• A Caliper Style contact measuring device specializing in long length parts and materials beyond the scope of a typical dial or vernier caliper.
  • The AP Gauge’s LDMD 3.0 comes in a 50″ Hand-Held version as well as a 105″ measurable mounted version.
  • The LDMD 3.0 is accurate to within .005″ of nominal over full travel and repeatable to .001″.
  • AAA Battery Operated, Low cost, accurate solution for those longer travel measuring challenges found in the metal working and manufacturing environments.
  • Use it as a handheld device or bolt it down as a rigid, integrated “in process” device.

Use as an Inspection Device to Measure Length, ID and OD

Use as an In Process Device built into a Machine Structure

Use as a length Gauge for Cutoff Applications

Linear digital measuring device at 110" long
Click Photo to see How To Use the LDMD 3.0

LDMD 3.0

The LDMD 3.0 features a robust precision machined aluminum base design that reduces weight allowing for the unit to be easily moved around the shop to meet any measurement needs. 50″ version weighs 12 lbs. The custom base extrusion is designed to be lightweight and extremely rigid. Slide containing the digital display is actuator smooth with preloaded sliding elements with virtually no pitch, roll or yaw introduced error. This is not a flimsy device. The LDMD 3.0 can handle the rough shop environments without fear of sensitive re-calibration issues. This all aluminum constructed device is hard anodized on all wear surfaces and is virtually impervious to washdown issues except at the digital display. All End of Arm tooling is interchangeable and adaptable to your needs. AP Gauge offers specialized tooling to make your device accommodating to your needs. Use our tooling options or build your own referencing from our precision pin locations for easy alignment and in house accuracy. 


Error Reporting

Each LDMD 3.0 is meticulously inspected and the stated device accuracy (Within .005″ of the nominal, repeatable to .001″) is verified by Laser Interferometer traceable to NIST standards. An Error Report is then generated and transmitted with each LDMD shipped and correlated to the serial number of that device. This Error Graphical report can be used in the field for extrapolation and Error Compensation.

Laser Interferometer generated Error Report and Graph Serialized by device
  • 50″ LDMD 3.0 can be hand held and easily carried to the work piece or table mounted
  • 105″ measurable units fit the typical profile aluminum 40 x 80 extrusion making it easily adaptable to other structures for table mounted or built in units
  • Inch or Metric output
  • Absolute or incremental operations
  • Measures ID, OD as well as Length
  • Zero reset anywhere along its path
  • Accurate to  within .005″ of nominal over full travel
  • Repeatable to .001″
  • Display resolution to .0004″
  • 2 AAA Battery powered operation with no exposed wires to manage or tangle 
  • Batteries are user replaceable with a simple screw driver
  • Direct reference or offset value input capability
  • Use of magnetic sensor for consistent accuracy and reliability
  • Robust anodized aluminum allows for reduced weight and mobility
  • Compact
  • Lightweight
  • Modular
  • Configurable end plates
  • Absolute and incremental
  • Mount in any orientation


  • Tool room
  • Cutoff Saw Gauge
  • In Process Gauge
  • Machine Shop
  • Clean room
  • Large Scale dimensional analysis


50” and 105″ Measurable Strokes available

.001” Resolution

Accuracy within .005″ of nominal over full travel

Magnetic tape is IP54 rated,

display is IP40 rating (avoid any exposure to moisture and condensation)

read head IP 67 rating

50″ unit weighs 12 lbs.

Display Range 6 Digit LCD

Operating Temperature -32F to 140F

Storage Temperature -22F to 175F

Max Speed of Travel 200″/s

Operating voltage 1 to 3.3V DC

The Wooden Box that houses the LDMD 3.0 is designed as a shipping Container as well as a storage unit when the device is not in use.

The box is framed in 3/4″ x 1.5″ Select New Zealand Pine and covered with a .180″ thick Birch veneer and stapled with 1/2″ long  stainless Staples. Clasps and corner protectors added for durability and simple operation.

The LDMD 3.0 is held in place on the ribs which are covered with a felt material as to not scratch or deform precision shafting or Digital Display. The device is held in place and pre-loaded between top and bottom halves upon closing.

For shipping purposes, the wooden box is sandwiched with cardboard and banded to insure integrity. The entire unit at 50″ weighs 25 lbs. 

Need A Fixed or Rolling Gauging Table?

Need a Custom Precision Gauging Table solution, not a problem. Let us know your special needs and let AP design your ideal Mobile Measuring System complete with LDMD 3.0 and a perfectly matched Gauging Table System.