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).
AnalysisThe 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.
DesignBasing 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.
ConstructionI 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.
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