Reworked the core examples to exclude contributed examples.

examples/Ex006_Moving_the_Current_Working_Point.py

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+import cadquery as cq
+
+# These can be modified rather than hardcoding values for each dimension.
+circle_radius = 3.0     # The outside radius of the plate
+thickness = 0.25        # The thickness of the plate
+
+# Make a plate with two cutouts in it by moving the workplane center point
+# 1.  Establishes a workplane that an object can be built on.
+# 1a. Uses the named plane orientation "front" to define the workplane, meaning
+#     that the positive Z direction is "up", and the negative Z direction
+#     is "down".
+# 1b. The initial workplane center point is the center of the circle, at (0,0).
+# 2.  A circle is created at the center of the workplane
+# 2a. Notice that circle() takes a radius and not a diameter
+result = cq.Workplane("front").circle(circle_radius)
+
+# 3.  The work center is movide to (1.5, 0.0) by calling center().
+# 3a. The new center is specified relative to the previous center,not
+#     relative to global coordinates.
+# 4.  A 0.5mm x 0.5mm 2D square is drawn inside the circle.
+# 4a. The plate has not been extruded yet, only 2D geometry is being created.
+result = result.center(1.5, 0.0).rect(0.5, 0.5)
+
+# 5.  The work center is moved again, this time to (-1.5, 1.5).
+# 6.  A 2D circle is created at that new center with a radius of 0.25mm.
+result = result.center(-1.5, 1.5).circle(0.25)
+
+# 7.  All 2D geometry is extruded to the specified thickness of the plate.
+# 7a. The small circle and the square are enclosed in the outer circle of the
+#      plate and so it is assumed that we want them to be cut out of the plate.
+#      A separate cut operation is not needed.
+result = result.extrude(thickness)
+
+# Displays the result of this script
+show_object(result)