The Birth of the Rotisserie Scanner
WARNING: Don’t try this unless you have some training in electronics. Running equipment open to the air (and your fingers) can be a fire hazard and/or an electrocution hazard.
Step one was disassembling the scanner to see how it functioned. My first idea was to remove the scanning element, and build a free-standing scanner that would rotate around a person’s head. Ha.
This old scsi scanner goes through an elaborate calibration phase, where it jiggles back and forth to align itself with an on-board sensor. I like a challenge, but it seemed that I would never be able to replicate the feedback loop that initializes the scanner if I removed the head (it fails frequently as it is, requiring a power-cycle to recalibrate).
Ok. Here’s where the divergence happened. I got keen on the idea of making a spinning element that would track with the moving head element, essentially a controlled version of my initial hand-held test.
Break out the Legos! I’m pretty proud of the hack. The pictures above are the Mark I design. The idea is simple: use the motion of the scan head to push a carriage along side. The big wheel drives a series of pulleys and gears that rotates the item to be scanned (show above, a green block of foam).
It sort-of worked, but the rubber bands gave the system too much play, and the results were ultimately disappointing.
Then I replaced the pulleys & bands with an all gear system, and the damn thing now works…better:
Scanner in Action - 2.7 meg DivX avi
The marble candlestick is a counter-weight to keep the main wheel firmly planted on the desktop. It produces a recognizable image, though currently of poor quality. Removing the case top has let light into places there should be no light. As soon as I track down the leak, I’ll build a light box around it, and that should improve the image quality dramatically.
[Link] The vertical stripes are the rubber bands that currently hold the item-to-scan in the rotisserie element. Aside from the light box fix, I think the next step is to do away with the mechanical drive, and power the rotisserie with a Lego robot brick.
This will make a more robust element that I can more easily adjust to bring the items as close as possible to the scan head, for best picture quality.
File Under: How-To, DIY, Mad Science, Make, Hardware, Rotisserie Scanner
