Cylinder¶

In one sentence: Create a parametric cylinder with a configurable radius, height, and angular sweep that can be changed at any time.

Overview¶

Workbench: Part · Menu: Part → Primitives → Cylinder
Toolbar: Part Primitives · Shortcut: none

The Cylinder primitive creates a right circular cylinder (or a partial cylinder sector if Angle < 360°). Radius and Height are live parameters.

Intuition¶

Cylinders are the workhorse of mechanical part modelling: shafts, bosses, through-holes (as cutters), and flanges are all cylinders. Part Cylinder gives you a standalone solid that you can subtract from a box (making a through-hole) or fuse with another solid (adding a boss).

Setting Angle to less than 360° produces a cylindrical sector (pie slice), useful for ventilation ribs or arc-shaped parts.

When to use it¶

Quick shaft or boss outside a Part Design Body.
A through-hole cutter: make a cylinder the same diameter as the hole, then Part Cut it from the base solid.
A partial arc shell when combined with Thickness.

When NOT to use it¶

Inside a Part Design Body — use Additive/Subtractive Cylinder.
Hollow cylinder — use Tube which has both inner and outer radius.

Step-by-step walkthrough¶

Part → Primitives → Cylinder.
A 2 mm radius, 10 mm tall cylinder appears at the origin.
In the Data panel, set Radius and Height to your values.
Leave Angle at 360° for a full cylinder, or reduce it for a sector.
Adjust Placement to position the cylinder axis where needed.

Parameters¶

Parameter	Type	Default	Description
Radius	Distance	2 mm	Outer radius of the cylinder
Height	Distance	10 mm	Axial length along Z
Angle	Angle	360°	Angular sweep of the cross section (1°–360°)
Placement	Placement	Identity	Position and orientation

Note: The cylinder axis is always along the local Z axis. Rotate Placement to reorient it to X or Y.

Common mistakes and pitfalls¶

Cylinder axis is Z — not the axis you expect

The cylinder's axis runs along the local Z axis of its Placement. To create a horizontal shaft, rotate the Placement 90° around X or Y.

Radius, not diameter

FreeCAD uses radius here. If your drawing specifies ⌀20 mm, enter 10 mm.

Python API¶

import FreeCAD as App

doc = App.newDocument()

# Full cylinder
cyl = doc.addObject("Part::Cylinder", "Shaft")
cyl.Radius = 5.0     # mm — 10 mm diameter shaft
cyl.Height = 50.0    # mm
cyl.Angle  = 360.0   # degrees — full circle

doc.recompute()
print(f"Volume: {cyl.Shape.Volume:.2f} mm³")

# Reorient to lie along X axis
import math
cyl.Placement = App.Placement(
    App.Vector(0, 0, 0),
    App.Rotation(App.Vector(0, 1, 0), 90)  # rotate 90° around Y
)
doc.recompute()

Partial cylinder (sector)¶

sector = doc.addObject("Part::Cylinder", "Sector")
sector.Radius = 20.0
sector.Height = 5.0
sector.Angle  = 90.0   # quarter-circle wedge
doc.recompute()