"""ISO 10642 (DIN 7991) countersunk socket screw. Envelope: 90 degree head and plain shank in one revolved
profile, hex socket. The head's top face is on the XY plane at the origin; `length` is the overall length."""
from steve import Model

size = "M4"  # Thread size
length = 12  # mm Overall length (head included)

# size: (head diameter dk, head height k, hex key s)
HEADS = {
    'M3': (6.72, 1.86, 2.0),
    'M4': (8.96, 2.48, 2.5),
    'M5': (11.2, 3.1, 3.0),
    'M6': (13.44, 3.72, 4.0),
    'M8': (17.92, 4.96, 5.0),
    'M10': (22.4, 6.2, 6.0),
    'M12': (26.88, 7.44, 8.0),
}
NOMINAL = {
    'M3': 3.0,
    'M4': 4.0,
    'M5': 5.0,
    'M6': 6.0,
    'M8': 8.0,
    'M10': 10.0,
    'M12': 12.0,
}
dk, k, s = HEADS[size]
d = NOMINAL[size]
cone = (dk - d) / 2  # 90 degree countersink: as deep as it is wide
total = max(length, cone + 0.5)

model = Model()
with model.sketch("profile", on="XZ", name="Profile") as sk:
    sk.polyline("outline", [(0, 0), (dk / 2, 0), (d / 2, -cone), (d / 2, -total), (0, -total)])
model.revolve("body", "profile", axis="Z")
with model.sketch("socket_sketch", on="XY", name="Hex socket") as sk:
    sk.polygon("hex", (0, 0), s / 2, 6, inscribed=False)
model.extrude("socket", "socket_sketch", distance=-0.8 * k, op="cut")
result = model.result()