| name | lril3d-dfm |
| description | Use when a part needs checking for printability rather than correctness — before committing to a print, after a design change, or when the user asks whether something will print, needs supports, or is too thin. |
lril3d-dfm — will it print?
Thin skill, thick library. No thresholds belong in this file. Every number lives in
profiles/dfm-rules.json next to the source that justifies it. Read PRD.md §7 for where this
sits in the loop.
lril3d-inspect answers "is this the part I asked for?". This answers "will that part come off
the plate?". They are independent: a dimensionally perfect part can be unprintable, and a
printable part can be the wrong part.
Run it
from threedp import dfm
report = dfm.evaluate(feats.mesh, "PLA_generic", part="bearing-holder")
print(report)
Materials are the keys of profiles/dfm-rules.json — the same names as profiles/calibration.json.
An unknown one raises and names the valid list; do not guess one.
Read the report
Every line carries the measured value, the threshold it was compared against, and the source
string. Report those, not an impression.
BLOCKER max_overhang_deg measured 75.099 deg threshold 45.000 deg above the 45.000 deg
maximum - past this angle from vertical the underside droops without support
[conventional FDM support threshold, measured from vertical]
- A BLOCKER is a blocker. Do not downgrade one in prose. If you believe the threshold is wrong
rather than the part, say that explicitly and ask — a rule quietly narrated away is a rule that
is not there.
- A WARNING is not a gate, and saying so is not the same as ignoring it. Report it with its
number and let the user decide.
skipped lines are not clean bills of health. "No bore was small" and "no bore was
measurable" are different facts and the report distinguishes them. Pass the distinction on.- Overhang angles are measured from vertical: 0 is a vertical wall and perfectly fine, 90 is a
horizontal ceiling and the worst case.
- Wall, feature and bridge numbers are sampled or derived from face geometry, and every one of
them says ESTIMATE. Never present one as a dimension.
Changing a threshold
Edit profiles/dfm-rules.json, and change the source in the same edit. A threshold with no
traceable source will not load — dfm.load_rules refuses it — and that refusal is deliberate:
an uncited number cannot be argued with by anyone who was not in the room.
Per-material overrides sit under the material key and inherit _defaults for everything they do
not mention. ABS and PETG are stricter on overhangs and bridges than PLA, and the reason is in
the note on each rule.
Making DFM gate a verdict
By default it does not, and that is correct: DFM is advice about a process, intent.json is a
claim about a part. To make it gate for a specific part, assert on it:
{"dfm_blockers": [0, 0], "source": "user-confirmed",
"measure": {"kind": "dfm_violation_count", "severity": "BLOCKER", "material": "PLA_generic"}}
Now a DFM regression fails an ordinary assertion, in the ordinary report, with a measured count.
Non-negotiable
Banned from a critique: "looks printable", "seems fine", "should be OK", "appears thin". Every
claim carries a measured number and the rule it was measured against, or an explicit ESTIMATE
label. State the verdict plainly at the top — blockers or none — then the numbers, then what to
change and by how much.
