Workflow
Keep dimensions connected to the shape they are meant to control
PurCad treats visible dimensions as part of the design contract. Parameters carry units, bounds and provenance, and the geometry pipeline checks that user-visible dimensional controls actually affect the built result.
Choose parameters that represent design decisions
Useful controls describe fit, envelope, fasteners, wall thickness and clearance. Avoid exposing decorative numbers that users cannot relate to the part. PurCad groups parameters by purpose so a mating diameter is not confused with an overall size.
Change a value or request a focused revision
Edit an existing parameter directly for deterministic dimensional changes. When the required feature is missing, use a follow-up request that names the feature and target relationship. Every change becomes a new version with a recorded delta.
Prove that the parameter changes geometry
PurCad rejects dead visible dimensions whose value does not influence a supported geometric field. After an edit, inspect the new bounds and relevant feature, then compare the version summary before preparing fresh exports.
Parametric does not mean every shape is unconstrained
Large changes can invalidate clearances, topology or the original manufacturing intent. Respect declared bounds and re-run physical-fit checks after significant edits. Restore a known-good version when a revision moves beyond the tested design envelope.