and you’re going to see every horrifyingly bad weld and questionable choice of hardware. Here’s what “open source” will entail:

  • First, a series of posts which chronicle the design process from the first sketch to the latest complete configuration – spanning a period roughly from last November to just a few weeks ago. Expect the first one soon!
  • Next, I will attempt to update at least weekly – if not more – with photos from the build process and explanations of what is happening. The current date is March 3rd. There are only 5 weeks to “ship date” at this point, so expect some rapid-fire posting.
  • Finally, to the limit that I am permitted to and which will not spoil tournament results and the TV episodes, I will chronicle the leadup to the event and activities at the venue itself, hopefully day by day, with more details after the season finishes airing in separate posts.
  • And lastly, after the dust settles, I will upload all of the design files and documents associated with Overhaul 2. Every CAD model, technical drawing, parts sourcing invoice, and last minute hasty edit will be available.

Like with Chibikart, the intention is not to spawn a hundred clones of the bot (Good luck sneaking that past the entrant selection for Season 3, right!?), but to push the technological bounds and the design space of the sport. There’s a lot of new things I’m planning on trying, and some of it terrifies even me. I’m not afraid of sharing full designs, because no matter how poorly you clone something, in the end, you were forced to build something even if it was missing one critical detail that real life copy-paste didn’t include! That’s basically how 2.00gokart worked. If Overhaul 2 throws a hundred new builders into the wider sport because Dude, I didn’t know you could do that with a Harbor Freight 18V Nose-hair Trimmer w/ Flesh… Flashlight Attachment, then I’ve succeeded on my terms, even if it loses its only match.

Before we begin with the juicy details, here’s the social media promotional kibbles you should Like & Subscribe and back my kickstarter (Oops, that already finished…)

  • First, let’s get the 800lbs of Gorilla Glue in the room (that’s the saying, right?) out of the way. Team JACD, the boy band, as you knew it during Season 1, is splitting into 4 indepdendent bot efforts for #season2 and onwards. Check out the JACD page for the information!
  • My “branch” is Equals Zero Robotics, and I am adopting the Overhaul design. The Facepage will be more “up to the minute” and casual; photos posted to it will likely end up here in a long-form post later on.
  • The unlocking of publicity and creation of E0R has finally forced me to update Equals Zero Designs with information relevant to RageBridge 2! Product stuff will all live on Equals Zero Designs. RageBridge 2 will be available on E0D and Robot Marketplace in the coming weeks!

And that concludes my pre-season angry rant. You can tell that the forced secrecy is a thing which has really been nagging on me, since it really is antithesis to what I am set out to do. I’m genuinely NOT out to spite the network or shit on the presentation. I bite the hand that feeds me for its own damned good; that’s my story, and I’m sticking to it.