classification There are several variables in dial indicators: Analog versus digital/electronic readout (most are analog) Dial size. Typically referred to be American Gauge Design Specification (AGD): {| class="wikitable" |- ! AGD !! Diameter range (in) !! Diameter range (mm) |- | 0 || 1 > 1-⅜ || 25 > 35 |- | 1 || 1-⅜ > 2 || 35 > 50 |- | 2 || 2 > 2-⅜ || 50 > 60 |- | 3 || 2-⅜ > 3 || 60 > 75 |- | 4 || 3 > 3-¾ || 76 > 95 |} Accuracy Range of travel Number of dial revolutions Dial style: balanced (e.g., −15 to 0 to +15) or continuous (e.g., 0 to 30) Graduation style: positive numbers (clockwise) or negative numbers (counterclockwise) Revolution counters, which show the number of revolutions of the principal needle. Principles Indicators inherently provide relative measure only. But given that suitable references are used (for example, gauge blocks), they often allow a practical equivalent of absolute measure, with periodic recalibration against the references. However, the user must know how to use them properly and understand how in some situations, their measurements will still be relative rather than absolute because of factors such as cosine error (discussed later). Applications In a quality environment to check for consistency and accuracy in the manufacturing process. On the workshop floor to initially set up or calibrate a machine, prior to a production run. By toolmakers (such as moldmakers) in the process of manufacturing precision tooling. In metal engineering workshops, where a typical application is the centering of a lathe's workpiece in a four jaw chuck. The dial indicator is used to indicate the run-out (the misalignment between the workpiece's axis of rotational symmetry and the axis of rotation of the spindle) of the workpiece, with the ultimate aim of reducing it to a suitably small range using small chuck jaw adjustments. In areas other than manufacturing where accurate measurements need to be recorded (e.g., physics). To check for lateral run-out when affixing a new rotor to an automotive disc brake. Lateral run-out (lack of perpendicularity between the disc surface and the shaft axis, caused by deformations or more frequently by a lack of proper cleaning of the mounting surface of hub. This run-out can produce brake pedal pulsations, vibration of the vehicle when brakes are applied and can induce uneven wear of the disc. The