Dfam Check

DfAM Check

Provenance: maintained in earthtojake/text-to-cad. Use the installed local skill files as the runtime source of truth; the repository link is only for provenance and release review.

Use this skill to produce conservative, evidence-backed DfAM reports for mesh files before slicing or printing. It measures geometry facts locally and compares them against per-process design limits; it never slices, uploads, or starts print jobs.

Geometry Inspection

Use scripts/dfam_tool.py in the active project Python environment for all geometry facts (install requirements.txt first — every run needs it). The tool is fact-only: it reports measurements and never emits pass/fail or readiness statuses. Comparisons and verdicts belong to this workflow. Do not estimate wall thickness, overhang angles, or support volume by eye or from renders when the tool can measure them.

bashCopy code
python scripts/dfam_tool.py measure part.stl --angle-limit 45
python scripts/dfam_tool.py orientations part.stl --angle-limit 45

Set --angle-limit to the target process's self-supporting angle from references/process-limits.md before measuring, and re-run when the target process changes: the aggregate support-area facts are binned against it.

STEP/STP input is boundary-representation CAD, not a mesh. When the $cad skill is installed, export an STL sidecar with it first, then measure the STL here. Report that remediation instead of attempting raw STEP parsing. measure on a STEP exits 1 with {"error": "failed to load mesh: ..."}; that is the wrong-input signal, not a missing dependency — do not install extra mesh loaders to work around it.

A fact family that cannot compute returns {"error": ...} in its place rather than costing the report its other measurements — wall_thickness does this when the dependency set is incomplete, support_volume on geometry with no convex hull. That report is PARTIAL: it carries "partial": true, names the families in partial_sections, and the command exits 2 (0 is a complete report, 1 a mesh that would not load at all). Treat every such object as an unmeasured fact (❓ need more info), never as a measurement of zero, and reinstall requirements.txt before comparing wall limits.

Workflow

1. Collect print intent: target process, material, layer height, and any machine or material datasheet the user can provide. If the process is unknown, measure once with the default 45° limit, then present findings per candidate process rather than guessing a single verdict.
2. Read references/process-limits.md and select the limit column for the target process. A user-provided machine/material datasheet overrides the defaults; cite whichever source is used for every comparison.
3. Run measure on the exact upload file. Do not inspect only a generator script, source CAD model, or console summary of the file.
4. Run orientations when the process requires supports and the measured support area is nonzero. Report any candidate that materially reduces support area, with its build-height tradeoff.
5. Compare each measured fact to the cited limit and report findings with restrained status labels:
   • ✅ pass: the measured fact satisfies the cited limit.
   • ❌ fail: a measured fact directly violates the cited limit.
   • ❓ need more info: missing process context, unmeasured geometry, sampling too sparse to trust, or tool limitations.
6. Order findings by severity: watertightness first (blocks slicing for every process), then wall thickness, then overhangs/supports, then orientation and cost signals.

Comparison

Compare only trustworthy pairs of evidence.

• Cite the limit source (process-limits table row, or the user's datasheet field) and the measured fact (JSON field path) for every finding.
• Treat p05_mm below the wall-thickness limit as a violation even when min_mm alone could be a sampling outlier; report both values.
• On an assembly, wall_thickness reports body_count and a per_body breakdown. Attribute a violation to the body it belongs to; a thin figure pooled across bodies is not a finding against the part as a whole.
• Do not apply support-angle findings to powder processes (SLS, MJF); the relevant powder-process check is trapped-volume powder escape, which this tool does not yet measure — report that as ❓ need more info when enclosed cavities are likely.
• Do not silently rescale geometry. scale.units_suspect is measured from the bounding-box diagonal: when it is true, the source is probably in meters or inches, every down-facing face reads as resting on the plate, and overhang and support figures of 0.0 mean nothing. Report a unit/scale finding and ask the user to confirm units before comparing anything against a material limit.
• Support-volume ratios are coarse upper bounds; report them as cost signals, not hard failures, unless the user has set an explicit budget.

Redesign Handoff

For every ❌ fail, include a concrete, plain-language redesign instruction with target numbers (for example "thicken the wall at [12.4, 3.0, 8.1] from 0.6 mm to ≥1.2 mm" or "chamfer the overhang at [23.3, 10.0, 52.0] to ≥45°"). When the $cad skill is installed, offer to apply the redesign instructions with it and re-measure the regenerated geometry here, repeating until no ❌ fail findings remain. When $cad-viewer is installed, hand the measured file path(s) to it so the user can inspect the findings visually.