1541 Alignment disk

On 01/26/2014 11:22 AM, Fred Cisin wrote: Well, I don't claim to be able to duplicate a digital alignment disk, but I think one could be fabricated with a slightly modified "ordinary" drive in good condition. As an analogy, suppose one has a 1% tolerance carbon composition reference resistor. It's certainly possible to come up with another 1% tolerance resistor by selecting from a mixed batch of 20% resistors, assuming the the closer tolerance components haven't been selected out by the vendor. In a similar manner, I think that if a drive can be slightly modified so that the hub clamp has a slight eccentricity (with respect to the spindle), a pattern would result upon writing that centered around the ideal track location, but would also vary a bit outside and inside with respect to it. (Picture a 45 RPM audio record being played on a standard turntable without an adapter. The result would be a playback with a lot of "wow", but at some point, would be the correct pitch. Sort of like a broken clock being accurate twice a day. At any rate, given such a disk, one would only need to identify the position and address marks closest to the ideal position and note that. When inserted into an ordinary drive, one could simply sample address headers and determine that the particular address mark lay in the center of a cluster of readable address marks. Not lab-grade alignment, but surely something that could be useful. I haven't tried this myself, but I see no reason why it shouldn't work. And I don't think that I'm an ignorant asshole. --Chuck