Osg 1500301205 Go No-go Thread Gage 1/2-20 Unjf 3B

Product Description

The OSG 1500301205 is a double-end Go/No-Go thread limit gage designed to verify internal thread conformance to 1/2-20 UNJF tolerance class 3B specifications. Manufactured from high-speed steel with a TiN (titanium nitride) coating, it delivers consistent dimensional accuracy and extended service life under repeated use. The Go end confirms that the thread falls within the minimum material condition, while the No-Go end confirms the thread does not exceed the maximum material condition. Factory-calibrated out of the box, this gage is suitable for quality control inspection on the shop floor, receiving inspection, or in-process thread verification. Machinists, QC inspectors, and aerospace component fabricators are the primary users of this tool.

This gage is used to inspect 1/2-20 UNJF (Unified National Fine series with controlled root radius) internal threads machined to class 3B tolerance, which represents a tight-tolerance fit commonly specified in aerospace, defense, and precision mechanical assemblies. The double-end design consolidates both Go and No-Go functions into a single tool, reducing handling time during inspection. It is appropriate for production environments where thread gauging is performed frequently and calibration traceability is required.

Key Features

• Go and No-Go members on a single double-end gage body for efficient inspection workflow
• TiN coating increases surface hardness and wear resistance for extended gage life
• High-speed steel construction provides dimensional stability across normal shop temperature ranges
• Factory-calibrated to 1/2-20 UNJF 3B thread specifications
• Compact single-tool format reduces gage kit complexity

Compatibility

Designed to inspect internal threads conforming to 1/2-20 UNJF tolerance class 3B specifications per applicable thread standards for unified inch screw threads with controlled root radius.

Installation Notes

Thread limit gages require no installation but should be handled and stored carefully to protect the precision ground thread members from impact and contamination. Apply a light coat of appropriate instrument oil before and after use to prevent corrosion on the high-speed steel surfaces. Verify calibration status before use in any inspection application where traceability is required. Do not force the No-Go member into a threaded hole, as resistance under hand pressure is the expected functional result.