Dros

DRO stands for digital readout. A DRO is a display and sensor system used on manual machine tools to indicate the position of one or more axes of motion. It translates the position read from linear scales or encoders into numeric coordinates, typically X, Y, and Z, allowing the operator to read machine travel directly without angular measurements or counting dials. DROs are used on lathes, milling machines, grinders, and other equipment to improve positioning accuracy and repeatability and to speed setup and measurement tasks.

DROs are distinct from CNC systems; a DRO does not control the motion of the machine but provides feedback and visualization. In contrast to traditional dial indicators, DROs can store origin points, perform simple arithmetic on measured values, and may incorporate backlash compensation and presetting features.

Components include linear scales attached along each axis; readheads that convert scale position to electronic signals; a display unit to show the coordinate values; power supply; and interface cables. Scales can be optical glass, magnetic, or hybrid. Some systems are modular to add extra axes or to integrate with existing controls.

Types include incremental and absolute scales; single-axis, two-axis, or multi-axis configurations; and different formats of display, from simple numeric readouts to multi-axis panels with keypad entry.

Operation is straightforward: as the tool moves, the scales report position to the readhead, which updates the display. Operators can zero the readout at a reference point, set offsets, or quickly compare tool position to a stored origin. DROs speed setup and improve accuracy at the bench, but they do not correct inherent machine errors.

See also: machine tools, CNC, measurement tools.