PlyWooder

Try it: https://taylorjonpeters.github.io/PlyWooder/

Open a STEP file and get plywood cut sheets. Each solid in the file becomes a part. PlyWooder lays the flat parts out on sheets, shows an animation of the model coming apart onto the sheets, and exports DXF files for a CNC.

Run it

npm install
npm run dev

Then open the printed URL and drop a .step / .stp file onto the page.

What it does

• Reads the parts. Each solid's largest flat face sets its thickness direction. The tool projects the solid onto that face to get the true through-cut outline: notches, slots and through holes. Faces that sit between the two skins become pockets, with their depth. Parts that are not flat stock (such as turned legs) start unticked.
• Groups by thickness. Each stock thickness gets its own set of sheets. When the parts don't fit on one sheet, the layout continues onto more.
• Two packing modes.
  • Manual cut: three-stage guillotine layout. Crosscut strips, rip rows, then crosscut parts. Every cut runs edge to edge, so a table saw or track saw works.
  • CNC cut: true-shape nesting on a fine grid. Bottom-left fill with a search over part order. Small parts can nest inside holes and notches. Uses the least plywood.
• Margins. Sheet edge margin, bit or blade width, and an extra gap for human error. Parts are kept at least bit + extra gap apart.
• Shared cuts (common-line cutting). On by default. Neighbouring parts sit exactly one bit apart, so one pass cuts both edges. After the grid pass, the efficient nester slides every part left and down until it butts against a neighbour. It then keeps the candidate layout with the fewest plunges and the least cutting. Off: parts get the extra error gap and are cut separately.
• Through cuts. In either mode, PlyWooder finds the straight lines that run edge to edge across the sheet, or across a piece already cut free, without touching a part. It splits the sheet recursively and numbers each cut in order. The sheet view draws them and lists them as "Through-cut order". It also reports which parts can only be freed by a CNC or jigsaw. They export on the SAW_CUTS layer.
• Cut plan. Each sheet's toolpaths are merged into one network, with shared edges cut once. The network is split into passes that run straight through junctions. Lines that stop within the edge margin get a lead-in to the sheet edge, so the cut starts outside the material. Passes are ordered so each starts at the sheet edge or on an earlier cut where possible. A plunge is a pass that has to start mid-sheet. Each sheet shows plunges, passes, cut length and shared length. "Show cut paths" draws the network, with shared runs highlighted.
• Display. Toggle between actual cuts and convex hulls. Hulls also pack as hulls, so no part goes into another part's notch. Lengths show in mm or inches.
• Rotation. Any 90° turn, grain-locked (0°/180° only), or 45° and 15° steps.
• Export. DXF (R12, mm or inches), per sheet or all sheets, plus SVG. DXF layers: CUT_OUTSIDE, CUT_INSIDE, POCKET_<depth>, CUT_PATHS, SAW_CUTS, LABELS, SHEET. CUT_PATHS holds the merged tool-centre passes in cutting order. Profile it on the line with the same bit, so shared edges are cut once. Round holes are written as true circles. DWG is a closed Autodesk format. Every CAM package reads DXF, and any CAD program can re-save it as DWG.
• 3D / Animate. The model as designed, then every part flies to its spot on the sheet. Use play/pause and scrub.

Tests

npm test -- path/to/model.step

Runs the STEP → parts → nesting → DXF pipeline in Node. It checks that no two parts come closer than the requested gap and that every part stays on the sheet.

License

MIT. See LICENSE.

PlyWooder uses three.js (MIT), Clipper (Boost Software License), and occt-import-js. occt-import-js is a WebAssembly build of Open CASCADE (LGPL-2.1) and ships as its own separate .wasm file. Files open in your browser and are never uploaded.