Towards the end of the Edo period (1600-1868), a carpenter living in Shimane Prefecture obtained an abacus from Hiroshima made by a specialist and made a very good one using locally sourced oak, Japanese apricot and a smoked form of bamboo called susudake.
Later on after two men from the district of Yokota-cho, Takahashi Tsunesaku and Murakami Asakichi, perfected a hand lathe for making the beads, production increased remarkably quickly and the foundation of today's small craft industry was established. The abacus made here are of the very best quality and the name Unshu is synonymous with the abacus.
One of the most important elements of an abacus is the beads. They should move freely and should produce a clear click as they strike the frame or another bead. Because much attention is given to the way that the bamboo shafts and the hole passing through the beads is finished, it is a particular feature of these abacus that the more they are used the better they become.
The most important thing in soroban are the beads. The best beads are said to be the ones that move well and make a very clear sound. Since great care is used to give a proper finishing to the beads’ holes and the bamboo cores, they will become easier to use the longer they are used.
How to make
Beads are made from wood like birch, boxwood or ebony, while the frame is made out of ebony or specially-reinforced wood and smoked or processed bamboo is used for the axis. All of the above materials are properly inspected and only the ones that are found to be sufficiently dry and undistorted will be used.