Spi 34-215-4 Plug Thread Gage 4-40 6H No Go

Product Description

The SPI 34-215-4 is a single-end No Go plug thread gage designed to verify 4-40 UNC internal threads to 6H tolerance class. It is manufactured from steel for dimensional stability and long service life in production or inspection environments. The gage is used to confirm that a threaded hole does not exceed its maximum material condition, rejecting any feature that the No Go member fully enters. Traceability documentation conforming to NIST standards is included, supporting quality management and calibration recordkeeping. A size 0 handle is required for use but is not included with this gage.

This gage is suited for machine shops, manufacturing facilities, and quality inspection departments working with 4-40 threaded components. Typical applications include incoming inspection, in-process verification, and final acceptance testing of small internally threaded fastener holes in precision assemblies. The 6H classification makes it appropriate for standard-tolerance commercial and industrial threading applications where fit and function must be confirmed before assembly.

Key Features

• No Go single-end design checks maximum material condition of 4-40 internal threads
• 6H tolerance class meets ANSI threading standards for commercial-grade fits
• Steel construction provides dimensional stability under repeated inspection use
• NIST-traceable certification included for calibration and quality system compliance
• Conforms to ANSI and NIST standards for thread gage accuracy
• Size 0 handle compatible — handle sold separately

Compatibility

Designed for use with a size 0 thread gage handle, sold separately. Intended for inspection of 4-40 UNC internally threaded features held to 6H tolerance class per ANSI standards.

Installation Notes

Thread gages are used by quality technicians and machinists and require no permanent installation. Store the gage in a protective case away from other metal tooling to prevent wear to the gage members. Do not force the No Go member into a threaded hole — if it enters fully, the feature is out of tolerance and should not be accepted. Periodic recalibration against a known standard is recommended to maintain measurement integrity.