11/16-24 tap drill size

    Use a 41/64 drill (0.6406 in) for a 11/16-24 cutting tap at 75% thread.

    Drills for 11/16-24 (UNEF)
    Tap typeDrillDecimal (in)
    Cutting tap, 75% thread41/640.6406
    Cutting tap, 50% thread (hard material)21/320.6563
    Roll / form tap, 65% thread43/640.6719
    Pitch
    1.0583 mm (24 TPI)
    Major Ø
    0.6875
    Pitch Ø
    0.6604
    Minor Ø
    0.6424

    Common questions

    What size drill for a 11/16-24 tap?
    Use a 41/64 drill (0.6406 in) for a 11/16-24 cutting tap at 75% thread.
    What drill for a 11/16-24 roll (form) tap?
    About 0.6691 in; the nearest standard drill is 43/64. Check your tap maker's table.

    Other UNEF sizes

    Drill sizes from Machinery's Handbook and ASME B1.1/B1.13M; roll tap sizes from the form-tap formula. Tap and insert makers' tables are authoritative.

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