The Pattern · the phenotype, made adjustable
The Pattern Configurator
The genotype does not move: the posture, and two congruent 40-60-80 triangles sharing a keel. Everything below that is phenotype, and this page is where you can push on it. Set the free parameters and the drawings redraw from the same code that cuts the chair.
Three drawings, the same three the Keel Panel plans print. The side elevation is what the chair becomes when the parts close. The keel layout is the one part that asks for care. The parts plate is what you take to the saw. All three are generated here in your browser, out of the same geometry the Recipe and the technical notes use.
Every number on the drawings is derived, not typed. The two 80 degree apexes, B where the seat meets the back and F where the tie meets the front, are dimensioned along both of their members from the keel kiss, and the seat also carries a reference to the keel's inside corner, which is the one a tape can actually hook. Both acute tails of the keel are trimmed parallel to the back, because a 40 degree point chips.
The colours are the members: keel red, back blue, seat yellow, front green, tie black.
The drawing code in k2.js is a transliteration of the Python generators, so this page and the print set are drawn from the same parameters. Nothing currently checks one against the other, so they can drift, and any difference between what you see here and what the print set shows is a bug rather than a variant.
the Pattern · the Keel Panel plans · TN-9, the keel · hundredyearchair.com