Servo - April 2012

Version 3 SpindleBot (bottom view).

robot. On this SpindleBot, I used a PIR motion sensor and three CDS photoresistors. The outputs are configured to drive two main drive servos, a small piezo speaker, an optional pico servo for pen up/down, and a 74HC595 shift register to control a set of eight LEDs for some cool lighting effects. Most of these are optional, and you can use whatever sensors you want when you build your own version.

The top center of the CD case and the top center of the Spindle were drilled out. This hole allows for a pen to be placed in the center of the robot so it can draw while moving. When drilling into plastic, you need to be very careful not to crack it. To start, just use a small drill to make a pilot hole. Any drill bit 1/8” or less will do. Then, follow up with a Unibit or stepped drill to enlarge the hole. The stepped drills are much less likely to damage the plastic. If you try using a larger drill bit, it will more often than not break the plastic instead of making a proper hole.

When using a 25 or 50 CD spindle, a small pico servo can be added to raise/lower the pen. Since they are so small and the pens are light, it can be attached to the top cover of the CD spindle with double-sided tape. For a more secure mounting, small aluminum angle brackets with screws are an excellent option. An example program that I wrote to test my robot turns the robot into an art bot. It has been a popular demo whenever I have shown off SpindleBots at local schools. I’ve also tried Scribbler 1 code which worked with some minor modifications to the motor control code and adjustments to pin assignments to match my board.

Creating the Ultimate SpindleBot

The latest version of the SpindleBot is even more refined. It uses one of the tall 100 CD spindles for its body. The construction is exactly the same as the shorter SpindleBot but has room for more levels of electronics and batteries. The CDPCB boards can be stacked on standoffs to