[Ben] just finished building this time-lapse dolly and decided to share his experience. We think he struck just the right balance of diy and commercially available materials to create a rig that is stable yet relatively inexpensive.
The project was inspired by Project Chronos. It gives a lot of details about the drive electronics and code used, but there are some gaps in the instructions for building the track itself. [Ben] forged ahead, purchasing linear bearings and a double-guide rail from IGUS. He didn’t mention the price on that item but we found 1000mm of the stuff (about 40 inches) for under $75 so it’s not outrageous. The part he couldn’t get for a reasonable price was precision thread bar. He ended going with regular threaded rod and a couple of nuts combined with a spring mechanism to keep the sled steady. That seems to work just fine. You can see the rod bouncing a bit in the clip after the break but it doesn’t harm the stability of the captured images.
The end stops including the one to which the stepper motor is mounted are his own work. It sounds like they required a bit more fabrication work than he was planning on but we figure if you don’t challenge your skill set you never get any better.