Category Archives: Tutorial

3D Printed Molds for Small Robot Wheels

For my antweight combat robot DetCord, I wanted a wheel that could improve upon the Banebots wheels that I used before. I wanted something shock absorbing, which would extend the life of my gearboxes. The tires need to be soft and have high traction. The wheel does not have to be very strong because the robot has thick armour to protect the wheels.

I ended up with a cool way to make a wheel that’s cleaner than the more popular methods I see on the internet! Continue reading

3D Printed Mechanical Iris Dome All-One-Piece

It’s that time of year when we think about gift giving. I decided to design a dome shaped box that opened with moving curved doors.



(dear iPhone users, sorry if the videos don’t work for you, please consider upgrading)

Keep reading for more pictures and a full tutorial teaching you how to create this in CAD.

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Upgrade a Passive HDMI Switch with 5V Power

I have many things connected to my single computer monitor via HDMI. I use a HDMI switch so I don’t have to unplug and replug cables all the time. But my cheap $6 HDMI switch is an unpowered passive switch, so it has problems working when the video source does not provide enough power to the switch.

For example, when my Mac Mini is plugged in, the 5V pin only supplies about 3 volts. Inside of the switch is a set of diodes and a AMS1117 voltage regulator that is supposed to output 3.3V using 5V, but instead it is only outputting about 2V. This made the LEDs in the switch flicker and blink (which seemed like a symptom of a bad power supply) and switch refused to function (no video output). My solution was to add a USB micro connector so I can add an external 5V power supply.

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After adding the power supply, the switch is able to function properly with a steady supply of power.
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Improved “Third Hand” Using Coolant Hose

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I don’t really like my “third-hand” tool so I decided to build a better one using flexible ball-jointed coolant spraying pipe hoses. It’s not a totally new idea, SparkFun even sells some of these parts as a kit. But my way is slightly better, and I got the hoses from eBay (look for “Flexible Water Oil Coolant Pipe Hose for Lathe CNC”) instead because SparkFun’s prices were excessively expensive.
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Alternative Way to Dual Boot TrueCrypt’ed Windows and Fully Encrypted Linux

    I am a mainly Windows 7 user who needs to use Linux only sometimes, so I need a dual boot system. I also want to encrypt my entire hard drive for privacy. I used to have TrueCrypt encrypting my entire hard drive, but TrueCrypt does not really support dual boot systems with GRUB, because TrueCrypt must reside on the Master Boot Record (MBR).

    There are several guides on the Internet about how to create a dual boot system with TrueCrypt but all of them involve placing the TrueCrypt rescue disk image into a separate partition. This is an ugly solution as a mainly Windows user because it involves a few extra keystrokes to activate the rescue partition, and the rescue partition is not hidden. I came up with an alternative solution for people who wants to boot directly into Windows with a silent TrueCrypt login most of the time, but needs a few extra keystrokes to get into Linux.

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LED Pocket Watch


This is a LED pocket watch. It has 12 LEDs to show the hour, 60 LEDs to show the minute, and 60 LEDs to show the second. The LEDs are arranged in three rings. There is a button on the top to activate the pocket watch, and a button on the back to change modes and settings.


The battery is a rechargable lithium ion coin cell battery and it is charged from a micro USB connector. The battery life depends on how heavily the pocket watch is used, but if you leave it alone, it is estimated to last several months. There is a low battery indication feature. This pocket watch also feature a buzzer and a vibration motor, which are used for the alarm feature, and the motor causes a short “tick” as each second passes by. The pocket watch is constructed of a PCB, two pieces of laser cut clear acrylic plastic, and a 3D printed casing.

Click Me!! More instructions, pictures, animations, and videos.

Tutorial about USB HID Report Descriptors

This page is from my old website, and it is sort of popular, so I’ve moved it here.

A USB HID report descriptor is one of the descriptors that a USB host can request from a USB device. HID devices send data to the host using reports, and the descriptor tells the host how to interpret the data. I will try to show you how to write one of these descriptors.
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MMC/SD Card and FAT Tutorial

On my old website, the article “MMC/SD Card and FAT Tutorial” was really popular (it still holds almost top ranking on Google). However, the information there is so old that most of it is obsolete. Elm-Chan’s FatFs library has been updated many times since then, rendering some of the old webpage I wrote obsolete. But I will put up some of the old content here so you may still see it.

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