Jun 11

Empire State of Mind

amp I don’t really remember why, but for some reason I decided to create some vector artwork of a stormtrooper last weekend. I grabbed an image of a helmet and then did some tracing and editing to get a pretty good silhouette of a stormtrooper helmet. When it was done I was very happy with the results and needed to figure out what to do with it. It turns out that once you’ve got some simple vector art you can do a lot with it.

Paper Soldier

I started out by cutting a piece of cardstock with the Craft Robo paper cutter to make sure that all the contours were closed, etc. I took the resulting piece of paper and stuck it on a little 15-watt keyboard amp just to butch it up a bit. Since the paper I chose was white it looks best against a black background and the amp fit the bill.

Next I used the vector art to cut a screen-printing mask from adhesive-backed vinyl. That plus some yellow screen printing ink applied with a gentle uneven pressure on the screen gave me a T-Shirt with a distressed looking stormtrooper on the front.


Big Finish

The final project I did was something I’ve been thinking of for a while. It’s actually just the first prototype of a more ambitious project that involves motion and some electronics, but first I wanted to verify if the visual effect was what I had imagined. What I did was take the vector image and cut it into strips using geometrics operations in Corel Draw. These strips were then cut from 3mm thick acrylic on the laser cutter. Finally, I cut a base and frame from birch plywood and clear acrylic. The birch got 6 layers of finish and some final polishing so it took a week to complete the project. You can see a few views of it below.

topright-1 closeup

corner-34 off-axis-1

The individual white acrylic slices can be rearranged in the holes at different depths, but I found that it’s best to have adjacent strips no more than one row distant from each other. Otherwise, perspective effects from the difference in distance distort things too much unless you’re very far away. I finished up with a Galactic Empire logo cut from black vinyl on the base. The display looks fairly abstract from most angles and then snaps into a stormtrooper when you square-off right in front of it.


May 11

Chocolate & Peanut Butter

chocolatepbIn the opening day Google I/O Keynote, Android announced numerous cool new products. I had the pleasure of introducing our new Movie Rental Service for Android Market, and we also talked about our new Music Beta service as well as the Accessory Development Kit for the first time. Combining devices with cloud services is a Chocolate & Peanut Butter experience – each benefits from the other to create a whole larger than the sum of their parts, so I wanted to try out the ADK and do a project that captures this. My buddy Joe hooked me up with an ADK board a week before I/O so I could play around with the ADK and I did a project that combines the coolness of devices and hardware with the awesome new Music Beta service.

First a little background on the ADK. The board that Google was handing out at I/O is based on Arduino and has a built-in Circuits@Home USB Host shield. The details can be found at the Android Open Accessory page at the Android Developer portal. A library is provided for the Arduino board that allows you to identify your device and very easily detect when an Android Device is connected to it and transfer data.

I already had a box of Sure Electronics LED matrices left over from Maker Faire last year. That plus some ShiftBrite RGB LEDs and the judicious application of a laser beam to build an acrylic enclosure was sufficient to get the basic sign up and running. It sported a two-line display (64×8 pixels each) driven by my LED Matrix Library and a Music Beta by Google logo backlit through a diffuser panel by 6 ShiftBrites.

Then I linked to the Android ADK library and it was literally just a few lines of code to detect a device connection and read some data. The other very cool feature of Android Open Accessory is you can provide a URL in your device description metadata. When a user plugs in their Android Phone, if there isn’t a compatible application for your device the user can follow the link to download the supporting application directly from Android Market. In my case, I needed a simple service application that listened to the Intents the Music App sends when it changes track metadata. Then, the app writes the metadata to the Arduino board. So the end-user experience is seamless – anyone can walk up to the sign and plug in their phone and be up and running in a few seconds.


Once I’ve decompressed from I/O a bit, I’ll publish the source code and CAD files so others can put one of these together. For now here’s a video of the Music Beta Now Playing accessory in action. The fun spectrum analyzer animation is just for effect – it’s not actually analyzing the audio, but maybe some clever person can make that part more real.


Feb 11

Not Actual Size


When I was younger I was a big fan of Peter Sellers in The Pink Panther as Chief Inspector Clouseau. One of my favorite running gags was his butler, Cato, who in addition to answering the phone and preparing meals was also responsible for attacking Clouseau without warning. These attacks were designed to keep Clouseau vigilant and in fighting shape, and there were many epic battles between them. Several decades later I’ve come to realize that I have my own personal Cato in the form of my cat. Our cat is sweet and loving with everyone else in the family, but with me her favorite thing to do is attack me when I least expect it. She will literally wait by the door for hours and when I come home she jumps at me with her back arched waiting to be chased around the house. Like Clouseau, I am responsible for my attacker’s behavior – having trained her to attack me with our games.

A Heartless Killing Machine

As a result, when I think of the cat I don’t think of a cuddly little pet but rather a vicious killing machine. My wife took a picture of her that captures the cold depths of the cat’s evil soul and I really like it. So I decided to make a big version of it to hang on the wall using my CNC router and some custom software I wrote.

The idea was to do a halftone-style picture by cutting circles of varying size in a panel of wood that would show through a black background. I modified my Paper Pixels software to take a picture of the cat and sample the average brightness in a grid pattern and then turn this into an array of circles. Large circles for dark areas (which thus show more of the black background) and small circles for light areas (which thus show the light birch wood I was planning to use). The picture on the left below is the original image I started with and the one on the right it the output after my software processed it.


We Love Constraints

My CNC router has a table size of 24” x 16” and I wanted the resulting picture to be larger than that. I was going for 3 feet square, so I chopped the picture up into 6s panels of different sizes that I would assemble to make the finished picture. I’ve spoken many times about the fact that constraints like these can be used to improve the result. So rather than try to hide the fact that I cut the image up I accented it by splitting the panels up with space between them. I used 1/4” thick birch plywood sheets and finished them with several coats of amber Shellac to give a nice warm color. Then I cut each panel out with the router, after producing toolpaths with CAM software. Some of the holes ended up with ragged edges depending on how worn the tool was but some light sanding fixed things up quickly.



Once all 6 panels were cut, I sprayed the back with tacky adhesive from the local art supply store and glued thick black posterboard to the back. I mounted the panels to the wall right above the bed where the cat sleeps. The result is a nice combination of a geometric/abstract form with a somewhat photographic effect the further away you get from it.