INSIZE 3-Point Analog Diameter Caliper 12–20 mm, Model 3227-202

The INSIZE 3-Point Analog Diameter Caliper 12–20 mm Model 3227-202 is a precision workshop instrument for measuring internal diameters and locating centers in bores and cylindrical features. The three-contact-point design ensures stable centering on the measured surface, while the analog scale provides a direct, easy-to-read measurement of diameter within the 12–20 mm range. This caliper is intended for machining, inspection and quality-control tasks where repeatable positioning and reliable internal-diameter measurement are required.

Advantages

The three-point contact system gives consistent centering and reduces measurement error caused by off-axis alignment. The analog reading eliminates battery dependence and allows immediate visual interpretation of results. The robust construction is suitable for workshop environments and frequent handling. Compact measuring range and simple operation make the tool suitable for routine checks and setup tasks on lathes, milling machines and inspection benches.

Suitable for

• Measuring internal diameters of small bores and cylindrical parts
• Center finding inside holes for setup and alignment
• Quality control and inspection of machined components
• Routine workshop checks and machine tool setup

Key specifications

• Measuring range: 12–20 mm
• Contact configuration: three-point centering contact
• Display type: analog scale for direct diameter reading
• Intended use: internal diameter measurement and center locating
• Construction: workshop-grade mechanical body for repeated handling

How to use

Place the three contact points of the caliper inside the bore so that all points contact the cylindrical surface. Gently rotate or adjust the tool until the contacts seat evenly; the three-point geometry will center the instrument on the axis of the hole. Read the diameter directly from the analog scale. For repeatable results, ensure consistent contact pressure and verify seating of all three points before taking the final reading.

Usage recommendations

Before measurement, clean the bore and the contact points to remove chips, oil and debris. Use light, consistent pressure when seating the contacts to avoid deforming thin-walled parts. Store the caliper in a protective case or drawer to prevent distortion of the contact arms and to maintain measurement accuracy.