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Machining - brunius.me

Tap Drill Chart

I got sick of online tap drill charts giving you weird numbers for stuff. So I made my own!
The 100% - 50% columns correspond to thread engagement - how much of the thread is in contact with the material.

TapDrillMath.ods

Metric Coarse Tap Drill Size
(Rounded to nearest 0.5mm)
Size Pitch Inner Diameter 100% 75% 50%
Metric Fine Tap Drill Size
(Rounded to nearest 0.5mm)
Size Pitch Inner Diameter 100% 75% 50%