How to Validate DXF/STEP Files for Manufacturing with the SendCutSend Skill

The SendCutSend skill audits DXF and STEP files against SendCutSend.com manufacturing requirements, checking units, geometry, and material constraints to prevent order rejections.

In the earthtojake/text-to-cad repository, the SendCutSend skill provides a pre-flight validation system for CNC manufacturing files. Whether you are preparing 2D laser-cut profiles or 3D routed parts, this skill inspects your CAD exports for geometry errors, unit mismatches, and service-specific tolerances before you upload to SendCutSend.com.

Understanding the SendCutSend Skill

The SendCutSend skill is a specialized validator designed for the SendCutSend.com manufacturing service. It operates as an extension of the core CAD skill ($cad) referenced in skills/cad/SKILL.md, leveraging build123d to extract reliable geometry facts from source files.

Unlike generic CAD viewers, this validator applies conservative checks tailored to production realities. It never silently rescales geometry or suppresses errors; instead, it generates explicit pass/fail verdicts based on the specifications documented in plugins/cad/skills/sendcutsend/SKILL.md.

Validation Workflow

The validation process follows a six-step pipeline that inspects both 2D and 3D manufacturing files.

File Loading and Geometry Extraction

For STEP/STP files (3D CNC routing), the skill invokes build123d.import_step to load solid geometry. For DXF files (2D laser cutting), it uses build123d.ezdxf to parse the drawing structure. This extraction captures bounding boxes, layer names, entity types, and contour data required for manufacturing analysis.

Unit Verification

The validator inspects the DXF $INSUNITS header to confirm the drawing uses supported units. Valid codes are 1 (inches) or 4 (millimeters). If the header is missing or contains an unsupported value, the skill immediately flags a unit-scale error and advises re-export rather than attempting automatic conversion.

Geometry and Manufacturing Checks

The skill performs service-specific validations depending on the file type:

• Laser sheet cutting (DXF): Verifies the profile is a single closed contour at 1:1 scale, detects open or duplicate contours, flags zero-area shapes, and identifies bend-line candidates and flange depths.
• CNC routing (STEP): Validates solid volume, material thickness suitability, and required tolerances for 3D machining.

These checks reference the template defined in plugins/cad/skills/sendcutsend/references/report-template.md.

Running the Validation

You can execute validations via the command-line interface or programmatically through the Python API.

CLI Validation for STEP Files

To validate a 3D part for CNC routing, run the following from the repository root with your virtual environment activated:

# Validate a STEP file for SendCutSend

cad sendcutsend --input my_part.step

This command loads the geometry via build123d.import_step, measures the bounding box and volume, and prints a JSON report to stdout. The report is also saved as my_part.sendcutsend.report.json in the working directory.

CLI Validation for DXF Files

For 2D laser-cut profiles, use the same CLI pattern with a DXF input:

# Validate a DXF sheet profile

cad sendcutsend --input sheet_profile.dxf

The skill checks the $INSUNITS header, validates layer integrity, and confirms the drawing represents a single, upload-ready profile without unsupported annotations or open paths.

Programmatic Validation with Python

For integration into automated pipelines, import the skill module directly:

from plugins.cad.skills.sendcutsend import sendcutsend

# Validate DXF and extract summary

report = sendcutsend.validate_dxf("sheet_profile.dxf")
print(report.summary())

# Validate STEP file

report = sendcutsend.validate_step("my_part.step")
print(report.summary())

The returned report object provides structured access to validation results, with the summary() method formatting findings consistently with the CLI output.

Interpreting the Validation Report

The pre-flight report generated by the skill follows the structure defined in plugins/cad/skills/sendcutsend/references/report-template.md. It lists specific failures such as unit mismatches, open contours, or invalid geometry, alongside suggested fixes. A clear pass/fail verdict indicates whether the file is ready for upload to SendCutSend.com without risking production delays or order rejections.

Summary

• The SendCutSend skill validates both 2D DXF and 3D STEP files against SendCutSend.com manufacturing requirements.
• It uses build123d.import_step for STEP files and build123d.ezdxf for DXF parsing to extract geometry.
• DXF validation requires the $INSUNITS header to be 1 (inches) or 4 (mm); unsupported units trigger explicit errors.
• The validator detects open contours, duplicate entities, zero-area shapes, and material thickness issues.
• Reports follow the template in plugins/cad/skills/sendcutsend/references/report-template.md and are saved as JSON alongside the input file.

Frequently Asked Questions

Can the SendCutSend skill fix unit errors automatically?

No. The skill is designed to be conservative and will never silently rescale geometry. If the DXF $INSUNITS header is missing or set to an unsupported value, the validation fails with instructions to re-export the file with correct units.

What DXF unit codes does SendCutSend support?

According to the source documentation in plugins/cad/skills/sendcutsend/SKILL.md, only unit codes 1 (inches) and 4 (millimeters) are accepted for laser-cut profiles. Any other value results in a unit-scale error.

How does the skill handle 3D STEP files differently from 2D DXF?

For STEP files, the skill validates solid volume and material thickness for CNC routing using build123d.import_step. For DXF files, it verifies closed 2D profiles, bend lines, and flange geometries using build123d.ezdxf, ensuring the file represents a single laser-cut sheet at 1:1 scale.

Where is the validation report saved?

When using the CLI, the skill generates a JSON report in the working directory using the naming convention {filename}.sendcutsend.report.json. The report content follows the template structure defined in plugins/cad/skills/sendcutsend/references/report-template.md.

{
  "mcpServers": {
    "instagit": {
      "command": "npx",
      "args": ["-y", "instagit@latest"]
    }
  }
}