The "Facit" company was established in Stockholm in 1918 to builda line of pin-wheel calculators based on the Odhner mechanism.

In 1924 Facit became part of Atvidaberg Industries, along-established firm of office furniture and equipment suppliers.Facit production moved to Atvidaberg, and the model range developedrapidly. At its peak the company had over a thousand employees, with sales agents in a hundred countries, before collapsing in the early 1970s.

The early Facit calculators were similar to the Odhner. In the early 1930s engineer Karl Rudin made aradical design change which retained the pin-wheel principle buteliminated the external moving carriage. The pin-wheel mechanism waseffectively turned upside-down, with the accumulator and counter registers being fixed in position at the top of the machine, and the rotor arranged to travel laterally within the confines of the body. At the same time, the rotary setting levers were replaced with the two-row "Dalton" keyboard mechanism. The operating levers and the cranking handle were the only external moving parts.

This "inverted" pin-wheel mechanism formed the basis of the Facit model range for the next 40 years. Model TK (being sold here) started production in 1932,