""" Bridge box: the printed enclosure for Control's bridge, the one board that transmits. A tub and a lid. The lid carries the stop button, the activate button, the status light and the antenna; the board lies on the floor, held by a zip tie; the USB cable comes in through a slot in one end. Run from the cad/ folder: uv run bridge-box/model.py It writes, for the site: site/public/files/control/stl/*.stl printed parts, laid flat for printing site/public/files/control/bridge-box-stl.zip site/public/files/control/bridge-box.step the whole assembly, for editing site/public/files/control/bridge-box.glb the 3D model shown on the page site/public/files/control/bridge-box-motion.json site/public/files/control/bridge-box-cad.py this script site/src/content/instruments/bridge/drawings/bridge-box-render.svg Coordinates, in millimeters: X runs along the box from the cable end (0) to the stop-button end (L). Y runs across it, front (0) to back (W). Z is up; the floor's underside is at 0 and the tub's rim at H. The board doesn't need to line up with any hole: the cable plugs in inside the box, so the ESP32-S3 board, with or without a screw-terminal expansion board, can sit anywhere on the floor between the two zip-tie slots. All numbers are a first design, untested in print. Measure your buttons before printing and change the hole sizes below to match. """ from pathlib import Path import re import shutil import sys import zipfile from build123d import ( Axis, Box, Circle, Color, Compound, Cylinder, ExportSVG, Plane, Pos, Rot, Spline, Unit, export_gltf, export_step, export_stl, sweep, ) HERE = Path(__file__).resolve().parent sys.path.insert(0, str(HERE.parent)) from recipe import compact_glb, slide, write_motion # noqa: E402 REPO = HERE.parent.parent OUT = REPO / "site/public/files/control" DRAWINGS = REPO / "site/src/content/instruments/bridge/drawings" # --------------------------------------------------------------------------- # The design, in one place # --------------------------------------------------------------------------- L, W, H = 140.0, 100.0, 72.0 # tub outside, without the lid. H leaves room under the stop button. WALL = 2.4 # six lines of a 0.4 mm nozzle FLOOR = 3.0 # thick enough for the zip-tie groove underneath R = 6.0 # outside corner radius LID_T = 3.0 # most panel buttons clamp panels up to about 5 mm RIM_H, RIM_W, FIT = 3.0, 1.6, 0.3 # the lip under the lid that locates it inside the walls BOSS_R = 4.5 # corner posts for the lid screws BOSS_C = WALL + BOSS_R - 0.5 # post center, in from each outside edge INSERT_R, INSERT_D = 2.1, 6.0 # M3 heat-set insert hole SCREW_R = 1.7 # M3 clearance in the lid CY = W / 2 # everything on the lid sits on the center line ANT_X, LED_X, REL_X, GO_X, STOP_X = 14.0, 28.0, 50.0, 72.0, 108.0 STOP_D = 22.4 # standard 22 mm panel button RELEASE_D = 16.2 # a 16 mm momentary button; change for 12 or 19 mm GO_BUTTON = False # True adds a third hole, the same size, for a Go button LED_D = 8.0 # a 5 mm LED in a panel holder SMA_D = 6.5 # SMA bulkhead thread is 1/4 inch USB_SLOT = (16.0, 9.0, 20.0) # width, height and center height of the cable slot; a USB-C plug passes through TIE_X, TIE_SPAN, TIE_SLOT = 55.0, 76.0, (5.0, 2.6) # zip-tie slots: across the floor, this far apart MOUNT_DX, MOUNT_R = 60.0, 2.7 # two M5 holes in the floor, for T-nuts in a 20 mm extrusion slot # --------------------------------------------------------------------------- # Helpers # --------------------------------------------------------------------------- def box(x0, x1, y0, y1, z0, z1): return Pos((x0 + x1) / 2, (y0 + y1) / 2, (z0 + z1) / 2) * Box(x1 - x0, y1 - y0, z1 - z0) def cyl_z(x, y, r, z0, z1): return Pos(x, y, (z0 + z1) / 2) * Cylinder(r, z1 - z0) def rounded(x0, x1, y0, y1, z0, z1, r): """A box with its four vertical edges rounded.""" b = box(x0, x1, y0, y1, z0, z1) return b.fillet(r, b.edges().filter_by(Axis.Z)) def usb_cable(route=None, end_dir=None): """The USB cable: its USB-C plug through the slot in the end, a round cable along `route`, and a USB-A plug at the far end, for the computer, pointing along `end_dir` (by default, the way the route's last stretch runs). The default route drops to the desk and curves away to the front.""" z = USB_SLOT[2] if route is None: route = [(-26, CY, z), (-58, CY, 9), (-80, CY - 18, 2.2), (-96, CY - 75, 2.2), (-120, CY - 135, 2.2)] plug_c = box(-20, 4, CY - 6, CY + 6, z - 3.25, z + 3.25) + Pos(-23, CY, z) * Rot(0, 90, 0) * Cylinder(3, 6) end_dir = end_dir or tuple(b - a for a, b in zip(route[-2], route[-1])) path = Spline(*route, tangents=[(-1, 0, 0), end_dir]) cable = sweep(Plane(origin=path @ 0, z_dir=path % 0) * Circle(2.2), path=path) end = Plane(origin=path @ 1, z_dir=path % 1) plug_a = end * (Pos(0, 0, 3) * Cylinder(3, 6) + Pos(0, 0, 15) * Box(16, 8.5, 18) + Pos(0, 0, 30) * Box(12, 4.5, 12)) return plug_c + cable + plug_a def corners(inset): return [(x, y) for x in (inset, L - inset) for y in (inset, W - inset)] # --------------------------------------------------------------------------- # Printed parts, in assembly position # --------------------------------------------------------------------------- def tub(): """The box itself, open at the top. Prints upright with no supports.""" p = rounded(0, L, 0, W, 0, H, R) p -= rounded(WALL, L - WALL, WALL, W - WALL, FLOOR, H + 1, R - WALL) for x, y in corners(BOSS_C): p += cyl_z(x, y, BOSS_R, FLOOR, H) p -= cyl_z(x, y, INSERT_R, H - INSERT_D, H + 1) w, h, zc = USB_SLOT p -= box(-1, WALL + 1, CY - w / 2, CY + w / 2, zc - h / 2, zc + h / 2) sx, sy = TIE_SLOT for y in (CY - TIE_SPAN / 2, CY + TIE_SPAN / 2): p -= box(TIE_X - sx / 2, TIE_X + sx / 2, y - sy / 2, y + sy / 2, -1, FLOOR + 1) p -= box(TIE_X - sx / 2, TIE_X + sx / 2, CY - TIE_SPAN / 2 - 2, CY + TIE_SPAN / 2 + 2, -1, 1.4) # tie lies flush underneath for dx in (-MOUNT_DX / 2, MOUNT_DX / 2): p -= cyl_z(L / 2 + dx, CY, MOUNT_R, -1, FLOOR + 1) return p def lid_holes(): """The bridge's own lid: everything on the center line. (x, y, diameter)""" holes = [(STOP_X, CY, STOP_D), (REL_X, CY, RELEASE_D), (LED_X, CY, LED_D), (ANT_X, CY, SMA_D)] if GO_BUTTON: holes.append((GO_X, CY, RELEASE_D)) return holes def lid(holes=None, windows=()): """Prints top face down, so the lip is on top and nothing needs support. holes: (x, y, diameter), the bridge's own by default. windows: (x, y, width, height) cutouts.""" p = rounded(0, L, 0, W, H, H + LID_T, R) rim = rounded(WALL + FIT, L - WALL - FIT, WALL + FIT, W - WALL - FIT, H - RIM_H, H, R - WALL - FIT) rim -= rounded(WALL + FIT + RIM_W, L - WALL - FIT - RIM_W, WALL + FIT + RIM_W, W - WALL - FIT - RIM_W, H - RIM_H - 1, H + 1, 1) for x, y in corners(BOSS_C): rim -= cyl_z(x, y, BOSS_R + 0.6, H - RIM_H - 1, H + 1) p += rim for x, y in corners(BOSS_C): p -= cyl_z(x, y, SCREW_R, H - 1, H + LID_T + 1) for x, y, d in lid_holes() if holes is None else holes: p -= cyl_z(x, y, d / 2, H - RIM_H - 1, H + LID_T + 1) for x, y, w, h in windows: p -= box(x - w / 2, x + w / 2, y - h / 2, y + h / 2, H - RIM_H - 1, H + LID_T + 1) return p # (name, builder, rotation that lays it flat for printing) PRINTED = [ ("tub", tub, Rot(0, 0, 0)), ("lid", lid, Rot(180, 0, 0)), ] # --------------------------------------------------------------------------- # Bought parts, simplified, for the assembly only # --------------------------------------------------------------------------- TOP = H + LID_T # the lid's top face ON_LID = ["printed:lid", "bought:stop-button", "bought:release-button", "bought:status-light", "bought:antenna"] def bought_parts(): z0 = FLOOR + 2 # on a strip of foam tape parts = [ ( "stop-button", cyl_z(STOP_X, CY, 20, TOP + 8, TOP + 22) + cyl_z(STOP_X, CY, 15, TOP, TOP + 8) + box(STOP_X - 15, STOP_X + 15, CY - 20, CY + 20, H - 45, H - RIM_H), (0.8, 0.15, 0.12), ), ("release-button", cyl_z(REL_X, CY, 9, TOP, TOP + 7) + cyl_z(REL_X, CY, 8, H - 28, H - RIM_H), (0.15, 0.15, 0.15)), ("status-light", cyl_z(LED_X, CY, 4.5, TOP, TOP + 3) + cyl_z(LED_X, CY, 2.5, TOP + 3, TOP + 7), (0.92, 0.92, 0.9)), ("antenna", cyl_z(ANT_X, CY, 5, TOP, TOP + 12) + cyl_z(ANT_X, CY, 4.5, TOP + 12, TOP + 190), (0.12, 0.12, 0.12)), ("expansion-board", box(10, 82, CY - 30, CY + 30, z0, z0 + 12), (0.1, 0.25, 0.15)), ("esp32-s3-board", box(14, 83, CY - 14, CY + 14, z0 + 12, z0 + 17), (0.12, 0.12, 0.14)), ("zip-tie", box(TIE_X - 2, TIE_X + 2, CY - TIE_SPAN / 2, CY + TIE_SPAN / 2, z0 + 17, z0 + 18.2), (0.9, 0.9, 0.85)), ("usb-cable", usb_cable(), (0.2, 0.2, 0.22)), ] return parts # --------------------------------------------------------------------------- # Build and export # --------------------------------------------------------------------------- def lay_flat(shape, rotation): s = rotation * shape bb = s.bounding_box() return Pos(-(bb.min.X + bb.max.X) / 2, -(bb.min.Y + bb.max.Y) / 2, -bb.min.Z) * s def main(): (OUT / "stl").mkdir(parents=True, exist_ok=True) assembly = [] print(f"{'part':8} {'volume cm3':>10} {'print size (mm)':>18} valid") for name, build, rotation in PRINTED: part = build() part.label = f"printed:{name}" part.color = Color(0.86, 0.42, 0.28) assembly.append(part) flat = lay_flat(part, rotation) size = flat.bounding_box().size print(f"{name:8} {part.volume / 1000:10.1f} {size.X:5.0f} x {size.Y:4.0f} x {size.Z:4.0f} {part.is_valid}") export_stl(flat, OUT / "stl" / f"bridge-box-{name}.stl", tolerance=0.02, angular_tolerance=0.2) for name, shape, rgb in bought_parts(): shape.label = f"bought:{name}" shape.color = Color(*rgb) assembly.append(shape) model = Compound(children=assembly, label="bridge-box") export_step(model, OUT / "bridge-box.step") export_gltf(model, OUT / "bridge-box.glb", unit=Unit.MM, binary=True, linear_deflection=0.08, angular_deflection=0.3) compact_glb(OUT / "bridge-box.glb") write_motion( OUT / "bridge-box-motion.json", duration=7, tracks=[slide(ON_LID, (0, 0, 1), [(0, 0), (0.8, 0), (2.2, 70), (4.8, 70), (6.2, 0), (7, 0)])], captions=[ (0, "The lid carries the stop button, the activate button, the light and the antenna."), (2.2, "Underneath, the board lies on the floor, held by one zip tie. The cable comes in at the end."), (4.8, "Four screws hold the lid down."), ], ) with zipfile.ZipFile(OUT / "bridge-box-stl.zip", "w", zipfile.ZIP_DEFLATED) as z: for stl in sorted((OUT / "stl").glob("bridge-box-*.stl")): z.write(stl, f"bridge-box/{stl.name}") shutil.copyfile(__file__, OUT / "bridge-box-cad.py") DRAWINGS.mkdir(parents=True, exist_ok=True) render(model, DRAWINGS / "bridge-box-render.svg") print("written to", OUT) def sheet(path, title, note, views): """Line drawings of the model, framed like the other drawing sheets. views: (shape, eye, look_at, caption) for each figure, stacked top to bottom.""" figures, y = [], 110 for i, (shape, eye, look_at, caption) in enumerate(views, start=1): visible, _hidden = shape.project_to_viewport(eye, viewport_up=(0, 0, 1), look_at=look_at) svg = ExportSVG(margin=4, line_weight=0.25) svg.add_layer("visible", line_color=(0.067, 0.067, 0.067), line_weight=0.25) svg.add_shape(visible, layer="visible") raw = path.with_suffix(f".{i}.svg") svg.write(raw) inner = raw.read_text() raw.unlink() view_box = re.search(r'viewBox="([^"]+)"', inner).group(1) body = inner[inner.index(">", inner.index("")] _, _, vw, vh = (float(v) for v in view_box.split()) w = min(1120, round(560 * vw / vh)) h = round(w * vh / vw) figures.append(f'{body}') figures.append(f'FIG. {i} {caption}') y += h + 80 height = y path.write_text( f'\n' f"{title}\n" f'\n' 'THE MACHINE\n' f'{title}\n' f'{note}\n' '2026-10-19\n' '\n' + "\n".join(figures) + "\n\n" ) def render(model, path): """The box closed, from the front corner, with its antenna up and its cable running off to the computer.""" sheet( path, "Bridge: the box", "Drawn from the CAD model.", [(model, (L + 160, -170, H + 180), (L / 2 - 40, W / 2 - 40, H / 2 + 30), "THE BOX: STOP, ACTIVATE AND LIGHT ON THE LID, THE ANTENNA, AND THE CABLE TO THE COMPUTER")], ) if __name__ == "__main__": main()