Draft Arc 3Points

Other languages:

Arc

Circle

Draft

Menu location
Draft Arc 3Points
Drafting → Arc tools → Arc by 3 points 2D Drafting → Arc by 3 points
Workbenches
Draft, BIM
Default shortcut
A T
Introduced in version
0.19
See also
Draft Arc, Draft Circle

Description

The Draft Arc 3Points command creates a circular arc on the current working plane from three points that define its circumference. The center and radius are calculated from these points.

A Draft Arc is in fact a Draft Circle with a DataFirst Angle that is not the same as its DataLast Angle.

Arc defined by three points on its circumference

Usage

See also: Draft Tray, Draft Snap and Draft Constrain.

There are several ways to invoke the command:
- Press the Arc by 3 points button.
- Draft: Select the Drafting → Arc tools → Arc by 3 points option from the menu.
- BIM: Select the 2D Drafting → Arc by 3 points option from the menu.
- Use the keyboard shortcut: A then T. introduced in version 0.20
The Arc by 3 points task panel opens. See Options for more information.
Pick the first point in the 3D view, or type coordinates and press the Enter point button.
Pick the second point in the 3D view, or type coordinates and press the Enter point button.
Pick the third point in the 3D view, or type coordinates and press the Enter point button.

Options

The single character keyboard shortcuts available in the task panel can be changed. See Draft Preferences. The shortcuts mentioned here are the default shortcuts (for version 1.0).

To manually enter coordinates enter the X, Y and Z component, and press Enter after each. Or you can press the Enter point button when you have the desired values. It is advisable to move the pointer out of the 3D view before entering coordinates.
Press R or click the Relative checkbox to toggle relative mode. If relative mode is on, coordinates are relative to the last point, if available, else they are relative to the coordinate system origin.
Press G or click the Global checkbox to toggle global mode. If global mode is on, coordinates are relative to the global coordinate system, else they are relative to the working plane coordinate system. introduced in version 0.20
Press N or click the Continue checkbox to toggle continue mode. If continue mode is on, the command will restart after finishing, allowing you to continue creating arcs. introduced in version 0.20
Press S to switch Draft snapping on or off.
Press Esc or the Close button to abort the command.

Notes

A Draft Arc can be edited with the Draft Edit command.

Preferences

See also: Preferences Editor and Draft Preferences.

If the Edit → Preferences... → Draft → General → Create Part primitives if possible option is checked, the command will create a non-editable Part Feature instead of a Draft Circle.

Properties

See Draft Circle.

Scripting

To create a Draft Arc by 3 points use the make_arc_3points method of the Draft module:

arc = make_arc_3points(points, placement=None, face=False, support=None, map_mode="Deactivated", primitive=False)

Creates an arc object from the given points list.
If a placement is given, the center of the circular arc will be moved to this place. See Placement for more information.
If face is True, the arc will make a face, that is, it will appear filled.
If support is given, it is a LinkSubList, that is, a list indicating an object and a subelement of that object. This is used so that the object appears referenced to this support.

For example: support=[(obj, ("Face1"))].

If map_mode is given, it is a string defining a type of mapping, for example: map_mode='FlatFace', map_mode='ThreePointsPlane', etc. See Part EditAttachment for more information.
If primitive is True, the arc created will be a simple Part Feature, not a complex Draft object.

Example:

import FreeCAD as App
import Draft

doc = App.newDocument()

points = [App.Vector(0, 0, 0),
          App.Vector(5, 10, 0),
          App.Vector(10, 0, 0)]

arc = Draft.make_arc_3points(points)

doc.recompute()