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self-tapping screw

Belong to module:Nails&Screws  Add date:2016-06-02  Click volume:198

self-tapping screw information

A self-tapping screw is a screw that can tap its own hole as it is driven into the material. For hard substrates such as metal or hard plastics, the self-tapping ability is often created by cutting a gap in the continuity of the thread on the screw, generating a flute and cutting edge similar to those on a tap. Thus, whereas a regular machine screw cannot tap its own hole in a metal substrate, a self-tapping one can (within reasonable limits of substrate hardness and depth). For softer substrates such as wood or soft plastics, the self-tapping ability can come simply from a tip that tapers to a gimlet point (in which no flute is needed). Like the tip of a nail or gimlet, such a point forms the hole by displacement of the surrounding material rather than any chip-forming drilling/cutting/evacuating action.

Some self-tapping screws are also self-drilling, which means that, in addition to the tap-like flute in the leading threads, there is also a preliminary drill-like fluted tip that looks much like the tip of a center drill. These screws combine a thrilling-like action and the fastener installation itself into only one driving motion (instead of separate drilling, tapping, and installing motions); they are thus very efficient in a variety of hard-substrate applications, from assembly lines to roofing.

Self-tapping screws are used in a variety of applications ranging from DIY carpentry to surgery. Many dental implants andorthopedic bone screws are examples of self-tapping screws used in surgery.

Nominal
Screw
Size

Number
Of Thread
Starts

D

A

H

P

Recommened
Hole Size

Outside
Diameter

Head
Diameter

Head
Height

Pilot
Diameter

Drill Size
No.

Hole
Diameter

Max.

Min.

Max.

Min.

Max.

Min.

Max.

Min.

00
0
2
4

6
6
8
7

0.060
0.075
0.100
0.116

0.057
0.072
0.097
0.112

0.099
0.127
0.162
0.211

0.090
0.118
0.146
0.193

0.034
0.049
0.069
0.086

0.026
0.041
0.059
0.075

0.049
0.063
0.083
0.096

0.046
0.060
0.080
0.092

55
51
44
37

0.052
0.067
0.086
0.104

6
7
8
10

7
8
8
8

0.140
0.154
0.167
0.182

0.136
0.150
0.162
0.177

0.260
0.285
0.309
0.359

0.240
0.264
0.287
0.334

0.103
0.111
0.120
0.137

0.091
0.099
0.107
0.123

0.116
0.126
0.136
0.150

0.112
0.122
0.132
0.146

31
29
27
20

0.120
0.136
0.144
0.161

12
14

8
9

0.212
0.242

0.206
0.236

0.408
0.457

0.382
0.429

0.153
0.170

0.139
0.155

0.177
0.202

0.173
0.198

11
2

0.191
0.221

L

Nominal
Screw Length


3/16

1/4

5/16

3/8

1/2

5/8

3/4

1 in. and
over

S

Pilot Length

0.047

0.047

0.047

0.047

0.062

0.062

0.078

0.078

0.125

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