American Precision Gauge LLC was established to create, design and build linear digital measuring devices (LDMDs), or long travel calipers. The LDMD was created as a solution to one of those situations where no good alternative existed.

For years, providers of shafting, piping, tubing, wood products and other long-length components had to rely on simple tape measures for cut-to-length operations and inspection and set up. Even in today’s machine shop environments where 24 in to 72 in parts are commonplace, there remains a need to inspect and verify on the floor. The typical caliper cannot meet the needs and few options were available, until now.

American Precision Gauge has created and built several versions of the LDMD, including the ultra-precise linear scale with digital read out (DRO), the LDMD 2, specifically for round-type products up to 4 in diameter, with a separate DRO.

These devices proved to be accurate and reliable with travel lengths up to 120 in. The shortcomings were cost, the need to have 110 V AC nearby and transportability. Each of the previous LDMDs needed to be fully supported, and usually meant mounting it to a rolling table with a precision top. The units transportable but came with a cost premium.

The new LDMD 3.0 solves many cost and transportability challenges. Made from a lightweight, custom-designed, aluminum base that is precisely machined to incorporate two ultra-precision, ground-aluminum shafts with ceramic coating, which makes the LDMD 3.0 lightweight and precise.

Standalone handheld units measure to 48 in, accurate within .005 in over the full travel, with .001 in repeatability. Standard handheld sizes are 48 in, 60 in and 70 in measurable lengths.

The carriage which houses the LCD digital display and read head slides effortlessly along 48.8 in measurable travel length on pre-loaded linear bearings, which are matched to the coated shafts for long life and consistent straight-line travel, with negligible pitch, roll or yaw issues.

Each LDMD display is operated with two AAA batteries, meaning no cords to tangle or wires to interfere. Battery life expectancy is three years with standard usage, and is replaceable with a simple screwdriver.

The display offers a fully programmable, LCD, single-line output, with inch or metric output that is capable of four decimal place resolution. The unit is operated in absolute or incremental modes, along with programmable offsets, reference set points, sleep timer and selectable direction-of-travel feature. Any movement of the carriage wakens the display without position loss.

The end plate, carriage and contact paddles are configured to allow them to be removed and replaced, with custom end-of-arm tooling to suit applications, or reversed to allow the LDMD to be custom configured.

The LDMD 3.0 does not have error compensation. However, each unit is meticulously tested via a laser interferometer that is traceable to NIST standards, ensuring every unit that leaves the shop operates within the quoted accuracy. That accuracy is to be within .005 in of the nominal anywhere along its full length of travel, and repeatable within .001 in. With each unit, documentation is included as to how the unit performed during this testing and along with a graph showing exactly where the error does occur, and how the user can mathematically remove the error for even more precise results.

The net result is the LDMD 3.0 is accurate, repeatable, light enough to carry around the shop, easy-to-use right out of the box and can be easily adapted to the application needs, either through programming or by reconfiguring end-of-arm tooling. If carrying the LDMD 3.0 is not a preference or if longer lengths are required, American Precision Gauge offers fixed tables and rolling stands.

Want to learn more about American Precision Gauge LLC and their line of LDMDs? See their site for additional information, including FAQs.