In collaboration with the Dietz laboratory, we created and characterized a nanoscale rotary object, the first of its kind, that couples large scale mechanical transitions of the stator with rotation of the shaft. The rotary object was made using DNA origami with several interlocking parts that iterative design guided by experimental cryo-EM reconstructions and MD simulations. Experiments revealed that the shaft rotates randomly, dwelling at intervals spaced 120 degrees, which matches the three-fold pseudo-symmetry of the stator. Simulations characterized the conformation and dynamics of multiple rotary assembly designs, and revealed how the cam in the rotary shaft and the stator conformation are coupled. This study represents a breakthrough in the design and fabrication of nanoscale rotary systems, bringing macroscopic mechanical principles to a microscopic world.