Choose the functional intent. DraftFit takes you to a family of controls to evaluate — it does not automatically generate a drawing tolerance.
Load a realistic starting point, then edit any input.
Copy a URL that restores the current calculation inputs.
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Copy a compact engineering summary for email, Teams, notes or reports.
Copy a URL that restores the current calculation inputs.
Copy result
Copy a compact engineering summary for email, Teams, notes or reports.
Load a realistic starting point, then edit any input.
Choose the functional intent. DraftFit takes you to a family of controls to evaluate — it does not automatically generate a drawing tolerance.
ISO mode uses ISO 1101:2017 as the reference framework for this educational guide. Educational reference only — always interpret the production drawing according to the explicitly invoked standard, revision and company requirements.
Form Tolerances
NO
two-planes
Use it when an entire surface must be flat in itself, independent of another surface or datum.
Flatness is not parallelism. Flatness does not reference a datum; parallelism does.
Controls the form of an entire surface independently of any datum. Flatness limits how much the actual surface may depart from an ideal plane.
The complete controlled surface must lie between two parallel planes separated by the flatness tolerance.
No datum reference
Flatness does not require and is not referenced to a datum.
Typical inspection methods include CMM surface sampling, surface-plate methods, precision scanning or dedicated form-measuring equipment. The measured points are evaluated against two parallel planes defining the minimum or specified tolerance zone.
Simply placing the controlled surface directly on a surface plate can constrain or mask its natural form. The setup and support strategy must be appropriate for the inspection objective.
* Educational example only — the actual FCF must follow the drawing requirement.
Engineering report
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