aniva
/
Cosplay
1
1
Fork 0
Code Issues 1 Pull Requests 2 Packages Projects Releases Wiki Activity

cosplay: Touhou/Houjuu Nue #4

Open
aniva wants to merge 189 commits from touhou/houjuu-nue into main
pull from: touhou/houjuu-nue
merge into: aniva:main
Conversation 0 Commits 189 Files Changed 12 +54 -91
2 changed files with 54 additions and 91 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files
Showing only changes of commit af56e28ac3 - Show all commits

130
nhf/joints.py
View File

@ -4,126 +4,86 @@ import cadquery as Cq
import nhf.springs as NS
from nhf import Role
def hirth_tooth_angle(n_tooth):
"""
Angle of one whole tooth
"""
return 360 / n_tooth
@dataclass(frozen=True)
class HirthJoint:
"""
A Hirth joint attached to a cylindrical base
"""
# r
radius: float = 60
# r_i
radius_inner: float = 40
base_height: float = 20
n_tooth: float = 16
# h_o
tooth_height: float = 16
tooth_height_inner: float = 2
def __post_init__(self):
# Ensures tangent doesn't blow up
assert self.n_tooth >= 5
assert self.radius > self.radius_inner
assert self.tooth_height >= self.tooth_height_inner
@property
def _theta(self):
return math.pi / self.n_tooth
@property
def tooth_angle(self):
return hirth_tooth_angle(self.n_tooth)
return 360 / self.n_tooth
def generate(self, tag_prefix="", is_mated=False, tol=0.01):
"""
is_mated: If set to true, rotate the teeth so they line up at 0 degrees.
FIXME: The curves don't mate perfectly. See if non-planar lofts can solve
this issue.
FIXME: Mate is not exact when number of tooth is low
"""
c, s, t = math.cos(self._theta), math.sin(self._theta), math.tan(self._theta)
span = self.radius * t
radius_proj = self.radius / c
span_inner = self.radius_inner * s
# 2 * raise + (inner tooth height) = (tooth height)
inner_raise = (self.tooth_height - self.tooth_height_inner) / 2
# Outer tooth triangle spans 2*theta radians. This profile is the radial
# profile projected onto a plane `radius` away from the centre of the
# cylinder. The y coordinates on the edge must drop to compensate.
# The drop is equal to, via similar triangles
drop = inner_raise * (radius_proj - self.radius) / (self.radius - self.radius_inner)
outer = [
(span, -tol - drop),
(span, -drop),
(0, self.tooth_height),
(-span, -drop),
(-span, -tol - drop),
]
adj = self.radius_inner * c
# In the case of the inner triangle, it is projected onto a plane `adj` away
# from the centre. The apex must extrapolate
# Via similar triangles
#
# (inner_raise + tooth_height_inner) -
# (tooth_height - inner_raise - tooth_height_inner) * ((radius_inner - adj) / (radius - radius_inner))
apex = (inner_raise + self.tooth_height_inner) - \
inner_raise * (self.radius_inner - adj) / (self.radius - self.radius_inner)
inner = [
(span_inner, -tol),
(span_inner, inner_raise),
(0, apex),
(-span_inner, inner_raise),
(-span_inner, -tol),
]
tooth = (
phi = math.radians(self.tooth_angle)
alpha = 2 * math.atan(self.radius / self.tooth_height * math.tan(phi/2))
#alpha = math.atan(self.radius * math.radians(180 / self.n_tooth) / self.tooth_height)
gamma = math.radians(90 / self.n_tooth)
# Tooth half height
l = self.radius * math.cos(gamma)
a = self.radius * math.sin(gamma)
t = a / math.tan(alpha / 2)
beta = math.asin(t / l)
dx = self.tooth_height * math.tan(alpha / 2)
profile = (
Cq.Workplane('YZ')
.polyline(inner)
.polyline([
(0, 0),
(dx, self.tooth_height),
(-dx, self.tooth_height),
])
.close()
.workplane(offset=self.radius - adj)
.polyline(outer)
.close()
.loft(ruled=False, combine=True)
.extrude(-self.radius)
.val()
.rotate((0, 0, 0), (0, 1, 0), math.degrees(beta))
.moved(Cq.Location((0, 0, self.base_height)))
)
angle_offset = hirth_tooth_angle(self.n_tooth) / 2 if is_mated else 0
h = self.base_height + self.tooth_height
teeth = (
core = Cq.Solid.makeCylinder(
radius=self.radius_inner,
height=self.tooth_height,
pnt=(0, 0, self.base_height),
)
angle_offset = self.tooth_angle / 2 if is_mated else 0
result = (
Cq.Workplane('XY')
.cylinder(
radius=self.radius,
height=self.base_height + self.tooth_height,
centered=(True, True, False))
.faces(">Z")
.tag(f"{tag_prefix}bore")
.cut(core)
.polarArray(
radius=adj,
radius=self.radius,
startAngle=angle_offset,
angle=360,
count=self.n_tooth)
.eachpoint(lambda loc: tooth.located(loc))
.intersect(Cq.Solid.makeCylinder(
height=h,
radius=self.radius,
))
.cut(Cq.Solid.makeCylinder(
height=h,
radius=self.radius_inner,
))
.cutEach(
lambda loc: profile.moved(loc),
)
base = (
Cq.Workplane('XY')
.cylinder(
height=self.base_height,
radius=self.radius,
centered=(True, True, False))
.faces(">Z").tag(f"{tag_prefix}bore")
.union(
teeth.val().move(Cq.Location((0,0,self.base_height))),
tol=tol)
.clean()
)
#base.workplane(offset=tooth_height/2).circle(radius=radius,forConstruction=True).tag("mate")
(
base
result
.polyline([
(0, 0, self.base_height),
(0, 0, self.base_height + self.tooth_height)
@ -131,11 +91,11 @@ class HirthJoint:
.tag(f"{tag_prefix}mate")
)
(
base
result
.polyline([(0, 0, 0), (1, 0, 0)], forConstruction=True)
.tag(f"{tag_prefix}directrix")
)
return base
return result
def assembly(self):
"""

3
nhf/test.py
View File

@ -13,7 +13,10 @@ class TestJoints(unittest.TestCase):
self.assertIsInstance(
obj.val().solids(), Cq.Solid,
msg="Hirth joint must be in one piece")
def test_joints_hirth_assembly(self):
for n_tooth in [16, 20, 24]:
with self.subTest(n_tooth=n_tooth):
j = nhf.joints.HirthJoint()
assembly = j.assembly()
isect = binary_intersection(assembly)