Mitutoyo 178-392 Small Hole Detector for SJ-310/410 Surface Roughness Tester

The Mitutoyo 178-392 is a precision replacement detector designed specifically for measuring surface roughness in small holes and hard-to-reach areas. Compatible with SJ-310 and SJ-410 Surface Roughness Tester models (Standard, Retractable, and Transverse Drive Unit configurations), this specialized detector enables accurate roughness measurements in confined spaces where standard detectors cannot reach.

Key Specifications:

• 4mN measuring force for gentle, accurate surface contact
• 90-degree orientation with 5-micron stylus tip radius
• Minimum hole diameter: 4.5mm (0.177")
• Skidded measuring system for stable, repeatable measurements
• Direct replacement for Mitutoyo SJ-310 and SJ-410 series testers

This small hole detector is essential for quality control applications requiring surface finish verification in bores, recesses, and other confined geometries. The skidded design ensures the detector maintains proper orientation and measurement stability even in challenging access conditions, making it ideal for automotive, aerospace, and precision manufacturing applications.