Cosplay/nhf/parts/springs.py

import math
import cadquery as Cq

def torsion_spring(radius=12,
                   height=20,
                   thickness=2,
                   omega=90,
                   tail_length=25,
                   right_handed: bool = False):
    """
    Produces a torsion spring with abridged geometry since sweep is very slow in
    cq-editor.
    """
    if right_handed:
        omega = -omega
    base = (
        Cq.Workplane('XY')
        .cylinder(height=height, radius=radius,
                  centered=(True, True, False))
    )
    base.faces(">Z").tag("top")
    base.faces("<Z").tag("bot")

    box_shift = -radius if right_handed else radius-thickness
    result = (
        base
        .cylinder(height=height, radius=radius - thickness, combine='s',
                  centered=(True, True, True))
        .transformed(
            offset=(0, box_shift),
            rotate=(0, 0, 0))
        .box(
            length=tail_length,
            width=thickness,
            height=thickness,
            centered=False)
        .copyWorkplane(Cq.Workplane('XY'))
        .transformed(
            offset=(0, 0, height - thickness),
            rotate=(0, 0, omega))
        .center(-tail_length, box_shift)
        .box(
            length=tail_length,
            width=thickness,
            height=thickness,
            centered=False)
    )
    r = -radius if right_handed else radius
    plane = result.copyWorkplane(Cq.Workplane('XY'))
    plane.polyline([(0, r, 0), (tail_length, r, 0)],
                   forConstruction=True).tag("dir_bot")
    omega = math.radians(omega)
    c, s = math.cos(omega), math.sin(omega)
    l = -tail_length
    plane.polyline([
        (-s * r,        c * r, height),
        (c * l - s * r, c * r + s * l, height)],
        forConstruction=True).tag("dir_top")
    return result