Scale¶

In one sentence: Scale a shape by independent X, Y, and Z factors, producing a uniformly or non-uniformly scaled copy.

Overview¶

Workbench: Part · Menu: Part → Scale
Toolbar: Part Modeling · Shortcut: none

Part Scale creates a scaled copy of the selected shape. Scaling factors can be different for X, Y, and Z (non-uniform scaling), enabling stretching, squashing, or mirroring (negative scale factor) along individual axes.

Intuition¶

Scaling is rarely the primary modelling operation, but it fills several gaps:

Converting unit systems — scale by 25.4 to convert inches to millimetres.
Proportional resizing — scale all three axes equally to resize a complex imported shape.
Stretching a symbol — scale only along one axis to stretch a logo or extrusion profile.
Mirroring via negative scale — scale X by −1 to flip a shape left-to-right.

Parameters¶

Parameter	Type	Default	Description
Shape	Part object	—	The shape to scale
Uniform	Bool	Yes	When on, a single Scale factor applies to all axes
Scale	Float	1.0	Uniform scale factor (active when Uniform = Yes)
Scale X	Float	1.0	X-axis scale factor
Scale Y	Float	1.0	Y-axis scale factor
Scale Z	Float	1.0	Z-axis scale factor

Step-by-step walkthrough¶

Select the shape to scale.
Part → Scale.
In the dialog, turn off Uniform if you need different factors per axis.
Enter the scale factors.
Click OK.

Python API¶

import FreeCAD as App
import Part

doc = App.newDocument()

box = doc.addObject("Part::Box", "Box")
box.Length = 10; box.Width = 10; box.Height = 10
doc.recompute()

# Non-uniform scale: stretch X by 2, keep Y and Z
import math
mat = App.Matrix()
mat.scale(2.0, 1.0, 1.0)   # X×2, Y×1, Z×1
scaled_shape = box.Shape.transformGeometry(mat)

feat = doc.addObject("Part::Feature", "Scaled")
feat.Shape = scaled_shape
doc.recompute()
print(f"Scaled BBox: {feat.Shape.BoundBox.XLength} × "
      f"{feat.Shape.BoundBox.YLength} × "
      f"{feat.Shape.BoundBox.ZLength}")
# → 20.0 × 10.0 × 10.0

# Parametric Scale object (FreeCAD 1.0+)
scale_obj = doc.addObject("Part::Scale", "ScaledPart")
scale_obj.Base = box
scale_obj.Uniform = False
scale_obj.XFactor = 3.0
scale_obj.YFactor = 1.0
scale_obj.ZFactor = 0.5
doc.recompute()

Common mistakes and pitfalls¶

Negative scale produces a mirrored shape

Setting Scale X = −1 mirrors the shape about the YZ plane. This is intentional for generating mirrored variants, but unintentional if you mistype a negative value.

Non-uniform scaling invalidates fillet/chamfer radii

If you scale a filleted part non-uniformly, the fillet radii are scaled along each axis differently, producing elliptical cross-sections. Fillet after scaling if uniform radii are required.