# Change a dimension on a copy

> Propose a new value, run it on a copy, check the result independently, then accept or reject. Your original is never touched.

Status: Available · Level: Everyday · About 8 minutes · Canonical: https://paracrux.com/docs/change-a-dimension-safely

## You need

- The app activated
- One SOLIDWORKS session with a clean, saved, rebuilt part active
- The part has one configuration and no equations or external references

## You'll come away with

- Capture a part into a worksheet
- Propose and review a dimension change
- Read the evidence before you accept

## Step by step

1. **Capture the part.** Open the Worksheets tab and write the change brief. Choose Capture current part and references: it pins copies of the source and records their fingerprints, so later you can prove what you started from.
   Try saying: "Make the plate 12 mm thick for the heavier bracket."
2. **Propose new values.** Pick up to 16 of the captured driving dimensions and enter new positive values in millimetres or degrees. Say why. You can add volume, area or mass limits the result must meet, each with a minimum, a maximum and where the requirement comes from. Then choose Save proposal for review.
3. **Run it on a copy.** Choose Accept plan and execute on copy. The change is made on a new copy, rebuilt and checked; native and STEP outputs are saved and the native file is reopened.
4. **Check it independently.** Choose Import STEP and check in ParaCrux. It measures the output with a separate geometry engine and compares solid count and volume with the native result.
5. **Accept or reject.** Write a result review note. With both checks passed, Accept result is enabled; Reject result needs only the note. Neither changes the original. Choose Export printable worksheet for your records.

## Walkthrough

The values are from a recorded run on 23 September 2026: a 60 × 40 × 10 mm plate made 12 mm thick. The dimension name is typical SOLIDWORKS naming, shown for illustration.

- **You:** Make the plate 12 mm thick for the heavier bracket.
- **Captured:** Part = 60 × 40 × 10 mm plate; Configurations = 1; Source copy = pinned, fingerprint recorded
- Provenance: recorded

- **Proposal:** D1@Boss-Extrude1 = 10 mm → 12 mm; Reason = Heavier bracket; Expected volume = 28,800 mm³
- *60 × 40 × 12 = 28,800 mm³. Adding a volume bound means a wrong result fails loudly.*
- Provenance: calculated

- **Gate:** Review the proposal. Nothing runs until you accept execution.
- Provenance: illustrative

- **Run on a copy:** Rebuild = no errors; Native reopen volume = 28,800 mm³; Original = unchanged
- Provenance: recorded

- **Independent STEP check:** Solids = 1 valid closed body; Quarantined = none; Imported volume = 28,800 mm³; Agreement = native and import match
- Provenance: recorded

- **Gate:** Both checks passed. Write a review note, then accept or reject.
- Provenance: illustrative

- **Agent:** Accepted. The printable worksheet records the source, the change, both measurements and your note.
- Provenance: illustrative

## What it won't do

- One part at a time: no assembly edits, and only parts with one configuration, no equations and no external references.
- The worksheet records are hash-chained local records, not signed identity attestations.
- If a run times out, the outcome is marked uncertain and never replayed automatically.
- Passing checks shows the result matches the stated values and bounds, not that the design is right.
- The printable worksheet's full record includes local file paths. Check it before you share it.

## Covers

- Reviewed dimension changes (Available): Pick up to 16 driving dimensions, set new values, run the change on a copy and check the outputs before you accept. Where: In the app, Worksheets tab

## Next

- [How a job spends AI credit](https://paracrux.com/docs/how-a-job-spends-credit.md): What leaves your machine, how each step reserves its cost, and where a job always stops.