Digital Internal Bore Micrometer 6-50mm – 0.004mm Accuracy Electronic Three-Point Gauge with IP54

Description

I. In-Depth Product Analysis

Measuring internal diameters with precision across a wide range of bore sizes demands a tool that eliminates off-center measurement errors. The Electronic Three-Point Internal Micrometer (6-50mm) utilizes a precision-engineered three-contact measuring system. As the spindle rotates, three equally spaced measuring contacts expand radially outward at a synchronized rate. This mechanism automatically self-centers the gauge within the bore, ensuring that every reading reflects the true geometric diameter—whether checking a standard through hole, a deep blind hole, or inspecting internal tapers.

This series is built to withstand rigorous workshop conditions. The body features a robust chrome-plated surface that resists corrosion and scratches from metal chips. Models measuring above 12mm are equipped with hardened carbide measuring faces , providing superior wear resistance when repeatedly measuring abrasive materials like cast iron or high-strength steel. The IP54 protection rating ensures that the sensitive digital electronics are fully safeguarded against coolant splashes, oil, and grinding dust, guaranteeing reliable operation even in the harshest machining environments. Combined with the integrated ratchet thimble and data output capabilities, this bore gauge is the definitive solution for precision quality control.

II. Technical Specifications

The H-335-950 series offers 9 precise measurement ranges, covering a wide 6mm to 50mm spectrum. Please note that carbide measuring faces are standard on models above 12mm.

Core Digital Functions:

• Display System: Power On/Off with auto-sleep, ABS/INC (Absolute/Relative) modes, Metric/Imperial unit switching.

• Data Output: RS232C data output (compatible with P1505 cable) or optional wireless data transmission module (P1805).

• Power: Long-life CR2032 battery with auto power-off.

III. FAQ (Frequently Asked Questions)

Q1: What is the primary advantage of a three-point internal micrometer over a two-point caliper?
A: When using a two-point caliper inside a bore, it is very easy to tilt the jaws slightly, leading to false off-angle readings. The three-point system features three contacts that expand synchronously, forcing the gauge into perfect self-centering alignment with the bore's true centerline. This ensures exceptional repeatability and eliminates angular errors, making it far superior for accurately measuring ovality, taper, and precise internal diameters.

Q2: Why are carbide measuring faces used on larger models, but not on the 6-12mm range?
A: Tungsten carbide provides extreme wear resistance, which is vital when measuring hard or abrasive metals over millions of cycles. For the miniature 6-12mm measuring heads, the physical space for three mechanical contacts is extremely limited. These smaller heads are machined from specially treated, ultra-hardened steel to maintain compact dimensions while still providing excellent longevity. For ranges 12mm and above, the use of carbide tips maximizes durability.

Q3: What is the purpose of the included calibration ring?
A: The calibration ring is a precision-ground master standard with a highly accurate internal diameter (e.g., exactly 16.000mm). Before measuring your workpieces, you insert the micrometer into the ring and press the SET button. This instantly establishes the absolute zero baseline, guaranteeing that your subsequent production measurements are fully traceable to the master standard.

Q4: How do the extension rods work for deep bore measurements?
A: The 6-12mm models come with a 100mm extension rod, while the 12-50mm models come with a 150mm extension rod. These attach securely to the digital display head, allowing you to measure deep inside holes far beyond the standard measuring depth, while keeping the digital screen easily visible. This makes the tool ideal for measuring deep hydraulic cylinders or long machined tubes.

Q5: How can I connect this gauge to my computer for data logging?
A: The instrument is equipped with an RS232C data output port. You can connect it directly to your computer or data collector using the optional P1505 data cable. If you prefer a cable-free environment, an optional P1805 wireless data transmission module is also available. Both options allow for seamless integration with Statistical Process Control (SPC) software.

IV. Applications & Industry Uses

• Precision CNC Machining: Accurate inspection of bore diameters, internal tapers, and stepped holes in milled and turned parts.

• Automotive & Engine Manufacturing: Measuring cylinder bores, valve seats, injector bores, and transmission housings to strict quality standards.

• Aerospace Component Inspection: Verifying internal diameters of hydraulic valves, actuator housings, and structural fasteners.

• Mold & Die Manufacturing: Precision checking of core pin holes, ejector pin bores, and complex injection mold cavities.

• Quality Control Laboratories: A trusted secondary standard for verifying the size of gauge rings and internal master fixtures.

• Maintenance & Repair: Assessing internal wear on pumps, compressors, and industrial hydraulic cylinders.

V. Accuracy & Working Principle (Accuracy & Mechanics)

The H-335-950 series achieves its rigorous 0.004mm to 0.005mm accuracy through a precise mechanical wedge and digital encoder hybrid. When the digital thimble is rotated, a precision micrometer screw drives three internal wedges forward. Because these wedges are machined to exact equal angular tolerances, they expand the three measuring contacts outward at identical rates, guaranteeing concentric self-centering. This mechanical displacement is continuously monitored by a high-resolution digital linear encoder. The encoder transmits the precise position data to the microcomputer, which instantly calculates and displays the exact internal diameter on the LCD screen. The ratchet thimble ensures that the measuring force is perfectly consistent across all measurements, eliminating mechanical compression errors.

VI. Calibration & Maintenance

1. Daily Verification with Calibration Ring: At the start of every shift, use the included matching calibration ring. Insert the measuring head, gently tighten using the ratchet thimble, and use the SET button to input the known ring diameter if a zero deviation is detected.

2. Clean the Contacts: Wipe the three measuring contacts with a soft, lint-free cloth after every use. Metal chips or grit left on the small contacts are the primary cause of erroneous readings and premature wear.

3. Protect the Mechanism: The measuring contacts are delicate. Always insert the tool carefully into the bore. Avoid "snapping" the instrument into place to prevent damage to the internal wedge mechanism.

4. Annual Professional Calibration: For strict ISO 9001 or AS9100 compliance, a full, traceable calibration by a certified metrology lab is required every 12 months .