INSIZE Digital Wide Range Three Points Internal Micrometer

The INSIZE Digital Wide Range Three Points Internal Micrometer are precision bore-measuring instruments designed for accurate measurement of internal diameters in machining, manufacturing, inspection, and quality-control applications. Using a three-point measuring system with carbide measuring faces, these digital internal micrometers provide stable, repeatable measurements across a wide range of bore sizes.

Designed to meet DIN 863-4, the 3128 series combines a digital display, 0.001 mm resolution, IP54 dust and water resistance, data output, and included extension rods for applications requiring precise internal dimensional measurement.

Key Features

• Three-Point Internal Measurement — Three measuring contacts provide stable positioning inside a bore for accurate internal diameter measurement.

• Wide Measuring Ranges — Five configurations cover internal diameters from 50 mm through 300 mm.

• High Resolution — Provides 0.001 mm / 0.00005" resolution on most models.

• Carbide Measuring Faces — Durable carbide contact surfaces are designed for repeated precision measurement.

• IP54 Protection — Dust and water resistance helps protect the instrument in demanding shop-floor environments.

• Digital Display — Provides a clear electronic measurement readout in metric or inch format.

• Data Output — Supports electronic transfer of measurement data for inspection and quality-control workflows.

• Setting Rings — Setting rings are included with the 50–70, 70–100, 100–150, and 150–250 mm models for calibration and setup.

• Extension Rods Included — Supplied with 150 mm extension rods to expand measurement capability.

• Ratchet Stop — Helps provide consistent measuring force during operation.

• Automatic Power-Off — Conserves battery power when the instrument is not in use.

Precision Three-Point Bore Measurement

Unlike general-purpose calipers, an internal micrometer is designed specifically for measuring the inside diameter of a bore. The three-point configuration contacts the internal surface at multiple points, helping establish a stable measurement position within cylindrical features.

This makes the INSIZE 3128 series particularly useful when accurate bore dimensions are important for machining, component inspection, and quality control.

The carbide measuring faces provide durable contact surfaces for repeated measurements, while the ratchet stop helps the operator apply consistent measuring force.

Wide Measurement Capability

The 3128 series provides five overlapping measurement ranges:

Specifications are based on the current INSIZE 3128 product documentation.

Digital Measurement & Data Output

The INSIZE 3128 series provides digital measurement in both millimeters and inches, with dedicated buttons for on/off, setting, and unit selection.

The instrument also provides data output, making it suitable for inspection environments where measurement results need to be transferred into a digital quality-control or measurement-recording system. An optional data output cable is available for compatible configurations.

Calibration & Setting Rings

Proper calibration is essential when performing precision bore measurements.

Setting rings are included with the 3128-70, 3128-100, 3128-150, and 3128-250 models. The 3128-300 uses a Ø200 mm setting ring, available separately.

The supplied setting rings allow the micrometer to be checked and adjusted against a known reference before measurement.

Extension Rods

Each 3128 configuration is supplied with a 150 mm extension rod, providing additional flexibility when measuring deeper internal features.

Because the extension rod changes the measuring configuration, proper calibration should be performed after installing an extension rod to maintain measurement accuracy.

IP54 Protection

The 3128 series features an IP54 dust and water-resistant design, making it suitable for use in manufacturing and inspection environments where the measuring instrument may be exposed to shop-floor dust or incidental moisture.

Applications

The INSIZE Digital Wide Range Three Points Internal Micrometers are well suited for:

• Bore diameter measurement

• Internal diameter inspection

• Machined component inspection

• Precision machining

• Manufacturing quality control

• Dimensional inspection

• Production inspection

• Tool and die work

• Engineering applications

• Component verification

• Large-part inspection

Industries

Typical applications include:

• Precision machining

• Manufacturing

• Automotive

• Aerospace

• Metalworking

• Tool and die

• Industrial equipment

• Engineering

• Quality assurance

• Production inspection

Technical Specifications

Choosing the Right Model

Selecting the correct 3128 model depends primarily on the internal diameter you need to measure.

For example:

• Choose 3128-70 for 50–70 mm bores.

• Choose 3128-100 for 70–100 mm bores.

• Choose 3128-150 for 100–150 mm bores.

• Choose 3128-250 for 150–250 mm bores.

• Choose 3128-300 for 200–300 mm bores.

When selecting an internal micrometer, choose a range that accommodates the bore diameter you need to inspect while providing an appropriate measurement range for your application.

If you're unsure which model is right for your application, contact CRB Supply before ordering. We can help you select the appropriate INSIZE configuration.

Technical Documentation

For complete specifications, dimensions, accuracy information, and additional technical details, refer to the official INSIZE documentation:

View INSIZE 3128 Series Technical Documentation

Need Help Selecting the Right Internal Micrometer?

Choosing the correct bore-measuring instrument can depend on the diameter, depth, required accuracy, and inspection process.

If you know the bore diameter, required tolerance, and measurement depth, contact CRB Supply before ordering and we'll help you identify the appropriate INSIZE model.