The head read as a lampshade pushed onto a stick, and two numbers were
responsible.
The spray angle is derived as atan((tip - tie) / span), which at a tip
radius of 0.102 came to five degrees. Five degrees is not a besom; the
reference fans out until the spread at the sweeping end is comparable to
the length of the bundle itself, which is about twenty. The tip radius
carries that, and the slider range moves with it.
The twig lengths varied by three percent, so every twig finished within a
few millimetres of its neighbours and the bundle ended in a straight cut
across the bottom. That single edge is most of what made it look
manufactured: no bundle of cut birch ends level, and the ragged tip is
what identifies a besom on sight. Lengths now spread by about a third --
downwards only, never above the nominal span. Centring the spread on 1.0
first produced a 1.32 m broom from a declared length of 1.2, which the size
guard caught and which was a real inconsistency rather than a tolerance
problem.
Two supporting changes. The bundle ran from the binding down for 36% of the
broom against roughly half in the reference, so it is longer. And each
sheaf was a 31 mm slat, which at thirty-two of them read as a fan of laths;
they are narrower now and there are forty-six, keeping about the same mass
in the bundle with the pieces at the right scale.
One correction to the record: the head was not, as I first estimated by
eye, a fifth of the broom. Measured, it was 46% of the whole and 36% below
the binding. The eye was reading a diagonal reference against a vertical
render.
27 models, 18021 triangles, all checks pass, 0 floating cases.
CRT
f136250707