The electronic height gage is a flexible tool that can be used for a wide range of evaluation options, such as first-part qualification, inspecting incoming parts, or measuring a series of parts. Its direct-reading measurement capabilities, ergonomic handling, and versatility make it the preferred choice for many. In fact, digital height gages can be compared to single-axis CMMs or even 2-axis versions if the built-in functions to measure straightness or squareness are used.

Like a CMM, modern electronic height gages are computer-based systems operated via touchscreens. These systems offer automated measuring routines, error correction, and multiple probe offsets, empowering the user to easily create and execute serial part programs. The typical height gage size ranges between 350 mm and 600 mm, but they are available in sizes up to 1000 mm. With extensions, even more capacity is possible.

The surface plate is the foundation of all precision and serves as the reference for height gages (height gages cannot take measurements accurately without a reference). Once the height gage is in position, two crucial references must be established. The first reference is the zero point for the measuring system. With automated height gages, this is done when the gage is switched on—the gage will automatically move down to touch the surface to set its reference point.

Another crucial reference is accounting for the correction related to the probe ball diameter. If a height gage is exclusively utilized for length measurements by moving the probe downwards, the probe diameter may not hold much significance. The contact point of the probe will remain the same as it was during zeroing. However, if measurements are taken while moving the probe upwards, or when measuring grooves, diameters, or hole locations, then the probe ball diameter must be known and taken into account.

With the advent of new motorized digital height gages, taking measurements has become as easy as pressing an icon on a large touchscreen. When ready to make a measurement, for example, the height of a part with reference to the zero point, simply slide the measuring carriage over the part and press the height measurement icon, which approaches the surface from the top. The motorized drive takes care of bringing the contact to the surface, and the measurement is completed and displayed. 

However, this is just the tip of the iceberg, as modern height gages offer a plethora of measuring capabilities. There are dedicated icons for most common measuring functions, such as up/down lengths from the reference, outside/inside diameters, center distance, flatness, and even taper measurements. If the height gage has 2D functions, straightness and perpendicularity are just a touch of an icon away.

As measurements are taken, they are stored internally, and additional relationships between the saved data, such as center distance and other correlations, can be established without the need to measure the part again. This measuring process also serves as the foundation for a part program. Since every measurement and routine is stored on the gage, this historical record of past measurements can be utilized as a new part program. This way, when the part comes along again or a series of similar parts require measurement, this routine can be used as the part program for replicating the measuring process.

In addition to using the measurement sequence as a basis to create the part program, the measurement results can be saved or stored in various ways. The raw results can be saved as a file, stored on a USB stick, saved in a preformatted and customized PDF file, or transferred to the network or cloud for long-term storage and analysis via cable or wireless connection.

In summary, today's height gages are not just feature-packed and sophisticated, but also highly adaptable measuring systems. They can implement canned measuring modes, store part programs, use different probes with varying contact configurations and diameters, and have the ability to store and print gaging results, giving them all the capabilities of a CMM for a single axis. When used on a sound surface reference, electronic height gages can deliver significant benefits in terms of time and productivity savings. They allow for high-quality measurements to be taken right on the shop floor or as part of a receiving inspection area at a cost that provides excellent value for the results obtained.