The other day I saw this link from dsvilko and thought it was a really good idea. He uses the sled from a cd or dvd player to accurately position a subject for macrophotography. If you have never tried it before, then shooting something macro usually means that there is very light coming in to the camera and it makes manually focusing something (by twisting the lens) almost impossible.
Initially I wanted to directly duplicate dsvilko’s rig, but the sled I have doesn’t have the belts traveling in the same direction as his, so there was no easy way for me to replace the dc motor with a stepping motor. I decided to just roll with the punches and stick with what I had. By limiting the amount of time the motor was on I could build a reasonable facsimile of a repeatable step. I am currently moving the sled in 20 millisecond periods.
I directly soldered wires to the existing motor’s terminals. I zip tied them to the sled and then started work on the arduino side of things. I am using a l298 h bridge motor driver to control the motor. It takes 3 wires from the arduino. Two wires control the direction of the motor, and the third turns it on.
more after the jump