"""ISO 7045 pan head screw with cross recess. Envelope: head, a simplified cross recess, plain shank.
The head's bearing face is on the XY plane at the origin; the shank points down -Z."""
from steve import Model

size = "M3"  # Thread size
length = 10  # mm Length under the head

# size: (head diameter dk, head height k, cross recess number)
HEADS = {
    'M2': (4.0, 1.6, 1),
    'M2.5': (5.0, 2.0, 1),
    'M3': (5.6, 2.4, 1),
    'M4': (8.0, 3.1, 2),
    'M5': (9.5, 3.8, 2),
    'M6': (12.0, 4.6, 3),
    'M8': (16.0, 6.0, 4),
}
NOMINAL = {
    'M2': 2.0,
    'M2.5': 2.5,
    'M3': 3.0,
    'M4': 4.0,
    'M5': 5.0,
    'M6': 6.0,
    'M8': 8.0,
}
dk, k, recess = HEADS[size]
d = NOMINAL[size]
arm = 0.55 * dk
slot = 0.12 * dk

model = Model()
with model.sketch("head_sketch", on="XY", name="Head") as sk:
    sk.circle("head", (0, 0), dk / 2)
model.extrude("head", "head_sketch", distance=k)
with model.sketch("shank_sketch", on="XY", name="Shank") as sk:
    sk.circle("shank", (0, 0), d / 2)
model.extrude("shank", "shank_sketch", distance=-length)
model.plane("head_top", on="XY", offset=k, name="Head top")
with model.sketch("cross_x", on="head_top", name="Recess X") as sk:
    sk.center_rect("bar", (0, 0), arm, slot)
model.extrude("recess_x", "cross_x", distance=-0.5 * k, op="cut")
with model.sketch("cross_y", on="head_top", name="Recess Y") as sk:
    sk.center_rect("bar", (0, 0), slot, arm)
model.extrude("recess_y", "cross_y", distance=-0.5 * k, op="cut")
result = model.result()