UNIFIED PLUG, RING AND CALIPER THREAD GAUGES
Gauges for testing Unified threads to BS 1580:Parts
1&2:1962,
BS 1580:Part 3: 1965; and
BS 919:Part 1:1960.
BS 1580: Pts 1&2:1962 specifies details of product threads. (The basic
profile is the same as that for ISO threads as illustrated on page 4). The
standard includes nominal sizes and limits of size for standard threads for
1A, 2A and 3A for external threads, and 1B, 2B, and 3B for internal threads
in the following sizes:-
UNC
(coarse pitch) from 1/4” to 4” dia.
UNF
(fine pitch) from 1/4” to 11/2” dia.
UNEF
(extra fine pitch) from 1/4” to 111/16” dia.
UN
(constant pitch) for 4,6,8,12,16,20,28, and 32 tpi for various diameters as
specified.
Allowances
(deviation from basic size)
1A and 2A provide allowances of 30% of the effective diameter tolerances of
2A external threads. 3A is basic (no allowance). 2AG is 0.001” smaller
on diameter to provide for plating to finish at 2A. (0.001” on diameter
will allow for an average deposit of 0.00025”). 1B, 2B and 3B for internal
threads are all basic. Before plating threads are not designated. They are
referred to as before plating, and are 0.001” larger on diameter than
basic size.
Classes of fit
1A/lB are used where easy assembly is required. 2A/2B are the classes used
for the majority of general engineering purposes. 3A/3B apply to threads requiring
a closer fit, and are only used when a close accuracy of form and pitch are
required.
BS 1580:Pt 3:1965 specifies nominal sizes
and limits of size for standard threads for 2A and 3A for external threads,
and 2B and 3B for internal threads for UNC, UNF, and UNEF for threads below
1/4” diameter. The allowances and classes of fit are the same as above.
BS 919:Pt 1:1960 specifies the limits
for gauges for testing the product thread. The basis for determining the gauge
limits is the diameter/pitch. Generally, the larger the diameter, and coarser
the pitch, the larger the gauge limits within defined diameter/pitch bands.
The types of gauges used are the same as for ISO threads, described on page
4.
Gauges can be supplied to comply with the requirements of the American National
Standards Institution specification ANSI/ASME B1.1 1989 for product threads,
and B1.2 1983 for gauges.
The designated diameter/pitch combinations are similar to those in
BS 1580, with similar allowances and classes of fit. The gauging philosophy
however in B1.2 differs from the British system. In the ANSI system generally
the gauging limits are contained within the product tolerance, whereas in
the British system the gauging limits may transgress the minimum material
limit. Further, the ANSI standard specifies that the major diameter of the
Not Go plug gauge is truncated to high addendum, whilst the British standard
specifies low addendum truncation.
The regular checking of gauges in constant use
is important, and should be carried out as for
ISO gauges.
|
| Size | G0 | NOGO | 'E' | Go | NOGO | ROLLER | KNIFE |
| Class of fit | Class of fit | Class of fit | |||||
| 2B | 2B | 2B | 2A | 2A | ANY | ANY | |
| N?1-64 UNC |
0070 | 0071 | 0070B | 0860 | 0861 | 1830 | 2030 |
| N?2-56 UNC | 0072 | 0073 | 0072B | 0862 | 0863 | 1831 | 2031 |
| N?3-48 UNC | 0074 | 0075 | 0074B | 0864 | 0865 | 1832 | 2032 |
| N?4-40 UNC | 0076 | 0077 | 0076B | 0866 | 0867 | 1833 | 2033 |
| N?5-40 UNC | 0079 | 0080 | 0079B | 0868 | 0869 | 1834 | 2034 |
| N?6-32 UNC | 0081 | 0082 | 0081B | 0870 | 0871 | 1835 | 2035 |
| N?8-32 UNC | 0084 | 0085 | 0084B | 0872 | 0873 | 1836 | 2036 |
| N?10-24UNC |
0087 | 0088 | 0087B | 0874 | 0875 | 1837 | 2037 |
| N?12-24UNC | 0090 | 0091 | 0090B | 0876 | 0877 | 1838 | 2038 |
| 1/4?-20 UNC | 0092 | 0093 | 0092B | 0878 | 0879 | 1839 | 2039 |
| 5/16?-18 UNC | 0095 | 0096 | 0095B | 0880 | 0881 | 1840 | 2040 |
| 3/8?-16 UNC | 0098 | 0099 | 0098B | 0882 | 0883 | 1841 | 2041 |
| 7/16?-14 UNC | 0100 | 0101 | 0010B | 0884 | 0885 | 1842 | 2042 |
| 1/2?-13 UNC | 0103 | 0104 | 0103B | 0886 | 0887 | 1843 | 2043 |
| 9/16?-12 UNC | 0106 | 0107 | 0106B | 0888 | 0889 | 1844 | 2044 |
| 5/8?-11 UNC | 0109 | 0110 | 0109B | 0890 | 0891 | 1845 | 2045 |
| 3/4?-10 UNC | 0111 | 0112 | 0111B | 0892 | 0893 | 1846 | 2045 |
| 7/8?-9 UNC | 0113 | 0114 | 0113B | 0895 | 0896 | 1847 | 2046 |
| 1?-8 UNC | 0116 | 0117 | 0116B | 0898 | 0899 | 1848 | 2047 |
| 11/8?-7 UNC | 0119 | 0120 | 0119B | 0901 | 0902 | 1849 | 2048 |
| 11/4?-7 UNC | 0122 | 0123 | 0122B | 0904 | 0905 | 1850 | 2049 |
| 13/8?-6 UNC | 0125 | 0126 | 0125B | 0907 | 0908 | 1851 | 2050 |
| 11/2?-6 UNC | 0128 | 0129 | 0128B | 0910 | 0911 | 1852 | 2052 |
| N?0-80 UNF | 0001 | 0002 | 0001B | 0800 | 0801 | 1800 | 2000 |
| N?1-72 UNF | 0003 | 0004 | 0003B | 0802 | 0803 | 1801 | 2001 |
| N?2-64UNF | 0006 | 0007 | 0006B | 0804 | 0805 | 1802 | 2002 |
| N?3-56 UNF | 0008 | 0009 | 0008B | 0806 | 0807 | 1803 | 2003 |
| N?4-48 UNF | 0010 | 0011 | 0010B | 0808 | 0809 | 1804 | 2004 |
| N?5-44 UNF | 0013 | 0014 | 0013B | 0810 | 0811 | 1805 | 2005 |
| N?6-40 UNF | 0015 | 0016 | 0015B | 0812 | 0813 | 1806 | 2006 |
| N?8-36 UNF | 0017 | 0018 | 0017B | 0814 | 0815 | 1807 | 2007 |
| N?10-32 UNF | 0019 | 0020 | 0019B | 0816 | 0817 | 1808 | 2008 |
| N?12-28 UNF | 0022 | 0023 | 0022B | 0818 | 0819 | 1809 | 2009 |
| 1/4?-28 UNF | 0024 | 0025 | 0024B | 0820 | 0821 | 1810 | 2010 |
| 5/16?-24 UNF | 0027 | 0028 | 0027B | 0822 | 0823 | 1811 | 2011 |
| 3/8?-24 UNF | 0030 | 0031 | 0030B | 0824 | 0825 | 1812 | 2012 |
| 7/16?-20 UNF | 0033 | 0034 | 0033B | 0827 | 0828 | 1813 | 2013 |
| 1/2?-20 UNF | 0035 | 0036 | 0035B | 0829 | 0830 | 1814 | 2014 |
| 9/16?-18 UNF | 0038 | 0039 | 0038B | 0831 | 0832 | 1815 | 2015 |
| 5/8?-18 UNF | 0041 | 0042 | 0041B | 0833 | 0834 | 1816 | 2016 |
| 3/4?-18 UNF | 0044 | 0045 | 0044B | 0835 | 0836 | 1817 | 2017 |
| 7/8?-14 UNF | 0047 | 0048 | 0047B | 0838 | 0839 | 1818 | 2018 |
| 1?-12 UNF | 0050 | 0051 | 0050B | 0841 | 0842 | 1819 | 2019 |
| 11/8?-12 UNF | 0052 | 0053 | 0052B | 0844 | 0845 | 1820 | 2020 |
| 11/4?-12 UNF | 0055 | 0056 | 0055B | 0847 | 0848 | 1821 | 2021 |
| 13/8?-12 UNF | 0058 | 0059 | 0058B | 0850 | 0851 | 1822 | 2022 |
| 11/2?-12 UNF | 0060 | 0061 | 0060B | 0853 | 0855 | 1823 | 2023 |
| N?12-32 UNEF | 2232 | 2233 | 2233B | - | - | - | - |
| 1/4?-32 UNEF | 2200 | 2201 | 2200B | 2300 | - | - | - |
| 5/16?-32 UNEF | 130 | 131 | 0130B | 913 | - | - | - |
| 3/8?-32 UNEF | 132 | 133 | 0132B | 914 | - | - | - |
| 7/16?-28 UNEF | 134 | 135 | 0134B | 915 | - | - | - |
| 1/2?-28 UNEF | 136 | 137 | 0136B | 916 | - | - | - |
| 9/16?-24 UNEF | 138 | 139 | 0138B | 917 | - | - | - |
| 5/8?-24 UNEF | 2202 | 2203 | 2202B | 2302 | 2303 | - | - |
| 1/16?-24 UNEF | 2204 | 2205 | 2204B | 2304 | - | - | - |
| 3/4?-20 UNEF | 2206 | 2207 | 2206B | 2306 | 2307 | - | - |
| 13/16?-20 UNEF | 2208 | 2209 | 2208B | 2308 | - | - | - |
| 7/8?-20 UNEF | 2210 | 2211 | 2210B | 2310 | 2311 | - | - |
| 15/16?-20 UNEF | 2212 | 2213 | 2212B | 2312 | - | - | - |
| 1?-20 UNEF | 2214 | 2215 | 2214B | 2314 | 2315 | - | - |
| 11/16?-18 UNEF | 2216 | 2217 | 2216B | 2316 | - | - | - |
| 11/8?-18 UNEF | 2218 | 2219 | 2218B | 2318 | 2319 | - | - |
| 13/16?-18 UNEF | 2220 | 2221 | 2220B | 2320 | - | - | - |
| 11/4?-18 UNEF | 2222 | 2223 | 2222B | 2322 | - | - | - |
| 15/16?-18 UNEF | 2224 | 2225 | 2224B | 2324 | - | - | - |
| 13/8?-18 UNEF | 2226 | 2227 | 2226B | 2326 | - | - | - |
| 17/16?-18 UNEF | 2229 | 2228B | 2328 | - | - | - | - |
| 11/2?-18 UNEF | 2230 | 2231 | 2230B | 2330 | - | - | - |
| 19/16?-18 UNEF | 2238 | - | - | - | - | - | - |
| 15/8?-18 UNEF | 2236 | 2237 | 2236B | - | - | - | - |
| 111/16?-18 UNEF | 2234 | 2235 | 2234B | - | - | - | - |
