Thursday, October 6, 2016

D-Walker build part 3 - Head

The mechanics and electronics in D-Walker's head.

D-walker's head was a lot of fun to make.  It is primarily 3mm and 6mm Celtec (expanded PVC).  The material strikes a great balance between rigid and easy to tool.  I made most of it over the course of one day in the comfort of my bedroom-workshop, with little more than a heavy box cutter, a drill press and some hand files.  All of the "screws" are fake, imprinted in the plastic with drill bits.  I didn't really plan how I would build the head, instead just starting with the side panels and figuring out how to add on each part as I got to it. 

Taped connections were for testing only.

The head can be broken down into a few parts to make final installation and maintenance of the electronics easier.  The majority of the framework is superglued to the left armor panel, while the right panel is removable.  The antenna acts as a lynch pin, threading through the top of the head and a tab in the right panel.  It holds the right panel in place, along with neodymium magnets to keep the bottom snug.  An assortment of other tabs also help align the right panel, and hold the GoPro in place.  The GoPro can be controlled with a smart phone mounted in the cockpit, and the little red record light is visible through a small hole in D-Walker's face.  I hadn't originally planned on using the GoPro at all, but while looking through my stuff for a lens, it was the best thing I could find.  It was just luck that it fit perfectly in the already-made frame and could still be used as a camera to boot.
Wire routing and the head tilting mechanism hidden beneath the heatsink.

The heatsink is removable as well, as it also acts as a cover for the wire port at the base of the head.  A furniture foot (a round piece of plastic with a nail coming out of it) through the top acts as a pin to lock the heatsink in place.  This pin and the antenna were originally only cosmetic (and I was very lucky to already have such perfect suitable cosmetic pieces in my junk bin).  Rather than cut them to length and glue them in place, it was apparent that it would be both easier and more functional if I used them to hold the head together.

Right panel light housing, disassembled.

I made a couple light diffusing housings for the head.  The right panel has a rectangular light - a reflector bowl lined with aluminum foil tape and a clear acrylic lens tinted with a blue adhesive vinyl.  A white, perpendicularly aimed LED reflects inside the foil-lined cavity, evenly diffusing the light through the blue lens.  This is a minor detail, but obscuring the origin point of an LED helps a costume look more intricately crafted.  

Notice the lack of bright spots in the rectangle.  The little Snake face is just to mask off that part for painting.

The round light housing is a foil-lined plastic bottle with a white LED glued into the cap and more blue vinyl on the round bottom.  A fiber washer from the hardware store borders the blue vinyl.  There is also a tiny PC fan attached to the heat sink.  Officially it is there to vent heat from the GoPro, as the GoPro does get hot, and keeping it a few degrees cooler might just extend the battery life a little.  More importantly, I thought it would be cool if the head made some noise and the heatsink actually mitigated heat.  At this point it started really feeling like a robot.

All of the wires for the electronics are stuffed into a grey wire sheath and routed out the back.  This triple wire harness, accurate to the in-game model, also acts as a spring that returns the head to the resting position.  The clutch cable, the mechanism for tilting the head, anchors near this wire port.  The clutch cable pulls down on the back of the hinged head, raising the front, and the wire harness pushes it back down when released.

Except for that fiber washer I mentioned, every single part of the head is something I had lying around from some other project.  The 3mm Celtec was purchased for my MIDA Multitool, after I had accidentally purchased the 6mm variety.  I had a lot of both leftover.   The blue vinyl (sold as headlight tint) was also from the MIDA, tint for the tiny blue flashlight. The magnets came from my Rick and Morty portal gun project - each portal gun has an LED nametag display, and each nametag comes with two magnets that are not used in the gun.  I had a few hundred to spare.  The plastic bottle is also from the portal gun project and just happened to be the perfect size.  The foil tape and all my clear acrylic were appropriated from the dusty shelves of an old retail job.  The grey wire sheath is a vintage vacuum cleaner cord that I found in a junk pile on my street and ripped the wires out of, replacing them with my own.  The furniture foot is a doodad leftover from my Destiny Warlock helmet.  The PC fan is from an old IT firm that closed down and gave everything away for free on Craigslist (this source will come up a lot more later in this build).  The antenna had broken off of an old M/A-COM Jaguar 700P radio that I bought years ago but never really used (technically that was $200 down the drain, but I pretend that using the antenna in this project ultimately justified it).  I bought the GoPro Hero 3 a few years prior for no real reason other than my friend could get it with a massive employee discount, and I use it for moto adventures.  Almost forgot the chin antenna - that was cobbled together out of a plastic mount for a bicycle light, and a broken multimeter probe.  Just more junk from my junk bin.

Sure, I spent money on almost all of those parts, but none of it was specifically for D-Walker and may have gone to waste otherwise.  I felt like I was squeezing value out of my previous purchases, like eating leftovers for lunch.  MMmmmm, savings!

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