What Makes It Spin



Inside the Mind Orbit is a heavy sintered-iron ring embedded within a plastic rotor, and a rigidly attached shaft and magnet. When the rotor is made to spin very fast on its axis, it acts as a gyroscope, and will resist forces that try to change the direction in which it points.

In the video clip at top left, the rotor has been spun to high rpm by a blast of compressed air, and suspended by a string at one end. Instead of hanging straight down, the rotor resists the pull of gravity and moves sideways. This is called gyroscopic precession.

In the bottom photo the top of the housing has been removed. The white ring fits loosely between the top and bottom housing shells, and is free to rotate. It serves to keep the rotor centered in the housing, but does not otherwise support the rotor shaft. The small diameter ends of the shaft rest on circular tracks on the inside edges of the shells.

In operation, wrist motion tilts the spinning rotor by pushing the upper and lower tracks against opposite ends of the shaft. This causes the rotor to precess just like it does in the video clip, forcing the shaft ends to spin faster as they roll around the tracks. By imparting a rocking motion to the housing, in time with the precession of the rotor, the rotor can be "pumped up" to a very high speed.

Note that the magnetization direction is always parallel to the rotor shaft, and the magnetic field is rotationally symmetrical. Thus, there is no high speed modulation of the field.