Summary

The Otis King Calculator Model K, with scale #423 on top, and #412 on the bottom. This is the standard model with logarithmic scales for multiplication and division. It is a cylindrical spiral slide rule patented by Otis King in the 1920s.

I attached the scales to the print with packaging tape wrapped all the way around. You may need to wrap the tape around an extra layer to get the correct amount of friction between the three pieces.