3-Point Internal Micrometer Holtest

Mitutoyo - 3-Point Holtest Internal Micrometer

The Mitutoyo Holtest series is designed for accurate measurement of internal diameters in situations where a standard two-point internal diameter gauge is no longer sufficient. The Holtest's three-point design automatically places the micrometer in the center of the hole, with the measuring surfaces making contact with the inside wall at 120-degree intervals. This self-centering design eliminates user errors and ensures that the measurement is always aligned with the actual diameter of the hole.

The Holtest is particularly useful when inspecting machined holes, bushings, tubes, or precision cylinders where the inside diameter directly affects the fit or functionality. The measuring surfaces are carbide-tipped and micro-lap finished, which prolongs service life and maintains good measuring accuracy even with hard materials. The design also allows measurement through deep holes, and the mechanical ratchet stop ensures consistent measuring force with every measurement.

Key features:
- Measuring system: 3-point internal measurement that automatically centers the micrometer
- Measuring surfaces: carbide-tipped, wear-resistant, and maintaining their accuracy
- Standard measuring force: Ratchet stop provides a constant force and minimizes user errors
- Accurate and clear scale: easy-to-read mechanical scale for even small changes
- Suitable for deep and blind holes: Measurement is possible when the tool cannot reach the bottom
- Robust construction: the high-quality Mitutoyo mechanism guarantees repeatable measurement results and a long service life

What are the benefits of the three-point Holtest design?

The three-point design offers a fundamental advantage over the traditional two-point internal measurement: the device automatically positions itself in the center of the hole. The user does not need to locate the correct point, as the measuring surfaces naturally guide the micrometer into position. As a result, the measurement results are more stable, consistent, and repeatable, and easier to perform even for a less experienced operator.

Applications:
- Machined holes and bushings
- Internal diameters of bearing housings
- Internal dimensions of tubes and cylindrical parts
- Precision machined fittings that must have a precise diameter
- Quality control, metrology laboratory, serial production control

Holtest is an excellent choice for accurate, reliable, and fast internal diameter measurement, especially when the target is a hole or bushing whose quality and tolerances directly affect product performance.