Jayce: The Cosplay of Tomorrow (overdue) Version 1

hicharleslookimmakingablogpostaboutthefammerfinallyareyouhappynow?
_________________________________________________________________________________

Introduction

This guy:

is my favorite character in the popular online strategy game League of Legends. This is not because I like his mechanics, his character, or dashing good looks. Okay fine I like those too. But I loved the concept of the transforming hammer/cannon. This was directly in my line of 'thingsiliketocosplaywish' and so I embarked on the ambitious task of building the Mercury Hammer/Cannon for a Debonair Jayce Cosplay (Debonair is one of his skins, or appearance modified options).

Analysis

The weapon has two forms: the hammer and the cannon. Pictures below:

The hammer is distinguished by a yellow color, and full retraction of all the motion parts. The "wings" are in the closed position or positioned axially with the handle and the "rods" are fully retracted.

The cannon is distinguished by a cyan color and full extension of the motion parts. The wings are tilted outwards at an angle, and the rods are at full extension.

Immediately the engineering and design mindset went to work. The major question: "how can I replicate these shapes with enough rigidity using manufacturing methods available to me?". Immediately I began to gravitate towards plate methods for the majority of the body work, which meant waterjet and laser cutter. I had little experience foam and freeform sculpting, so I naturally gravitated towards 3D printing for high volume work of complex surface geometries. For materials, I scavenged. Luckily for me, the MIT Hobby Shop was undergoing renovations and were generously donating materials to reduce the amount of stock they had to pack. I started with a steel pole for the main mast and went ahead from there.

Design

Basing everything off the 1" steel tube presented some proportionality issues. The weapon appears to have a larger diameter mast than 1" when compared to Jayce's hands. Still in lieu of saving money I persisted. Below are some captures of the modeling done in SolidWorks.

 


I started with the 1" dia pole and began modeling the hammer's most distinguishing features. In my mind, this was the "lamp" shaped bulb on the bottom and the four "wings" on the sides.

Construction

I decided to build the hammer from the inside out. This way any imperfections that could propagate through the design could be accounted for in parts not yet made. However items that would be 3D printed could be done in parallel since they take far longer than traditional machining techniques.

First order of business was building the frame. I enlisted  the help of a friend to waterjet some aluminum at CSAIL.

After some sanding, things began to take shape!

For the first round of 3D printing, I opted to finish the body components first. These were made on a Stratasys Dimension 1200es with lowest fill density settings.

 

Upon assembly, I discovered them to be fairly good missile launchers. Maybe reuse for future work? :P

Suddenly, the body appears! Starting to look like a Debonair Jayce Mercury Hammer!

 

 

Now its time to add the motors. To make them hammer duty, I had to cut a corner off the gearbox but more importantly I had to replace the shaft. Having that lengthy 12" dual shaft was key for my dual use clutch idea to work. At the same time, I also pushed some ball bearings in the frame to help alleviate off axis loading on the motors.

 

 

 

Speaking of motor work, I bet it isnt quite obvious how so many mechanisms are being powered off a single motor. Well, since this design uses pure rotation to change the angle of the wings, the gearmotor makes sense. But what about the linear action of the "rods"?

 

For this I am implementing an elevator mechanism powered by a tension cord. Basically, there are multiple stages that can move linearly along each other all connected by a string. The string is wound throughout the stages. When the string is taught, the relative length decreases and forces the parts to move. This idea would be very difficult to implement in such a small space and with limited materials. However, it turns out to work in my bench tests! Hooray concepts!









 Next came the flurry of laser cutting. All the non-structural paneling was done in craft wood (thin plywood), laser cut to shape, sanded, and painted.

 




I would like to shout out to a piece of software called 123D Make. This program from Autodesk takes STL files and affords you several methods for creating its volume. This was incredibly useful for the "wings" because of their high volume but desire for low weight. I use 123D Make to make the "wings" from several slotted panels. Then I joined them together with a dab of super glue.

Now things are beginning to take shape!

 

 

 


The next hard part was figuring out how to skin the "wings". I had  tried several things like covering in duct tape and filling with expanding foam (very messy). I ended up exporting the faces of the "wings" as dxf files with sketched bend lines and laser cutting from "tank board", aka the backing on notepads.

 

 

 

From then on, it was about making duplicates of things that worked, decorating, and making finer details. Here are some laser cut decorations for the body face panels, the tips of the "rods" and some spray painting. I have the hammer here suspended using fiber straps from a garage assembly. One unfortunate aspect was the hammer ended up being really heavy or at least feeling very heavy due to physics. To help relieve weight, I tried to pocket the metal pieces. The heaviest part ended up being the "wings" but not much could be done about those now that they were assembled.

 

 

Despite all the hard work, I could not actually finish the fully functional hammer. Because of the ~16 hour drive to Atlanta for Dragon Con, I had to focus on decoration instead of mechanics. As a result, I could not properly debug issues regarding high stress points in the elevator mechanism, or clutch tuning for the wings. I decided to lock Jayce's weapon into a hammer configuration for the duration of the trip. Here are the final pictures.

 

 

Even though I didnt do much with electronics this time around, its worth noting. I left out the LEDs and effects and wanted to focus on purely mechanical aspects. In that respect, I only needed a method of transmitting power and the ability to reverse the direction of current. I was able to do this easily with a DPDT (dual position, dual throw) switch and a push button. The push button was used to flow current (read: complete circuit) and the switch was used to swap the direction of current. I could use two single throw switches, but this method is more fool proof since there is no shorting condition.

There was some cloth involved, but it did not involve much work on my end. I essentially bought towards a white tuxedo with tailcoat. Ebay is your friend in this case.

Implementation

I bought this guy to Dragon Con 2013 and later to Anime Boston 2014. At both events, the hammer was well received. A lot of good comments about detail, craftsmanship, and OMGWTFSOHEAVY. The question I loved and hated to hear was "Can it actually transform?!". Because it was essentially broken and perma-hammer mode it was heartbreaking. I had to simply respond, "I accidentally did the thing."

Dragon Con 2013

 

 

 

 

 

Anime Boston 2014

 

 

 


I hope you enjoyed this very late recap of this build. I was rather sparse on some sections because of the last-minute rush; I was not able to document those stages very well (with regards to painting and wiring). Still I would like to say a few things.

First, a thanks to my friends who supported and helped me through the build. This includes Charles Guan, Steven Jorgensen, Julia Hopkins, and many more!

Second, I would like the point out the title of this post "... Version 1". There was a version 2 supposed to debut at Anime Boston but could not be finished in time. It will be done by the next convention however. See you guys are Pax East 2014!

___________________________________________________________________
Some photos taken by Ace T. Cosplay & Photography
Some photo taken by Zuli's Cosplay

Peeling Up: An Up Mini Temperature Hack

Just purchased a 3D Printer for a certain special course that I am TA for this spring term. See below, its an Up Mini!

These guys had great reviews off the MAKE Magazine 3D Printer guide for 2014 and with a nominally low cost we were interested in making these become the primary workhorse of the course. The Form-1's and Mojo's may feel a bit sad.

There is a lot of good to say about this guy; nearly plug-and-play operation for Windows 8*, a superb software that considers the end user (except their ears), and a PCB print surface that enhances adhesion during the print but also facilitates easy removal after the job.

The one bad part is the warping for ABS materials. I made several calibration test prints and anything with gratuitous flat surface came up with nasty warping on one side. The Up Plus that my buddy Charles has never suffered from this issue and its hard to imagine that they downgraded between revisions.

Investigation showed the bed temperature was 60 deg C for both ABS and PLA. Two things strange about this. PLA doesn't need temperature stability to print well (especially on this perforated surface) and the bed temperature for ABS is half that of what other machines report as an ideal setting.

So how do I change it? In the Up Plus, the user could view the temperature settings under the "Maintenance" options. The bed temperature displays under the extruder temperature in the upper right of the window. However, when connected to the Up Mini the temperature option disappears! Stratasys holds a patent on heated enclosure systems, a feature that happens to be advertised by others when considering this machine. Is this Up's hilarious method of avoiding legal?

Okay, how about hardware fixes? I remove two screws and a ribbon cable to access the heated bed itself. The ribbon cable presumably connects to a heating element, the temperature sensor, etc...

NOPE. The bed is a routed circuit board resistive heater with a SINGLE component on it. Its not even a magical IC, its a single transistor. This engineer is good at saving money.

Investigation of this KSD-01F shows that a) it is native chinese and b) is nothing more than a temperature switch (thermostat). The controller pumps current into the board until it reaches a temperature threshold. Then the transistor shuts off and the board is assumed to maintain steady state as it switches on and off and temperature fluctuates about the cutoff. These thermostats appear to sell in a variety of different temperature cutoffs.

This is so ghetto, I decided to hack it. Using the Up Plus as the paragon of 3D printing, I set my target temperature to 100 deg C. I purchased a higher temperature model from amazon and soldered it onto the board in place of the old one.

As a simple test, I allowed the bed to preheat for and hour and began a print. The result was simply phenomenal. No warping at any section of the part. Subsequent prints of various size and shape also returned similar results.

 

 


Before you declare this a godsend and perform this on your printer consider this piece of heat transfer; the preheat is now absolutely necessary to achieve the higher bed temp. The printer has no feedback mechanism to monitor bed temp so if you hit "Print" the printer will not heat for longer to accommodate the higher temperature threshold; the heating cycle is likely hard-coded into the printer ROM which I do not yet know how to change. Also, given the printer dumps constant current into the bed means the input energy rate is constant; to achieve max temperature the time of heating needs to be increased. This assumes the ambient heat loss rate does not cause the bed temperature to reach steady state before the temperature threshold...

Later science posts regarding Up Mini:

1. transient temperature profile for
2. input current hack for heated bed (and temperature profile after)
3. hack to lower or remove annoying buzzer

Cake Slice and PA Bot Blast 2013

Hi Charles, I'm writing a blog post.

________________________________________________________________________________

Part of my joy of moving up to MIT was the fact that I was now in prime vicinity of a more lively roboting community. In the Northeast region, we have well established competitions like the Franklin Institute of Motorama.

Another regular event in Pennsylvania was PA Bot Blast, held in Bloomsburg every July. My friend Aaron fan from the Georgia Tech Invention Studio convinced me to go, so I convinced my long time bot buddy Charles Guan to make the trip with me. We created enough hoobaloo in MITERS to spawn a small team and soon we had an entire van committed to go. Hence fourth it was time to get prepared as the date loomed closer and closer.

DDT was definitely going. The new version was completed in late 2012 after Dragon Con in preparation for GMX robot battles where it went undefeated and unscathed. The only work I needed/wanted to do on him was trim the through bolts that hold the frame halves together. This way, the robot was actually invertable.

I hope heating those screws don't melt the nylocks

I was previously intending to bring Cake, my old Beetleweight made in 2010/2011, but I had lent it out to some friend going to Robogames and it returned to me... missing a few things.

Without a waterjet, there was no hopes of finishing the parts needed to make it competitive or solid. Time to move on.

Instead I opted to make a joke bot. Lets design a wedge with absolutely insane speed for the sole purpose of box rushing people and maybe decking them into the wall. No way it would win, but it would be extremely entertaining to watch and drive.

I grabbed a pair of 280-sized motors from my spares bin. These motors were surplus back from Florida but had some serious power. First indicator of this were EXTERNAL BRUSH HOUSINGS WITH HUGE CONTACTS. This is of course opposed to the dinky precious metal springs that daintily drape over the commutator. I knew this motor had some serious current carrying capabilities.

And they did. They drew 3 amps no load.

To make the robot a tad more reasonable I mated these motors to the 10:1 gearboxes of the ever popular "1000 RPM Gearmotors". First I had to remove the pinions from the old motors. Then I had to secure them to the new splined shafts of the surplus motors. Historically, we know that a press fit simply isnt enough for these motors since their monstrous torque essentially reams out the pinion if any excessive load is on the shaft (i.e. robot weight). I remedied the problem by complimenting the press with a flux and solder treatment.

With the drive motors finished, I began arranging the parts to develop a chassis design. While a traditional wedge could have worked, I felt it was to boring. Some creative arrangement later turned up an old friend of a robot: the dustpan.

3D printing frames is cheating

By this time, we only had two days left until the event. The only option was to 3D print the frame on the IDC's Dimension 1200es ABS FDM printer. It saved a lot of time on parts machining but it also introduced some headaches of its own along the way.

Robot taking shape! Control electronics were selected to hopefully run the powerful motors. I whipped out my 9 year old Scorpion HX esc for the drives, and pulled an orange RX for the control. It was then I discovered the esc was not enough to handle those surplus motor hacks. Sad day. I suppose we will have to compromise with a Pololu 4.41:1 HP gearmotor.

The wheels were leftover Banebots 40A durometer wheels with a hex bore. I made hubs from some metric hex stock center drilled for the 4mm motor shafts, drilled to hold a 6-32 set screw, and pressed into the BB wheels.

robut.

so far so good

To save some time on printing, I elected to make the dustpan bottom from a thin sheet of garolite. This sheet would be held on the bottom using adhesives.

It was decided that this robot, being made from parts of the robot cake, would refer to its inheritance in some way. Also being a wedge shape, I decided to name it Cake Slice. It would be a part (or slice if you prefer) of Cake, while having a slice-like shape. So brilliant, I know.

Apparently I don't have any finished photos :(

On the Friday evening two hours before our departure, I came home hoping to test drive the robot. Unfortunately I left my transmitter on and was unable to practice with the robot. Its first match would also serve as a driving test.
_______________________________________________________________________________

Game Day

Five hours of Miku later, we arrive at a waffle house and meet Aaron for a 4am meal. From there we venture down the last hour to the Columbia Mall in Bloomsburg to see the wonderful new arena that Jeremy and his parents had put up.

THIS IS IT. jk, test box

builders watching the robot being tested outside the test box

okay, the new arena seriously

omg prizes! best trophies in the US

Being the first builders that morning (we better have after camping out in the parking lot), we picked prime seating in a center row, right above a power outlet.

Aaron's robot ,"Final Exam" without hat

My two robots DDT and Cake Slice. Washers taped to the front to prevent wheelies

delran-bumble:a stepper motor drive robot from out MIT crew

threecoil: an innovative flywheel 4-bar flipper robot

Alex Hone's stuff

After a smooth check-in and drivers meeting, it was time to begin the fray. Leggo robots!
______________________________________________________________________________
DDT vs Slim Pickens
DDT drew the first match of the event against a sheet metal wedge. Slim was based off a viper kit if I recall correctly, and added some extra steel to strengthen the front plate from my horizontal blows. Unfortunately for him, DDT doesnt attack the body as much as he punishes the corners of any robot. DDT ripped and bent up the front wedge enough to high-center Slim and he tapped out.


Cake Slice vs TTI Wedge
Titan Tech Industries is developing a series of modular robot kits for interested persons. In this Bot Blast, they are debuting their wedge kit, which looks like a sloped Weta without an active weapon. By this, I mean a classic cheese wedge shape with UHMW wheel guards bend around the frame. My only concerns were CS's tendency to lift up when he charges the opponent. I would need to get a running start to keep the drive aggressive and the front end down.


What ended up happening was completely unexpected. I actually stripped the gears running around the box. When I opened them up, it appears the boxes were design to have about 1/5 gear face contact. Ugh. So terrible engineering. If you buy these ever, remember to remove some of the spacers on the intermediate stages to get better contact.

DDT vs Speed Bump
Nooooo! I have to fight one of our own :( Speed bump was a low wedge bot made from the donated frame of a fellow bot builder. It was less than an inch tall, and features a gaussian cross-section double wedge. The top was made of a plastic found in 3-ring binders and I was a bit afraid of blasting through it and hitting the lithium battery.


Luckily, there were no fires. The match was also far more difficult than I had imagined. The low angle of the wedge and the flexibility of the binder material made it early impossible to get a bite. My only good shots were the aluminum sides. After a few taps late into the match, Speedy was high-centered and tapped out.

Cake Slice vs Speed Bump
q.q

DDT vs Dust Pandemonium
Now I have to fight the style robot i was originally famous for: the dustpan. Pandemonium was a custom made CF almost-unibody with a meanacing thresher type weapon protruding from the front. He would charge opponents, capture them in the dustpan, and gnaw on their frames with the thresher. As long as I kept my blade out front, I knew I would be able to stay out of the pan and away from the weapon.


When the match began, he charged straight at me figuring he would not be able to maneuver around my blade. I hit straight into the gut of the dustpan and luckily hit a seam. That one hit penetrated into his electronics and gave me the fastest KO at 15 seconds.

Cake Slice vs Guildenstern
Guildenstern is a vertical bar spinner what didn't alarm me at first. But it turns out the bar is asymmetrical, made of steel, and packs quite a punch as seen in its previous matches. For Cake Slice, this would pose a problem  because he could probably easily punch through the front wall and hit my gooey insides.

I added a layer of padding on the inside wall to dampen any blows just in case. I was mainly hoping I could suspend his frame using the dustpan pontoons. This was actually feasible since unlike many other vertical spinners, Guildenstern lacked anti-wedge devices. Either way, all strategies soon went kaput when I lost a drive side early on.

eep.

It appears layered ABS is easily ablated. No throwing hits though

DDT vs Ripto
Ripto is the classic vertical disk design of a talented builder and driver Kyle Singer. He scaled down his beetleweight for this competition to enter this antweight version. He also has gone through thus far undefeated. I knew there would be no mistakes allowed in this match. I could not allow any wasted movement since Kyle could easily capitalize on my gyro dances. I would need to aim for a disabling hit or weapon kill early on.



I think I was lucky my first hit. Taking out the drive made things easy for me in that he couldn't hit me in my instability. After that, it went downhill for him. I was able to sneak in behind him and chop up his o-ring wheels.

DDT vs Ripto (finals)
Same strategy with a little more desperation. This time, it was for the infamous Bot Blast light tree trophy! The hits were far better this time but the result was the same. This version of DDT is an absolute keeper!

Before the finals!

Unhappy bearing trying to escape

Cake Slice did was Cake Slice was supposed to do. But DDT performed flawlessly going 5 wins and 0 losses. The match against Dust Pandemonium also went in as the quickest knockout. Below is a shot of DDT and his spoils of war.

DDT and his spoils of war

More Guavascooter: Speed and Distance Testing

Today I took a little adventure to visit my good buddy Chris down over at Bolt IO, a new shiny hardware startup incubator located conveniently close to campus (and chinatown!). Needless to say, I'll be visiting often.

This trip, for this time anyway, included the use of the T, so I had to park my scooter somewhere on campus. When I returned, I visited the ME graduation banquet and then returned home for a bit. Later, I left my housing again for a meeting with my PI over in building 35. Nowhere throughout the day did I charge guavascooter. This was a perfect additional data point to hopefully better estimate traversal distance. Here is the route:

A total of 3.5 miles. using the numbers from last post, we expect a battery expenditure of about 1170 mAh per mile. However, today's route only used 3170 mAh, which means approximately 905 mAh were expended per mile. This results in a projected distance of 7.6 miles. Lets say 7 miles just to be safe.

The second test that day was the speed test. I selected the section of road between Amherst Alley and Mass Ave as the trial space. This is a roughly half-mile section of road.

My timer showed I made the trip in approximately 1 minute and 52 seconds. This meant that my scooter maxed out at about 16 miles per hour. That's pretty slow for my tastes considering Razor Wind was estimated to run at 30 miles per hour and Razor Reloaded was to run at ~25. This is not a major issue but if I decide to address it I could change the sprocket ratios or select a new motor.

Cambridge and Guavascooter

I made it alive to MIT. Today marks one week of life up here. One week of life walking about because my latest scooter  just came today. Discussing the name with Charles, we decided a more fitting name for it was "Guavascooter", as an extension of Melonscooter except using the guava sized SK3 motors.

Without delay, here comes testing.

Tonight I drove this route to MITERS from my temp housing at Tang. Its about 1.68 miles as indicated by the picture above.

This route expended 1967mAh of battery capacity. From a 6900mAh pack, this means I could run this route about three times safely assuming voltage drop does not fall below 21V (ESC cutoff).

Tomorrow, I will determine the max speed of this scooter via time trials down Vassar street. More to post later.

An additional note, I am no longer using the chatparts.ltd esc in Guavascooter. The current ESC is a elifebike esc, which Charles and I will touch on later in the coming weeks. Cheers!