This is a small treadle operated model of a grinding wheel. The scale is unknown, but a US quarter in the photo provides scale reference. The wheel is only about 2” in diameter. These grinding wheels were used to sharpen knives and other tools before electric motors.
Birk Petersen created a vast array of projects over his lifetime, ranging from miniature engines to hand-cranked animations and more. He built functional miniatures like a 1/3 scale Gatling gun or a 1/4 scale Case steam tractor, but he also built mechanical creations for the fun and enjoyment of his family. When Birk passed away in 2015, his family graciously donated over 150 items from his collection for display at the Miniature Engineering Craftsmanship Museum, where they are currently on display. We thank the Petersen family for sharing his extensive collection, which demonstrates the broad interests and many talents of Birk Petersen.