One case step by step

The path in eight steps

Here is how the case ran chronologically — each station points to the section with the evidence:

1. Receive the task package — drawing (vector PDF), nearly empty text-recognition output, task statement (§0).
2. Assign the views — the title block names projection method E, so the top view lies below the front view (§1).
3. Substantiate every dimension — 17 dimension texts, each with evidence level OCR/image/PDF; the drawing is converted to mm and measured (§2).
4. Resolve contradictions — “R9” is a recognition error (really: R8 + Ø9); the “60” is a hole spacing, not the plate width (§4).
5. Derive undimensioned quantities — plate width 44 = 2 × R22, overall height 74 = 52 + 22, rib angle redundantly confirmed (§3).
6. Build the model — via the command interface as an executable sequence of operations; the build path is given, redacted, in “The build path” below.
7. Self-check — three projections measured by machine: 44 checks, 0 deviations; all 47 template edges individually reconciled; volume computed against the analytic value (§5).
8. Deliver and state the limits — STEP re-imported and validated; seven assumptions explicitly marked (§6, §7).

1. The views and their assignment

Title block: “Projektion: Methode E (ISO 5456-2)” ⇒ European method / first angle.

By method E, the view below the front view is the top view (looking from above), and its edge facing the front view is the rear edge of the part. That is where the upright plate stands in the template — consistent with the front view. The view on the right is the view from the left.

Model coordinates: X = width 0…90, Y = depth 0 (front, R8 corners) … 50 (rear, upright plate), Z = height 0 (underside of base plate) … 74.

5. Projection check — mandatory part of the delivery

5a. Measured self-check: 44 checks, 0 deviations

From the finished solid, three TechDraw projections are generated via the command interface and read out and measured by machine — no image inspection. The view orientation is derived from the projection (which axis carries height/depth, which side is the front), not assumed — otherwise one would be checking one's own assumption.

Overall check: passed (44/44).

The three deviations reported at first were errors in the checking procedure, not in the model: the side view maps height and depth onto the view axes differently than assumed, and one edge was searched over the maximum instead of by position. Both were fixed; the view orientation has since been derived.

5b. Edge-by-edge comparison against the vector geometry of the template

Beyond the self-check, every visible part edge of the template (all 47 thick paths, converted to mm) was held against the corresponding edge of the run's own projection (tolerance 0.02 mm):

Coincident: yes. The difference “line ↔ spline” is purely a matter of representation: where a circle is projected parallel to an edge, the template draws a straight line, and the run's own projection draws the same segment as a degenerate spline of the same length and position — each of these edges was individually matched by length and position.

5c. Weight check — not applicable

The title block names neither material nor density nor weight; the weight check is dropped for lack of a target value. As a substitute, the volume was checked against the value computed analytically from the dimensions:

V(model) = 81 496.8314 mm³ · V(analytic) = 81 496.8314 mm³ · deviation 0.0000 %

The build path — from the agent's build script, redacted

The delivered build script is an executable program against the command interface; every value in it carries, as a comment, its origin in the drawing. Here is the sequence in essence (pseudo-commands — the concrete interface names remain internal):

1. Coordinate system and dimension check first. X = width 0–90, Y = depth 0–50 (front = rounded corners), Z = height 0–74. All 17 dimensions sit in a table with an origin comment. Before the first build step, the script checks the redundant dimensions against each other: rib legs 38 − 14 = 24 and 36 − 12 = 24 ⇒ exactly 45°; hole pattern 15 + 60 + 15 = 90. Were the drawing self-contradictory, the script would abort here.
2. Base plate from four sub-bodies. Rear cuboid (sharp corners), front strip, and two corner cylinders R8 — so the roundings arise only at the two front corners, exactly as the drawing shows them.
3. Upright plate at the rear, flush. Cuboid 44 × 12 from the top of the base plate up to the bore axis (52), and above it a lying half-cylinder R22 as the head — the plate width 44 follows from 2 × R22 (flanks tangential).
4. Rib as a triangular profile. Right triangle (legs 24/24) as a closed polyline, extruded 10 mm thick and tilted centered between base plate and upright plate.
5. Unite. Fuse all sub-bodies into one blank.
6. Drill with overshoot. Bearing bore Ø20 across through the head, two Ø9 vertically through the base plate — the drilling cylinders deliberately protrude on both sides beyond the material, so the cut is guaranteed to go through. Form the difference, clean the result to exactly one body.
7. Self-check within the script. Volume against the formula computed analytically from the dimensions: 81 496.8314 mm³, deviation 0.0000 % (§5c/§6); exactly one valid solid.
8. The gate first, then the export. The script generates three projections of its own model and measures them through by machine — those are the 44 checks from §5. Only then does it write the STEP file.

Source: build script of the run Claude Code · opus-5 · run 1 (delivery artifact); values and order unchanged, command names redacted.