Twist to dim
Sheet 5 draws No. 002, the 13-inch Vuelta Lamp, open and closed. Two of its numbers are guesses until one is built.
The lamp is two cages, one inside the other, each of 16 slats 11/16 inch wide and 1/4 inch thick. The inner slats stand in the hub and the outer slats in a ring at the bottom; each cage has a ring at the top. Every slat is housed 3/8 inch at each end, with 11 inches showing between. The hub is glued to the base plate, and the outer cage’s bottom ring turns around it. The base is 7 5/8 inches across, and the only hardware in the lamp is the socket.
The slats are spaced 22 1/2 degrees apart, which leaves a gap of 7 1/2 degrees between each pair on the inner cage, a third of the circle open. Turn the outer cage half a pitch, 11 1/4 degrees, 3/4 inch at the rim, and each of its slats lands over a gap in the inner cage and overlaps it by about 2 degrees a side.
The bulb sits in a socket in the base, inside the inner cage, and the cord leaves through the plinth. The top is open inside the inner ring, 4 1/2 inches across, and that is where the heat is meant to go out.
What stops the outer cage at open and at closed is still being drawn, and the species is not chosen; I will pick it from the boards on the rack before the drawing is final. The 2 degrees of overlap is measured from the center of the bulb, and a standard bulb is 2 3/8 inches across, so light from its sides still slips past the slats at an angle: closed should leave the stripes faint and soft, not gone. The first lamp will show on camera how faint they are and whether the 4 1/2-inch opening lets the heat out, and the sheet will be reissued as Rev. B with whatever changes.