1. Russian Abacus. I first took measurements to decide how large my abacus should be and then found suitably sized beads. We originally tried to make our own beads out of polymer clay, but they wouldn't harden properly. I then took my measurements to the machine shop and found suitable wood for the frame, which I then cut with the table saw, and smoothed it down to an even size with the planer. I then cut a six by eight-inch frame with 45-degree angle edges using the band saw. I then found brass wiring to make my rods from and cut them into 6 and a half inch pieces. My next, and hardest step was drilling all the holes for the rods in precise measurements, it was a bit of a chore, but after getting done with the drill, I was able to fashion my abacus together quite easily and we then just glued the corners and clamped it until it dried. Amanda Richmond
2. Japanese soroban. I began by making a frame in scale with the 12-mm wooden beads I had found. The frame had to be long enough for 21 columns of beads to be placed 18mm apart, and tall enough to allow movement of the beads upward and downward. I cut wooden rods to the appropriate length and then drilled holes the size of the rods halfway through the frame. Next I used the same measurements to drill 21 holes through the centerpiece of the abacus. I put the rods through the center piece, put the beads on the rods, connected the rods to the frame, and then put on the opposite side of the frame (it was a process that required much patience!). I pounded the top and bottom of the abacus with a wooden mallet to make sure the rods were attached securely. Finally, I glued the last two sides on and clamped it together to dry. Leyra Ryan
Moon, Parry. The Abacus. Gordon and Breach Science Publishers: New York, 1971.
Pullman, J.W. The History of tha Abacus. Penguin Putnam, Inc.: New York, 1978.
http://indigo.ie/~billyb/slide-rules/
http://www.ee.ryerson.ca:8080/~elf/abacus/