Island

kerfmaster pin list · Definitions

recordclosed d16States what the code does today. Auditable against the code — this is the only type that can go stale.

Content last changed 2026-08-06 — computed from the item itself, not typed.

Vocabulary — QC stage

⚠ Known defects

This item's subject has a known defect in the code. Source: cadmaster/defects.json → cadmaster/KNOWN_DEFECTS.md, not this page — the text below is generated from the register so the two can never disagree.

D16 — A ring's inner hole is knocked out of the plate behind it (CLOSED)
mvt_prep.build() and build_mvt_preview.geometry() (~line 139) both compute CLOUD.difference(din), where din is the disc inside the ring's inner radius. That subtracts the ring's HOLE from the cloud sitting behind the ring.
Cost today: Options A and B are built with the cloud whole. The reissue is still outstanding: the withdrawn revision Q0QB is the last thing the customer has seen.
Verified: 2026-08-06, FIXED and verified. Both expressions are unions now -- mvt_prep.build() and build_mvt_preview.geometry() -- and both run through mvt_geom.changed(). Measured on the modified art: the cloud visible through the ring hole is 794.5 pt2 = 22.62 in2 = 0.803 lb, which is what the subtraction was deleting. That is larger than the 518 pt2 recorded when this was diagnosed, because that figure was measured on the old truncated cloud at the old ring position. NOT YET DONE: the published sheets have not been reissued.

Island = a piece of kept metal fully surrounded by cut-away area (the MVT play triangle inside its ring; the centre of an ‘O’ or ‘A’; any stencil counter). Cutting the surrounding hole frees it and it drops out — so an island needs bridges to stay in place — permanent, by design (item 2b). A tab is the sacrificial hold, at a different stage (items 3a, 3b). Detected geometrically in bridges.islands(): the material is rastered even-odd at ~20 thou/px, every candidate neck is cut in the raster, and connected components are labelled once — a region that separates only because of those cuts was being held by them, so it is a real island and those necks are its bridges. Full spec: item 2b. Assembly caveat (2026-08-06): connectivity is a property of the assembly, not of the artwork — a shape can look joined in the composition and be a free island the moment the plates are split, so the island test is re-run per plate after every split. See item 2d.