UNEF Thread Ring Gauges | McMaster-Carr

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70 Products

Threaded Ring Gauges with Calibration Certificate

Not only were these gauges calibrated in a lab, but they also come with a certificate that's traceable to NIST. The certificate, sometimes called a test report and long form certificate, details the tested measurements. They’re for checking a part’s external threads to ensure they fall within tolerance.

A part is within tolerance if it’s easy to thread a go gauge onto the part but difficult to thread a no-go gauge more than two turns. Inspect faster by holding more than one ring gauge with a threaded ring gauge holder.

Class X Gauges

Go Gauge—Go gauges check the maximum external thread size.

No-Go Gauge—No-go gauges check the minimum external thread size.

For Thread Fit—Threads have different classes of fit. Thread fit designates the tightness or looseness of the mating threads. For example, inch threads with a 3A fit have tighter tolerances than threads with a 2A fit.

						Go Gauge			No-Go Gauge
	Thread Size	Thread Direction	Hardness	Material	Certificate Type	Pitch Dia. Tolerance		Each	Pitch Dia. Tolerance		Each
For Class 2A Unified Standard Thread Fit







				UNEF Thread

				12-32	Right Hand	Rockwell C60	Tool Steel	Calibration Certificate Traceable to NIST	-0.0003" to 0"	3160A412	0000000	0" to 0.0003"	3160A414	0000000


				1/4"-32	Right Hand	Rockwell C60	Tool Steel	Calibration Certificate Traceable to NIST	-0.0003" to 0"	3160A416	000000	0" to 0.0003"	3160A418	000000
				5/16"-32	Right Hand	Rockwell C60	Tool Steel	Calibration Certificate Traceable to NIST	-0.0003" to 0"	3160A421	000000	0" to 0.0003"	3160A423	000000
				3/8"-32	Right Hand	Rockwell C60	Tool Steel	Calibration Certificate Traceable to NIST	-0.0003" to 0"	3160A425	000000	0" to 0.0003"	3160A427	000000
				7/16"-28	Right Hand	Rockwell C60	Tool Steel	Calibration Certificate Traceable to NIST	-0.0003" to 0"	3160A429	000000	0" to 0.0003"	3160A432	000000
				1/2"-28	Right Hand	Rockwell C60	Tool Steel	Calibration Certificate Traceable to NIST	-0.0003" to 0"	3160A434	000000	0" to 0.0003"	3160A436	000000
				9/16"-24	Right Hand	Rockwell C60	Tool Steel	Calibration Certificate Traceable to NIST	-0.0003" to 0"	3160A438	000000	0" to 0.0003"	3160A441	000000
				5/8"-24	Right Hand	Rockwell C60	Tool Steel	Calibration Certificate Traceable to NIST	-0.0003" to 0"	3160A443	000000	0" to 0.0003"	3160A445	000000
				11/16"-24	Right Hand	Rockwell C60	Tool Steel	Calibration Certificate Traceable to NIST	-0.0003" to 0"	3160A447	000000	0" to 0.0003"	3160A449	000000
				3/4"-20	Right Hand	Rockwell C60	Tool Steel	Calibration Certificate Traceable to NIST	-0.0003" to 0"	3160A452	000000	0" to 0.0003"	3160A454	000000
				7/8"-20	Right Hand	Rockwell C60	Tool Steel	Calibration Certificate Traceable to NIST	-0.0003" to 0"	3160A458	000000	0" to 0.0003"	3160A461	000000


				1"-20	Right Hand	Rockwell C60	Tool Steel	Calibration Certificate Traceable to NIST	-0.0003" to 0"	3160A467	000000	0" to 0.0003"	3160A468	000000


				For Class 3A Unified Standard Thread Fit







								UNEF Thread

								12-32	Right Hand	Rockwell C60	Tool Steel	Calibration Certificate Traceable to NIST	-0.0003" to 0"	3160A413	000000	0" to 0.0003"	3160A415	000000


								1/4"-32	Right Hand	Rockwell C60	Tool Steel	Calibration Certificate Traceable to NIST	-0.0003" to 0"	3160A417	000000	0" to 0.0003"	3160A419	000000
								5/16"-32	Right Hand	Rockwell C60	Tool Steel	Calibration Certificate Traceable to NIST	-0.0003" to 0"	3160A422	000000	0" to 0.0003"	3160A424	000000
								3/8"-32	Right Hand	Rockwell C60	Tool Steel	Calibration Certificate Traceable to NIST	-0.0003" to 0"	3160A426	000000	0" to 0.0003"	3160A428	000000
								7/16"-28	Right Hand	Rockwell C60	Tool Steel	Calibration Certificate Traceable to NIST	-0.0003" to 0"	3160A431	000000	0" to 0.0003"	3160A433	000000
								1/2"-28	Right Hand	Rockwell C60	Tool Steel	Calibration Certificate Traceable to NIST	-0.0003" to 0"	3160A435	000000	0" to 0.0003"	3160A437	000000
								9/16"-24	Right Hand	Rockwell C60	Tool Steel	Calibration Certificate Traceable to NIST	-0.0003" to 0"	3160A439	000000	0" to 0.0003"	3160A442	000000
								5/8"-24	Right Hand	Rockwell C60	Tool Steel	Calibration Certificate Traceable to NIST	-0.0003" to 0"	3160A444	000000	0" to 0.0003"	3160A446	000000
								11/16"-24	Right Hand	Rockwell C60	Tool Steel	Calibration Certificate Traceable to NIST	-0.0003" to 0"	3160A448	000000	0" to 0.0003"	3160A451	000000
								3/4"-20	Right Hand	Rockwell C60	Tool Steel	Calibration Certificate Traceable to NIST	-0.0003" to 0"	3160A453	000000	0" to 0.0003"	3160A455	000000
								7/8"-20	Right Hand	Rockwell C60	Tool Steel	Calibration Certificate Traceable to NIST	-0.0003" to 0"	3160A459	000000	0" to 0.0003"	3160A462	000000

Threaded Ring Gauges

Check a part’s external threads to make sure they fall within tolerance. You can use these for bolts, threaded rods, bits, and more. All gauges come with a manufacturer’s certificate of accuracy, also known as a certificate of compliance or a short form certification, that verifies the thread sizes are within tolerance.

The part is within tolerance if it’s easy to thread a go gauge onto, but difficult to thread a no-go gauge more than two turns. Use a threaded ring gauge holder to keep two gauges on hand at once for faster inspection.

Go Gauge—Go gauges check the maximum external thread size.

No-Go Gauge—No-go gauges check the minimum external thread size.

							Go Gauge			No-Go Gauge
	Thread Size	Thread Type	Hardness	Material	Thread Direction	Choose a Thread Fit	Pitch Dia. Tolerance		Each	Pitch Dia. Tolerance		Each
Class X Gauges



		12-32	UNEF	Rockwell C60	Tool Steel	Right Hand	Unified Standard Class 2A, Unified Standard Class 3A	-0.0003" to 0"	2356A019	0000000	0" to 0.0003"	2356A021	0000000


		1/4"-32	UNEF	Rockwell C60	Tool Steel	Right Hand	Unified Standard Class 2A, Unified Standard Class 3A	-0.0003" to 0"	2356A022	000000	0" to 0.0003"	2356A023	000000
		5/16"-32	UNEF	Rockwell C60	Tool Steel	Right Hand	Unified Standard Class 2A, Unified Standard Class 3A	-0.0003" to 0"	2356A024	000000	0" to 0.0003"	2356A025	000000
		3/8"-32	UNEF	Rockwell C60	Tool Steel	Right Hand	Unified Standard Class 2A, Unified Standard Class 3A	-0.0003" to 0"	2356A026	000000	0" to 0.0003"	2356A027	000000
		7/16"-28	UNEF	Rockwell C60	Tool Steel	Right Hand	Unified Standard Class 2A, Unified Standard Class 3A	-0.0003" to 0"	2356A028	000000	0" to 0.0003"	2356A029	000000
		1/2"-28	UNEF	Rockwell C60	Tool Steel	Right Hand	Unified Standard Class 2A, Unified Standard Class 3A	-0.0003" to 0"	2356A031	000000	0" to 0.0003"	2356A032	000000
		9/16"-24	UNEF	Rockwell C60	Tool Steel	Right Hand	Unified Standard Class 2A, Unified Standard Class 3A	-0.0003" to 0"	2356A033	000000	0" to 0.0003"	2356A034	000000
		5/8"-24	UNEF	Rockwell C60	Tool Steel	Right Hand	Unified Standard Class 2A, Unified Standard Class 3A	-0.0003" to 0"	2356A035	000000	0" to 0.0003"	2356A036	000000
		11/16"-24	UNEF	Rockwell C60	Tool Steel	Right Hand	Unified Standard Class 2A, Unified Standard Class 3A	-0.0003" to 0"	2356A037	000000	0" to 0.0003"	2356A038	000000
		3/4"-20	UNEF	Rockwell C60	Tool Steel	Right Hand	Unified Standard Class 2A, Unified Standard Class 3A	-0.0003" to 0"	2356A039	000000	0" to 0.0003"	2356A041	000000
		7/8"-20	UNEF	Rockwell C60	Tool Steel	Right Hand	Unified Standard Class 2A, Unified Standard Class 3A	-0.0003" to 0"	2356A042	000000	0" to 0.0003"	2356A043	000000


		1"-20	UNEF	Rockwell C60	Tool Steel	Right Hand	Unified Standard Class 2A	-0.0003" to 0"	2356A578	000000	0" to 0.0003"	2356A579	000000