8mm Film Scanner

Disclaimer: This is one way to do it.  I make no claim that any of this would work for anyone else, but I'll answer any questions I can. - Todd Campbell

Parts

Epson 3200 Flatbed scanner
Lego gears and axles (parts #10076 and #10074)
Two sprockets from an old Sears Tower projector, along with the plastic guides that fit against them
A small piece of aluminum tubing that fits snug inside the sprockets as well as outside the Lego axles
A motor from an old VCR
A roller switch
Various electronic parts to build a serial port motor controller and switch reader
Structural plastic, for a film guide that sits on the scanner glass
Structural aluminum, for the gearbox sides as well as a cam wheel that hits the roller switch
Some wood
Software that can activate the serial port controller as well as the TWAIN driver for scanning
Software that can find frames in the resulting raw scans and create an AVI file.
A small, inexpensive tabletop drill press is a must for building the gearbox.  I use a GMC LSR13R from Lowes for $69.
Lotsa time

Hardware Images

Scanner glass with plastic film guide.  The scanner is an Epson 3200 (firewire).  The guide is structural plastic from a hobby shop, glued together.  The flat parts of the guide are 0.030" thick, which seems to keep the film close enough for focus. The near edge of the film is held 6 5/8" from the near edge of the glass. Experimenting tells me that you must pull the film horizontally across the glass as shown.  When pulled vertically, the scanner doesn't correctly set the color levels  - perhaps due to the configuration of the scan head.  Horizontally also works faster, probably for the same reason.
Feed reel holder, feed sprocket, feed sprocket guide.  The sprocket & guide are from an old Sears Tower projector. In these images I've forgotten to remove the scanner pad which blocks the transparency scanning light.  This can lead to problems with image quality.
View of takeup reel and the gearbox that pulls the film across the scanner.  The takeup reel is not motorized yet - so far I just reach over and spool it up when it has a lot of slack.
The gearbox assembly, removed from the platform to photograph.  The motor is from an old VCR.  The gears and axles are from Lego.  As it happens, the 8mm sprocket (again from the Tower projector) has 18 teeth.  The large gear at the top to the left of the sprocket has 36.  So the worm gear driving that large gear rotates twice for each sprocket tooth, meaning twice for each frame.  The worm gear is on the same shaft as the cam wheel, so the roller switch is hit twice for each frame.  As long as the motor turns fairly slowly (resistors slow it down), the controller circuit below seems to keep an accurate count of the frames going by.
A view of the gearbox opened at the hinge (to allow film loading and unloading).  The worm gear is visible.  The film sprocket is hidden by a black plastic guide.
A plastic project box from Radio Shack containing a circuit based on the ELM621 serial port controller chip ( http://www.elmelectronics.com ).  This chip costs $8.50 plus shipping, and the parts around it cost about $30.  I can provide an image of the circuit diagram if requested. This circuit turns the motor on and monitors the roller switch.  When the software counts 28 activations (14 frames), the motor is turned off and a scan is initiated.

Sample Output

raw2003-12-23-183640.jpg - a sample raw scan
part7-183640.avi - a movie made from the sample bitmap

Links