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3BG Class-of-Fit (obsolete)

MIL-STD-8879C (obsolete) contained paragraph 6.3 which is titled: Class 3BG.

MIL-STD-8879C: 6.3 Class 3BG
According to MIL-S-8879C paragraph 6.3 Class 3BG states: Class 3BG for high temperature applications shall no longer be used in new designs. This special class-of-fit for internal threads provides an allowance to both the GO and NOGO work plug gage pitch diameters of +0.0030" for 32-TPI and coarser. For finer ptch threads (finer than 32-TPI) +0.0010".

The above paragraph was not carried over to ANSI/ASME SAE AS8879. Also, 3BG is not mentioned at all in ANSI/ASME SAE AS8879.

 

MIL-STD-8879C (obsolete)
UNJF Class 3BG only applies to internal threads
THREAD SIZE
MINOR DIAMETER
PITCH DIAMETER
MAJOR DIAMETER
MIN
MAX
MIN
MAX
MIN
#0-80 UNJF-3BG
0.0489
0.0521
0.0529
0.0546
0.0610
#1-72 UNJF-3BG
0.0605
0.0641
0.0650
0.0669
0.0740
#2-64 UNJF-3BG
0.0718
0.0759
0.0769
0.0789
0.0870
#3-56 UNJF-3BG
0.0826
0.0872
0.0884
0.0905
0.1000
#4-48 UNJF-3BG
0.0927
0.0981
0.0995
0.1018
0.1130
#5-44 UNJF-3BG
0.1039
0.1098
0.1112
0.1136
0.1260
#6-40 UNJF-3BG
0.1147
0.1212
0.1228
0.1253
0.1390
#8-36 UNJF-3BG
0.1380
0.1452
0.1470
0.1497
0.1650
#10-32 UNJF-3BG
0.1626
0.1705
0.1727
0.1756
0.1930
#12-28 UNJF-3BG
0.1842
0.1926
0.1958
0.1989
0.2190
1/4"-28 UNJF-3BG
0.2182
0.2259
0.2298
0.2330
0.2530
5/16"-24 UNJF-3BG
0.2749
0.2829
0.2884
0.2920
0.3155
3/8"-24 UNJF-3BG
0.3374
0.3447
0.3509
0.3546
0.3780
7/16"-20 UNJF-3BG
0.3918
0.4000
0.4080
0.4121
0.4405
1/2"-20 UNJF-3BG
0.4543
0.4621
0.4703
0.4747
0.5030
9/16"-18 UNJF-3BG
0.5114
0.5196
0.5294
0.5338
0.5655
5/8"-18 UNJF-3BG
0.5739
0.5818
0.5919
0.5964
0.6280
3/4"-16 UNJF-3BG
0.6922
0.7007
0.7124
0.7173
0.7530
7/8'-14 UNJF-3BG
0.8085
0.8182
0.8316
0.8369
0.8780
1"-12 UNJF-3BG
0.9219
0.9319
0.9489
0.9546
1.0030
1-1/8"-12 UNJF-3BG
1.0469
1.0569
1.0739
1.0798
1.1280
1-1/4"-12 UNJF-3BG
1.1719
1.1819
1.1989
1.2049
1.2530
1-3/8"-12 UNJF-3BG
1.2969
1.3089
1.3239
1.3300
1.3780
1-1/2"-12 UNJF-3BG
1.4219
1.4319
1.4489
1.4552
1.5030

Disclaimer:
Gage Crib Worldwide Inc has provided this content for general information purposes only and it does not constitute advice. Gage Crib Worldwide Inc tries to provide content that is true and accurate as of the date of writing; however, we give no assurance or warranty regarding the accuracy, or applicability of any of the content. Visitors should not act upon Gage Crib Worldwide Inc content or information without first seeking appropriate professional advice or referencing the official industry standards. 

Comments:
Original Posting: 11/13/2012
Last Revision: 8/8/2016
Error corrections in, or comments about, the above data can be sent to: gageguy@gagecrib.com

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