Cut List Generator: Inputs, Kerf, and Layouts Explained
Posted: October 29, 2026
Key takeaways
- A cut list generator takes finished part dimensions, sheet size, usable area, kerf, trim allowance, and grain constraints, then outputs a labeled layout, cut list, and offcut map.
- Kerf is consumed per cut line, not per part, so a grid that fits on paper can spill onto a second sheet once each shared edge loses its kerf width.
- Grain-locked parts shrink the optimizer's search space, so only flag parts whose visible grain direction actually matters.
- Guillotine placement matches table saws and panel saws, while free nesting suits CNC and laser work where the toolpath can go anywhere.
- Measure kerf on your own machine with a test cut and calipers rather than trusting a published figure, and re-test whenever material, power, or speed changes.
A cut list generator takes your part dimensions, sheet size, kerf, and grain constraints, then computes the tightest layout across your sheets and hands you a labeled cut list plus an offcut map. Below, the same six-part organizer runs through the math twice, so you can see exactly how kerf and grain direction move pieces between sheets and judge any tool before trusting it with a $60 Baltic birch panel.
What does a cut list generator actually do?
A cut list generator takes the finished dimensions of every part in a project, plus your material setup, and produces a cutting plan: which piece goes where on each sheet, in what order, with what kerf compensation. You type in part sizes, sheet size, blade or laser kerf, and grain constraints. The output is a labeled layout, a cut list, and often an offcut map you can reuse.
Where it sits between Boxes.py and Fusion 360
Boxes.py-style generators give you a parametric box with finger joints but little control beyond that; makers on the LightBurn forum still report limits like kerf that can't differ between X and Y (source). Full CAD/CAM like Fusion gives total control at the cost of modeling every joint by hand. A tool like GCrafter sits between: you design the object and its joints parametrically, then export cut-ready sheets.
What inputs does a cut list generator need before it can optimize a layout?
Part dimensions and quantities
List every finished part with its cut size, not its assembled size. A 24" × 16" × 12" box from 3/4" ply is five or six parts depending on your construction, and the generator needs each one named, dimensioned, and quantified. If you double the sides and forget, the layout is wrong before optimization even starts.
Sheet size and usable area
Enter the nominal sheet (48" × 96" for a full 4x8) and then subtract what the machine can't reach. A 4x8 CNC with a gantry clamp might cost you an inch on two edges; a laser needs its travel limits respected. Trim allowance for the factory edge, typically 1/4" to 1/2" per side, comes off here too.
Kerf and blade width settings
Kerf is the width of material the cut removes: roughly 1/8" for a router bit, 0.004"–0.01" for a laser depending on power and speed, about 0.09" for a table saw blade. Every part after the first cut on a shared edge shrinks by this amount, so the generator must know it.
| Input | Example value | Why it matters |
|---|---|---|
| Part list | 2× sides 24" × 12" | Wrong quantity = wrong layout |
| Sheet size | 48" × 96" | Sets the optimization boundary |
| Usable area | 46" × 94" | Clamps and travel limits |
| Trim allowance | 1/2" per edge | Factory edges aren't square |
| Kerf | 1/8" (bit) | Shared-edge cuts lose width |
| Grain direction | Long grain on sides | Constrains part rotation |
GCrafter takes the same six inputs, and it also needs joint type per edge, since finger joints consume material that a plain butt joint doesn't.
How does kerf width change the cutting layout a generator produces?
Kerf is the material the cutter removes, so every part shrinks by half a kerf on each cut edge unless the generator widens it to compensate.
Why kerf is added per cut, not per part
Take one 48" x 96" sheet of Baltic birch and a job of sixteen 12" x 18" panels. With zero kerf you fit twelve per sheet in a 4x3 grid: 48/12 and 96/18 both divide evenly. Now add a 0.125" saw kerf. Each cut consumes an eighth of an inch, so four columns of 12" panels need 47.625" of stock, not 48", and the sixth row of 18" panels needs 94.75", not 96".
Twelve still fits, barely, with 0.375" to spare. Bump the kerf to a 0.25" router bit and the same grid needs 48.75" x 95.5", so the twelfth panel no longer fits and the job spills onto a second sheet. This is exactly the arithmetic Fusion users end up doing by hand when they try to slot and tab sheet assemblies together, which is why the Autodesk forum thread on tabbed sheet-metal assemblies keeps coming up in CNC searches. A generator runs this math per cut line, not per part, because a shared edge between two parts costs one kerf, not two.
Laser kerf vs saw kerf vs router bit diameter
A 60W CO2 laser might remove 0.006"–0.01" depending on power and speed, a table saw blade 0.118", a 1/4" spiral bit 0.25". The same part list can yield a one-sheet layout on the laser and a two-sheet layout on the router, so set kerf per machine, not per material.
How do grain direction and material constraints affect generated cut lists?
Grain-locked vs rotatable parts
Plywood parts can rotate freely on the sheet; solid-wood and veneered-face parts cannot. A shelf cut from Baltic birch can go anywhere the optimizer finds room, but a door with a visible grain direction must stay oriented, so the optimizer treats it as grain-locked. In GCrafter you flag a part as rotatable or locked, and locked parts shrink the search space the way a fixed dimension does. On a 4x8 sheet, one locked 24x72 panel can force three other parts onto a second sheet, so lock only the parts that actually show grain.
Separating sheet pools by material
A generator needs one pool per material: 18mm birch, 6mm ply, and MDF never share a sheet. GCrafter assigns each part to a material pool and optimizes each pool separately, so a 3/4" part never lands on your 1/8" laser stock. The honest limitation: pools mean no cross-material nesting, so you buy more partial sheets than a single-pool run would. That is the price of layouts you can actually load on the machine.
How does the optimizer decide which pieces go on which sheet?
An optimizer takes your parts plus sheet size, kerf, and grain constraints, then searches for a placement that wastes the least material. "Optimized" just means the best result its algorithm family can find within a time limit, not a mathematically perfect layout.
Guillotine cuts for saws
Guillotine algorithms assume every cut runs edge to edge across the sheet, splitting it into rectangles. That matches a table saw or panel saw, where you physically cannot stop a cut mid-sheet. First-fit and shelf methods sort parts by height or length, fill rows (shelves) left to right, and open a new shelf when one fills up. Fast, predictable, and slightly wasteful on irregular part mixes.
Free nesting for CNC and laser
Free placement lets parts sit anywhere, rotated, with parts of different heights interleaving. That squeezes more per sheet on a CNC or laser, where the toolpath can go anywhere. GCrafter uses guillotine placement because its output is a cut-ready sheet for saws and CNC work with straight, full-depth passes. The tradeoff: free nesters can beat guillotine layouts on odd-shaped part sets, so a generator's number is a floor to sanity-check, not gospel.
When should you override a generator's suggested layout by hand?
The optimizer maximizes yield per sheet, but you cut the sheet, so a few overrides are worth making every time.
Preserving usable offcuts
An optimizer will happily consume a 14-inch strip to squeeze out 2% more yield. If you batch-produce organizers or drawer boxes, that strip is tomorrow's sides and dividers. Nudge parts off the strip and accept the waste; a sawmill thread on cabinet software makes the same point about designing around stock you actually have, with one Fusion user noting parameters help but "there's a learning curve to that though" (Sawmill Creek forum).
Sequencing cuts for safety
Generators don't know your clamps. Reorder the cut path so every rip has a full-length fence side and no piece gets trapped mid-sheet, and keep rips before crosscuts so parts never ride between blade and fence.
What outputs should a good cut list generator give you besides the cut list?
A cut list alone doesn't get a sheet cut. The outputs that matter are labeled diagrams, per-part markings, offcut maps, and files your machine can actually load.
Labels and edge markings
Every part on the diagram needs an ID that matches the cut list, plus grain direction arrows and edge annotations (glue edge, front face, finished edge). Without labels, you're matching a 16 x 22-1/4" panel to three near-identical siblings by eye. An offcut map matters just as much: it shows the usable remainder per sheet with its dimensions, so the next job starts from stock you already own instead of a fresh 4x8.
Export formats your machine can cut
Look for DXF and SVG export at 1:1 scale, one file per part or one nested sheet, with kerf already compensated. SVG loads straight into LightBurn for the laser; DXF imports into your CNC CAM tool. GCrafter exports both, and because the joints are parametric, changing a cabinet width regenerates every finger and slot as cut-ready geometry rather than a sketch you rebuild. Where it falls short: it's built around parametric jointed assemblies, so a plain shelf-only job with no joinery is faster in a spreadsheet-based generator.
How do you verify a generated cut list before cutting your first sheet?
The test-cut ritual
Cut a small square with the generator's kerf setting on your actual material, then measure it with calipers. If a 100 mm test piece comes out at 99.6 mm, your laser is eating 0.4 mm and the generator should be told that number, not a guess. Laser kerf varies by machine and material, and community documentation for tools like LightBurn recommends running a kerf test rather than trusting a published figure (LightBurn documentation). Re-run the test whenever you change material thickness, power, or speed.
Cross-checking against your design model
Open the DXF or SVG output next to your model and measure one part's length, width, and slot depth before exporting to the machine. Confirm grain direction arrows on long parts match how you want the finished piece to look, since the optimizer may rotate parts to pack sheets. Finally, check the offcut map: if it claims a 4x8 sheet leaves only scraps, add up the part areas by hand and see whether the math agrees.
How do the popular tools compare on these criteria?
Run every tool through the same checklist: kerf handling, per-axis kerf, grain constraints, labeled layouts, offcut maps, and editable parameters. Boxes.py and MakerCase handle box joints well but lock you into preset shapes, so anything custom means exporting and fixing elsewhere. PanelOrca focuses on sheet layout from a cut list. Fusion does everything and therefore makes you model every finger by hand or with an add-in. SketchList 3D sits closer to full furniture design than joinery generation.
GCrafter covers parametric joinery plus cut-ready sheet output with kerf, grain direction, and trim allowance as first-class inputs.
Where GCrafter falls short too
It does not do 3D assemblies, molded parts, or anything outside flat sheet goods. If your project needs carved surfaces or hardware modeling, you still need Fusion or VCarve alongside it. The gallery of 100 designs covers common furniture and organizers, but a genuinely unusual joint means editing parameters rather than sketching freely. Treat it as the joinery and layout layer, not a CAD replacement.
FAQ
Does kerf get added to every part or only to the cuts between parts?
Only to the cuts. Two parts sharing an edge cost one kerf width total, not two, because each side of the cut line loses half a kerf. A part with no neighbors only shrinks if the generator compensates its outer boundary. This per-cut accounting is why sixteen 12" x 18" panels fit with a 0.125" saw kerf but spill onto a second sheet with a 0.25" router bit.
Can I use a cut list generator for a table saw with a stacked panel, or is it only for CNC?
Yes, and saws are arguably the better fit. Guillotine-based generators assume every cut runs edge to edge, which matches how a table saw or panel saw physically works: you split the sheet into rectangles and can't stop a cut mid-panel. Free-nesting tools suit CNC and laser work, but a guillotine layout maps directly onto a safe saw sequence of rips before crosscuts.
What kerf value should I use for a 3mm laser on Baltic birch?
Measure it on your own machine rather than trusting a published figure. A 60W CO2 laser typically removes somewhere around 0.006" to 0.01", but the exact value shifts with power, speed, and material. Cut a small test square at your production settings, measure it with calipers, and feed that number into the generator. Re-test whenever you change thickness, power, or speed.
Why does my generator put a part on a new sheet when it looks like it fits?
Kerf and trim allowance are eating the margin you're eyeballing. A grid that divides evenly on paper can need 48.75" of stock once each cut line consumes its kerf, and usable area is often an inch or more smaller than the nominal sheet because of clamps, travel limits, and factory-edge trimming. Grain-locked parts also shrink the optimizer's options. Check the reported usable dimensions before overriding.
Is a cut list generator worth it if I already model everything in Fusion 360?
For jointed sheet-goods work, yes, because Fusion makes you model and arrange every finger and slot by hand, then do the kerf arithmetic per cut line yourself. A parametric generator regenerates cut-ready sheets when a dimension changes. Keep Fusion for anything outside flat stock: carved surfaces, hardware, 3D assemblies. The two layers complement each other rather than compete.