Settings — kerf, trim, tolerance & cost
Every setting in CutOptim lives in the Settings panel of the left sidebar — it is always visible on desktop, and available from the Settings tab on mobile. There is no separate settings modal; what you see in the sidebar is the full configuration surface for the active project.
Settings split into two groups:
- Basic (always visible): kerf width, minimum offcut.
- Advanced (collapse arrow): minimum offcut size (W×H), kerf tolerance, trim (per side in 2D, start / end in 1D and Wood), profile width (1D Linear only), cost per cut, calibration cut, max. cutting stages, minimise rotation, first cut direction, currency, optimization goal, detailed cost entry, grain matching.
Some of those controls are 2D-only — trim per side, max. cutting stages, minimise rotation and first cut direction. Switch to 1D Linear or Wood and they are swapped out: a bar has two ends rather than four edges, so the start / end trim pair takes the place of the per-side grid. One control runs the other way: Profile width appears in 1D Linear alone.
The calibration cut is not one of them: a bar head is as likely to be out of square as a board edge, so it runs in every mode. Only its side picker is 2D — see below.
All values are saved on the project — when you open the project again, every setting comes back exactly as you left it.
Measurement units — millimetres or inches
The Settings panel has an mm / in toggle right under the kerf and minimum-offcut fields. It sets the working unit for everything you type and everything on screen — stock and part tables, kerf, trims, tolerance, minimum offcut, and the cut-plan results.
Set it before you enter your data. If you switch once your own numbers are already in the tables, CutOptim converts every dimension for you after a quick confirmation (÷25.4 from mm to inch, ×25.4 back) — a faithful conversion, so a 3 mm kerf lands on its exact 0.118″ value, not a rounded 1/8″. Switch while the workspace is still untouched — the starting demo, or an empty table — and you instead get idiomatic imperial defaults: the kerf default becomes 1/8″ (0.125), and the demo re-seeds with imperial sizes (a 96×48″ sheet, nominal 2×4 lumber).
The unit is remembered in three places, so it survives a reload and follows you to another device:
- Per cut — every saved cut carries its own unit. A single project can hold a metric cut and an imperial cut side by side; the project list shows an
mm/inbadge next to each cut name so a mixed-unit project stays legible. Opening a cut switches the app to that cut’s unit automatically. - On your profile — your last choice is saved to your account and loads on any device.
- In your browser — a local fallback for guests and offline use.
A finished optimization keeps the unit it was generated in. Switching the toggle afterwards never re-labels or invalidates a completed plan, and never costs you an optimization run. The offcut inventory is always stored in millimetres (it’s shared across projects, so it can’t carry mixed units) and converts at the boundary when you save into it.
Only millimetres and inches are supported as working units — there is no centimetre mode. Centimetres are accepted only as an Excel-import source unit, where the importer converts them to your active working unit on the spot.
Kerf width
Kerf is the width of material removed by each saw cut. Every pass converts a thin strip into sawdust, and over a few dozen cuts that loss adds up. Getting kerf right is the difference between a cut plan that fits and one that runs over.
Why kerf matters
Cut a 2440 mm sheet into 600 mm pieces:
- Without kerf: 4 × 600 = 2400 mm → fits with 40 mm spare.
- With 3 mm kerf: 4 × 600 + 3 × 3 = 2409 mm → still fits, but only 31 mm spare.
- Five pieces: 5 × 600 + 4 × 3 = 3012 mm → does not fit. The optimizer needs a second sheet.
If kerf is set too low the planner will produce a layout the saw physically can’t make. If it’s set too high it wastes material defensively.
Reference values
| Tool | Material | Typical kerf |
|---|---|---|
| Table saw — full kerf | Wood, sheet goods | 3.0–3.2 mm |
| Table saw — thin kerf | Wood, sheet goods | 2.4–2.6 mm |
| Track saw / circular saw | Wood, sheet goods | 2.6–3.2 mm |
| Panel saw / beam saw | Wood, sheet goods | 3.2–4.0 mm |
| Angle grinder 1 mm disc | Steel, aluminium | 1.0–1.5 mm |
| Cold saw | Steel, aluminium | 1.5–3.0 mm |
| Laser cutter | Steel, acrylic, wood | 0.1–0.5 mm |
| CNC router (straight bit) | Wood, aluminium, acrylic | 3.0–8.0 mm |
| Water jet | Steel, stone, glass | 0.8–1.2 mm |
| Glass cutter wheel | Float glass | 0.5–1.5 mm |
| Band saw | Wood, metal | 1.5–3.5 mm |
Always measure, don’t assume. Blade wear, material hardness, feed speed and even temperature all shift the actual kerf. Make a cut in scrap, push the halves together and read the gap with a dial calliper — that’s your real kerf for today.
Minimum offcut
The minimum offcut value is the threshold below which a leftover piece is treated as waste rather than a reusable offcut. Pieces above the threshold go into the offcut inventory; smaller pieces disappear.
The basic field is a single number used for both width and height. Advanced Settings exposes a finer-grained control:
| Feature | Type | Description |
|---|---|---|
| Minimum offcut (basic) | number (mm) | Single threshold applied to both width and height (2D) or to length (1D / Wood). Default 100 mm. |
| Minimum offcut width (Advanced) | number (mm) | Overrides the basic threshold for the width dimension in 2D mode. Only used when set above 0. |
| Minimum offcut height (Advanced) | number (mm) | Overrides the basic threshold for the height dimension in 2D mode. Only used when set above 0. |
| Minimum offcut length (Advanced) | number (mm) | Overrides the basic threshold for length in 1D and Wood modes. Only used when set above 0. |
If both the basic and advanced fields have values, the larger of the two wins. That keeps the basic field as a floor — you can never accidentally collect offcuts smaller than the basic number.
Recommended starting values
| Trade | 2D recommendation | Reasoning |
|---|---|---|
| Cabinet making | 200 × 200 mm | Drawer fronts, shelf tabs, panel offcuts |
| Glass cutting | 300 × 300 mm | Smaller pieces are unsafe to handle |
| Sheet metal | 150 × 150 mm | Bracket / patch usable |
| Signage / display | 100 × 100 mm | Letters, mounts |
For 1D and Wood, 200–500 mm is the typical range — a 150 mm steel offcut is rarely worth storing; a 500 mm timber offcut often is.
Too low and your offcut inventory fills with tiny scraps you’ll never use. Too high and useful pieces vanish into waste. Review the inventory once a month and prune what hasn’t moved.
Advanced settings
The ▸ Advanced Settings arrow in the sidebar expands the rest of the controls. They are collapsed by default to keep the everyday interface clean.
Kerf tolerance New
Kerf tolerance lets you accept pieces that overshoot the bar or sheet by up to a small amount — useful when the saw’s effective kerf isn’t perfectly stable. The optimizer always prefers an exact fit; tolerance is only consulted when an exact fit fails.
Default value: 0 (tolerance disabled). Range: 0–20 mm. Typical values: 1–3 mm.
When a tolerated fit is accepted, the result page shows a “Within tolerance” stat counting how many pieces fitted only because of the relaxation. That count is your audit trail — it tells you how many cuts will be running tight to the limit on the shop floor.
For a deep dive — when to use it, how to measure it, when to leave it alone — see the Kerf tolerance guide.
Tolerance is not free yield: every tolerated cut is a piece that physically wouldn’t have fitted without bending the rules. Keep it below 5 mm in production, and only when your saw measurement supports it.
Trim New
Most bars and sheets need a clean-up cut before parts can be cut from them: a damaged factory edge, paint overspray, a defaced sticker zone, or the clamp end on a bandsaw. Trim removes a fixed amount from the material before the optimizer places anything.
The control follows the material. A sheet has four edges, a bar has two ends — so the sidebar shows a different control per mode:
Trim per side (2D)
In 2D mode the Advanced panel shows Trim per side: four separate inputs, labelled left, right, top and bottom. The working rectangle shrinks inward by whatever each one says, and each edge is independent.
That independence is the point. A damaged or out-of-square edge needs more than the others, and trimming all four the same does not give you a worse plan there — it gives you a wrong one: too little on the bad edge and your first part carries the defect, too much everywhere else and you have paid for material you never had to lose.
Default: 0 on all four sides. Plan: every plan, guests included — there is no gate on this control.
Start trim / End trim (1D and Wood)
In 1D Linear and Wood modes the same idea has only two values:
- Start trim — removes a fixed length from the start of every bar.
- End trim — removes a fixed length from the end. Use it for the clamp / waste-end on bandsaws and cold saws.
Defaults: 0 / 0 (no trim).
Trim counts as waste, not offcut — the trimmed strip is gone for good, it isn’t stored in the inventory. The result page shows it as part of the total waste stat (mm or m²).
Kerf and trim can travel with the material. If you keep your standard sheets and bars in the Material inventory (Pro), saving one also stores whatever kerf and edge trim are set here at that moment — four edges for a sheet, two ends for a bar — and loading it puts them back, naming the fields it changed. A material saved before that feature existed carries nothing and changes nothing when loaded.
Profile width (1D Linear only) New
Linear stock is a length and nothing else. That is enough to plan the cuts, but not enough to say how far the blade actually travels — there is no cross-section for it to cross. So by default a 1D Linear plan reports stop positions and no cut length, rather than a figure nobody measured.
Profile width is where you supply the missing number: how wide the material is that the blade crosses on one cut. A 50 × 30 box section fed flat is 50; the same section fed on edge is 30. Enter it and the sawn length is reported in four places:
- the results header, alongside the other run statistics — every plan;
- the run summary (“How this was optimized”) — every plan;
- the PDF, in the framed key figures under the sawing plan — Pro, because the sawing-plan page is Pro;
- the Excel Cutting Sequence tab, in the Length column and in the totals at the bottom — Pro, because the workbook is Pro.
Every counted cut crosses the profile exactly once, so the total is the cut count times the width you entered.
Default: 0 — no cut length is reported and nothing about the plan changes. Plan: the field itself is not gated, and the on-screen figure it produces is available on every plan.
The field is deliberately absent from the other two modes. Wood already knows the cross-section of each material and reports a sawn length on its own; 2D measures the blade path from the cut tree. And because Profile width is a single number for the whole job, a job mixing several sections belongs in Wood mode, which tracks the section per material.
Cost per cut Pro
Adds a per-cut charge to the cost summary. Useful when one of these is a real expense:
- CNC machine time billed per cut.
- Blade wear amortised across cuts.
- A per-cut fee from your subcontractor cutting service.
How CutOptim counts cuts:
- 1D mode — one cut per placed piece.
- 2D mode — the charge is applied to the saw passes figure: every strip crossed separately, counted from the actual layout rather than estimated per piece. That is the number shown as the sub-line under the Cuts stat in the results header, and it is normally higher than the Cuts figure above it, which counts one fence setting once. See Reading your results for what the two numbers mean.
Cut cost shows in the results as a dedicated stat alongside material cost. The total is also stored in the project and surfaces in the Quotation PDF export (Workshop plan).
Default: 0 (no cut cost added).
Don’t pad cost per cut with overhead — keep this value clean (saw blade depreciation, electricity, per-cut tooling). Overhead and labour belong in a higher-level project markup, not on every cut.
Calibration cut Pro
Every mode. A calibration cut skims a thin strip off the material before any part is cut. You measure that strip, compare it with the number you asked for, and correct the fence or stop by the difference — so the first real part is already accurate instead of being the one you sacrifice to find out the setup was off.
The control is a checkbox, a value in millimetres, and — in 2D only — a side selector (left, right, top or bottom).
On a sheet (2D)
- The skim comes off the edge you pick in the side selector.
- The material it removes counts towards that edge’s trim and towards the Cut length figure — it is a real pass of the saw, so it is in the totals rather than hidden.
- It adds one cut per board.
- In the Cutting Sequence it becomes the first step on every board, labelled as the calibration step.
On a bar (1D Linear and Wood)
- The skim always comes off the head — the start of the bar. The side picker is hidden, because a bar has one head: offering a choice of four edges would be a control the plan could not honour.
- It rides on the start trim. The material reserved at the head is start trim + calibration, and that is what turns step 0 of the sawing plan into a real stop position rather than a line drawn on a picture.
- With both a start trim and a calibration cut set, the head is crossed twice — once for the strip you measure, once to take the rest of the trim off — and the sawing plan lists both passes, in that order.
- It adds one cut per bar, which the Cuts figure in the results header already counts.
Plan: Pro. Ticking the box without Pro puts it straight back and opens the upgrade dialog; switching it off is always allowed.
Max. cutting stages Workshop
2D only. A stage is a run of parallel cuts between two turns of the material. Panel saws are specified exactly this way — 2-stage, 3-stage, 4-stage cutting — and this setting tells the optimizer how many stages your machine or your patience allows.
A stage is not the raw depth of the cut tree. Depth counts how many splits sit above a part and is not a machine specification: a kitchen job can measure 9 deep and still be cut in 3 stages. The limit constrains stages.
Set 0 for no limit, which is what every plan gets by default.
Capping the stages usually costs you nothing on the sheet and saves you setups at the saw. On the standard 40-part demo job (2440×1220, kerf 3), the unconstrained plan needs 44 cuts and 35.21 m of sawing; capped at 2 stages the same job drops to 30 cuts and 32.88 m — with the same yield, the same number of sheets, and all 40 parts still placed.
An impossible limit never fails the run. If some boards still need more stages than you allowed, the optimizer returns the plan anyway and warns you which boards need extra setups on the saw — a usable plan with a caveat, not an error.
Plan: Workshop. Entering a limit above 0 without it resets the field to 0 and opens the upgrade dialog.
Minimise rotation Workshop
2D only. A checkbox that tells the optimizer to prefer layouts which turn fewer parts. It is a preference, not a lock: a layout that rotates fewer parts is only chosen when it costs no extra sheet. A sheet is money, a rotation is seconds — so yield is never traded away for it.
This is different from the per-part Rot. checkbox in the Parts table, which forbids rotating one specific part outright (for grain, print direction or a finished face) and is available on every plan.
Plan: Workshop. Ticking it without the plan puts it back and opens the upgrade dialog; switching it off is always allowed.
First cut direction
The first cut direction controls which axis is cut first on a 2D sheet. It has no effect in 1D or Wood modes (there’s only one axis there).
| Feature | Type | Description |
|---|---|---|
| Auto ⚡ | option | The optimizer tries both directions per sheet and picks whichever yields the most. Default and recommended. |
| Horizontal ↔ | option | Every sheet's first cut runs left-to-right. Use this when your panel saw has a fixed-height fence (the panel must fit between the fence rails). |
| Vertical ↕ | option | Every sheet's first cut runs top-to-bottom. Use when your machine has a maximum horizontal travel constraint. |
Leave on Auto — it tries both directions and keeps the higher-yield layout, so it’s never worse than locking one. Only force a direction if your saw physically requires it; the wrong choice can cost a whole extra sheet.
Currency
The currency selector sets the symbol used in the cost summary, the Quotation PDF, and any cost-related output. Available currencies: EUR (€), USD ($), GBP (£), HUF (Ft), RON (lei), PLN (zł), CZK (Kč), CHF (Fr).
Currency is stored per project. Changing it does not convert any entered prices — it only changes the symbol displayed next to the values.
Optimization goal
The goal selector decides how CutOptim orders the available stock when packing pieces. Minimize waste (the default) is available on every plan; Minimize cost is a Pro feature.
| Feature | Type | Description |
|---|---|---|
| Minimize waste 📉 | option | Default, available on all plans. Stock is used in the order you entered it, modified by any priority stars. Yield is maximised for the available stock. |
| Minimize cost 💰 (Pro) | option | Stock with prices is sorted cheapest first, so cheaper sheets/bars fill before more expensive ones. Priority stars still override price. Useful when you have stock at meaningfully different unit prices. |
Minimize cost only matters if you have entered per-item prices in the stock table. Enable Show price columns (below) to surface those price inputs. Without prices, both goals produce identical results.
Show price columns Pro
Show price columns is a checkbox that toggles a price (💰) column on the Stock and Parts tables. When on:
- Stock table gets a price-per-sheet (or per-bar) input.
- Parts table gets a price-per-piece input (for quoting).
- Both feed the cost summary on the results page and the Quotation PDF.
Off by default to keep tables clean. The toggle state is saved per project.
Grain matching Workshop
Grain matching tells the optimizer that some pieces must come from the same parent panel — for visual continuity on book-matched cabinet doors, drawer fronts, or wall panels. Groups are defined per project. See the 2D Panel Cutting guide for the workshop background.
Where settings live
All settings are stored on the project record (projects.settings JSONB). When you reopen a project, every setting reloads with it. You can also save the current values as your own defaults for new projects — the controls appear in the Settings panel once you are signed in, and they write to your profile (profiles.default_kerf_tolerance, default_start_trim, default_end_trim, default_cost_per_cut). Saving defaults needs an account but no paid plan.
A “template project” carrying your shop’s standard kerf, trim, cost-per-cut and currency is still a useful pattern for anything the per-user defaults do not cover — duplicate it as the starting point for new work.
What’s coming next
One phantom control was removed from the sidebar in an earlier update because it was never wired to anything:
- Cut type “Nested” — true nested (free-form) cutting will come back as part of the upcoming Maximum-efficiency optimization mode (Pro / Workshop, roadmap).
Working units are already covered: millimetres and inches are both supported today via the mm / in toggle described above. There is no centimetre working mode (centimetres are accepted only as an Excel-import source unit).
If this is a workflow blocker for you, tell us — feature priority is shaped directly by user requests.