Value Collection 1/4-28 UNF-3B STI Go/NoGo Thread Plug Gauge
Couldn't load pickup availability
Use this text to encourage communication or promote sharing on social networks.
This new Value Collection double-ended thread plug gauge is designed to inspect 1/4-28 UNF-3B STI (Screw Thread Insert) internal threads, confirming that tapped holes intended to accept helical coil inserts (e.g., HeliCoil) meet tolerance requirements for Class 3B fit. The GO member has a pitch diameter of 0.2732 in and the NOGO member has a pitch diameter of 0.2754 in, both visibly stamped on the green-anodized aluminum handle alongside full thread designation markings. STI gauges are oversized relative to standard UNF gauges to account for the wall thickness of the installed wire thread insert, and are not interchangeable with standard 1/4-28 UNF plug gauges. The gauge features knurled ends for positive grip during inspection and a double-ended configuration for single-tool GO/NOGO verification, conforming to ANSI/ASME B1.2 tolerancing practices for Class X or W plug gauges (verify on calibration certificate).
Product Specifications
| Thread Size | 1/4-28 |
| Thread Series | UNF (Unified National Fine) |
| Thread Class | 3B |
| Application | STI (Screw Thread Insert / HeliCoil) |
| Gauge Type | Double-ended Go/NoGo thread plug gauge |
| GO Pitch Diameter | 0.2732 in |
| NOGO Pitch Diameter | 0.2754 in |
| Handle Color | Green anodized aluminum |
| Handle Style | Double-ended, knurled ends |
| Standard | ANSI/ASME B1.2 |
| Condition | New |