Rhino 3D Tip: Precise single-axis and in-plane scaling with Scale1D and Scale2D

Scale1D and Scale2D are precise tools to reshape geometry along one or two axes while preserving critical features. Use them to hit exact dimensions fast without rebuilding.

When to use which

• Scale1D: Change an object’s size along a single direction (length-only adjustments, fitting parts between limits, stretching handles, etc.).
• Scale2D: Change size in the current CPlane’s X and Y while keeping the third axis unchanged (sheet thickness preserved, faceplates resized in-plane, logos scaled on a surface).
• Prefer these over uniform Scale (all directions) or ScaleNU (X/Y/Z all different) when one axis (or plane) must remain unchanged.

Key concepts

• Reference-based accuracy: Both commands let you pick an origin, a reference distance, and a target distance or factor. Enter exact numbers (e.g., “125mm” or “1.25”).
• Origin choice matters: Pick a midpoint or logical anchor to keep scaling symmetric and avoid shifting your model.
• CPlane alignment for Scale2D: Scale2D respects the active CPlane’s X and Y. Use CPlane > 3Point or CPlane > Object to align axes to your part before scaling.
• Copy option: Use Copy=Yes to keep an original for comparison.

Workflow 1: Fit a part to an exact length with Scale1D

1. Run Scale1D and select the object.
2. Set the origin at the part’s centerline or neutral anchor.
3. Pick a reference point along the direction you want to change (e.g., from origin to an end).
4. For the final pick, snap to a target reference or type the exact target length. Rhino computes the factor automatically.
5. Verify with Distance or dimensions.

Workflow 2: Resize a plate in-plane with Scale2D (keep thickness)

1. Align the CPlane to the plate: CPlane > Object or 3Point.
2. Run Scale2D, select the plate, set origin at its centroid (e.g., Osnap=Center or midpoint intersection).
3. Define the first and second reference points along CPlane X and Y directions.
4. Type target widths/heights or use factor input. Because the CPlane Z is ignored, thickness stays unchanged.
5. Check with BoundingBox + Distance for final size.

Pro tips

• Create a temporary BoundingBox to measure clear, stable extents for reference picks.
• To keep features centered, set the origin at the geometric center; to preserve a mounting face, set the origin on that face.
• Use units in numeric input (“42in”, “210mm”) to avoid scale-factor math.
• For repeated tasks, make aliases (e.g., “s1” for Scale1D, “s2” for Scale2D).
• Scaling block instances adjusts their X/Y/Z scales; if that’s not desired, work on geometry inside the block or explode a copy first.

Avoid common pitfalls

• Distorting rounds/holes: Non-uniform scaling can turn circles into ellipses. Scale along the hole axis (Scale1D) or rebuild those features after scaling if circularity is critical.
• Wrong plane for Scale2D: If the CPlane isn’t aligned, you’ll scale in unexpected directions. Set the CPlane first.
• Unintended shifts: A poor origin choice moves the part. Use midpoints/centers for symmetric changes.

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