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ajandClaude Opus 5.5
e6d438629f
On an enclosed machine a cutout slug that tips once cut free can stand up above the sheet and catch the enclosure door when the pallet changes. The head already keeps off cut cutouts, so this is about clearing the door, not the head. Cutting Settings > Cutouts > "Slice slugs the support grid can't hold level" (CuttingParameters.SliceTippingSlugs, off by default, saved per machine thickness and written only when on) makes Plan Cutting cut each such slug along the bed's contact lines (grid rows and columns, slat center lines) before the cutout, so no piece keeps a contact and the pieces drop between the supports. Each slice stops a kerf short of the cutout, so the pieces stay attached until the cutout's own kerf frees them together. A slug the bed holds level, or one on no contact, is left whole; a cutout holding another part or another of its part's cuts is never sliced. Slices are break cuts emitted right after the drawing's own break cuts, pierced on themselves and led straight back to their start. The released-contour proof now leaves out straight break cuts lying wholly inside one of the part's closed holes, since the grid cells they free are scrap; break cuts in material still take part. The plan fingerprint only changes when the setting is on. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
68 lines
3.9 KiB
Markdown
68 lines
3.9 KiB
Markdown
# Breakoffs
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A breakoff is scrap drawn on a part, such as a forming backgauge tab, that must stay
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attached through cutting and forming and is snapped off afterwards. In the CAD
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Converter's **Breakoffs** panel, **Add Breakoff**, then click the line that joins the
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part and the scrap. Lines or arcs that end partway along another visible line or arc
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first split it there (the first piece keeps its entity ID), so a joining line can end
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exactly where it meets the outline. The clicked entity then grows into the chain that
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continues as a single path. Its ends must touch, within 0.001, one closed outline
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drawn around both part and scrap, and the chain must run inside it: either a separate
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line drawn across the outline, or a section of the part outline with the scrap's
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outside edges drawn separately.
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The smaller side is the scrap; **Flip** (or "Larger side is scrap" in the dialog)
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swaps it. The dialog sets the tab count (both end tabs included, at least 2) and tab
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width; tabs start evenly spaced and can be dragged along the joining line. Edit
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re-spaces the tabs only when the count or width changes. The view shades the scrap,
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draws the cuts and marks where each cut is pierced.
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## Geometry contract
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`BreakoffBuilder` (`OpenNest.Core/Breakoffs`) resolves each `Drawing.Breakoffs` entry
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against the entities being cut:
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- The two sides are the outline from one end of the joining line to the other, closed
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back along the joining line. They must add up to the outline within 1%. Tab
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positions are measured from the joining line's end with the smaller X (then Y).
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- The outline is kept, with every joint snapped exact (lines move their endpoint; a
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short connecting line is added between arcs), because the planner closes contours within
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1e-6 and the program is re-chained from any entity.
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- The joining line between consecutive tabs becomes open cuts on the `Break` layer
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(`LayerType.Break`, `SpecialLayers.Break`), each traveling with the scrap on its
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left. The joining line itself is not cut at the tabs; end tabs keep cuts off the
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outline.
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## Cutting break cuts
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Break cuts cut like `Cut` motions but are not material: `SpecialLayers.IsMaterial`,
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material capture, overlap checks, nesting and area ignore them. `ShapeProfile` and
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`ConvertGeometry` pass them through in order without re-chaining or re-winding.
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Both Plan Cutting (`PreparedContours`, emitted after scribes and before contours in
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every full or prefix emission, never in single-contour probes) and the manual lead-in tool
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(`ContourCuttingStrategy.Apply`/`ApplySingle`) emit them through
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`ContourCuttingStrategy.EmitBreakCuts`:
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- Each cut is entered from its scrap side with the internal lead-in; `NoLeadIn`
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pierces on the line. There is no lead-out, since the cut ends at a tab.
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- It is entered at whichever end has more scrap before the part's contours along the
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scrap direction (`BreakCutEntry`), because the scrap narrows to a wedge near the
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outline. Entering at the far end cuts it in reverse.
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Plan Cutting also cuts [slug slices](support-tabs.md#slug-slices) on the `Break` layer: open
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cuts inside a cutout's slug, pierced on themselves with a straight lead-in along the cut.
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Checks treat them as intentional open cuts retained by tabs: `ReleasedContourState`
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never makes them rapid obstacles or "open fragment" warnings, but reports a missing
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lead-in like any contour. `LeadPathValidator` lets a lead into a break cut run
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through its own part's material, and still refuses one that touches any of the part's
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boundaries or another part. The posts cut them: Gravograph IS maps `Break` to its cut
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settings; CI Fiber and Cincinnati treat any non-lead, non-scribe layer as cut.
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Breakoffs that do not resolve (hidden or missing joining line, overlapping tabs) are
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listed with the reason and not applied, but stay on the drawing.
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`CadImporter.BuildDrawing` applies breakoffs and copies them to the drawing;
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`SourceEntities` keep the original geometry so a reopened drawing can be edited. Split
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pieces get no breakoffs.
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