M20x2.5 Tap Drill — 17.5mm
The recommended tap drill for a M20x2.5 thread is 17.5mm. Thread engagement: ~75%.
Result
Answer
17.5mm drill bit
Standard
Thread SizeM20x2.5
Pitch2.5mm (coarse)
Tap Drill (mm)17.5mm
Tap Drill (fractional)11/16"
Thread Engagement~75%
For a M20x2.5 thread, use a 17.5mm drill bit (nearest fractional: 11/16"). This targets approximately 75% thread engagement, which is the standard recommendation for most applications.
Note
Reference value from published fastener data. Always verify with the fastener manufacturer for critical applications.
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About M20x2.5 Tap Drill
For an M20x2.5 thread (2.5mm coarse pitch), the recommended tap drill size is 17.5mm (nearest fractional: 11/16"). This produces approximately 75% thread engagement, which is the industry standard for most applications. Always use a sharp HSS or cobalt drill bit and proper cutting fluid when tapping.