Engineering Methodology & Architecture
StepSTLTools is an in-browser CAD meshing platform engineered to convert ISO 10303 STEP and STP models into clean, 3D-printable STL and OBJ meshes with complete confidentiality.
Conventional Online Converters
- ✕Upload proprietary CAD files to third-party cloud servers.
- ✕Files may be retained or cached in unknown jurisdictions.
- ✕Black-box meshing without interactive tolerance or deflection feedback.
StepSTLTools Architecture
- ✓100% In-Browser Execution: WebAssembly OpenCASCADE kernel.
- ✓Zero Server Uploads: Files never leave your local RAM sandbox.
- ✓Interactive 3D Verification: Caliper measurement and manifold checks.
1. OpenCASCADE WebAssembly Pipeline
StepSTLTools compiles the industry-standard OpenCASCADE Technology (OCCT) C++ CAD modeling kernel directly into WebAssembly (WASM). When a STEP file is loaded, a dedicated background Web Worker instantiates the WASM virtual machine, allocates an isolated linear memory buffer, parses the STEP file's EXPRESS entity graph (ISO 10303-21), and builds a topological Boundary Representation (TopoDS_Shape).
2. Linear & Angular Deflection Tessellation
A STEP file stores curved CAD surfaces analytically (e.g. NURBS surfaces, tori, cylinders). To 3D print or render them, they must be converted into a triangular mesh via tessellation. StepSTLTools provides precise control over:
3. Topological Manifold Validation
Unlike naive format converters, StepSTLTools audits the generated mesh for 3D printing feasibility:
- Watertightness: Checks that every edge is shared by exactly two triangles (2-manifold).
- Degenerate Facets: Identifies zero-area or sliver triangles that could cause slicer computation crashes.
- Consistent Normals: Verifies that outward-facing surface normals are consistently oriented across shells.