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Tap Drill (Fine) Spec Table
Tap Drill (Fine) KS Specifications — 9 sizes
KS B 0204
Drill size table for tapping fine-pitch metric threads.
Practical Notes
- Fine threads have larger pilot holes and shallower threads than coarse. Ensure 60%+ effective thread engagement as clamping force is lower.
- Fine pitch taps have poor chip evacuation. Use spiral point (through-hole) or spiral flute (blind hole) taps.
Selection Guide
Pilot drill sizes for fine-pitch metric threads. Larger drill than coarse equivalent with shallower effective depth. For thin-walled parts, hydraulic ports, and precision adjustment screws requiring fine threads.
KSTap Drill (Fine)
9 sizes| Tap | P | Drill | Steel | Cast Iron | Aluminum |
|---|---|---|---|---|---|
| M6 | 0.75 | 5.2 | - | - | Fine Thread |
| M8 | 1 | 7 | - | - | Fine Thread |
| M10 | 1 | 9 | - | - | Fine Thread |
| M10 | 1.25 | 8.8 | - | - | Fine Thread |
| M12 | 1.25 | 10.8 | - | - | Fine Thread |
| M12 | 1.5 | 10.5 | - | - | Fine Thread |
| M14 | 1.5 | 12.5 | - | - | Fine Thread |
| M16 | 1.5 | 14.5 | - | - | Fine Thread |
| M20 | 1.5 | 18.5 | - | - | Fine Thread |
Key Features
- Pilot drill diameter for fine thread only; larger hole than coarse thread equivalent
- Shallower effective thread depth suits tapping in thin-walled and sheet parts
- Detailed pilot diameters for each pitch: M8×1.0, M12×1.25, etc.
Key Applications
Hydraulic ports (fine thread), aviation lightweight tapping, thin brackets, precision adjustment screw holes, instrument fastening
FAQ
Why is fine thread pilot hole larger?
Fine threads have smaller pitch, so (drill = diameter − pitch) yields larger drill size. E.g., M10×1.25 (fine)→8.75mm vs M10×1.5 (coarse)→8.5mm.