Before screw thread insert installation , the Drilled hole has to be tapped with a STI hand tap or machine tap of the correct tap size.

Types of STI Taps available include:
1. Standard Plug screw thread insert taps (4-Thread Chamfer): Easy starting for through-holes and blind holes.

2.Standard Bottoming screw thread insert taps (2-Thread Chamfer): Ideal for blind holes that are Drilled to a minimum depth.

3.Spiral Pointed Plug screw thread insert taps (4-Thread Chamfer): Free-cutting for use in long through-holes and in blind holes

with chip clearance.

4.Spiral Flute Bottoming screw thread insert taps (2-Thread Chamfer): Pulls chips out of deep or blind holes in soft materials.

                                     Unified Thread Series  

 

thread size overall length thread length shank Dia. Square drive   thread size overall length thread length shank Dia. Square drive
2-56
1.875
0.562
0.141
0.110
  
3-56
1.937
0.625
0.141
0.110
3-48
1.937
0.625
0.141
0.110
  
4-48
2.000
0.687
0.141
0.110
4-40
2.000
0.687
0.141
0.110
  
6-40
2.125
0.750
0.168
0.131
5-40
2.125
0.750
0.168
0.131
  
8-36
2.375
0.937
0.220
0.165
6-32
2.375
0.875
0.194
0.152
  
10-32
2.500
1.000
0.255
0.191
8-32
2.375
0.937
0.220
0.165
  
12-28
2.718
1.125
0.318
0.238
10-24
2.500
1.000
0.255
0.191
  
1/4-28
2.718
1.125
0.318
0.238
12-24
2.718
1.125
0.318
0.238
  
5/16-24
2.937
1.250
0.381
0.286
1/4-20
2.718
1.125
0.318
0.238
  
3/8-24
3.156
1.438
0.323
0.242
5/16-18
2.937
1.250
0.381
0.286
  
7/16-20
3.375
1.656
0.367
0.275
3/8-16
3.375
1.656
0.367
0.275
  
1/2-20
3.593
1.656
0.429
0.322
7/16-14
3.593
1.656
0.429
0.322
  
9/16-18
3.812
1.812
0.480
0.360
1/2-13
3.812
1.812
0.480
0.360
  
5/8-18
4.031
1.812
0.542
0.406
9/16-12
4.031
1.812
0.542
0.406
  
3/4-16
4.468
2.000
0.652
0.489
5/8-11
4.250
2.000
0.590
0.442
  
7/8-14
5.125
2.500
0.800
0.600
3/4-10
4.687
2.218
0.697
0.523
  
1-12
5.437
2.562
0.896
0.672
7/8-9
5.125
2.500
0.800
0.600
  
1-14
5.437
2.562
0.896
0.672
1-8
5.750
2.562
1.021
0.766
  
11/8-12
5.750
2.562
1.021
0.766
11/8-7
6.062
3.000
1.108
0.831
  
11/4-12
6.062
3.000
1.108
0.831
11/4-7
6.375
3.000
1.233
0.925
  
13/8-12
6.375
3.000
1.233
0.925
13/8-6
6.687
3.187
1.305
0.979
  
11/2-12
6.687
3.187
1.305
0.979
11/2-6
7.000
3.187
1.430
1.072
  

                                        Metric Series

thread size overall length thread length shank Dia. Square drive
M2 x 0.4
45
10
2.80
2.24
M2.2 x 0.45
48
11
3.15
2.50
M2.5 x 0.45
48
11
3.15
2.50
M3 x 0.5
50
13
3.55
2.80
M3.5 x 0.6
53
13
4.50
3.55
M4 x 0.7
58
16
5.00
4.00
M5 x 0.8
66
19
6.30
5.00
M6 x 1
72
22
8.00
6.30
M7 x1
72
22
9.00
7.10
M8 x 1.25
80
24
10.00
8.00
M9 x 1.25
85
25
8.00
6.30
M10 x 1.5
89
29
9.00
7.10
M11 x 1.5
89
29
9.00
7.10
M12 x 1.75
95
30
11.20
9.00
M14 x 2
102
32
12.50
10.00
M15 x 2
112
37
14.00
11.20
M16 x 2
112
37
14.00
11.20
M18 x 2.5
118
38
16.00
12.50
M20 x 2.5
130
45
18.00
14.00
M22 x 2.5
135
48
20.00
16.00
M24 x 3
135
48
20.00
16.00
M27 x 3
151
51
22.40
18.00
M30 x 3.5
162
57
25.00
20.00
M30 x 3
162
57
25.00
20.00
M33 x 3.5
170
60
28.00
22.40
M36 x 4
170
60
28.00
22.40
M39 x 4
187
67
31.50
25.00
M42 x 4.5
187
67
31.50
25.00
M42 X 4
200
70
35.50
28.00
M52 X 5
221
76
40.00
31.50