Workflow
Change the measurement, not an anonymous mesh vertex
PurCad exposes the dimensions that control generated geometry. Direct edits are deterministic where possible, and each accepted change records a new project version rather than overwriting the last working model.
Find the dimension by function
Sizes groups overall envelope, fit dimensions and fasteners. Labels and source information explain whether a value came from you or from a model default. Confirm the unit and the physical feature before typing a replacement.
Use direct edits for values and prompts for structure
Change an existing parameter when only a number is wrong. Use a follow-up request when the part needs a new hole, rib, opening or relationship. This split keeps simple revisions predictable and reserves generation for structural work.
Inspect the delta and current version
After the edit, compare overall bounds and the affected feature in the viewport. Read the version delta, then rebuild downloads for that version. Previous exports remain evidence of earlier states and should not be confused with the new geometry.
A valid number can still be a bad design choice
Parameter bounds prevent obviously unsupported values, but they do not prove fit or strength. Large dimensional changes can alter wall thickness and load paths. Re-check the complete part and test the interface physically.