Digital read out

In machine-shop terminology, the complete digital read-out system (consisting of a computer, axis-position encoders, and a numeric display) is referred to by the acronym DRO.

CNC machines can usually be switched to manual operation, and in this case a form of DRO is simulated on its control panel.

Commercial models are enclosed in an aluminum "box" with a rubber protection on the side where the encoder slides.

Instead of glass, a printed circuit on a stainless steel ruler is used to trigger at least two microelectronic Hall effect sensors.

These models use a rack (toothed metal strip) that meshes with a gear that turns a rotary encoder.

Claimed accuracy of 0.002 inches per foot, though users frequently report it Is much more accurate, with no measurable deviation over several feet of travel.

At this part of the machine coolant splash, flying chips and accidental shock are day-to-day events, therefore it is a very bad place for a glass scale used in conventional DROs.

It also gives the operator a lot of comfort by being placed right in front of his eyes next to the controls that adjust the machine and it doesn't have any wires that could get trapped in the cluttered quill area.