Class 2A Ring Gauges | McMaster-Carr

Filter by

Thread Size

Thread Fit

Unified Standard Class 2A

Unified Standard Class 3A

Thread Direction

Left Hand

Right Hand

Gauge Measurement Type

Thread Type

Certificate Type

Accuracy Certificate Traceable to NIST

Calibration Certificate Traceable to NIST

DFARS Specialty Metals

Exempt

Export Control Classification Number (ECCN)

Hardness

Material

REACH

U.S.–Mexico–Canada Agreement (USMCA) Qualifying

Yes

RoHS

Compliant

Size-Checking Gauge Class

Forward

How can we improve?

316 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







				UNC Thread

				1-64	Right Hand	Rockwell C60	Tool Steel	Calibration Certificate Traceable to NIST	-0.0002" to 0"	3160A123	0000000	0" to 0.0002"	3160A225	0000000


				2-56	Right Hand	Rockwell C60	Tool Steel	Calibration Certificate Traceable to NIST	-0.0002" to 0"	3160A127	000000	0" to 0.0002"	3160A229	000000
				3-48	Right Hand	Rockwell C60	Tool Steel	Calibration Certificate Traceable to NIST	-0.0002" to 0"	3160A132	000000	0" to 0.0002"	3160A234	000000
				4-40	Right Hand	Rockwell C60	Tool Steel	Calibration Certificate Traceable to NIST	-0.0002" to 0"	3160A136	000000	0" to 0.0002"	3160A238	000000
				5-40	Right Hand	Rockwell C60	Tool Steel	Calibration Certificate Traceable to NIST	-0.0002" to 0"	3160A141	000000	0" to 0.0002"	3160A243	000000
				6-32	Right Hand	Rockwell C60	Tool Steel	Calibration Certificate Traceable to NIST	-0.0003" to 0"	3160A145	000000	0" to 0.0003"	3160A247	000000
				8-32	Right Hand	Rockwell C60	Tool Steel	Calibration Certificate Traceable to NIST	-0.0003" to 0"	3160A149	000000	0" to 0.0003"	3160A252	000000
				10-24	Right Hand	Rockwell C60	Tool Steel	Calibration Certificate Traceable to NIST	-0.0003" to 0"	3160A154	000000	0" to 0.0003"	3160A256	000000
				12-24	Right Hand	Rockwell C60	Tool Steel	Calibration Certificate Traceable to NIST	-0.0003" to 0"	3160A158	000000	0" to 0.0003"	3160A261	000000
				1/4"-20	Right Hand	Rockwell C60	Tool Steel	Calibration Certificate Traceable to NIST	-0.0003" to 0"	3160A163	000000	0" to 0.0003"	3160A265	000000
				5/16"-18	Right Hand	Rockwell C60	Tool Steel	Calibration Certificate Traceable to NIST	-0.0003" to 0"	3160A167	000000	0" to 0.0003"	3160A269	000000


				3/8"-16	Right Hand	Rockwell C60	Tool Steel	Calibration Certificate Traceable to NIST	-0.0003" to 0"	3160A172	000000	0" to 0.0003"	3160A274	000000
				7/16"-14	Right Hand	Rockwell C60	Tool Steel	Calibration Certificate Traceable to NIST	-0.0003" to 0"	3160A176	000000	0" to 0.0003"	3160A278	000000
				1/2"-13	Right Hand	Rockwell C60	Tool Steel	Calibration Certificate Traceable to NIST	-0.0003" to 0"	3160A181	000000	0" to 0.0003"	3160A283	000000
				9/16"-12	Right Hand	Rockwell C60	Tool Steel	Calibration Certificate Traceable to NIST	-0.0003" to 0"	3160A409	000000	0" to 0.0003"	3160A411	000000
				5/8"-11	Right Hand	Rockwell C60	Tool Steel	Calibration Certificate Traceable to NIST	-0.0003" to 0"	3160A185	000000	0" to 0.0003"	3160A287	000000
				3/4"-10	Right Hand	Rockwell C60	Tool Steel	Calibration Certificate Traceable to NIST	-0.0003" to 0"	3160A189	000000	0" to 0.0003"	3160A292	000000
				7/8"-9	Right Hand	Rockwell C60	Tool Steel	Calibration Certificate Traceable to NIST	-0.0003" to 0"	3160A194	000000	0" to 0.0003"	3160A296	000000
				1"-8	Right Hand	Rockwell C60	Tool Steel	Calibration Certificate Traceable to NIST	-0.0003" to 0"	3160A198	000000	0" to 0.0003"	3160A301	000000
				1 1/8"-7	Right Hand	Rockwell C60	Tool Steel	Calibration Certificate Traceable to NIST	-0.0004" to 0"	3160A471	000000	0" to 0.0004"	3160A472	000000
				1 1/4"-7	Right Hand	Rockwell C60	Tool Steel	Calibration Certificate Traceable to NIST	-0.0004" to 0"	3160A209	000000	0" to 0.0004"	3160A312	000000


				1 3/8"-6	Right Hand	Rockwell C60	Tool Steel	Calibration Certificate Traceable to NIST	-0.0004" to 0"	3160A473	000000	0" to 0.0004"	3160A474	000000
				1 1/2"-6	Right Hand	Rockwell C60	Tool Steel	Calibration Certificate Traceable to NIST	-0.0004" to 0"	3160A218	000000	0" to 0.0004"	3160A321	000000




						UNEF Thread

						12-32	Right Hand	Rockwell C60	Tool Steel	Calibration Certificate Traceable to NIST	-0.0003" to 0"	3160A412	000000	0" to 0.0003"	3160A414	000000


						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




UNF Thread

0-80	Right Hand							Rockwell C60	Tool Steel	Calibration Certificate Traceable to NIST	-0.0002" to 0"	3160A121	000000	0" to 0.0002"	3160A223	000000


1-72	Right Hand							Rockwell C60	Tool Steel	Calibration Certificate Traceable to NIST	-0.0002" to 0"	3160A125	000000	0" to 0.0002"	3160A227	000000
2-64	Right Hand	Rockwell C60						Tool Steel	Calibration Certificate Traceable to NIST	-0.0002" to 0"	3160A129	000000	0" to 0.0002"	3160A232	000000
3-56	Right Hand	Rockwell C60	Tool Steel					Calibration Certificate Traceable to NIST	-0.0002" to 0"	3160A405	000000	0" to 0.0002"	3160A407	000000
4-48	Right Hand	Rockwell C60	Tool Steel					Calibration Certificate Traceable to NIST	-0.0002" to 0"	3160A138	000000	0" to 0.0002"	3160A241	000000
5-44	Right Hand	Rockwell C60	Tool Steel					Calibration Certificate Traceable to NIST	-0.0002" to 0"	3160A401	000000	0" to 0.0002"	3160A403	000000
6-40	Right Hand	Rockwell C60	Tool Steel					Calibration Certificate Traceable to NIST	-0.0002" to 0"	3160A147	000000	0" to 0.0002"	3160A249	000000
8-36	Right Hand	Rockwell C60	Tool Steel					Calibration Certificate Traceable to NIST	-0.0002" to 0"	3160A152	000000	0" to 0.0002"	3160A254	000000
10-32	Right Hand	Rockwell C60	Tool Steel					Calibration Certificate Traceable to NIST	-0.0003" to 0"	3160A156	000000	0" to 0.0003"	3160A258	000000
12-28	Right Hand	Rockwell C60	Tool Steel					Calibration Certificate Traceable to NIST	-0.0003" to 0"	3160A161	000000	0" to 0.0003"	3160A263	000000
1/4"-28	Right Hand	Rockwell C60	Tool Steel					Calibration Certificate Traceable to NIST	-0.0003" to 0"	3160A165	000000	0" to 0.0003"	3160A267	000000


5/16"-24	Right Hand	Rockwell C60	Tool Steel					Calibration Certificate Traceable to NIST	-0.0003" to 0"	3160A169	000000	0" to 0.0003"	3160A272	000000
3/8"-24	Right Hand	Rockwell C60	Tool Steel					Calibration Certificate Traceable to NIST	-0.0003" to 0"	3160A174	000000	0" to 0.0003"	3160A276	000000
7/16"-20	Right Hand	Rockwell C60	Tool Steel					Calibration Certificate Traceable to NIST	-0.0003" to 0"	3160A178	000000	0" to 0.0003"	3160A281	000000
1/2"-20	Right Hand	Rockwell C60	Tool Steel					Calibration Certificate Traceable to NIST	-0.0003" to 0"	3160A183	000000	0" to 0.0003"	3160A285	000000
9/16"-18	Right Hand	Rockwell C60	Tool Steel					Calibration Certificate Traceable to NIST	-0.0003" to 0"	3160A114	000000	0" to 0.0003"	3160A118	000000
5/8"-18	Right Hand	Rockwell C60	Tool Steel					Calibration Certificate Traceable to NIST	-0.0003" to 0"	3160A187	000000	0" to 0.0003"	3160A289	000000
3/4"-16	Right Hand	Rockwell C60	Tool Steel					Calibration Certificate Traceable to NIST	-0.0003" to 0"	3160A192	000000	0" to 0.0003"	3160A294	000000
7/8"-14	Right Hand	Rockwell C60	Tool Steel					Calibration Certificate Traceable to NIST	-0.0003" to 0"	3160A196	000000	0" to 0.0003"	3160A298	000000
1"-12	Right Hand	Rockwell C60	Tool Steel					Calibration Certificate Traceable to NIST	-0.0003" to 0"	3160A201	000000	0" to 0.0003"	3160A303	000000
1 1/8"-12	Right Hand	Rockwell C60	Tool Steel					Calibration Certificate Traceable to NIST	-0.0003" to 0"	3160A207	000000	0" to 0.0003"	3160A309	000000


1 1/4"-12	Right Hand	Rockwell C60	Tool Steel					Calibration Certificate Traceable to NIST	-0.0003" to 0"	3160A212	000000	0" to 0.0003"	3160A314	000000
1 3/8"-12	Right Hand	Rockwell C60	Tool Steel					Calibration Certificate Traceable to NIST	-0.0003" to 0"	3160A475	000000	0" to 0.0003"	3160A477	000000
1 1/2"-12	Right Hand	Rockwell C60	Tool Steel					Calibration Certificate Traceable to NIST	-0.0003" to 0"	3160A221	000000	0" to 0.0003"	3160A323	000000




		UNS Thread

		1"-14	Right Hand					Rockwell C60	Tool Steel	Calibration Certificate Traceable to NIST	-0.0003" to 0"	3160A463	000000	0" to 0.0003"	3160A465	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	For Thread Fit	Pitch Dia. Tolerance		Each	Pitch Dia. Tolerance		Each
Class X Gauges



		0-80	UNF	Rockwell C60	Tool Steel	Right Hand	Unified Standard Class 2A	-0.0002" to 0"	2356A301	0000000	0" to 0.0002"	2356A401	0000000


		1-64	UNC	Rockwell C60	Tool Steel	Right Hand	Unified Standard Class 2A	-0.0002" to 0"	2356A501	000000	0" to 0.0002"	2356A502	000000
		1-72	UNF	Rockwell C60	Tool Steel	Right Hand	Unified Standard Class 2A	-0.0002" to 0"	2356A303	000000	0" to 0.0002"	2356A403	000000
		2-56	UNC	Rockwell C60	Tool Steel	Right Hand	Unified Standard Class 2A	-0.0002" to 0"	2356A304	000000	0" to 0.0002"	2356A404	000000
		2-64	UNF	Rockwell C60	Tool Steel	Right Hand	Unified Standard Class 2A	-0.0002" to 0"	2356A011	000000	0" to 0.0002"	2356A012	000000
		3-48	UNC	Rockwell C60	Tool Steel	Right Hand	Unified Standard Class 2A	-0.0002" to 0"	2356A113	000000	0" to 0.0002"	2356A613	000000
		3-56	UNF	Rockwell C60	Tool Steel	Right Hand	Unified Standard Class 2A	-0.0002" to 0"	2356A013	000000	0" to 0.0002"	2356A014	000000
		4-40	UNC	Rockwell C60	Tool Steel	Right Hand	Unified Standard Class 2A	-0.0002" to 0"	2356A308	000000	0" to 0.0002"	2356A408	000000
		4-48	UNF	Rockwell C60	Tool Steel	Right Hand	Unified Standard Class 2A	-0.0002" to 0"	2356A309	000000	0" to 0.0002"	2356A409	000000
		5-40	UNC	Rockwell C60	Tool Steel	Right Hand	Unified Standard Class 2A	-0.0002" to 0"	2356A311	000000	0" to 0.0002"	2356A411	000000
		5-44	UNF	Rockwell C60	Tool Steel	Right Hand	Unified Standard Class 2A	-0.0002" to 0"	2356A015	000000	0" to 0.0002"	2356A016	000000


		6-32	UNC	Rockwell C60	Tool Steel	Right Hand	Unified Standard Class 2A	-0.0003" to 0"	2356A313	000000	0" to 0.0003"	2356A413	000000
		6-40	UNF	Rockwell C60	Tool Steel	Right Hand	Unified Standard Class 2A	-0.0002" to 0"	2356A314	000000	0" to 0.0002"	2356A414	000000
		8-32	UNC	Rockwell C60	Tool Steel	Right Hand	Unified Standard Class 2A	-0.0003" to 0"	2356A315	000000	0" to 0.0003"	2356A415	000000
		8-36	UNF	Rockwell C60	Tool Steel	Right Hand	Unified Standard Class 2A	-0.0002" to 0"	2356A316	000000	0" to 0.0002"	2356A416	000000
		10-24	UNC	Rockwell C60	Tool Steel	Right Hand	Unified Standard Class 2A	-0.0003" to 0"	2356A317	000000	0" to 0.0003"	2356A417	000000
		10-32	UNF	Rockwell C60	Tool Steel	Right Hand	Unified Standard Class 2A	-0.0003" to 0"	2356A318	000000	0" to 0.0003"	2356A418	000000
		12-24	UNC	Rockwell C60	Tool Steel	Right Hand	Unified Standard Class 2A	-0.0003" to 0"	2356A121	000000	0" to 0.0003"	2356A721	000000
		12-28	UNF	Rockwell C60	Tool Steel	Right Hand	Unified Standard Class 2A	-0.0003" to 0"	2356A017	000000	0" to 0.0003"	2356A018	000000
		12-32	UNEF	Rockwell C60	Tool Steel	Right Hand	Unified Standard Class 2A	-0.0003" to 0"	2356A019	000000	0" to 0.0003"	2356A021	000000
		1/4"-20	UNC	Rockwell C60	Tool Steel	Right Hand	Unified Standard Class 2A	-0.0003" to 0"	2356A322	000000	0" to 0.0003"	2356A422	000000


		1/4"-28	UNF	Rockwell C60	Tool Steel	Right Hand	Unified Standard Class 2A	-0.0003" to 0"	2356A323	000000	0" to 0.0003"	2356A423	000000
		1/4"-32	UNEF	Rockwell C60	Tool Steel	Right Hand	Unified Standard Class 2A	-0.0003" to 0"	2356A022	000000	0" to 0.0003"	2356A023	000000
		5/16"-18	UNC	Rockwell C60	Tool Steel	Right Hand	Unified Standard Class 2A	-0.0003" to 0"	2356A324	000000	0" to 0.0003"	2356A424	000000
		5/16"-24	UNF	Rockwell C60	Tool Steel	Right Hand	Unified Standard Class 2A	-0.0003" to 0"	2356A325	000000	0" to 0.0003"	2356A425	000000
		5/16"-32	UNEF	Rockwell C60	Tool Steel	Right Hand	Unified Standard Class 2A	-0.0003" to 0"	2356A024	000000	0" to 0.0003"	2356A025	000000
		3/8"-16	UNC	Rockwell C60	Tool Steel	Right Hand	Unified Standard Class 2A	-0.0003" to 0"	2356A326	000000	0" to 0.0003"	2356A426	000000
		3/8"-24	UNF	Rockwell C60	Tool Steel	Right Hand	Unified Standard Class 2A	-0.0003" to 0"	2356A327	000000	0" to 0.0003"	2356A427	000000
		3/8"-32	UNEF	Rockwell C60	Tool Steel	Right Hand	Unified Standard Class 2A	-0.0003" to 0"	2356A026	000000	0" to 0.0003"	2356A027	000000
		7/16"-14	UNC	Rockwell C60	Tool Steel	Right Hand	Unified Standard Class 2A	-0.0003" to 0"	2356A127	000000	0" to 0.0003"	2356A727	000000
		7/16"-20	UNF	Rockwell C60	Tool Steel	Right Hand	Unified Standard Class 2A	-0.0003" to 0"	2356A329	000000	0" to 0.0003"	2356A429	000000


		7/16"-28	UNEF	Rockwell C60	Tool Steel	Right Hand	Unified Standard Class 2A	-0.0003" to 0"	2356A028	000000	0" to 0.0003"	2356A029	000000
		1/2"-13	UNC	Rockwell C60	Tool Steel	Right Hand	Unified Standard Class 2A	-0.0003" to 0"	2356A331	000000	0" to 0.0003"	2356A431	000000
		1/2"-20	UNF	Rockwell C60	Tool Steel	Right Hand	Unified Standard Class 2A	-0.0003" to 0"	2356A332	000000	0" to 0.0003"	2356A432	000000
		1/2"-28	UNEF	Rockwell C60	Tool Steel	Right Hand	Unified Standard Class 2A	-0.0003" to 0"	2356A031	000000	0" to 0.0003"	2356A032	000000
		9/16"-12	UNC	Rockwell C60	Tool Steel	Right Hand	Unified Standard Class 2A	-0.0003" to 0"	2356A547	000000	0" to 0.0003"	2356A548	000000
		9/16"-18	UNF	Rockwell C60	Tool Steel	Right Hand	Unified Standard Class 2A	-0.0003" to 0"	2356A181	000000	0" to 0.0003"	2356A185	000000
		9/16"-24	UNEF	Rockwell C60	Tool Steel	Right Hand	Unified Standard Class 2A	-0.0003" to 0"	2356A033	000000	0" to 0.0003"	2356A034	000000
		5/8"-11	UNC	Rockwell C60	Tool Steel	Right Hand	Unified Standard Class 2A	-0.0003" to 0"	2356A333	000000	0" to 0.0003"	2356A433	000000
		5/8"-18	UNF	Rockwell C60	Tool Steel	Right Hand	Unified Standard Class 2A	-0.0003" to 0"	2356A334	000000	0" to 0.0003"	2356A434	000000
		5/8"-24	UNEF	Rockwell C60	Tool Steel	Right Hand	Unified Standard Class 2A	-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	-0.0003" to 0"	2356A037	000000	0" to 0.0003"	2356A038	000000
		3/4"-10	UNC	Rockwell C60	Tool Steel	Right Hand	Unified Standard Class 2A	-0.0003" to 0"	2356A335	000000	0" to 0.0003"	2356A435	000000
		3/4"-16	UNF	Rockwell C60	Tool Steel	Right Hand	Unified Standard Class 2A	-0.0003" to 0"	2356A336	000000	0" to 0.0003"	2356A436	000000
		3/4"-20	UNEF	Rockwell C60	Tool Steel	Right Hand	Unified Standard Class 2A	-0.0003" to 0"	2356A039	000000	0" to 0.0003"	2356A041	000000
		7/8"-9	UNC	Rockwell C60	Tool Steel	Right Hand	Unified Standard Class 2A	-0.0003" to 0"	2356A337	000000	0" to 0.0003"	2356A437	000000
		7/8"-14	UNF	Rockwell C60	Tool Steel	Right Hand	Unified Standard Class 2A	-0.0003" to 0"	2356A338	000000	0" to 0.0003"	2356A438	000000
		7/8"-20	UNEF	Rockwell C60	Tool Steel	Right Hand	Unified Standard Class 2A	-0.0003" to 0"	2356A042	000000	0" to 0.0003"	2356A043	000000
		1"-8	UNC	Rockwell C60	Tool Steel	Right Hand	Unified Standard Class 2A	-0.0004" to 0"	2356A135	000000	0" to 0.0004"	2356A735	000000
		1"-12	UNF	Rockwell C60	Tool Steel	Right Hand	Unified Standard Class 2A	-0.0003" to 0"	2356A341	000000	0" to 0.0003"	2356A441	000000
		1"-14	UNS	Rockwell C60	Tool Steel	Right Hand	Unified Standard Class 2A	-0.0003" to 0"	2356A572	000000	0" to 0.0003"	2356A576	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
1 1/8"-7	UNC	Rockwell C60	Tool Steel	Right Hand	Unified Standard Class 2A	-0.0004" to 0"	2356A581	000000	0" to 0.0004"	2356A582	000000
1 1/8"-12	UNF	Rockwell C60	Tool Steel	Right Hand	Unified Standard Class 2A	-0.0003" to 0"	2356A344	000000	0" to 0.0003"	2356A444	000000
1 1/4"-7	UNC	Rockwell C60	Tool Steel	Right Hand	Unified Standard Class 2A	-0.0004" to 0"	2356A138	000000	0" to 0.0004"	2356A738	000000
1 1/4"-12	UNF	Rockwell C60	Tool Steel	Right Hand	Unified Standard Class 2A	-0.0003" to 0"	2356A346	000000	0" to 0.0003"	2356A446	000000
1 3/8"-6	UNC	Rockwell C60	Tool Steel	Right Hand	Unified Standard Class 2A	-0.0004" to 0"	2356A583	000000	0" to 0.0004"	2356A584	000000
1 3/8"-12	UNF	Rockwell C60	Tool Steel	Right Hand	Unified Standard Class 2A	-0.0003" to 0"	2356A046	000000	0" to 0.0003"	2356A047	000000
1 1/2"-6	UNC	Rockwell C60	Tool Steel	Right Hand	Unified Standard Class 2A	-0.0004" to 0"	2356A589	000000	0" to 0.0004"	2356A591	000000
1 1/2"-12	UNF	Rockwell C60	Tool Steel	Right Hand	Unified Standard Class 2A	-0.0003" to 0"	2356A048	000000	0" to 0.0003"	2356A049	000000

Left-Hand Threaded Ring Gauges with Calibration Certificate

Calibrated in a lab and backed by a certificate traceable to NIST, these gauges check if left-hand threads fall within tolerance. The certificate, sometimes called a test report and long-form certificate, details the tested measurements. Use these gauges on screws, threaded rods, and other parts with external threads. For faster tests, hold more than one ring gauge with a threaded ring gauge holder.

Your part is within tolerance if it’s easy to thread a go gauge onto it but difficult to thread a no-go gauge more than two turns.

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—Thread fit designates the tightness or looseness of mating threads. For inch threads, the higher the class number, the tighter the fit. These metric-threaded ring gauges are class 6g, which is comparable to the fit of those with unified standard class 2A threads.

						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







				UNC Thread

				6-32	Left Hand	Rockwell C60	Tool Steel	Calibration Certificate Traceable to NIST	-0.0003" to 0"	7836N31	0000000	0" to 0.0003"	7836N73	0000000


				8-32	Left Hand	Rockwell C60	Tool Steel	Calibration Certificate Traceable to NIST	-0.0003" to 0"	7836N32	000000	0" to 0.0003"	7836N74	000000
				10-24	Left Hand	Rockwell C60	Tool Steel	Calibration Certificate Traceable to NIST	-0.0003" to 0"	7836N33	000000	0" to 0.0003"	7836N75	000000
				1/4"-20	Left Hand	Rockwell C60	Tool Steel	Calibration Certificate Traceable to NIST	-0.0003" to 0"	7836N34	000000	0" to 0.0003"	7836N76	000000
				5/16"-18	Left Hand	Rockwell C60	Tool Steel	Calibration Certificate Traceable to NIST	-0.0003" to 0"	7836N35	000000	0" to 0.0003"	7836N77	000000
				3/8"-16	Left Hand	Rockwell C60	Tool Steel	Calibration Certificate Traceable to NIST	-0.0003" to 0"	7836N36	000000	0" to 0.0003"	7836N78	000000
				1/2"-13	Left Hand	Rockwell C60	Tool Steel	Calibration Certificate Traceable to NIST	-0.0003" to 0"	7836N37	000000	0" to 0.0003"	7836N79	000000
				5/8"-11	Left Hand	Rockwell C60	Tool Steel	Calibration Certificate Traceable to NIST	-0.0003" to 0"	7836N38	000000	0" to 0.0003"	7836N81	000000
				3/4"-10	Left Hand	Rockwell C60	Tool Steel	Calibration Certificate Traceable to NIST	-0.0003" to 0"	7836N39	000000	0" to 0.0003"	7836N82	000000
				1"-8	Left Hand	Rockwell C60	Tool Steel	Calibration Certificate Traceable to NIST	-0.0004" to 0"	7836N41	000000	0" to 0.0004"	7836N83	000000




						UNF Thread

						10-32	Left Hand	Rockwell C60	Tool Steel	Calibration Certificate Traceable to NIST	-0.0003" to 0"	7836N11	000000	0" to 0.0003"	7836N53	000000


						1/4"-28	Left Hand	Rockwell C60	Tool Steel	Calibration Certificate Traceable to NIST	-0.0003" to 0"	7836N13	000000	0" to 0.0003"	7836N55	000000
						5/16"-24	Left Hand	Rockwell C60	Tool Steel	Calibration Certificate Traceable to NIST	-0.0003" to 0"	7836N15	000000	0" to 0.0003"	7836N57	000000
						3/8"-24	Left Hand	Rockwell C60	Tool Steel	Calibration Certificate Traceable to NIST	-0.0003" to 0"	7836N17	000000	0" to 0.0003"	7836N59	000000
						7/16"-20	Left Hand	Rockwell C60	Tool Steel	Calibration Certificate Traceable to NIST	-0.0003" to 0"	7836N19	000000	0" to 0.0003"	7836N62	000000
						1/2"-20	Left Hand	Rockwell C60	Tool Steel	Calibration Certificate Traceable to NIST	-0.0003" to 0"	7836N22	000000	0" to 0.0003"	7836N64	000000
						5/8"-18	Left Hand	Rockwell C60	Tool Steel	Calibration Certificate Traceable to NIST	-0.0003" to 0"	7836N24	000000	0" to 0.0003"	7836N66	000000
						3/4"-16	Left Hand	Rockwell C60	Tool Steel	Calibration Certificate Traceable to NIST	-0.0003" to 0"	7836N26	000000	0" to 0.0003"	7836N68	000000
						1 1/4"-12	Left Hand	Rockwell C60	Tool Steel	Calibration Certificate Traceable to NIST	-0.0003" to 0"	7836N28	000000	0" to 0.0003"	7836N71	000000

Left-Hand Threaded Ring Gauges

Test if the left-hand threads on parts fall within tolerance. These gauges are often used with parts such as screws, bolts, and threaded rods. All 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.

Class X Gauges

Image of Product. Front orientation. Ring Gauges. Left-Hand Threaded Ring Gauges.

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 Direction	Hardness	Material	Certificate Type	Pitch Dia. Tolerance		Each	Pitch Dia. Tolerance		Each
For Class 2A Unified Standard Thread Fit







				UNC Thread

				6-32	Left Hand	Rockwell C60	Tool Steel	Accuracy Certificate Traceable to NIST	-0.0003" to 0"	8399N31	0000000	0" to 0.0003"	8399N73	0000000


				8-32	Left Hand	Rockwell C60	Tool Steel	Accuracy Certificate Traceable to NIST	-0.0003" to 0"	8399N32	000000	0" to 0.0003"	8399N74	000000
				10-24	Left Hand	Rockwell C60	Tool Steel	Accuracy Certificate Traceable to NIST	-0.0003" to 0"	8399N33	000000	0" to 0.0003"	8399N75	000000
				1/4"-20	Left Hand	Rockwell C60	Tool Steel	Accuracy Certificate Traceable to NIST	-0.0003" to 0"	8399N34	000000	0" to 0.0003"	8399N76	000000
				5/16"-18	Left Hand	Rockwell C60	Tool Steel	Accuracy Certificate Traceable to NIST	-0.0003" to 0"	8399N35	000000	0" to 0.0003"	8399N77	000000
				3/8"-16	Left Hand	Rockwell C60	Tool Steel	Accuracy Certificate Traceable to NIST	-0.0003" to 0"	8399N36	000000	0" to 0.0003"	8399N78	000000
				1/2"-13	Left Hand	Rockwell C60	Tool Steel	Accuracy Certificate Traceable to NIST	-0.0003" to 0"	8399N37	000000	0" to 0.0003"	8399N79	000000
				5/8"-11	Left Hand	Rockwell C60	Tool Steel	Accuracy Certificate Traceable to NIST	-0.0003" to 0"	8399N38	000000	0" to 0.0003"	8399N81	000000
				3/4"-10	Left Hand	Rockwell C60	Tool Steel	Accuracy Certificate Traceable to NIST	-0.0003" to 0"	8399N39	000000	0" to 0.0003"	8399N82	000000
				1"-8	Left Hand	Rockwell C60	Tool Steel	Accuracy Certificate Traceable to NIST	-0.0004" to 0"	8399N41	000000	0" to 0.0004"	8399N83	000000




						UNF Thread

						10-32	Left Hand	Rockwell C60	Tool Steel	Accuracy Certificate Traceable to NIST	-0.0003" to 0"	8399N11	000000	0" to 0.0003"	8399N53	000000


						1/4"-28	Left Hand	Rockwell C60	Tool Steel	Accuracy Certificate Traceable to NIST	-0.0003" to 0"	8399N13	000000	0" to 0.0003"	8399N55	000000
						5/16"-24	Left Hand	Rockwell C60	Tool Steel	Accuracy Certificate Traceable to NIST	-0.0003" to 0"	8399N15	000000	0" to 0.0003"	8399N57	000000
						3/8"-24	Left Hand	Rockwell C60	Tool Steel	Accuracy Certificate Traceable to NIST	-0.0003" to 0"	8399N17	000000	0" to 0.0003"	8399N59	000000
						7/16"-20	Left Hand	Rockwell C60	Tool Steel	Accuracy Certificate Traceable to NIST	-0.0003" to 0"	8399N19	000000	0" to 0.0003"	8399N62	000000
						1/2"-20	Left Hand	Rockwell C60	Tool Steel	Accuracy Certificate Traceable to NIST	-0.0003" to 0"	8399N22	000000	0" to 0.0003"	8399N64	000000
						5/8"-18	Left Hand	Rockwell C60	Tool Steel	Accuracy Certificate Traceable to NIST	-0.0003" to 0"	8399N24	000000	0" to 0.0003"	8399N66	000000
						3/4"-16	Left Hand	Rockwell C60	Tool Steel	Accuracy Certificate Traceable to NIST	-0.0003" to 0"	8399N26	000000	0" to 0.0003"	8399N68	000000
						1 1/4"-12	Left Hand	Rockwell C60	Tool Steel	Accuracy Certificate Traceable to NIST	-0.0003" to 0"	8399N28	000000	0" to 0.0003"	8399N71	000000