HeliCoil Insert Lengths & Drill Sizes

G (BSPF)
Insert Size Drill Size Screw Thread Insert Length
1D 1.5D 2D 2.5D 3D

1/8-28

 25/64 0.125 0.188 0.250 0.313 0.375

1/4-19

17/32 0.250 0.375 0.500 0.625 0.750

3/8-19

43/64 0.375 0.563 0.750 0.938 1.125

1/2-14

27/32 0.500 0.750 1.000 1.250 1.500

5/8-14

59/64 0.625 0.938 1.250 1.563 1.875

3/4-14

1-1/6 0.750 1.125 1.500 1.875

7/8-14

1-13/64 0.875 1.313 1.750
2.625

1-11

1-21/64 1.000 1.500 2.000

1.1/4-11

1-43/64 1.250 1.875 2.500
3.750

1.1/2-11

1-29/32 1.500 2.250 3.000
4.500
BA
Insert Size Drill Size Screw Thread Insert Length
1D 1.5D 2D 2.5D 3D

0BA

6.2 mm 0.236 0.354 0.472 0.590 0.708

1BA

5.5 mm 0.209 0.313 0.418 0.522 0.627

2BA

4.9 mm 0.185 0.277 0.370 0.462 0.555

3BA

4.3 mm 0.161 0.241 0.322 0.402 0.483

4BA

3.8 mm 0.142 0.213 0.284 0.355 0.426

5BA

3.3 mm 0.126 0.189 0.252 0.315 0.378

6BA

2.9 mm 0.110 0.165 0.220 0.275 0.330
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