3-Point Internal Micrometer Holtest Set

Mitutoyo - Holtest 3-point internal micrometer set

Mitutoyo's professionally designed internal micrometer set is 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 user-independent. The set covers the entire range of 0.275 to 0.5" inside diameter with three separate micrometers, making it versatile and widely applicable to various industries.

The Holtest range 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 users who want 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 drum. When the gauge is inserted into the hole, the surfaces naturally contact the inner wall of the hole. This automatic self-centering is one of Holtest's main advantages: the gauge does not remain skewed, and the user does not have to adjust the tool to find the 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 ensures that the measuring force remains constant throughout all measurements. The advantage of the Holtest design over 2-point gauges is clear: 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 geometry. 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:
- Three micrometers: 0.275-0.35", 0.35-0.425", 0.425-0.5"
- 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 verification certificate (no calibration).