Electronic Three-Point Internal Micrometer 6-12mm – Digital Bore Gauge with IP54 & Ratchet Stop

Description

I. In-Depth Product Analysis

Measuring small-diameter internal bores with high precision requires a tool that eliminates the angle errors and tilt common with standard two-point Calipers . The Electronic Three-Point Internal Micrometer solves this problem with a precision-engineered three-contact point design. As the measuring head is inserted into a bore, the three equally spaced contact points spread outward simultaneously, perfectly centering the instrument along the true geometric axis of the hole. This ensures that even subtle variations in the bore's ovality or taper are accurately captured.

This model features a robust housing with IP54 protection against dust and water splashes, allowing it to be used safely near coolants and cutting fluids in active machine shops. The integrated ratchet stop guarantees that the measuring force applied to the delicate internal surfaces is consistent and repeatable, preventing damage to the workpiece and ensuring reliable 0.004mm accuracy. Each kit includes a certified calibration ring matching the specific measuring range, allowing operators to instantly verify and set the zero point before beginning inspections. Optional RS232C and wireless data output modules allow for easy integration into digital quality assurance systems.

II. Technical Specifications

The H-335-850 series offers three precise measuring ranges to cover a specific small-bore spectrum. All models share the same IP54 protection, ratchet mechanism, and digital functionality.

All models feature a digital display with ON/OFF, ABS/INC switching, Metric/Imperial conversion, preset function, IP54 rating, and RS232C data output (compatible with P1505 cable) or optional wireless transmission (P1805 module).

III. FAQ (Frequently Asked Questions)

Q1: What is the advantage of the three-point measuring system over a standard two-point caliper?
A: Standard two-point Calipers can easily be tilted inside a bore, resulting in false readings. The three-point system utilizes three symmetrically spaced contacts. As the spindle rotates, all three contacts expand outward together, automatically locking the gauge into a perfectly concentric position relative to the bore's centerline. This eliminates off-angle errors and provides far superior repeatability for checking ovality and taper.

Q2: How does the ratchet stop benefit internal measurements?
A: Internal surfaces, especially in small blind bores, can be delicate. The ratchet stop mechanism prevents the operator from applying excessive force and over-expanding the contacts, which could deform the bore walls or the measuring head itself. It ensures the exact same, optimal measuring force is applied every time, guaranteeing highly repeatable 0.004mm accuracy.

Q3: Can this micrometer be used for measuring both blind and through holes?
A: Yes. The three-point head is designed with a semi-flush contact arrangement. For through holes, the contacts measure the full diameter. For blind holes (where the bottom of the hole has a flat surface), the contacts reach close to the bottom, allowing precise measurement of the effective depth of the bore.

Q4: What is the purpose of the included calibration ring?
A: The calibration ring is a precision-ground master standard with a known, exact internal diameter (e.g., exactly 6.000mm). By inserting the micrometer into the ring and pressing the SET button, you can instantly verify and adjust the zero point. This ensures that your measurements are perfectly traceable to the master standard at the start of every shift.

Q5: How do I connect the data output to my SPC system?
A: The micrometer features an RS232C data output port. You can connect a dedicated data cable (model P1505) to interface with a computer for Statistical Process Control (SPC) logging. For a cable-free solution, an optional wireless data transmission module (model P1805) is available. Both options allow for instant, error-free data logging.

IV. Applications & Industry Uses

• Precision Machining & Mold Making: Measuring internal bores, pin holes, and small-diameter core holes in precision molds and fixtures.

• Automotive Engine Inspection: Checking the precise diameters of fuel injector bores, valve guides, and small hydraulic cylinder ports.

• Quality Control & Metrology: Rapid verification of small internal diameters for incoming material inspection and final product compliance.

• Aerospace Manufacturing: Inspecting precision bores in hydraulic valve bodies and aircraft structural fasteners.

• Tool & Die Workshops: Verifying the internal dimensions of small-diameter die pins and punches.

• Maintenance & Repair: Assessing the wear of small bearings, bushings, and hydraulic passages during overhaul.

V. Accuracy & Working Principle (Accuracy & Mechanics)

The H-335 series achieves a reliable 0.004mm accuracy through a sophisticated mechanical and electronic hybrid system. The core mechanism involves a precision micrometer screw integrated with three internal wedges. As you rotate the digital thimble, the screw advances, pushing the three wedges outward. These wedges force the measuring contact points to expand radially until they firmly touch the internal wall of the bore. Because the three wedges are machined to identical angles, the contact points expand at exactly the same rate, ensuring perfect self-centering. The precise displacement of the spindle is read by a digital linear encoder and displayed on the LCD screen.

VI. Calibration & Maintenance

1. Calibration Ring Validation: Upon receiving the instrument and at the beginning of every shift, use the included certified calibration ring . Insert the measuring head into the ring, gently tighten with the ratchet stop, and if the display does not match the ring's engraved dimension, use the SET function to input the correct initial value.

2. Clean the Contact Points: The three measuring contacts are precision ground. After use, carefully wipe them with a soft, lint-free cloth to remove any oil, dust, or metal chips. Contamination on the contacts is the primary cause of reading deviations.

3. Protect the Extension Rod: The 100mm extension rod allows deep bore measurement. Ensure the threaded connection is clean before attaching it to avoid cross-threading.

4. Annual Professional Calibration: For compliance with ISO 9001 or AS9100, we recommend a formal traceable calibration by an accredited metrology laboratory every 12 months .