Mitutoyo 178-391 Surface Roughness Detector for SJ-210

Product Description

The MITUTOYO 178-391 is a replacement stylus detector designed for use with the SJ-210 Surftest portable surface roughness tester. It operates with a 4 mN measuring force and features a 90-degree diamond tip angle, making it suited for standard surface texture measurement on flat and gently contoured workpieces. With an overall length of 61.00 mm and a body diameter of 9.00 mm, the 178-391 fits directly into the SJ-210 detector mount without modification. Metrology technicians and quality control professionals install this detector when replacing a worn or damaged stylus on the SJ-210 platform.

The 178-391 is used in industrial metrology applications where surface roughness measurement is required per standard QC workflows. It is specifically designed for the Mitutoyo SJ-210 Surftest portable surface roughness tester, a handheld instrument commonly found in manufacturing, machine shops, and inspection labs. The 90-degree tip angle and 10.00 micrometer stylus tip radius are appropriate for general-purpose Ra and Rz measurements on machined surfaces. This detector is classified under UNSPSC code 41114500.

Key Features

• 4 mN contact measuring force for consistent stylus-to-surface loading
• 90-degree diamond tip angle for standard surface roughness measurement
• 10.00 micrometer stylus tip radius for general-purpose Ra and Rz profiling
• 61.00 mm overall length with 9.00 mm body diameter for direct SJ-210 fitment
• Drop-in replacement detector — no additional adapters required for the SJ-210

Compatibility

Designed for use with the Mitutoyo SJ-210 Surftest portable surface roughness tester.

Installation Notes

Installation should be performed by a qualified metrology technician or instrument service professional. Power down the SJ-210 unit before removing or installing the detector to avoid sensor damage. Handle the stylus tip carefully during installation — contact with hard surfaces can chip or deform the diamond tip, invalidating measurement accuracy. Follow the SJ-210 operator manual for proper detector seating and securing procedures.