Hexadecimal Slide Rule
The Hex Rule is my build from a patent application (GB12383736A).
The patent application attached below dates to 1969; the Hex Rule was invented by Philip J Wyatt, Albert S Trundle, and Judith B Bruckner. They also patented an octal base calculator. To the best of my knowledge, this didn't make it into a commercial implementation, the patent approval date was 1972 (I think), just in time for the electronic calculators to knock slide rules off the map.
The Hex Rule is designed as a 2 sided Gunter circular, each side requiring a set of divider cursors, a similar pattern to the Gilson models.
I built this as two sets of scales; the first was a 'normal' 8-inch design (common diameter for circular rules) and one sized to print on CDs. The latter is shown here.
The first cursors for I made this build look quite brutish I was experimenting with a hard plastic that I found at the hardware store. Art supply stores sell an acrylic that is easier to work with, but also quite thick.
In keeping with the overall stone age look to the piece, I was also having some difficulty figuring out how to get the cursors precisely centered over the CD centre. So I pulled some washers and bolts together from my spares, and used them. The large washers protect the fragile centre of the CD from cracking . The little washers fit snugly in the holes and kept the cursors centred:
Patent GB1283736A HEX SR.pdfThe original patent
HexSlideruleNotes.pdfNotes I made at the time of development
hexLarge.pdfA PDF format that will fit Letter / A4 sheets.
hexsmall.pdfA smaller format PDF, for CD cases.