/dfm

name: dfm
description: Design-for-manufacturing review of a part for sheet metal, CNC machining, or injection molding - bends, reliefs and flat patterns; machining access, internal corners, deep features and setups; draft, undercuts and projected area. Use when the user asks whether a part can be bent, machined or molded, asks about manufacturability or tooling, or asks for a DFM review or redesign.

DFM review

Provenance: maintained in [earthtojake/text-to-cad](https://github.com/earthtojake/text-to-cad). Use the installed local skill files as the runtime source of truth.

Produce a process-specific DFM review of the supplied design. This is a guided review skill, not an automatic feature-recognition or manufacturing certification engine. Report unavailable checks explicitly.

**Pick the process, then read its reference.** One of them, or more than one when the user is comparing:

| Process | Reference | Measurement | | --- | --- | --- | | Sheet metal | [references/sheet-metal.md](references/sheet-metal.md) | none; use CAD inspection or supplied dimensions | | CNC machining / turning | [references/cnc.md](references/cnc.md) | none; use CAD inspection or supplied dimensions | | Injection molding | [references/injection-molding.md](references/injection-molding.md) | `scripts/mold_tool.py` measures draft, undercuts and projected area |

Each reference carries that process's review checklist, its two fallback sources, and a worked reasoning example. The rules below apply to all three.

For additive manufacturing, use `$dfam-check`, which measures mesh printability per process.

Evidence first

Prefer the user's actual supplier/tooling specification over general guidance. Record conflicting specifications rather than silently choosing.

Identify the reviewed file and revision, units, and bodies. Prefer exact STEP/B-rep measurements for radii and analytic faces. If only a mesh is available, record its resolution and approximation limits. A screenshot supports a suspected issue, not a measured pass/fail. Source-code parameters describe design intent; verify that they match the artifact being reviewed before treating them as evidence.

When $cad is available, use its documented inspection workflow for geometry facts. If it cannot measure a required feature, use supplied dimensions with provenance or mark the check unverified; do not invent commands or measurements. Never infer alloy, resin, strength, or stock thickness from a rendering material or color.

Rule selection

1. Use the selected shop's specification for the actual material and process. 2. Where none is supplied, use the two references named in the process file as a starting point. Neither establishes the capabilities of an arbitrary machine, tool or fixture. 3. Record URL/document version, access date, section, units, and the applicable material/tooling conditions with every adopted limit. If the source cannot be checked, report the missing rule rather than manufacture a default.

Do not turn a supplier's recommendation into a physical law or its machine capacity into a universal process limit. Preserve uncertainty and distinguish measured geometry from planned manufacturing decisions.

Report and redesign

Return a concise Markdown report in chat or the user's requested report file:

• Scope: artifact/revision, parts, process, material, units, tooling assumptions.
• Findings: part/feature, evidence and measurement method, applicable rule and

source, result, and a concrete suggested change.

• Coverage: checks performed and checks not measured, including what is needed

to resolve them. No findings is not a blanket manufacturability approval.

| Part / feature | Evidence | Applicable rule | Result | Suggested action | | --- | --- | --- | --- | --- | | Named feature + location | Measured value, units, artifact revision, method | Source section + threshold + conditions | pass / fail / review / unverified | Specific change or missing evidence |

Use **pass** only for a measured feature satisfying a cited applicable limit; **fail** for a measured violation; **review** for a qualitative risk; and **unverified** when evidence or process context is missing. Include units, measurement uncertainty, and source section/table in numerical comparisons. If uncertainty straddles the threshold, leave the check unverified. Keep cost suggestions separate from manufacturing constraints. If only a render is provided, list visible concerns as review items and request geometry or dimensions for the required measurements. Never fill a report with invented feature IDs or sample values.

For requested redesign, preserve the original artifact and use $cad if available to modify the source, regenerate, and recheck the new artifact. Check affected neighboring features as well as the original finding. Without editing tools, provide a specific change list. A review request alone does not request edits, uploads, ordering, or machine operation.

Geometry measurement (injection molding only)

`scripts/mold_tool.py` is the one measurement script here; the other two processes have no geometry analyzer. Install `requirements.txt` first — only these measurements need it.

python scripts/mold_tool.py measure part.stl --pull z
python scripts/mold_tool.py pulls part.stl

The tool is fact-only: it reports measurements and never emits pass/fail. Comparisons against resin, texture and tooling limits belong to the review. [references/injection-molding.md](references/injection-molding.md) documents what each fact family means and how to read it.