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Newsgroups: rec.crafts.metalworking
Subject: Re: British Threads?
From: frisbie@flying-disk.com (Alan Frisbie)
Date: 6 Nov 95 21:39:11 PST
In article <47m8ki$7n5@agate.berkeley.edu>,
fasted@uclink.berkeley.edu (Edward W Claire) writes:
> I am working from some old plans which specify B.A. threads in number
> sizes-- i.e. 5 B.A., 6 B.A. etc. Can someone give me the appropriate
> equivalents in terms of American Stamdard machine screw sizes? Thanks.
Here is my table of British, American, and Metric machine screws and
their tap drills. This has been gleaned from a variety of sources,
none of which are guaranteed to be perfectly accurate. In particular,
there is considerable debate over the "correct" tap drill to use, hence
some alternates are offered. This list is sorted by outside diameter
for convenience in selecting the nearest size in another series.
I would appreciate any corrections, additions, comments, etc.
British American Metric Outside Tap Tap Drill Alternate Alternate
Sizes Sizes Sizes Diameter Drill Diameter Tap Drill Tap Diam.
(inches) (inches) (inches)
======= ======== ======= ======== ===== ======== ========= ==========
0-80 .0600 3/64 .0469
1/16-60 .0625 3/64 .0469
10-BA .0669 #54 .0550
1-64 .0730 #53 .0595
1-72 .0730 #53 .0595
9-BA .0748 #53 .0559
2-56 .0860 #50 .0700
2-64 .0860 #50 .0700
8-BA .0865 1.8 mm .0709 #50 .0700
3/32-48 .0937 #48 .0760
7-BA .0983 #47 .0785
3-48 .0990 #47 .0785
3-56 .0990 #46 .0810 #45 .0820
6-BA .1102 2.3 mm .0905 #43 .0890
4-40 .1120 #43 .0890 #44 .0860
4-48 .1120 #42 .0935 #43 .0890
3.0-0.6 .1181 2.4 mm .0945 3/32 .0938
3.0-0.5 .1181 2.5 mm .0984 #40 .0980
1/8-40 5-40 .1250 #38 .1015
5-44 .1250 #37 .1040
5-BA .1259 #37 .1040
3.5-0.6 .1378 2.9 mm .1142 #33 .1130
6-32 .1380 #36 .1065
6-40 .1380 #33 .1130
4-BA .1417 3.0 mm .1181 #32 .1160
4.0-0.75 .1575 3.2 mm .1260 1/8 .1250
4.0-0.7 .1575 3.3 mm .1299 #30 .1285
3-BA .1614 #29 .1360
8-32 .1640 #29 .1360
8-36 .1640 #29 .1360
2-BA .1850 4.0 mm .1575 #22 .1570
3/16-24 .1875 #27 .1440
3/16-32 .1875 #23 .1540
10-24 .1900 #25 .1495 #26 .1470
10-32 .1900 #21 .1590
5-0.9 .1968 4.1 mm .1614 #20 .1610
5-0.8 .1968 4.2 mm .1654 #19 .1660
1-BA .2086 4.5 mm .1772 #16 .1770
12-24 .2160 #16 .1770
12-28 .2160 #15 .1800 #14 .1820
7/32-24 .2187 #16 .1770
7/32-26 .2187 #15 .1800
7/32-28 .2187 #14 .1820
0-BA .2362 5.1 mm .2008 #7 .2010
6-1.0 .2362 5.0 mm .1968 #9 .1960
1/4-20 .2500 #9 .1960
1/4-20 .2500 #7 .2010
1/4-26 .2500 #4 .2090
1/4-28 .2500 #3 .2130
7-1.0 .2756 6.0 mm .2362 15/64 .2344
5/16-18 .3125 1/4 .2500
5/16-18 .3125 F .2570
5/16-22 .3125 G .2610
5/16-24 .3125 I (i) .2720
5/16-26 .3125 J .2770
8-1.0 .3150 7.0 mm .2756 I (i) .2720
8-1.25 .3150 6.8 mm .2677 H .2660
3/8-16 .3750 5/16 .3125
3/8-16 .3750 5/16 .3125
3/8-20 .3750 P .3230
3/8-24 .3750 Q .3320
3/8-26 .3750 Q .3320
10-1.5 .3937 8.5 mm .3346 Q .3320
10-1.25 .3973 8.8 mm .3465 S .3480
10-1.0 .3973 9.0 mm .3543 S .3480
7/16-14 .4375 23/64 .3594
7/16-14 .4375 U .3680
7/16-18 .4375 3/8 .3750
7/16-20 .4375 25/64 .3906
7/16-26 .4375 Y .4040
12-1.75 .4724 10.3 mm .4055 Y .4040
12-1.5 .4724 10.5 mm .4134 Z .4130
12-1.25 .4724 10.8 mm .4252 27/64 .4219
12-1.0 .4724 11.0 mm .4331 7/16 .4375
1/2-12 .5000 13/32 .4062
1/2-13 .5000 27/64 .4219
1/2-20 .5000 7/16 .4375
1/2-20 .5000 29/64 .4531
1/2-26 .5000 29/64 .4531
14-2.0 .5512 12.0 mm .4724 15/32 .4688
14-1.75 .5512 12.3 mm .4842 31/64 .4844
14-1.5 .5512 12.5 mm .4921 1/2 .5000
14-1.25 .5512 12.8 mm .5039 1/2 .5000
14-1.0 .5512 13.0 mm .5118 33/64 .5156
-- Alan E. Frisbie Frisbie@Flying-Disk.Com
-- Flying Disk Systems, Inc.
-- 4759 Round Top Drive (213) 256-2575 (voice)
-- Los Angeles, CA 90065 (213) 258-3585 (FAX)
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