Consider using dprism for extrude_taper instead of loft

[gumyr]

The surface of the sphere is this example is not correct; however, using a Cone does work.

from build123d import *
from ocp_vscode import show_all

ball_dia = 100
base_dia = 90
base_thickness = 10
base_fillet = 5
base_chamfer = 5
hole_dia = 20
hole_taper = 2

with BuildPart() as ball:
    Sphere(ball_dia / 2)
    with Locations((0, 0, -ball_dia / 2)):
        Cylinder(
            base_dia / 2, base_thickness, align=(Align.CENTER, Align.CENTER, Align.MIN)
        )
    top_surface_coord = -ball_dia / 2 + base_thickness
    fillet_edge, chamfer_edge = (
        ball.edges(Select.LAST)
        .filter_by_position(Axis.Z, top_surface_coord, top_surface_coord)
        .sort_by(SortBy.RADIUS)
    )
    fillet(fillet_edge, base_fillet)
    chamfer(chamfer_edge, base_chamfer)
    # with Locations(Plane.XZ.offset(ball_dia / 2)):
    #     Cone(
    #         hole_dia * 0.5,
    #         hole_dia * 0.4,
    #         ball_dia,
    #         mode=Mode.SUBTRACT,
    #         align=(Align.CENTER, Align.CENTER, Align.MAX),
    #     )
    with BuildSketch(Plane.XZ) as hole_sketch:
        Circle(hole_dia / 2)
    extrude(
        hole_sketch.sketch,
        # until=Until.LAST,
        amount=ball_dia,
        # both=True,
        mode=Mode.SUBTRACT,
        # mode=Mode.INTERSECT,
        taper=hole_taper,
    )
    extrude(
        hole_sketch.sketch,
        amount=-ball_dia,
        mode=Mode.SUBTRACT,
        taper=-hole_taper,
    )

The dprism method might be a good alternative to the loft currently used in extrude_taper.

[jdegenstein]

Here is a comparison @jrmobley made a long time ago when we were discussing something related. The differences in behavior are not intuitively obvious between the two methods.

EDIT: give proper credit to jrmobley