Head diameters and 82° countersink dimensions for inch flat head screws per ANSI B18.6.3.
Reference aid — verify before you cut. Thread data per ASME B1.1 (Unified), ASME B1.8 (Stub Acme) and ISO 965 (metric M profile); charts cite their source in each tool. Formulas and data are checked against published standards, but errors and edge cases are possible — always confirm critical dimensions against the controlling standard or a calibrated gage before machining. No warranty; use at your own risk. Tap the star on a tool to favorite it.
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82° countersink
Head Ø is the spec max (ANSI B18.6.3); countersink Ø and depth are computed from the 82° cone (depth from the sharp tip). Cut to the Ø and treat depth as a starting number — a real countersink has a truncated tip. Tap a row to copy the countersink Ø.