Sheet nesting, grain and offcuts

The Sheets view (key 5) shows one tab per material. Each sheet material is nested separately; solid stock and worktops get a 1D length optimisation instead.

Method

• Guillotine (panel saw) — every cut runs edge to edge, so the layout can be cut on a panel or table saw. Dashed lines show the cut sequence.
• MaxRects (CNC) — tighter packing that is not always guillotine-cuttable; ideal for a router.
• Auto — tries both with many strategies and keeps the best: fewest sheets, then the largest single offcut, then guillotine.

How close to optimal?

Above the sheets Kerfwise shows the lower bound: the smallest number of sheets any layout could possibly use, from the total part area (each part plus one kerf) and from parts that are too big to share a sheet. The gap is sheets used − lower bound.

• Gap 0 → the layout is proven optimal (green note). No other program can use fewer sheets.
• Gap 1 or more → a perfect layout might save that many sheets — the bound is not always reachable. Switch Optimisation to Deep search: Kerfwise then tries hundreds of seeded variations (shuffled orders, other fit and split rules, other rotations) within a time budget and stops as soon as the bound is reached. The same seed always gives the same layout.

Shaped parts

Bottoms, tops and shelves of diagonal and L-shaped corner cabinets, angled ends, quarter-round shelves and one-piece L worktops are polygons. Kerfwise nests them by their bounding box in four orientations (two on grained material) and gives the empty notch of the L or the cut-off corner back to the free space, so small parts like rails and drawer sides fill it. The sheet drawing shows the true outline over a dashed box; yield counts the true area. Shaped parts are cut on a CNC router (see CNC G-code export) or with a track saw and jigsaw from the part drawing.

Kerf and trim

The kerf (default 4 mm) is the width of material your blade removes. The trim (default 10 mm) is cut off every sheet edge because factory edges are rarely clean. A quick sanity check: on a 2800 × 2070 sheet the usable area is 2780 × 2050, and with 4 mm kerf exactly 16 parts of 600 × 500 fit (4 × 4) — yield 82.8 %. A 17th part needs a second sheet.

Grain

Materials with grain (veneers, plywood, solid panels, wood-decor melamine) keep grained parts with their length along the sheet length: sides run vertically, drawer fronts horizontally. Parts without grain may rotate. You can switch a material’s grain on or off in Edit → Materials & edge banding….

Standard sheet sizes (2800 × 2070, 2440 × 1220, 3050 × 1220, 2500 × 1250 …) are one click away in the Size column.

Yield and offcuts

• Yield = part area ÷ full sheet area, per sheet and per material.
• Offcuts kept are rectangles at least 300 × 100 mm (change the minimum in the project settings). Open Offcuts under a sheet to see their sizes and positions.
• Click a part on a sheet to select it everywhere (cut list, 3D, drawings).

Linear stock and worktops

Legs, battens, slats and worktops are cut from lengths. Kerfwise uses first-fit decreasing with the kerf between pieces and the trim at both ends, and splits a worktop that is longer than the stock (with a warning that you need a joint).

Export

• DXF (all sheets) — R12 ASCII in millimetres with layers SHEET, PARTS, LABELS, OFFCUTS and CUTS; opens in practically every CAD/CAM program.
• SVG / PNG per sheet, or all sheets at once from the File menu.