feat: Disk joint for wrist and elbow
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from dataclasses import dataclass
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import cadquery as Cq
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from nhf import Role
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from nhf.build import Model, target
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import nhf.parts.springs as springs
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import nhf.utils
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TOL = 1e-6
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@dataclass
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class DiskJoint(Model):
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"""
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Sandwiched disk joint for the wrist and elbow
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"""
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radius_housing: float = 22.0
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radius_disk: float = 20.0
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radius_spring: float = 9 / 2
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radius_axle: float = 3.0
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housing_thickness: float = 5.0
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disk_thickness: float = 5.0
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# Gap between disk and the housing
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#disk_thickness_gap: float = 0.1
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spring_thickness: float = 1.3
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spring_height: float = 6.5
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spring_tail_length: float = 45.0
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spring_angle: float = 90.0
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spring_angle_shift: float = 0
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wall_inset: float = 2.0
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# Angular span of movement
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movement_angle: float = 120.0
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# Angular span of tongue on disk
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tongue_span: float = 30.0
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tongue_length: float = 10.0
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generate_inner_wall: bool = False
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def __post_init__(self):
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super().__init__(name="disk-joint")
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assert self.housing_thickness > self.wall_inset
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assert self.radius_housing > self.radius_disk
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assert self.radius_disk > self.radius_axle
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assert self.housing_upper_carve_offset > 0
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def spring(self):
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return springs.torsion_spring(
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radius=self.radius_spring,
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height=self.spring_height,
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thickness=self.spring_thickness,
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tail_length=self.spring_tail_length,
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right_handed=False,
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)
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@property
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def total_thickness(self):
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return self.housing_thickness * 2 + self.disk_thickness
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@property
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def opening_span(self):
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return self.movement_angle + self.tongue_span
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@property
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def housing_upper_carve_offset(self):
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return self.housing_thickness + self.disk_thickness - self.spring_height
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@property
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def radius_spring_internal(self):
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return self.radius_spring - self.spring_thickness
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@target(name="disk")
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def disk(self) -> Cq.Workplane:
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cut = (
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Cq.Solid.makeBox(
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length=self.spring_tail_length,
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width=self.spring_thickness,
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height=self.disk_thickness,
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)
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.located(Cq.Location((0, self.radius_spring_internal, 0)))
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.rotate((0, 0, 0), (0, 0, 1), self.spring_angle_shift)
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)
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result = (
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Cq.Workplane('XY')
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.cylinder(
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height=self.disk_thickness,
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radius=self.radius_disk,
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centered=(True, True, False)
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)
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.copyWorkplane(Cq.Workplane('XY'))
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.cylinder(
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height=self.disk_thickness,
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radius=self.radius_spring,
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centered=(True, True, False),
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combine='cut',
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)
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.cut(cut)
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)
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plane = result.copyWorkplane(Cq.Workplane('XY'))
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plane.tagPlane("dir", direction="+X")
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plane.workplane(offset=self.disk_thickness).tagPlane("mate_top")
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result.copyWorkplane(Cq.Workplane('YX')).tagPlane("mate_bot")
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radius_tongue = self.radius_disk + self.tongue_length
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tongue = (
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Cq.Solid.makeCylinder(
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height=self.disk_thickness,
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radius=radius_tongue,
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angleDegrees=self.tongue_span,
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).cut(Cq.Solid.makeCylinder(
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height=self.disk_thickness,
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radius=self.radius_disk,
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))
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)
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result = result.union(tongue, tol=TOL)
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return result
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def wall(self) -> Cq.Compound:
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height = self.disk_thickness + self.wall_inset
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wall = Cq.Solid.makeCylinder(
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radius=self.radius_housing,
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height=height,
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angleDegrees=360 - self.opening_span,
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).cut(Cq.Solid.makeCylinder(
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radius=self.radius_disk,
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height=height,
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)).rotate((0, 0, 0), (0, 0, 1), self.opening_span)
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return wall
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@target(name="housing-lower")
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def housing_lower(self) -> Cq.Workplane:
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result = (
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Cq.Workplane('XY')
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.cylinder(
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radius=self.radius_housing,
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height=self.housing_thickness,
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centered=(True, True, False),
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)
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.cut(Cq.Solid.makeCylinder(
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radius=self.radius_axle,
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height=self.housing_thickness,
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))
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)
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result.faces(">Z").tag("mate")
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result.faces(">Z").workplane().tagPlane("dir", direction="+X")
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result = result.cut(
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self
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.wall()
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.mirror("XY")
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.located(Cq.Location((0, 0, self.housing_thickness + self.disk_thickness)))
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#.rotate((0, 0, 0), (1, 0, 0), 180)
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#.located(Cq.Location((0, 0, self.disk_thickness + self.housing_thickness)))
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)
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return result
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@target(name="housing-upper")
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def housing_upper(self) -> Cq.Workplane:
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carve = (
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Cq.Solid.makeCylinder(
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radius=self.radius_spring,
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height=self.housing_thickness
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).fuse(Cq.Solid.makeBox(
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length=self.spring_tail_length,
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width=self.spring_thickness,
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height=self.housing_thickness
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).located(Cq.Location((0, self.radius_spring_internal, 0))))
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).rotate((0, 0, 0), (0, 0, 1), self.spring_angle - self.spring_angle_shift)
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result = (
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Cq.Workplane('XY')
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.cylinder(
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radius=self.radius_housing,
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height=self.housing_thickness,
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centered=(True, True, False),
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)
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)
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result.faces(">Z").tag("mate")
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result.copyWorkplane(Cq.Workplane('XY')).tagPlane("dir", direction="+X")
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result = result.faces(">Z").hole(self.radius_axle * 2)
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# tube which holds the spring interior
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if self.generate_inner_wall:
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tube = (
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Cq.Solid.makeCylinder(
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radius=self.radius_spring_internal,
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height=self.disk_thickness + self.housing_thickness,
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).cut(Cq.Solid.makeCylinder(
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radius=self.radius_axle,
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height=self.disk_thickness + self.housing_thickness,
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))
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)
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result = result.union(tube)
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wall = (
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self.wall()
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.rotate((0, 0, 0), (1, 0, 0), 180)
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.located(Cq.Location((0, 0, self.disk_thickness + self.housing_thickness + self.wall_inset)))
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)
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result = (
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result
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.union(wall, tol=TOL)
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.cut(carve.located(Cq.Location((0, 0, self.housing_upper_carve_offset))))
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)
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return result
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def assembly(self) -> Cq.Assembly:
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result = (
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Cq.Assembly()
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.add(self.disk(), name="disk", color=Role.CHILD.color)
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.add(self.housing_lower(), name="housing_lower", color=Role.PARENT.color)
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.add(self.housing_upper(), name="housing_upper", color=Role.PARENT.color)
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.constrain("disk?mate_bot", "housing_lower?mate", "Plane")
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.constrain("disk?mate_top", "housing_upper?mate", "Plane")
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.solve()
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)
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return result
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if __name__ == '__main__':
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p = DiskJoint()
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p.build_all()
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