feat(task-3): the feature catalogue and its standards tables
engineering/mech/features.py is the nineteen typed features of spec section 5,
each answering the same four questions - is my placement legal, what do I
contribute to this view, to a cut face, and what dimension do I want - plus the
five structural hooks the view engine needs: removal_box, radial_edit,
corner_edit, outline_edit and omission. Pure arithmetic; a test asserts emitted
primitive tuples, not a screenshot.
Nothing restates a table the repository already owns: Keyway takes its width
and depth from engineering.keyway (DIN 6885-1) and is refused by name outside
that table's bore range; GearTeeth takes its outline from engineering.gear's
involute generator and is refused when its tip diameter disagrees with the
segment it sits on.
standards/threads.py transcribes ISO 261 Table 1 and Table 2 - first-choice
M1.6-M64 plus second-choice M14/M18/M22/M27/M33/M39/M45/M52/M60 - and computes
ISO 724's basic minor and pitch diameters from ISO 68-1's own formula, pinned
against the published values (M20x2.5 -> 17.294 / 18.376). The remaining
second-choice diameters, every third-choice diameter and fine pitches below M8
are not transcribed and are refused by name, never interpolated. The drawing
rules are ISO 6410: minor at 0.8 x major, a thread-length limit line across the
major, a three-quarter circle in the end view, and an internal thread whose
section hatch runs to the major diameter.
standards/{undercuts,rings,centres,orings}.py ship DIN 509, DIN 471/472,
DIN 332-1 and ISO 3601-2 with their SOURCE, their row-key contract and an
**empty** row set. That is deliberate and is the track's table rule taken at its
word: a row that could not be verified against the standard is not shipped,
because a wrong relief depth or groove diameter is a wrong workshop drawing
while a narrow table is merely narrow. Every lookup is refused by name and says
what to transcribe and where; the features accept explicit dimensions so the
geometry is fully exercised, and DIN 332 form R is refused outright rather than
approximated by the straight 60 degree cone of forms A and B. Filling any of
these tables later is a data edit with no code change, and a shape test already
fails any row that lands without a column the drawing code reads.
Three deviations from the plan text, each measured rather than assumed
(the merge agent should keep exactly one copy of the first):
1. standards/__init__.py (Task 1, on main) refused a registration with no rows
("registered no rows"), which would have made the four not-transcribed
tables impossible to register at all - and registering them is what keeps a
later transcription a data edit. register() now refuses a rows argument that
is not a dict and accepts an empty one; two tests in tests/test_mech_standards.py
pin both halves. No existing test asserted the old refusal.
2. ORingGroove's housing kind is carried by `housing`, not `kind`. A dataclass
field named `kind` overwrites the discriminator _Base.to_dict() writes:
measured, Probe(id='og').to_dict() == {'kind': 'radial', 'id': 'og'}, so
feature_from_dict would then refuse its own payload as an unknown feature
kind and no part carrying an O-ring groove could round-trip through XDATA.
A new test pins the round trip.
3. The plan's end-chamfer test asserted after == (75.0, 10.0) - the corner
itself - and before == (72.0, 8.268), a point on neither surface. The real
edit is before (72.0, 10.0) on the cylinder and after (75.0, 8.268) on the
end face, consistent with the 45-degree start chamfer the same file pins.
The test was corrected to the measured geometry; the behaviour is unchanged.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01FKFStjEFzpGyLq5bMpWxTd
This commit is contained in:
Umut CAN
co-authored by
Claude Opus 5
Claude Opus 5
parent
04d269318a
commit
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"""ISO 261 metric thread pitches and the ISO 6410 drawing representation.
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SOURCE
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------
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**Pitches.** ISO 261:2022, *ISO general purpose metric screw threads - General
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plan*, Table 1 (coarse pitch series) and Table 2 (fine pitch series).
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**Transcribed coverage.** The first-choice diameters M1.6 to M64, plus the
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second-choice diameters M14, M18, M22, M27, M33, M39, M45, M52 and M60. The
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small second-choice diameters (M1.8, M2.2, M3.5, M4.5, M5.5, M7, M9, M11),
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every third-choice diameter, everything above M64 and the fine pitch series
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below M8 are **not** transcribed and are refused by name rather than
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interpolated - the table rule of this track. Where a diameter's fine series
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here is shorter than the standard's, the pitch that is missing is refused by
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name as well; widening it is a data edit in ``FINE`` with no code change.
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**Basic diameters.** ISO 68-1:1998 fundamental triangle, H = (sqrt(3)/2) * P,
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with ISO 724's basic minor diameter d1 = d - 1.25*H = d - 1.082532*P and basic
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pitch diameter d2 = d - 0.75*H = d - 0.649519*P. That is the standard's own
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formula rather than transcribed table data, which is why it can be pinned
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against published ISO 724 values instead of trusted: M20x2.5 reproduces
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17.294 / 18.376 exactly, M10x1.5 reproduces 8.376 / 9.026, M8x1.25 reproduces
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6.647 / 7.188.
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**Representation.** ISO 6410-1:1993, *Technical drawings - Screw threads and
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threaded parts*: the minor diameter is drawn as a thin continuous line at
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0.8 x the major diameter (`MINOR_RATIO`); in a view along the axis that same
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circle is drawn as three quarters of a circle with the gap in one quadrant;
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the thread run-out / thread-length limit is a line across the full major
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diameter. An internal thread shown without a section is drawn hidden
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throughout.
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"""
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from __future__ import annotations
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import math
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import re
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from engineering.mech.primitives import Arc, Line, Prim
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from engineering.mech.standards import Coverage, register
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SOURCE_PITCH = (
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"ISO 261:2022 Table 1 (coarse) and Table 2 (fine); first-choice M1.6-M64 "
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"plus second-choice M14, M18, M22, M27, M33, M39, M45, M52, M60"
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)
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SOURCE_BASIC = "ISO 68-1:1998 fundamental triangle; values pinned against ISO 724 Table 1"
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SOURCE_REPRESENTATION = "ISO 6410-1:1993"
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#: ISO 6410-1: the minor diameter is represented at 0.8 x the major diameter.
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MINOR_RATIO = 0.8
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#: ISO 261 Table 1 - coarse pitch series, major diameter (mm) -> pitch (mm).
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COARSE: dict[float, float] = {
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1.6: 0.35,
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2.0: 0.40,
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2.5: 0.45,
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3.0: 0.50,
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4.0: 0.70,
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5.0: 0.80,
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6.0: 1.00,
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8.0: 1.25,
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10.0: 1.50,
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12.0: 1.75,
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14.0: 2.00,
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16.0: 2.00,
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18.0: 2.50,
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20.0: 2.50,
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22.0: 2.50,
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24.0: 3.00,
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27.0: 3.00,
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30.0: 3.50,
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33.0: 3.50,
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36.0: 4.00,
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39.0: 4.00,
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42.0: 4.50,
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45.0: 4.50,
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48.0: 5.00,
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52.0: 5.00,
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56.0: 5.50,
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60.0: 5.50,
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64.0: 6.00,
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}
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#: ISO 261 Table 2 - fine pitch series, major diameter (mm) -> pitches (mm),
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#: coarsest first. Transcribed from M8 upwards only.
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FINE: dict[float, tuple[float, ...]] = {
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8.0: (1.0, 0.75),
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10.0: (1.25, 1.0, 0.75),
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12.0: (1.5, 1.25, 1.0),
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14.0: (1.5, 1.0),
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16.0: (1.5, 1.0),
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18.0: (2.0, 1.5, 1.0),
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20.0: (2.0, 1.5, 1.0),
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22.0: (2.0, 1.5, 1.0),
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24.0: (2.0, 1.5, 1.0),
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27.0: (2.0, 1.5, 1.0),
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30.0: (2.0, 1.5, 1.0),
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33.0: (2.0, 1.5),
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36.0: (3.0, 2.0, 1.5),
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39.0: (3.0, 2.0, 1.5),
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42.0: (3.0, 2.0, 1.5),
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45.0: (3.0, 2.0, 1.5),
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48.0: (3.0, 2.0, 1.5),
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52.0: (3.0, 2.0, 1.5),
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56.0: (4.0, 3.0, 2.0, 1.5),
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60.0: (4.0, 3.0, 2.0, 1.5),
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64.0: (4.0, 3.0, 2.0, 1.5),
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}
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DIAMETERS: tuple[float, ...] = tuple(sorted(COARSE))
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COVERAGE = Coverage(DIAMETERS[0], DIAMETERS[-1], "mm")
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_DESIGNATION_RE = re.compile(
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r"^\s*M\s*(\d+(?:[.,]\d+)?)\s*(?:[x×X]\s*(\d+(?:[.,]\d+)?))?\s*(?:-\s*(LH|RH))?\s*$",
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re.IGNORECASE,
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)
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register(
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"ISO 261",
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{d: {"pitch": COARSE[d], "fine": FINE.get(d, ())} for d in DIAMETERS},
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COVERAGE,
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SOURCE_PITCH,
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)
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def _number(text: str) -> float:
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return float(text.replace(",", "."))
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def _pitch_text(pitch: float) -> str:
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"""A pitch in millimetres, always carrying a decimal: 2.5, 2.0, 0.75."""
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text = f"{float(pitch):g}"
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return text if "." in text else f"{text}.0"
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def pitch_for(d: float, pitch: float | None = None) -> float:
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"""The coarse pitch for ``d``, or validate an explicit fine pitch against the series."""
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diameter = float(d)
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if diameter not in COARSE:
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raise ValueError(
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f"ISO 261: M{diameter:g} is not in the transcribed table. "
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f"Coverage is M{DIAMETERS[0]:g}-M{DIAMETERS[-1]:g}, the first-choice diameters plus "
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"the second-choice M14, M18, M22, M27, M33, M39, M45, M52 and M60; the remaining "
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"second-choice diameters and every third-choice diameter are not transcribed and "
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"are not interpolated."
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)
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if pitch is None:
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return COARSE[diameter]
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value = float(pitch)
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if abs(value - COARSE[diameter]) < 1e-9:
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return COARSE[diameter]
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series = FINE.get(diameter, ())
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for candidate in series:
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if abs(value - candidate) < 1e-9:
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return candidate
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known = ", ".join(_pitch_text(p) for p in (COARSE[diameter], *series))
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raise ValueError(
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f"ISO 261: M{diameter:g} has no pitch {value:g} mm in the transcribed series. "
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f"Transcribed pitches for M{diameter:g}: {known}."
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)
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def parse_designation(designation: str) -> dict:
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"""``M20`` / ``M20x1.5`` / ``M20x1.5-LH`` -> d, pitch, series, hand."""
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match = _DESIGNATION_RE.match(str(designation or ""))
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if not match:
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raise ValueError(
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f"designation {designation!r}: expected an ISO metric thread such as "
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"'M20', 'M20x1.5' or 'M20x1.5-LH'."
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)
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diameter = _number(match.group(1))
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raw_pitch = _number(match.group(2)) if match.group(2) else None
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pitch = pitch_for(diameter, raw_pitch)
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hand = "left" if (match.group(3) or "RH").upper() == "LH" else "right"
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series = "coarse" if abs(pitch - COARSE[diameter]) < 1e-9 else "fine"
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text = f"M{diameter:g}" if raw_pitch is None else f"M{diameter:g}x{pitch:g}"
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if hand == "left":
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text += "-LH"
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return {
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"designation": text,
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"d": diameter,
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"pitch": pitch,
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"series": series,
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"hand": hand,
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}
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def _h(pitch: float) -> float:
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"""ISO 68-1 fundamental triangle height."""
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return math.sqrt(3.0) / 2.0 * float(pitch)
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def basic_minor_diameter(d: float, pitch: float) -> float:
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"""ISO 724 basic minor diameter d1 = d - 1.25 * H."""
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return float(d) - 1.25 * _h(pitch)
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def basic_pitch_diameter(d: float, pitch: float) -> float:
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"""ISO 724 basic pitch diameter d2 = d - 0.75 * H."""
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return float(d) - 0.75 * _h(pitch)
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def thread_axial_prims(
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*,
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x0: float,
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length: float,
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d: float,
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internal: bool = False,
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minor_ratio: float = MINOR_RATIO,
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limit_line: bool = True,
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) -> tuple[Prim, ...]:
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"""ISO 6410 representation in a view along the axis (axis on y = 0, +X along it).
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External: the two minor-diameter lines at 0.8 x d plus the thread-length
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limit line across the full major diameter. Internal (not sectioned): the
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same pair at the *major* diameter, hidden, because the drawn bore already
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carries the minor.
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"""
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x1 = float(x0) + float(length)
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role = "hidden" if internal else "visible"
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radius = float(d) / 2.0 if internal else float(minor_ratio) * float(d) / 2.0
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prims: list[Prim] = [
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Line((float(x0), radius), (x1, radius), role),
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Line((float(x0), -radius), (x1, -radius), role),
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]
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if limit_line:
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major = float(d) / 2.0
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prims.append(Line((x1, -major), (x1, major), role))
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return tuple(prims)
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def thread_end_prims(
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*,
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center: tuple[float, float],
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d: float,
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internal: bool = False,
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gap_center_deg: float = 45.0,
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minor_ratio: float = MINOR_RATIO,
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) -> tuple[Prim, ...]:
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"""ISO 6410 three-quarter circle for a view along the thread axis.
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External: three quarters of the *minor* circle. Internal: three quarters of
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the *major* circle. The quarter-circle gap is centred on ``gap_center_deg``
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(45 deg = the upper-right quadrant, the usual placement).
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"""
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radius = float(d) / 2.0 if internal else float(minor_ratio) * float(d) / 2.0
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start = (float(gap_center_deg) + 45.0) % 360.0
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end = (start + 270.0) % 360.0
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return (Arc((float(center[0]), float(center[1])), radius, start, end, "visible"),)
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