HeliCoil Insert Lengths & Drill Sizes

BSW
Insert Size Drill Size Wire Thread Insert Length
1D 1.5D 2D 2.5D 3D

1/8-40

3.3 mm 0.125 0.188 0.250 0.313 0.375

3/16-24

5.0 mm 0.188 0.281 0.375 0.469 0.563

1/4-20

6.7 mm 0.250 0.375 0.500 0.625 0.750

5/16-18

21/64 0.313 0.469 0.625 0.781 0.938

3/8-16

25/64 0.375 0.563 0.750 0.938 1.125

7/16-14

29/64 0.438 0.656 0.875 1.094 1.313

1/2-12

33/64 0.500 0.750 1.000 1.250 1.500

9/16-12

37/64 0.562 0.844 1.125 1.406 1.688

5/8-11

21/32 0.625 0.938 1.250 1.563 1.875

11/16-11

23/32 0.688 1.031 1.375 1.719 2.063

3/4-10

25/32 0.750 1.125 1.500 1.875 2.250

7/8-9

29/32 0.875 1.313 1.750 2.188 2.625

1-8

1-1/32 1.000 1.500 2.000 2.500 3.000

1.1/8-7

1-11/64 1.125 1.688 2.250 2.813 3.375

1.1/4-7

1-19/64 1.250 1.875 2.500 3.125 3.750

1.1/2-6

1-35/64 1.500 2.250 3.000 3.750 4.500
BSF
Insert Size Drill Size Wire Thread Insert Length
1D 1.5D 2D 2.5D 3D

3/16-32

4.9 mm 0.188 0.281 0.375 0.469 0.563

7/32-28

5.8 mm 0.219 0.328 0.438 0.547 0.656

1/4-26

6.6 mm 0.250 0.375 0.500 0.625 0.750

9/32-26

7.4 mm 0.281 0.422 0.563 0.703 0.844

5/16-22

8.3 mm 0.313 0.469 0.625 0.781 0.938

3/8-20

9.8 mm 0.375 0.563 0.750 0.938 1.125

7/16-18

29/64 0.438 0.656 0.875 1.094 1.313

1/2-16

33/64 0.500 0.750 1.000 1.250 1.500

9/16-16

37/64 0.563 0.844 1.125 1.406 1.688

5/8-14

41/64 0.625 0.938 1.250 1.563 1.875

11/16-14

45/64 0.688 1.031 1.375 1.719 2.063

3/4-12

49/64 0.750 1.125 1.500 1.875 2.250

13/16-12

53/64 0.813 1.219 1.625 2.031 2.438

7/8-11

57/64 0.875 1.313 1.750 2.188 2.625

1-10

1-1/32 1.000 1.500 2.000 2.500

1.1/8-9

1-5/32 1.125 1.688 2.250 2.813

1.1/4-9

1-9/32 1.250 1.875 2.500 3.125

1.3/8-8

1-13/32 1.375 2.063 2.750

1.1/2-8

1-17/32 1.500 2.250 3.000
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