SELF- TAPPING SCREWS

HOLE SIZE DATA Types A, AB, B, 25

AB AB

B A

25

Suggested Test Plate Thicknesses & Hole

Sizes for Types AB - B - 25
Suggested Hole Sizes for Type A
Nominal Hole Size
Thickness Hole Size Nominal Screw
Screw Size
Size Drill Size Hole Diam.
& No. of
Threads Drill Hole 6-18 #32 0.1160
per Inch Gage Max Min
Size Diam.
7-16 #30 0.1285
2-32 18 .0500 .0460 48 .0760 8-15 #29 0.1360

3-28 18 .0500 .0460 46 .0810 10-12 #21 0.1590

12-11 3/16 0.1875
4-24 18 .0500 .0460 44 .0860
14-10 5.5mm 0.2165
5-20 18 .0500 .0460 36 .1065 20-9 L 0.2900
24-9 11/32 0.3438
6-20 14 .0770 .0730 32 .1160

7-19 14 .0770 .0730 30 .1285

8-18 14 .1270 .1230 29 .1360

10-16 1/8 .1270 .1230 21 .1590

12-14 1/8 .1270 .1230 3/16 .1875

1/4-14 3/16 .1905 .1845 5.5 mm .2165

5/16-12 3/16 .1905 .1845 I .2720

3/8-12 3/16 .1905 .1845 21/64 .3281

Notes Regarding Hole Preparation:

• Preformed holes can be drilled, cored, punched, pierced or extruded. If edge burrs
can cause assembly difficulty, they should be removed. Wall ovality and/or taper can
affect load carrying ability.

• “Minimum torsional strength” is the torque that free standing screws must accept
without evidence of damage or failure.

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 SELF- TAPPING SCREWS

Types 1, 23, F, U & High-Low HOLE SIZE DATA

Type U
Drive Screw
Type 1

Recommended Hole Sizes -- Type-U Drive Screws

Type 23 Screw Size Drill Size No. Hole Diameter
00 55 .052
0 51 .067
Type F 2 44 .086
4 37 .104
6 31 .120

Suggested Test Plate Thicknesses & Hole Sizes for 7 29 .136

Types 1, 23 & F 8 27 .144
Thread Cutting Screws 10 20 .161

Nominal 12 11 .191
Thickness Hole Size
Screw Size 14 2 .221
& Thread
Pitch
Gage Max Min Drill Size Hole Diam.

2-56 18 .0800 .0760 49 0.0730

3-48 18 .0960 .0920 46 0.0810
4-40 18 .1110 .1070 41 0.0960 High-
5-40 18 .1110 .1070 37 0.1010
H-L
Low
6-32 14 .1425 .1385 31 0.1200
8-32 14 .1905 .1845 26 0.1470
10-24 1/8 .1905 .1845 17 0.1730
10-32 1/8 .1905 .1845 16 0.1770 Suggested Hole Sizes -- High-Low Screws
12-24 1/8 .1905 .1845 8 0.1990 Pilot Hole Diameter
Nominal Screw Size Flexural Modulus of Plastic
1/4-20 3/16 .2530 .2470 1 0.2280 & Number of
Threads per Inch Up to 200,000 200,000-400,000
5/16-18 3/16 .3155 .3095 L 0.2900 P.S.I. P.S.I.
3/8-16 3/16 .3780 .3720 T 0.3580 2-32 .0670 .0700
1/2-13 3/16 .471 .443 29/64 0.4531 3-28 .0730 .0781
4-24 .0810 .0860
5-20 .0935 .0995
6-19 .1015 .1100
7-19 .1200 .1250
8-18 .1200 .1285
10-16 .1360 .1440
12-16 .1570 .1660
1/4-15 .1890 .2010
5/16-14 .2380 .2500

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