Jerry
283 lines
8.2 KiB
Python
283 lines
8.2 KiB
Python
from math import cos, pi, sin, tau
|
|
|
|
from build123d import (
|
|
Align,
|
|
BuildPart,
|
|
BuildSketch,
|
|
Color,
|
|
Compound,
|
|
Cylinder,
|
|
Location,
|
|
Locations,
|
|
Mode,
|
|
Plane,
|
|
Polygon,
|
|
extrude,
|
|
)
|
|
|
|
|
|
# Units: millimeters.
|
|
# Origin: sun/ring center on the carrier axis.
|
|
# XY: gear plane. +Z: gear and pin axes.
|
|
|
|
GEAR_THICKNESS = 8.0
|
|
GEAR_BOTTOM_Z = 0.0
|
|
|
|
SUN_TEETH = 24
|
|
SUN_PITCH_DIAMETER = 48.0
|
|
SUN_ROOT_DIAMETER = 42.0
|
|
SUN_OUTSIDE_DIAMETER = 54.0
|
|
SUN_BORE_DIAMETER = 10.0
|
|
|
|
PLANET_TEETH = 18
|
|
PLANET_PITCH_DIAMETER = 36.0
|
|
PLANET_ROOT_DIAMETER = 31.0
|
|
PLANET_OUTSIDE_DIAMETER = 41.0
|
|
PLANET_CENTER_RADIUS = 42.0
|
|
PLANET_COUNT = 3
|
|
PLANET_BORE_DIAMETER = 6.8
|
|
|
|
EXTERNAL_TOOTH_ROOT_SPAN_FRACTION = 0.42
|
|
EXTERNAL_TOOTH_TIP_SPAN_FRACTION = 0.18
|
|
|
|
|
|
def _srgb_channel_to_linear(channel: int) -> float:
|
|
value = channel / 255.0
|
|
if value <= 0.04045:
|
|
return value / 12.92
|
|
return ((value + 0.055) / 1.055) ** 2.4
|
|
|
|
|
|
def _srgb_color(hex_color: str) -> Color:
|
|
value = hex_color.removeprefix("#")
|
|
if len(value) != 6:
|
|
raise ValueError(f"Expected #rrggbb color, got {hex_color!r}")
|
|
return Color(
|
|
_srgb_channel_to_linear(int(value[0:2], 16)),
|
|
_srgb_channel_to_linear(int(value[2:4], 16)),
|
|
_srgb_channel_to_linear(int(value[4:6], 16)),
|
|
1.0,
|
|
)
|
|
|
|
|
|
# Match the docs app's dark-mode hero render source colors.
|
|
PLANET_COLORS = (
|
|
_srgb_color("#61d4f6"),
|
|
_srgb_color("#a6ea90"),
|
|
_srgb_color("#ed9ee5"),
|
|
)
|
|
|
|
RING_TEETH = 60
|
|
RING_INTERNAL_PITCH_DIAMETER = 120.0
|
|
RING_INTERNAL_ROOT_DIAMETER = 126.0
|
|
RING_INTERNAL_TIP_DIAMETER = 115.0
|
|
RING_OUTSIDE_DIAMETER = 140.0
|
|
RING_TOOTH_ROOT_SPAN_FRACTION = 0.68
|
|
RING_TOOTH_TIP_SPAN_FRACTION = 0.34
|
|
RING_COLOR = _srgb_color("#c5adef")
|
|
SUN_COLOR = _srgb_color("#fdce76")
|
|
CARRIER_COLOR = _srgb_color("#bfcec8")
|
|
PIN_COLOR = _srgb_color("#818993")
|
|
|
|
CARRIER_DIAMETER = 105.0
|
|
CARRIER_BOTTOM_Z = -5.0
|
|
CARRIER_TOP_Z = -1.0
|
|
CARRIER_THICKNESS = CARRIER_TOP_Z - CARRIER_BOTTOM_Z
|
|
|
|
PIN_DIAMETER = 6.0
|
|
PIN_HEIGHT = 14.0
|
|
PIN_BOTTOM_Z = -5.0
|
|
PIN_CARRIER_CLEARANCE_DIAMETER = 6.4
|
|
|
|
|
|
def _polar_point(radius: float, angle: float) -> tuple[float, float]:
|
|
return (radius * cos(angle), radius * sin(angle))
|
|
|
|
|
|
def _trapezoid_tooth_profile(
|
|
*,
|
|
teeth: int,
|
|
root_radius: float,
|
|
tip_radius: float,
|
|
phase: float,
|
|
root_span_fraction: float = 0.72,
|
|
tip_span_fraction: float = 0.38,
|
|
) -> list[tuple[float, float]]:
|
|
"""Return a closed-profile point loop with straight-sided schematic teeth."""
|
|
pitch_angle = tau / teeth
|
|
points: list[tuple[float, float]] = []
|
|
|
|
for tooth_index in range(teeth):
|
|
center_angle = phase + tooth_index * pitch_angle
|
|
points.extend(
|
|
(
|
|
_polar_point(root_radius, center_angle - root_span_fraction * pitch_angle / 2.0),
|
|
_polar_point(tip_radius, center_angle - tip_span_fraction * pitch_angle / 2.0),
|
|
_polar_point(tip_radius, center_angle + tip_span_fraction * pitch_angle / 2.0),
|
|
_polar_point(root_radius, center_angle + root_span_fraction * pitch_angle / 2.0),
|
|
)
|
|
)
|
|
|
|
return points
|
|
|
|
|
|
def _make_external_gear(
|
|
*,
|
|
label: str,
|
|
teeth: int,
|
|
root_diameter: float,
|
|
outside_diameter: float,
|
|
phase: float,
|
|
center: tuple[float, float] = (0.0, 0.0),
|
|
bore_diameter: float | None = None,
|
|
color: Color | None = None,
|
|
):
|
|
with BuildPart() as gear:
|
|
with BuildSketch(Plane.XY):
|
|
Polygon(
|
|
_trapezoid_tooth_profile(
|
|
teeth=teeth,
|
|
root_radius=root_diameter / 2.0,
|
|
tip_radius=outside_diameter / 2.0,
|
|
phase=phase,
|
|
root_span_fraction=EXTERNAL_TOOTH_ROOT_SPAN_FRACTION,
|
|
tip_span_fraction=EXTERNAL_TOOTH_TIP_SPAN_FRACTION,
|
|
),
|
|
align=None,
|
|
)
|
|
extrude(amount=GEAR_THICKNESS)
|
|
|
|
if bore_diameter is not None:
|
|
with Locations(Location((0.0, 0.0, -0.5))):
|
|
Cylinder(
|
|
radius=bore_diameter / 2.0,
|
|
height=GEAR_THICKNESS + 1.0,
|
|
align=(Align.CENTER, Align.CENTER, Align.MIN),
|
|
mode=Mode.SUBTRACT,
|
|
)
|
|
|
|
part = gear.part.moved(Location((center[0], center[1], GEAR_BOTTOM_Z)))
|
|
part.label = label
|
|
part.color = color
|
|
return part
|
|
|
|
|
|
def _make_internal_ring_gear(*, label: str, phase: float, color: Color | None = None):
|
|
with BuildPart() as ring:
|
|
Cylinder(
|
|
radius=RING_OUTSIDE_DIAMETER / 2.0,
|
|
height=GEAR_THICKNESS,
|
|
align=(Align.CENTER, Align.CENTER, Align.MIN),
|
|
)
|
|
|
|
with BuildSketch(Plane.XY):
|
|
Polygon(
|
|
_trapezoid_tooth_profile(
|
|
teeth=RING_TEETH,
|
|
root_radius=RING_INTERNAL_ROOT_DIAMETER / 2.0,
|
|
tip_radius=RING_INTERNAL_TIP_DIAMETER / 2.0,
|
|
phase=phase,
|
|
root_span_fraction=RING_TOOTH_ROOT_SPAN_FRACTION,
|
|
tip_span_fraction=RING_TOOTH_TIP_SPAN_FRACTION,
|
|
),
|
|
align=None,
|
|
)
|
|
extrude(amount=GEAR_THICKNESS, mode=Mode.SUBTRACT)
|
|
|
|
part = ring.part
|
|
part.label = label
|
|
part.color = color
|
|
return part
|
|
|
|
|
|
def _make_carrier_plate():
|
|
with BuildPart() as carrier:
|
|
with Locations(Location((0.0, 0.0, CARRIER_BOTTOM_Z))):
|
|
Cylinder(
|
|
radius=CARRIER_DIAMETER / 2.0,
|
|
height=CARRIER_THICKNESS,
|
|
align=(Align.CENTER, Align.CENTER, Align.MIN),
|
|
)
|
|
for index in range(PLANET_COUNT):
|
|
center = _polar_point(PLANET_CENTER_RADIUS, tau * index / PLANET_COUNT)
|
|
with Locations(Location((center[0], center[1], CARRIER_BOTTOM_Z - 0.1))):
|
|
Cylinder(
|
|
radius=PIN_CARRIER_CLEARANCE_DIAMETER / 2.0,
|
|
height=CARRIER_THICKNESS + 0.2,
|
|
align=(Align.CENTER, Align.CENTER, Align.MIN),
|
|
mode=Mode.SUBTRACT,
|
|
)
|
|
|
|
part = carrier.part
|
|
part.label = "carrier_plate"
|
|
part.color = CARRIER_COLOR
|
|
return part
|
|
|
|
|
|
def _make_planet_pin(*, label: str, center: tuple[float, float]):
|
|
with BuildPart() as pin:
|
|
with Locations(Location((center[0], center[1], PIN_BOTTOM_Z))):
|
|
Cylinder(
|
|
radius=PIN_DIAMETER / 2.0,
|
|
height=PIN_HEIGHT,
|
|
align=(Align.CENTER, Align.CENTER, Align.MIN),
|
|
)
|
|
|
|
part = pin.part
|
|
part.label = label
|
|
part.color = PIN_COLOR
|
|
return part
|
|
|
|
|
|
def _planet_center(index: int) -> tuple[float, float]:
|
|
angle = tau * index / PLANET_COUNT
|
|
return _polar_point(PLANET_CENTER_RADIUS, angle)
|
|
|
|
|
|
def gen_step():
|
|
"""Return a labeled simplified planetary gear assembly in millimeters."""
|
|
sun_pitch_angle = tau / SUN_TEETH
|
|
ring_pitch_angle = tau / RING_TEETH
|
|
|
|
parts = [
|
|
_make_carrier_plate(),
|
|
_make_internal_ring_gear(
|
|
label="ring_gear_60_internal_teeth",
|
|
phase=-ring_pitch_angle / 2.0,
|
|
color=RING_COLOR,
|
|
),
|
|
_make_external_gear(
|
|
label="sun_gear_24_teeth",
|
|
teeth=SUN_TEETH,
|
|
root_diameter=SUN_ROOT_DIAMETER,
|
|
outside_diameter=SUN_OUTSIDE_DIAMETER,
|
|
phase=-sun_pitch_angle / 2.0,
|
|
bore_diameter=SUN_BORE_DIAMETER,
|
|
color=SUN_COLOR,
|
|
),
|
|
]
|
|
|
|
for index in range(PLANET_COUNT):
|
|
planet_angle = tau * index / PLANET_COUNT
|
|
center = _planet_center(index)
|
|
parts.append(
|
|
_make_external_gear(
|
|
label=f"planet_gear_{index + 1}_18_teeth",
|
|
teeth=PLANET_TEETH,
|
|
root_diameter=PLANET_ROOT_DIAMETER,
|
|
outside_diameter=PLANET_OUTSIDE_DIAMETER,
|
|
phase=planet_angle,
|
|
center=center,
|
|
bore_diameter=PLANET_BORE_DIAMETER,
|
|
color=PLANET_COLORS[index],
|
|
)
|
|
)
|
|
parts.append(_make_planet_pin(label=f"planet_pin_{index + 1}", center=center))
|
|
|
|
assembly = Compound(
|
|
obj=parts,
|
|
children=parts,
|
|
label="simplified_planetary_gear_assembly",
|
|
)
|
|
return assembly
|