Class 3A Ring Gauges | McMaster-Carr

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156 Products

Threaded Ring Gauges with Calibration Certificate

A certificate of calibration traceable to NIST states that these gauges have passed a test for accuracy. 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.

Go gauges check the maximum external thread size.

No-go gauges check the minimum external thread size.

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.

For technical drawings and 3-D models, click on a part number.

Inch

				Go Gauge		No-Go Gauge
				Class 3A		Class 3A
Thread Size	Thread Type	Hardness	Material		Each		Each
Class X
0-80	UNF	Rockwell C60	Tool Steel	00000000	0000000	00000000	0000000
1-64	UNC	Rockwell C60	Tool Steel	00000000	000000	00000000	000000
1-72	UNF	Rockwell C60	Tool Steel	00000000	000000	00000000	000000
2-56	UNC	Rockwell C60	Tool Steel	00000000	000000	00000000	000000
2-64	UNF	Rockwell C60	Tool Steel	00000000	000000	00000000	000000
3-48	UNC	Rockwell C60	Tool Steel	00000000	000000	00000000	000000
4-40	UNC	Rockwell C60	Tool Steel	00000000	000000	00000000	000000
4-48	UNF	Rockwell C60	Tool Steel	00000000	000000	00000000	000000
5-40	UNC	Rockwell C60	Tool Steel	00000000	000000	00000000	000000
6-32	UNC	Rockwell C60	Tool Steel	00000000	000000	00000000	000000
6-40	UNF	Rockwell C60	Tool Steel	00000000	000000	00000000	000000
8-32	UNC	Rockwell C60	Tool Steel	00000000	000000	00000000	000000
8-36	UNF	Rockwell C60	Tool Steel	00000000	000000	00000000	000000
10-24	UNC	Rockwell C60	Tool Steel	00000000	000000	00000000	000000
10-32	UNF	Rockwell C60	Tool Steel	00000000	000000	00000000	000000
12-24	UNC	Rockwell C60	Tool Steel	00000000	000000	00000000	000000
12-28	UNF	Rockwell C60	Tool Steel	00000000	000000	00000000	000000
1/4"-20	UNC	Rockwell C60	Tool Steel	00000000	000000	00000000	000000
1/4"-28	UNF	Rockwell C60	Tool Steel	00000000	000000	00000000	000000
5/16"-18	UNC	Rockwell C60	Tool Steel	00000000	000000	00000000	000000
5/16"-24	UNF	Rockwell C60	Tool Steel	00000000	000000	00000000	000000
3/8"-16	UNC	Rockwell C60	Tool Steel	00000000	000000	00000000	000000
3/8"-24	UNF	Rockwell C60	Tool Steel	00000000	000000	00000000	000000
7/16"-14	UNC	Rockwell C60	Tool Steel	00000000	000000	00000000	000000
7/16"-20	UNF	Rockwell C60	Tool Steel	00000000	000000	00000000	000000
1/2"-13	UNC	Rockwell C60	Tool Steel	00000000	000000	00000000	000000
1/2"-20	UNF	Rockwell C60	Tool Steel	00000000	000000	00000000	000000
9/16"-18	UNF	Rockwell C60	Tool Steel	00000000	000000	00000000	000000
5/8"-11	UNC	Rockwell C60	Tool Steel	00000000	000000	00000000	000000
5/8"-18	UNF	Rockwell C60	Tool Steel	00000000	000000	00000000	000000
3/4"-10	UNC	Rockwell C60	Tool Steel	00000000	000000	00000000	000000
3/4"-16	UNF	Rockwell C60	Tool Steel	00000000	000000	00000000	000000
7/8"-9	UNC	Rockwell C60	Tool Steel	00000000	000000	00000000	000000
7/8"-14	UNF	Rockwell C60	Tool Steel	00000000	000000	00000000	000000
1"-8	UNC	Rockwell C60	Tool Steel	00000000	000000	00000000	000000
1"-12	UNF	Rockwell C60	Tool Steel	00000000	000000	00000000	000000
1"-14	UNS	Rockwell C60	Tool Steel	00000000	000000	000000	00
1 1/8"-12	UNF	Rockwell C60	Tool Steel	00000000	000000	00000000	000000
1 1/4"-7	UNC	Rockwell C60	Tool Steel	00000000	000000	00000000	000000
1 1/4"-12	UNF	Rockwell C60	Tool Steel	00000000	000000	00000000	000000
1 1/2"-12	UNF	Rockwell C60	Tool Steel	00000000	000000	00000000	000000
1 1/2"-6	UNC	Rockwell C60	Tool Steel	00000000	000000	00000000	000000

Threaded Ring Gauges

Check a part’s external threads to ensure they fall within tolerance.

The 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.

Go gauges check the maximum external thread size.

No-go gauges check the minimum external thread size.

For technical drawings and 3-D models, click on a part number.

Inch

Go Gauge
Thread Size	Thread Type	Hardness	Material	For Thread Fit	Pitch Dia. Tolerance		Each
Class X
0-80	UNF	Rockwell C60	Tool Steel	Class 3A	-0.0002" to 0"	00000000	0000000
1-72	UNF	Rockwell C60	Tool Steel	Class 3A	-0.0002" to 0"	00000000	000000
2-56	UNC	Rockwell C60	Tool Steel	Class 3A	-0.0002" to 0"	00000000	000000
3-48	UNC	Rockwell C60	Tool Steel	Class 3A	-0.0002" to 0"	00000000	000000
4-40	UNC	Rockwell C60	Tool Steel	Class 3A	-0.0002" to 0"	00000000	000000
4-48	UNF	Rockwell C60	Tool Steel	Class 3A	-0.0002" to 0"	00000000	000000
5-40	UNC	Rockwell C60	Tool Steel	Class 3A	-0.0002" to 0"	00000000	000000
6-32	UNC	Rockwell C60	Tool Steel	Class 3A	-0.0003" to 0"	00000000	000000
6-40	UNF	Rockwell C60	Tool Steel	Class 3A	-0.0002" to 0"	00000000	000000
8-32	UNC	Rockwell C60	Tool Steel	Class 3A	-0.0003" to 0"	00000000	000000
8-36	UNF	Rockwell C60	Tool Steel	Class 3A	-0.0002" to 0"	00000000	000000
10-24	UNC	Rockwell C60	Tool Steel	Class 3A	-0.0003" to 0"	00000000	000000
10-32	UNF	Rockwell C60	Tool Steel	Class 3A	-0.0003" to 0"	00000000	000000
12-24	UNC	Rockwell C60	Tool Steel	Class 3A	-0.0003" to 0"	00000000	000000
1/4"-20	UNC	Rockwell C60	Tool Steel	Class 3A	-0.0003" to 0"	00000000	000000
1/4"-28	UNF	Rockwell C60	Tool Steel	Class 3A	-0.0003" to 0"	00000000	000000
5/16"-18	UNC	Rockwell C60	Tool Steel	Class 3A	-0.0003" to 0"	00000000	000000
5/16"-24	UNF	Rockwell C60	Tool Steel	Class 3A	-0.0003" to 0"	00000000	000000
3/8"-16	UNC	Rockwell C60	Tool Steel	Class 3A	-0.0003" to 0"	00000000	000000
3/8"-24	UNF	Rockwell C60	Tool Steel	Class 3A	-0.0003" to 0"	00000000	000000
7/16"-14	UNC	Rockwell C60	Tool Steel	Class 3A	-0.0003" to 0"	00000000	000000
7/16"-20	UNF	Rockwell C60	Tool Steel	Class 3A	-0.0003" to 0"	00000000	000000
1/2"-13	UNC	Rockwell C60	Tool Steel	Class 3A	-0.0003" to 0"	00000000	000000
1/2"-20	UNF	Rockwell C60	Tool Steel	Class 3A	-0.0003" to 0"	00000000	000000
9/16"-18	UNF	Rockwell C60	Tool Steel	Class 3A	-0.0003" to 0"	00000000	000000
5/8"-11	UNC	Rockwell C60	Tool Steel	Class 3A	-0.0003" to 0"	00000000	000000
5/8"-18	UNF	Rockwell C60	Tool Steel	Class 3A	-0.0003" to 0"	00000000	000000
3/4"-10	UNC	Rockwell C60	Tool Steel	Class 3A	-0.0003" to 0"	00000000	000000
3/4"-16	UNF	Rockwell C60	Tool Steel	Class 3A	-0.0003" to 0"	00000000	000000
7/8"-9	UNC	Rockwell C60	Tool Steel	Class 3A	-0.0003" to 0"	00000000	000000
7/8"-14	UNF	Rockwell C60	Tool Steel	Class 3A	-0.0003" to 0"	00000000	000000
1"-8	UNC	Rockwell C60	Tool Steel	Class 3A	-0.0004" to 0"	00000000	000000
1"-12	UNF	Rockwell C60	Tool Steel	Class 3A	-0.0003" to 0"	00000000	000000
1"-14	UNS	Rockwell C60	Tool Steel	Class 3A	-0.0003" to 0"	00000000	000000
1 1/8"-12	UNF	Rockwell C60	Tool Steel	Class 3A	-0.0003" to 0"	00000000	000000
1 1/4"-7	UNC	Rockwell C60	Tool Steel	Class 3A	-0.0004" to 0"	00000000	000000
1 1/4"-12	UNF	Rockwell C60	Tool Steel	Class 3A	-0.0003" to 0"	00000000	000000
No-Go Gauge
Class X
0-80	UNF	Rockwell C60	Tool Steel	Class 3A	0" to 0.0002"	00000000	000000
1-72	UNF	Rockwell C60	Tool Steel	Class 3A	0" to 0.0002"	00000000	000000
2-56	UNC	Rockwell C60	Tool Steel	Class 3A	0" to 0.0002"	00000000	000000
3-48	UNC	Rockwell C60	Tool Steel	Class 3A	0" to 0.0002"	00000000	000000
4-40	UNC	Rockwell C60	Tool Steel	Class 3A	0" to 0.0002"	00000000	000000
4-48	UNF	Rockwell C60	Tool Steel	Class 3A	0" to 0.0002"	00000000	000000
5-40	UNC	Rockwell C60	Tool Steel	Class 3A	0" to 0.0002"	00000000	000000
6-32	UNC	Rockwell C60	Tool Steel	Class 3A	0" to 0.0003"	00000000	000000
6-40	UNF	Rockwell C60	Tool Steel	Class 3A	0" to 0.0002"	00000000	000000
8-32	UNC	Rockwell C60	Tool Steel	Class 3A	0" to 0.0003"	00000000	000000
8-36	UNF	Rockwell C60	Tool Steel	Class 3A	0" to 0.0002"	00000000	000000
10-24	UNC	Rockwell C60	Tool Steel	Class 3A	0" to 0.0003"	00000000	000000
10-32	UNF	Rockwell C60	Tool Steel	Class 3A	0" to 0.0003"	00000000	000000
12-24	UNC	Rockwell C60	Tool Steel	Class 3A	0" to 0.0003"	00000000	000000
1/4"-20	UNC	Rockwell C60	Tool Steel	Class 3A	0" to 0.0003"	00000000	000000
1/4"-28	UNF	Rockwell C60	Tool Steel	Class 3A	0" to 0.0003"	00000000	000000
5/16"-18	UNC	Rockwell C60	Tool Steel	Class 3A	0" to 0.0003"	00000000	000000
5/16"-24	UNF	Rockwell C60	Tool Steel	Class 3A	0" to 0.0003"	00000000	000000
3/8"-16	UNC	Rockwell C60	Tool Steel	Class 3A	0" to 0.0003"	00000000	000000
3/8"-24	UNF	Rockwell C60	Tool Steel	Class 3A	0" to 0.0003"	00000000	000000
7/16"-14	UNC	Rockwell C60	Tool Steel	Class 3A	0" to 0.0003"	00000000	000000
7/16"-20	UNF	Rockwell C60	Tool Steel	Class 3A	0" to 0.0003"	00000000	000000
1/2"-13	UNC	Rockwell C60	Tool Steel	Class 3A	0" to 0.0003"	00000000	000000
1/2"-20	UNF	Rockwell C60	Tool Steel	Class 3A	0" to 0.0003"	00000000	000000
9/16"-18	UNF	Rockwell C60	Tool Steel	Class 3A	0" to 0.0003"	00000000	000000
5/8"-11	UNC	Rockwell C60	Tool Steel	Class 3A	0" to 0.0003"	00000000	000000
5/8"-18	UNF	Rockwell C60	Tool Steel	Class 3A	0" to 0.0003"	00000000	000000
3/4"-10	UNC	Rockwell C60	Tool Steel	Class 3A	0" to 0.0003"	00000000	000000
3/4"-16	UNF	Rockwell C60	Tool Steel	Class 3A	0" to 0.0003"	00000000	000000
7/8"-9	UNC	Rockwell C60	Tool Steel	Class 3A	0" to 0.0003"	00000000	000000
7/8"-14	UNF	Rockwell C60	Tool Steel	Class 3A	0" to 0.0003"	00000000	000000
1"-8	UNC	Rockwell C60	Tool Steel	Class 3A	0" to 0.0004"	00000000	000000
1"-12	UNF	Rockwell C60	Tool Steel	Class 3A	0" to 0.0003"	00000000	000000
1 1/8"-12	UNF	Rockwell C60	Tool Steel	Class 3A	0" to 0.0003"	00000000	000000
1 1/4"-7	UNC	Rockwell C60	Tool Steel	Class 3A	0" to 0.0004"	00000000	000000
1 1/4"-12	UNF	Rockwell C60	Tool Steel	Class 3A	0" to 0.0003"	00000000	000000