Sunday, November 30, 2014

Maker Faire 2014: さらし首 (sarashi kubi)

Apart from the stroboscope, I brought a scary robot arm to the Tokyo Maker Faire. This project actually started a few months ago during a Shinamonolab meetup.

During the meetup, participants had to sketch up an idea for the Maker Faire. I thought of building an arm robot that would scare children and take a photo of them. Three other guys were also interested in building a robot so we got together as a team called roboband (ロボバンド).

My first step was building up the robotic arm. Since Tokyo HackerSpace recently acquired a laser cutter, I decided to use it for cutting the open hardware meArm v0.4 robot. Unfortunately, my first attempt ended in failure because I was using a 6mm thick MDF wood sheet which was not appropriate.

After reviewing the CAD model more carefully, I decided to buy 3mm acrylic sheet and cut it again. This time I managed to assemble the robot correctly (I still had many problems with the accuracy of the laser printer software). The servo motors (standard 9G) are very cheap if you buy them in

Next, I created a 3D model of my scary robot using Blender. I tried not to make it too complicated because my intention was to later convert it into papercraft.

The 3D model was converted into 2D papercraft using a software called pepakura. Cutting and putting all those parts together can take you almost one day.

Then, I applied some Epoxy resin (GM-6600) to make it harder and more robust. I used an organic vapor respirator with appropriate filters, safety googles and nitrile gloves while handling the resin in my balcony. It is not as dangerous as polyester resin but I don't think it's good for health either.

Regarding to the software I used the Arduino servo library to control the servo motors and light up the LEDs in his face whenever a character was sent from Raspi through the serial port. The Raspi itself was used to detect the presence of a face, through a cheap webcam and the simpleCV library, emit a scary sound through the pygame library and communicate with Arduino through the serial library.

The robot was quite popular among children which made me very happy. However, some children were a bit cruel against my little robot haha. In fact, when I got back home I noticed that the SD card on my raspi was broken, meaning that I lost all the photos of scary faces I took during the event. Next time I should add a case.

Maker Faire 2014: Stroboscope

Last month I organized a small workshop in Tokyo HackerSpace about reusing the motors inside an old DVD drive.

In that workshop, I explained how to control DC motors, spindle motors, stepper motors as well as other devices using an Arduino board. However, we didn't have time to actually prepare some cool project with them. I got inspired by the stroboscope at elabz, so I decided to make my own. It took my about 1 day and a halft to complete it, this is the result:

Let's take a look at the components:

  • Transparent acrylic base: based on the meArm v0.4 design, and I used a laser cutter for cutting it.
  • LED lamp: I got it from a 100yen shop and cut off the USB connector.
  • Spindle motor: I salvaged it from a DVD drive.
  • Electronics:

Then, I printed the animation frames provided by elabz and cut a black thick paper following it.

My stroboscope worked almost without problems (apart from having to change the batteries) for two days, and attracted the attention of many visitors. That was very rewarding.

Tokyo Maker Faire 2014

During Nov 23-24th I attended the Tokyo Maker Faire 2014 which was held in Tokyo Big Sight. This is a personal memo of things that caught my attention:
  • Soracam: a drone that chases you wherever you go with a GoPro Hero3+ Black camera.

  • A shamisen instrument played by servo motors. The music notation for shamisen was based on Kanji characters!.
  • Small pen plotter CNCs (youtube channel) by Ishikawa Kyousuke:
    • Frame: universal boards (normally used for soldering circuits)
    • Motors: normal DC motors with a variable resistor for feedback (normally you would use steppers), and a servo motor for the head. The DC motors are connected to a gear box that you can buy in a robot store near Ishikawa neji in Akihabara.
  • PCB pick and place: this is a typical CNC but with a small air pump (not a vacuum pump because it would be difficult to release the parts).
  • YM2413 shield: an arduino shield for generating midi sounds
  • Elevators to the space: I was told that about 23 teams were building prototypes of elevators (クライマー) to the space. They put together some money (I think 100,000yen/person or so) and bought a balloon which was released near Fuji-san up to 1200m (they said that if it was until the space it would take around 1 week to arrive). The balloon is connected to the ground through a carbon-nanotube cable (テザー). Their next goal is to reach 2400m.
  • Incredible marble machines made of wood, brass wire and a bit of magic.
  • 3G shields for arduino (a bit expensive)
  • Hover gesture detector for arduino
  • Aquamodelers (see also here): a group of fans of submarine drones.  They rent a pool together every month to try out their submarines. The guy made this start trek-like submarine using different techniques.
    • He started designing it in a 3D modelling program.
    • Then, he converted the model into 2D papercraft (I guess using pepakura)
    • Then he used sheets of ABS plastic to build the main body (small windows and objects are also done by cutting the sheets and gluing them on the top)
    • Parts with curves where done by sculpting foamed styrol (発砲スチロール), creating a mold of plaster (石膏型) and using Polyester resine and Fiberglass (FRP).
    • A LED lamp connected to multiple optical fibers for giving the effect of millions of small lights.
    • The submarine has a RC receiver (controlled from outside the pool) and uses water pumps to pilot the submarine. He used a Siphon pump (石油 ポンプ) and changed its motor.
  • Hydroforming: a guy explained me how he created his version of a famous star wars robot using aluminum. I learned of a nice technique, called hydroforming, for creating rounded shapes on metals such as aluminum.
  • 2525 power generation: they created a rotating table using wood and a flowerpot. Then they attached 4 bicycle 3W dynamos and then rectify them using 4 schottky diodes. The output (0~2.5V) was connected to two 50F capacitors and 2 DC-DC converters that output 5V to a controller that manages a camera and 5 LEDs.
  • 3DVR: a nice set of stereo googles made of 100yen shop components: for each eye you glue together 3 magnifying glasses, and then put the result inside some protection googles to keep them together. Then you install an application in your phone such as DiveCityCoaster or Taovisor, and you can see stuff in 3D.
  • Podea: this is a small factor laser cutter. What I learned was that you can convert any black and white picture into a dotted picture using GIMP (convert image to 2bit black and white using the Floyd-Steinberg algorithm). Then you can easily use your laser cutter to print in grayscale (search 点画 in Japanese).
  • i.materialise: an on-line 3D printing company in Japan. They told me that printing in PA (polyamid) was cheaper than other companies. They many other materials as well including ceramic, silver, gold.. Other on-line companies I know are shapeways, rinkak, DMM.
  • 3D printing contest: the entry deadline is Jan 19th, 2015.
  • Makeblock: an open source robot construction platform.
Other summaries: