A magnetic mounting device is provided for mounting a vibrational sensor or other device to a machine or structure, and particularly a vibrating machine or structure. The magnetic mounting device includes a mount surface and a mounting base with an encapsulated magnet and including a three mounting projections projecting therefrom, which provide an exact constraint mounting of the magnetic mounting device on the vibrating machine or structure. The three-point mounting arrangement allows the magnetic mounting device to be rigidly mounted to flat, curved and irregular surfaces without requiring a specific orientation of the magnetic mounting device on the surface.