Can text-to-cad Generate STEP Files? A Complete Guide to CAD Export

Yes, text-to-cad can generate STEP files using the scripts/step CLI, which either converts Build123d Python sources into STEP format or imports existing STEP/STP files to create GLB topology artifacts for the CAD Viewer.

The earthtojake/text-to-cad repository provides a complete toolchain for STEP file generation and management, enabling both programmatic CAD creation from Python scripts and seamless integration with the web-based CAD Viewer. This workflow centers on the cadpy Python package and its step_artifact module, which handles the actual file serialization and catalog registration.

How text-to-cad Generates STEP Files

The system operates through two distinct pathways depending on your source material. Both pathways utilize the scripts/step command-line interface and ultimately invoke cadpy.step_artifact to write files to the filesystem.

Generating STEP Files from Python Sources

When working with Build123d-based Python files, the system expects a gen_step() function that returns a build123d shape or compound. Running the CLI against these files executes the Python code, captures the geometric result, and exports it as a STEP file. The tool automatically detects whether the source represents a single part or an assembly based on the --kind parameter.

Importing Existing STEP Files

If you already possess STEP or STP files, the CLI can import them directly without requiring a Python generator. This workflow creates a hidden GLB topology side-car file that enables preview and inspection within the CAD Viewer interface, effectively bridging legacy CAD assets into the text-to-cad ecosystem.

Using the scripts/step CLI

The scripts/step utility provides flexible output control and supports batch operations. Located in the repository root, this script serves as the primary interface for all STEP-related operations.

Basic STEP Generation Commands

Generate STEP files from Build123d Python sources using these patterns:

# Generate from a part definition

python scripts/step path/to/part.py

# Generate from an assembly definition

python scripts/step path/to/assembly.py --kind assembly

# Import an existing STEP file (creates GLB side-car only)

python scripts/step --kind part path/to/imported.step

When processing Python files, the CLI creates a sibling .step file with the same base name as the source. For assemblies, the --kind assembly flag ensures proper handling of compound geometries.

Custom Output Paths

Control output destinations using either the -o flag or the SOURCE=OUTPUT syntax for batch operations:

# Single file with explicit output path

python scripts/step path/to/part.py -o path/to/custom.step

# Multiple files with specific output names

python scripts/step path/to/a.py=out/a.step path/to/b.py=out/b.step

After generation, verify artifacts and inspect geometric properties using the inspection tool:

python scripts/inspect refs path/to/model.step --facts --planes --positioning

Core Implementation Files

The STEP generation pipeline spans multiple packages and languages, coordinated through these key components:

• packages/cadpy/src/cadpy/step_artifact.py – The Python implementation that serializes Build123d shapes to STEP format or passes through existing STEP files.

• viewer/src/server/step/pythonStepArtifact.mjs – Node.js wrapper that orchestrates calls to the Python STEP generator from the server environment.

• viewer/src/server/step/stepArtifactCompiler.mjs – Core logic determining when STEP artifacts require regeneration and handling error states during compilation.

• viewer/src/server/catalog/cadDirectoryScanner.mjs – Scans repository directories for STEP sources and registers them in the CAD Viewer catalog, linking generated GLB side-cars for visualization.

• skills/cad/references/step-generation.md – Comprehensive documentation detailing CLI options, workflow patterns, and integration guidelines for the STEP generation system.

Summary

• text-to-cad generates STEP files through the scripts/step CLI using the cadpy Python package.
• Two workflows exist: generating from Build123d Python sources (requiring a gen_step() function) or importing existing STEP/STP files.
• Assembly support is available via the --kind assembly flag when processing Python definitions.
• Flexible output options include automatic sibling placement, explicit -o paths, or batch SOURCE=OUTPUT syntax.
• GLB topology artifacts are automatically generated alongside STEP files to enable CAD Viewer preview and inspection.

Frequently Asked Questions

Does text-to-cad require Build123d knowledge to create STEP files?

While generating STEP files from Python sources requires a gen_step() function that returns Build123d shapes, you can bypass Python entirely by importing existing STEP or STP files directly. The python scripts/step --kind part path/to/file.step command processes legacy CAD files without requiring Build123d code.

What is the difference between part and assembly generation?

The --kind parameter determines how the CLI interprets the source material. Use --kind part for single solid geometries and --kind assembly when the Python source defines multiple components or compound assemblies. This distinction affects how the STEP file structure is organized and how the CAD Viewer renders the topology.

Where does text-to-cad store generated STEP files?

By default, the CLI creates STEP files as siblings to their source Python files in the same directory. You can override this behavior using the -o flag for single files or the SOURCE.py=OUTPUT.step syntax for batch operations, allowing placement in custom directory structures.

Can I preview STEP files before using them in production?

Yes. The system automatically generates GLB (GL Binary) topology side-car files alongside STEP exports. These lightweight 3D assets enable preview within the CAD Viewer interface. Additionally, the scripts/inspect command provides geometric analysis including facts, planes, and positioning data for validation.

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