but selecting 'Radius' then the radius must be >= the 'height'
of the protrusion. Setting the height smaller will make
the crown fail. Setting the Radius (much) greater than the
height the protrusion will be flat at the top. The protrusion
was a rectangle in this case.
Selecting 'Offset' then the value must be <= the height of the
protrusion.
Selecting 'Offset and takeoff' the take off angle and the offset
must be such that a valid body can be created.
protrusion height 60mm
offset 50mm
angle 30
will work, Increasing the angle to 40 won't work but angle 40
and offset 20mm will work
For 'Radius and TakeOff' the radius must be > than the height
protrusion height 60mm
radius 65mm
angle 3
will work, Increasing the angle to 5 won't work but angle 5
and radius 70 will work
So for the 2 latter ones the combination of angle and radius
must define the faces of the protrusion in a way that they don't
overlap each other at the top.
