Draft Arc

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Arrow-left.svg Previous: Draft Circle.svg Circle

Draft Arc.svg Draft Arc

Menu location
Draft → Arc
Workbenches
Draft, Arch
Default shortcut
A R
Introduced in version
0.7
See also
Draft Circle, Draft Ellipse


Description

The Arc tool creates a circular arc in the current work plane by entering four points, the center, a point that defines the radius, the first end point and the second end point, or by picking tangents, or any combination of those. It uses the Draft Linestyle set on the Draft Tray.

This tool works the same way as the Draft Circle tool, but adds start and end angles. To draw an elliptical arc use Draft Ellipse. You can also approximate a circular arc by using the Draft BSpline, Draft BezCurve, and Draft CubicBezCurve tools.

Draft Arc example.jpg

Arc defined by four points, center, radius, initial point of arc and final point of arc.


How to use

  1. Press the Draft Arc.png Draft Arc button, or press A then R keys.
  2. Click a first point on the 3D view, or type a coordinate and press the Draft AddPoint.svg add point button.
  3. Click a second point on the 3D view, or enter a radius value.
  4. Click a third point in the 3D view, or enter a start angle.
  5. Click a fourth point in the 3D view, or enter an aperture angle.

The arc can be edited by double clicking on the element in the tree view, or by pressing the Draft Edit.svg Draft Edit button. Then you can move the center point to a new position.

The arc can be turned into a circle after creation, by setting its first angle and last angle properties to the same value.

Options

  • The primary use of the arc tool is by picking four points: the centre, a point on the circumference, the start of the arc, and its end.
    • By pressing Alt, you can select a tangent instead of picking point, to define the base circle of the arc. You can therefore construct several types of circles by selecting one, two or three tangents.
  • The direction of the arc depends on the movement you are doing with your mouse. If you start to move clockwise after the third point is entered, your arc will go clockwise. To go counter-clockwise, simply move your mouse back over the third point, until the arc starts drawing in the other direction.
  • To enter coordinates manually, simply enter the numbers, then press Enter between each X, Y and Z component. You can press the Draft AddPoint.svg add point button when you have the desired values to insert the point.
  • Press T or click the checkbox to toggle continue mode. If continue mode is on, the Arc tool will restart after you finish the arc, allowing you to draw another one without pressing the tool button again.
  • Hold Ctrl while drawing to force snapping your point to the nearest snap location, independently of the distance.
  • Hold Shift while drawing to constrain your point horizontally or vertically in relation to the center.
  • Press Esc or the Close button to abort the current command.

Properties

An Arc object shares all properties from a Draft Circle, but some properties only make sense for the circle.

Data

  • DATAFirst Angle: specifies the angle of the first point of the arc.
  • DATALast Angle: specifies the angle of the last point of the arc.
  • DATARadius: specifies the radius of the arc.
  • DATAMake Face: specifies if the arc makes a face or not. This property only works if the shape is a full circle.
To make an arc a full circle set the DATAFirst Angle and DATALast Angle to the same value. The values 0° and 360° aren't considered the same, so if these two values are used, the circle will not form a face.

View

  • VIEWPattern: specifies a Draft Pattern with which to fill the face of the arc. This property only works if the arc is a full circle, and if DATAMake Face is True, and if VIEWDisplay Mode is "Flat Lines".
  • VIEWPattern Size: specifies the size of the Draft Pattern.

Scripting

See also: Draft API and FreeCAD Scripting Basics.

The Arc tool can be used in macros and from the Python console by using the same function to create circles, with additional arguments. See the information in Draft Circle.

Example:

import Draft

Arc1 = Draft.makeCircle(200, startangle=0, endangle=90)
Arc2 = Draft.makeCircle(500, startangle=20, endangle=160)
Arc3 = Draft.makeCircle(750, startangle=-30, endangle=-150)
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