3-Point Internal Micrometer Holtest Set

Mitutoyo - Holtest 3-point internal micrometer set

Mitutoyo's professionally designed internal micrometer set, one of the most accurate and practical internal measuring tools in the Holtest series. The three-point measuring system ensures that the gauge automatically centers itself on the measurement target, and the measurement results are accurate, symmetrical, and independent of the user. The set covers the entire 0.08" to 0.12" inside diameter range with two separate micrometers, making it versatile and widely applicable to a variety of industries.

The Holtest series is renowned for its ability to measure inside diameters directly, without the need for cumbersome fitting pieces or additional calibration jigs. The series is the perfect solution for the user who wants a gauge that works right out of the box, offers very high repeatability, and can withstand extended use in production environments.

Construction and technical principle of operation:

The Holtest's three-point design is based on three carbide, symmetrically positioned measuring surfaces that open gently with the rotation of the micrometer spindle. When the gauge is inserted into the hole, the surfaces naturally align against the inner wall of the hole. This automatic self-centering is one of the main advantages of Holtest: the gauge does not remain skewed, and the user does not need to reposition the tool to achieve center balance. When the measuring surfaces are in contact with the inner surface of the hole, the ratchet mechanism indicates the correct measuring force with a small but clear click. This ensures that the user does not over-tighten or under-tighten the gauge — both of which would lead to incorrect measurement results. This keeps the measuring force consistent across all measurements. The advantage of the Holtest design compared to 2-point gauges is evident: with 2-point gauges, the measurement result depends on how the user supports the tool and how well the measuring surfaces align with the hole's roundness. With 3 points, the gauge automatically aligns with the hole geometry and measures the actual diameter of the hole, not the distance between the two points.

Contents of the set and ready for use:

List of contents:

- Two micrometers 0.08-0.1", 0.1-0.12"
- Setting ring for calibration for each measuring range. These are very important as they allow accurate resetting of the micrometers and ensure measurement reliability.
- An extension arm for measuring deeper holes. Deep hole measurement is often a challenge, but the Holtest design also works well when the measuring surfaces are not visible from the outside.
- A robust protective case that protects the measuring equipment from dents, dust, moisture, and transport damage.
- Factory-issued verification certificate (not calibrated).