ISO 2768-1 · engine policy v1.1
CNC tolerance lookup
Prices assume ISO 2768-m by default. Finer grades or absolute ±0.05 / ±0.025 increase the estimate using engine rate factors; anything tighter than ±0.025 needs a manual quote.
默认按 ISO 2768-m 计价。更细等级或绝对公差 ±0.05 / ±0.025 按引擎费率系数上浮；严于 ±0.025 需人工报价。
Result
25 mm is in 6 < nominal ≤ 30.
| Grade | ISO 2768-1 limit | Engine price factor |
|---|---|---|
| f · fine | ±0.10000000000000001 mm | ×1.1499999999999999 heuristic · pm0_05 |
| m · medium | ±0.20000000000000001 mm | ×1 · standard |
| c · coarse | ±0.5 mm | ×1 · standard |
| v · very coarse | ±1 mm | ×1 · standard |
rates.tolerance_factors.default = ISO 2768-m; multiplier 1.0.
Absolute tolerance hooks
These keys are engine policy from rates v1.1, not ISO grades.
| Key | Meaning | Factor |
|---|---|---|
| standard | ISO 2768-m | ×1 |
| pm0_05 | ±0.05 mm | ×1.1499999999999999 |
| pm0_025 | ±0.025 mm | ×1.3500000000000001 |
| tighter | tighter than ±0.025 mm | Manual quote |
Roughness factors
- Ra1.6 ×1.1499999999999999 (rates.roughness_factors.Ra1.6)
- Ra0.8 ×1.3500000000000001 (rates.roughness_factors.Ra0.8)
Tolerance and roughness multipliers both apply in applyCommon (tolMult × roughMult on unit cost before finish). Material machine_time_factors (e.g. rates.cnc.machine_time_factors.IN718=2.5) are separate and already inside formula-cnc machine time.
ISO 2768-1 Table 1 reference
ISO 2768-1:1989 Table 1 — Permissible deviations for linear dimensions except broken edges (external radii and chamfer heights). Public general-tolerance values widely republished in machining handbooks; not derived from quote-engine rates.
| Nominal (mm) | f fine | m medium | c coarse | v very coarse |
|---|---|---|---|---|
| 0.5 < nominal ≤ 3 | ±0.050000000000000003 mm | ±0.10000000000000001 mm | ±0.20000000000000001 mm | not_defined |
| 3 < nominal ≤ 6 | ±0.050000000000000003 mm | ±0.10000000000000001 mm | ±0.29999999999999999 mm | ±0.5 mm |
| 6 < nominal ≤ 30 | ±0.10000000000000001 mm | ±0.20000000000000001 mm | ±0.5 mm | ±1 mm |
| 30 < nominal ≤ 120 | ±0.14999999999999999 mm | ±0.29999999999999999 mm | ±0.80000000000000004 mm | ±1.5 mm |
| 120 < nominal ≤ 400 | ±0.20000000000000001 mm | ±0.5 mm | ±1.2 mm | ±2.5 mm |
| 400 < nominal ≤ 1000 | ±0.29999999999999999 mm | ±0.80000000000000004 mm | ±2 mm | ±4 mm |
| 1000 < nominal ≤ 2000 | ±0.5 mm | ±1.2 mm | ±3 mm | ±6 mm |
| 2000 < nominal ≤ 4000 | not_defined | ±2 mm | ±4 mm | ±8 mm |
Questions
Which tolerance table is this?
ISO 2768-1:1989 Table 1, the public general tolerances for linear dimensions except broken edges, grades f, m, c, and v. The quote engine does not ship this numeric table. Buy the official text from iso.org. The figures here are the commonly cited Table 1 limits.
How do finer grades change the estimate?
Prices assume ISO 2768-m by default. Finer grades or absolute ±0.05 / ±0.025 increase the estimate using engine rate factors; anything tighter than ±0.025 needs a manual quote.
Is the fine-grade factor an ISO rule?
No. rates v1.1 have no dedicated ISO-f factor. Selecting fine maps to the engine hook pm0_05 as a labeled heuristic. Coarse and very coarse are not discounted versus ISO 2768-m. Anything tighter than ±0.025 mm needs a manual quote.
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Related: Part cost estimator · Manufacturing standards