STI Drill Size
Tap Drill Sizes - STI Taps - Metric
Minor Diameter (After Tapping) (in)
Tap Drill Diameter (Metric)
Tap Size
Pitch
Min
Max
Aluminum Steel, Magnesium, Plastic
M2
0.4
2.087 2.597 3.108 4.152 5.174 6.217 8.271
2.199 2.722 3.248 4.332 5.374 6.407 8.483
2.1 2.3 4.2 5.2 3.15 6.25 10.5 12.5 14.5 16.5 8.3
2.1
M2.5
0.45
2.35
M3 M4 M5 M6 M8
0.5 0.7 0.8 1.0
3.2
4.25
5.3 6.3 8.4
1.25
M10 M12 M14 M16 M18 M20 M22 M24
1.5
10.324 12.379 14.433 16.433 18.541 20.541 22.541 24.649
10.560 12.644 14.733 16.733 18.896 20.896 22.896 25.049
10.5 12.5 14.5 16.5
1.75
2 2
2.5 2.5 2.5
18.75 20.75 22.75 24.75
18.75 20.75 22.75
3 24.75 The suggested drill sizes for aluminum listed in the table are within the minor diameter limits for STI tapped holes specified in MS 33537. Alternate drill sizes are suggested in many instances for magnesium, steel and plastics to provide for maximum tap wear life. In the case of magnesium, the larger size is recommended to allow for material close-in. There are suggested drill sizes and any special requirements or specifications will supersede these recommendations.
Threading Technical
786
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