Nesting arranges pieces on sheets or rolls with as little waste as possible. Imposition jobs, the roll nests of estimates, and the nesting API all do it the same way, so a job nests the same way wherever it comes from.
What you set#
- Parts: each part's outline (its cut line), a quantity, and the rotations it may use. See Rotations and grain.
- A container: sheets of a fixed size with margins, or a roll of a fixed width with side margins, a lead-in and a lead-out, and optionally the cutter's beds. See Rolls, beds and lanes.
- Spacing and bleed: the gap between pieces, and extra printed area around each one.
- Time: how long you are willing to let the run search.
What a layout is checked for#
A true-shape nest places each outline at an angle you allowed, with the spacing and bleed you set.
- On sheets, the layout with the fewest sheets is kept, and then the one that leaves the last sheet emptiest. On rolls, the shortest roll is kept.
- Before you see a layout, every piece is inside the printable area, no two pieces overlap, and the gap between them is at least the spacing you set. On rolls with beds, pieces follow the bed-boundary setting. A layout that fails is dropped.
- You can stop a run early. The best layout found so far is kept.
Methods#
Imposition offers several methods. True shape is the nest above. N-up packs rectangles for guillotine cutting. Strips keeps items in straight strips between slit lines. Offset runs plan plates and run lengths, and use the job's method to lay out each plate. Estimates always nest true shape on a roll. Every method's layouts pass the same checks.
How long to let it run#
More time can find a better layout, especially when the job has many different shapes. Rectangles and simple shapes
usually settle within seconds. If a result matters, let the job run longer: Optimize (10 s) in estimates, the
job's Time in imposition, or time_limit_s in the API.
In imposition, open Solutions during the run to compare layouts as they are found. Sheet and roll nests show distinct arrangements, and offset jobs show complete, checked plate plans while the search continues. The best results are kept as new options arrive. More time gives the search more opportunity; it does not guarantee more options or a better result on every job. See The live Solutions list.
What it doesn't do#
- No part-in-part. Parts are nested by their outer outline. Holes inside a part are ignored, so nothing is placed inside another part's hole.
- No mirroring. Pieces are rotated, never flipped.
- Gaps can be a little wider than the spacing. Neighbours may sit a little further apart than the spacing you set.
Size and time limits are on Sizes and limits. How to read a result is on Evaluating nesting results.