Gusset

An open sheet metal kernel in Rust. Describe a part as JSON (a base plate and its flanges, hems, contour flanges, folds, faces joined by bends, holes and cut-outs) and Gusset gives you the folded solid, the flat pattern and its measurements, as STEP, DXF, SVG, a mesh or numbers.

Gusset is exact: the folded solid is an analytic B-rep, its mass properties are integrated, not meshed. What it doesn't build yet it refuses with a clear message; it never approximates.

Made by Bas Automation Services.

What it builds

• Base plates of lines and arcs (rounded corners), or a profile run along a width (a contour flange as the first feature: channels, hats, Z-sections).
• Flanges at any angle, every height datum, inside or outside, up or down, full or partial width with straight, round or tear reliefs; bend transitions (intersection, arc, trim to bend) where a flange ends next to a slanted edge; lips on their tips; rounded or chamfered tip corners.
• Corners between flanges at any angle: trim to bend with a miter gap, round, square, weld or tear reliefs, overlapping seams; flanges, hems and contours with different settings meeting by build order, or joined by a corner seam. Lips on both flanges at a corner are mitered there like one contour along both edges when flanges and lips are alike (one feature on two edges).
• Hems: single, double, teardrop, rolled, full or partial width.
• Contour flanges of lines and tangent arcs on a base edge or a flange's tip, full or partial width, or along several edges in one go, mitered at each corner (every leg and bend cut exactly, with corner reliefs).
• Rolled cones and cylinders: the sheet between two coaxial arcs (a lofted flange between them, or a straight line rolled around an axis), material on either side, unrolled on its neutral surface.
• Folds along a line across the plate or a flange, nested, at any angle to the outline; jogs (Z-steps by an offset).
• Faces joined by bends: plates on planes of their own, anywhere in 3D, each joined to the base or an earlier face by a bend between two parallel edges. The faces are extended or trimmed to meet the bend, with bend reliefs where a face carries on beside it. Faces at an angle get one bend; parallel faces two (fixed edges or 45 degrees side by side, 90 degrees or a full radius facing each other). Holes and cut-outs on a face, flanges and hems on its edges.
• Holes and cut-outs anywhere in the flat, across bends, and across the outline as notches, also through a mitered bend's curved end; or placed on a flange's face, measured along its edge and up from the mold line.
• Punches: a shape of holes and cut-outs stamped at several points, turned by an angle; the flat pattern marks each stamp's centre and punch ID.
• Embosses: round or rectangular embosses (dimples, ribs, pads) pressed out of the base plate, up or down, at the sheet's thickness: a drafted or straight wall between two rounded corners, exact (tori, cones, cylinders); the flat pattern marks the footprint.
• Bend order: every bend numbered in the order it's made (outermost first, or as you list them), with a note at each bend line in the flat DXF and SVG.
• Unfolding by K-factor (per part or per feature) or by a bend table (DIN 6935 style: bend deduction by radius and angle).
• Shop checks: bend radius, leg length, hole distance to bends and edges, hole size.
• Parts that fold into themselves are refused, naming the features and where they meet; clash::clashes gives the overlapping areas on the flat pattern, clash::preview the folded sheet anyway with the clash marked.

A part

{
  "id": "bracket",
  "thickness": 2, "bend_radius": 2, "k_factor": 0.4,
  "base": {
    "outline": [[0, 0], [100, 0], [100, 60], [0, 60]],
    "holes": [{ "center": [50, 30], "diameter": 8 }]
  },
  "flanges": [{
    "id": "f", "on": { "base": 2 }, "angle": 90, "length": 30,
    "datum": "outer", "position": "outside", "side": "up"
  }]
}

Millimetres and degrees. The full description is schema/part.schema.json.

Crates

Crate	What
gusset-sheet	The kernel: flat::flat_pattern, fold::fold (an exact B-rep), fold::exact_mass, check::check, clash::clashes
gusset-export	Flat pattern as DXF and SVG (bend notes, punch marks); the folded part as STEP AP214
gusset-wasm	All of it for the browser (wasm-bindgen): flat DXF/SVG, STEP, mesh, mass, checks, clashes
gusset-capi	A C library (gusset.dll): include/gusset.h, and dotnet/Gusset.cs for .NET 8

let part: PartSpec = serde_json::from_str(json)?;
let flat = gusset_sheet::flat::flat_pattern(&part)?;   // outline, holes, bend lines
let solid = gusset_sheet::fold::fold(&part)?;           // exact B-rep
let dxf = gusset_export::dxf::flat_dxf(&flat);
let step = gusset_export::step::part_step(&part)?;

var (volume, area, centre) = Gusset.Mass(json);
File.WriteAllText("flat.dxf", Gusset.FlatDxf(json));

Demo

Try it: https://bas-automation-services.github.io/gusset/

demo/ is a static page that runs the kernel as WebAssembly: edit a part, see it folded and flat, its mass, bend table and shop checks. A part that folds into itself shows the clash in red, folded and flat.

wasm-pack build crates/gusset-wasm --target web --release --out-dir ../../demo/pkg
python -m http.server -d demo 8000

Tests

cargo test checks flat patterns, folded solids, mass properties and exports of the main cases against known values. examples/measure.rs prints flat size, flat area and folded volume of any parts, for comparing with another CAD system; examples/fuzz.rs throws random parts at the kernel.

The geometry kernel is a fork of OpenGeometry (KERNEL.md: why, and what the fork changes).

License

MPL-2.0.