Detailed Pictures

The magic fingers holding a disc

The photo-diode/transistor pairs around the disc

The cutting-board material is the vertical white chunk with the two steel rods passing through it

The parallel port expander

I got a little happy with the label maker. (A little nod to Douglas Adams there! The "override" switch kills power to the motor systems in cases of runaway, generally due to my mistyping "perl" as "perk" :D )

Stepper controller (bottom)

Stepper controller (top)

One of the various PCBs adapting the optical sensors to TTL logic -- basically they're base and pull-high resistors

Another

The penalty box for coasters. The 'fence' is actually raingutter guard

The 8-bit LED bank

The picker, showing the fingers that grab the discs by the center

The motherboard ... all 170mm² of it. Tiny little thing, and all-inclusive ... I love these things!

And the end result, or at least one!

Conclusions

Overall I'm please with the results. Obviously with the development time involved I didn't save any time for the first backup set, but future ones will be much quicker and require much less work on my part. (And I had great fun with the project -- it is, after all, a project =))

The unit is much larger than I had anticipated and does not utilize the space consumed terribly well. I note that the commercial solutions often rotate around a semi-circle of disc stacks rather than sliding laterally as this one does. Were I to do this again I might choose such an arrangement to save space. (Finding a place to put this thing is hard enough, but finding one that my wife accepts is even harder =))

There are some bits that will need tweaking; after some months the balsa delaminated from the aluminum it was epoxied to. The process of aligning the stacks apparently stressed that junction. I suspect I'll drill holes in the aluminum and put some shallow sheetmetal screws through into the balsa. There's also an ongoing concern of the metal parts needing lubrication, which will be determined as time passes.

In any event, it was not terribly expensive, is actually useful, and is a fairly unique Mini-ITX project, and so for those reasons alone I consider Florian eminently successful.