Spi 34-348-3 Plug Thread Gage 3-48 3B Double End Go No Go

Product Description

The SPI 34-348-3 is a double-end plug thread gage used to inspect 3-48 unified national thread forms to Class 3B tolerance standards. One end carries the Go member and the opposite end carries the No Go member, allowing a technician to confirm both minimum material condition and maximum material condition in a single tool. The gage is manufactured from steel and ships with a handle included. NIST traceability certification is included, supporting quality-system documentation requirements in production and inspection environments. Machinists, quality technicians, and tool-room inspectors rely on plug thread gages like this one for in-process and final inspection of tapped holes.

This gage is suited for inspecting fine-pitch, small-diameter threaded holes — specifically the 3-48 thread size common in instrument components, small fastener assemblies, and precision mechanical subassemblies. The Class 3B designation applies to internal threads requiring a tight tolerance fit, making this gage appropriate for aerospace, electronics, and precision machining applications where thread fit is critical to function.

Key Features

• Double-end design: Go and No Go members on a single gage body for efficient inspection
• 3-48 thread size with Class 3B tolerance classification for tight-fit internal thread inspection
• Steel construction for durability in production and tool-room environments
• Handle included — no separate handle purchase required
• NIST traceability certification included to support ISO and quality-system recordkeeping

Compatibility

Designed for inspection of 3-48 Class 3B internal (tapped) threads in accordance with NIST standards. Suitable for use wherever Go/No Go plug thread gaging of this thread form is required.

Installation Notes

Plug thread gages are inspection tools, not cutting tools — never force the gage into a tapped hole or apply torque beyond hand pressure. The Go member should pass through the full thread length under hand pressure; the No Go member should not enter more than two turns. Store the gage in a protective case away from abrasives and temperature extremes to preserve calibration integrity. Periodic recalibration against NIST-traceable standards is recommended per your facility quality plan.