Disassembling a hair clipper

After several years of use, my electric hair clipper (a.k.a. trimmer) finally broke. For that reason, I decided to buy a new one. When I saw that the prices were actually quite cheap, I got interested about how manufacturers are cutting down on costs.


The body of my hair clipper consisted of just 2 pieces of plastic and a mechanical switch connected directly to the internal board. A detachable part (not shown in the picture) with two blades oscillates from side to side driven by the internal DC motor and a fancy spring. The electronics are as simple as it gets with just a classic AC->DC rectifier whose output is connected directly to a Mabuchi FK-290PY-051100 DC motor (100VDC, 6800RPM without load).


The motor has a cam attached that allows transforming rotary motion into linear motion for moving one of the two blades.


The board's circuit diagram is a classic that any electronics hobbyist should know. The input wave (mains electricity) is a SINE with 100V amplitude and a frequency of 50Hz (Tokyo). The 1MΩ resistor is used to increase the input impedance (ideally infinite). Then, a 100nF/125VAC ceramic capacitor is used to filter out noise from the mains signal. The result is rectified through a diode bridge (i.e.: a full-wave rectifier), and then smooth out with an electrolytic capacitor in parallel (a low pass filter). The output voltage is 98,88VDC instead of 100VDC because of the forward voltage (Vf≈0.56) of 2 diodes. In sum, here is the bill-of-materials (BOM):
  • Resistors: 1x1MΩ, 1x150Ω
  • Capacitors: 1x100nF (125VDC), 1x4.7μF (160VDC, electrolytic)
  • Diodes: 4x1N4004-TP (Vf=~0.56)
  • Motor: Mabuchi FK-290PY-051100 (~4 dollars)
  • Camshaft
  • Blades
  • Spring
  • Plastic body
  • Power cord
  • Others: size attachments, oil, brush..
  • PCB
Conclusions: making profit from selling an electric hair clipper at about 2000~4000 yen looks quite challenging to me, unless you sell enough of them so that you can average out the cost of the initial mold for the plastic body and attachments. There are lots of brands competing in the market with completely different plastic bodies. I wonder if all of them are selling enough to compensate those initial costs.

My first Blitz3D mini games

My first experience with programming games (actually, my first programming experience at all) was with DIV Games Studio, an awesome framework for making video games created by a Spanish company called Hammer technologies. At that time I also started learning about digital 3D modeling thanks to awesome magazines such as Jumping. I had the idea of making a 3D game, but unfortunately DIV Games Studio was designed mostly for 2D games. After some searching I found Blitz3D, a simple environment for game creation that supported 3D objects and seemed easy to program. With the help of a friendly IRC community, I managed to build my first demo games in no time.


Since Blitz3D recently went open source and can be downloaded from their site for free (instructions), I decided to recover those old games and put them on my github. Apart from a little game in Javascript, I haven't made any games since then. Lately, I've been experimenting with the popular Cocos2D platform and I hope I can get some time for Unity as well.

My first marble machine

Marble machines are one of the best ways I know of for experimenting with mechanisms such as levers, pulleys, inclined planes, gears, or cams. The one in the following video is the first one I've built:


But let's start from the beginning. During last year's Maker faire I got surprised by the skills of Denha sensei at building his own complex marble machines.


After the Maker Faire, I spent hours admiring his creations and how he checks every detail in a methodical way. I came to the conclusion that a marble machine is usually made of some of the following components:

For my first marble machine I tried to make it simple. For that reason, I only used two common artifacts: a wheel elevator and an inclined plane. For finding the centre of the wheel, I used simple geometry. However, I had to drill a big hole for the bearing to fit in. That affected the accuracy of the centre. For that reason, I had to use a small spring that would automatically adjust the distance between the wheel and the motor's shaft (probably it would have been easier if I had used brass wire for the wheel's axis instead of a bearing). The inclined plane was made using a chisel. This is the list of materials I used:
  • Geared motor: MOT114A1B 6V 60RPM 12GA (Sengoku 1280yen)
  • Gear for the shaft of the motor (Sengoku) and a rubber cover (Ishikawa-neji)
  • Balls 7mm diameter (Tokyu hands)
  • A small spring (from a pen)
  • Brass wire 1mm diameter (Radio depaato in Akiba)
  • Wood (a home center and Daiso)
  • On/Off push switch (from an junk board)
  • 2*AA batteries with a case (Daiso and Akizuki denshi)
  • Aluminium plate (Yokyu hands)
  • Bearing (from an broken stepper motor)
This is a list of tools I used:
  • A precision hand drill
  • A precision wood saw
  • Dremel 4000 with various bits
  • Tweezers
  • Cable cutter
  • Long/round nose pliers
  • Tape
  • A universal vise
  • Chisels
  • Sand paper
Conclusions: I failed many times, but I also learned a lot during the process of building my own marble machine. Indeed it was harder than what I had expected. I will try to build upon these lessons learned, and make a better marble machine next time.

Kanazawa: nicotech and tourism

I had wanted to visit Kanazawa city for more than 8 years, since my Japanese teacher in Spain (Hattori-sensei) made a reference to it during a class. After the Shinkansen to Kanazawa was finished a couple of months ago I had no choice but to visit it.


What a better excuse than the celebration of the Nicotech event in Kanazawa, which gathers DIY hackers/makers to show their new crazy inventions such as a dice that always comes up 6; or a relay-controlled melodica presented by nezumi-san. Other inventors: natok (@natok), and @mayusaki3 (check the twitter hash #NT金沢).


If anything, Kanazawa is famous for its splendorous Kenrokuen (兼六園) garden, developed by the Maeda clan and one of the 3 great gardens in Japan. If you were only going to spend a few hours in Kanazawa, the Kenrokuen garden would be the thing to see. When you are there, try to find a sign with a haiku written by Bashō that says: あかあかと日は難面もあきの風 (akaaka to hi wa tsurenaku mo aki no kaze). As many other haikus, this one also talks about the change between seasons, in particular from Summer to Autumn. My personal translation would be something like: "The sun shines red, ignoring the Autumn winds". Here are a few other translations. A decomposition of this haiku can be found here (in Japanese).


Other attractions in the city are its tea houses (Chaya). There are two famous tea house districts: Higashi (east) and Nishi (west) Chaya. However, I'd suggest you to check this non-touristic tea house called Shōkōan (旧園邸・松向庵). See the access map and pictures from inside.


Kanazawa also has a famous fish market called Ōmichō, where you can buy different types of fish and seafood. There are also a few restaurants if you want to try sushi, crab, kaisen-don (a bowl of rice with different slices of raw fish) or any other delicatessen. Here is a nice guide to the food of Kanazawa in pdf. I would also recommend the restaurant "arroz" (rice in Spanish) where you can eat a delicious "cocido" as the one in the picture above.


Kanazawa has also a Samurai district called Nagamachi (長町) though it's not as big as the other tourist attractions.


What I liked the most about Kanazawa was its relaxed atmosphere; the river that crosses the city which was very close to the place I stayed in; and the fact that you can rent a bicycle to go around the city.