Creating arcs

The Arc tool, which creates circular arcs of any angle, has seven modes. The Push/Pull mode is available in 3D views for instantly extruding the arc after creation.

The Arc tool and Quarter Arc tool share the same position on the Basic palette. Click and hold the mouse on the visible tool to open the Pop-out tools list and select the desired tool.

Mode

Description

Radius

Defines the arc by its center

Three Points

Defines the arc by clicking three points

Tangent to Line

Defines the arc by defining a tangent to a line

Center

Defines the arc by clicking two points and a center

Specified Radius

Defines the arc by two points and a specified radius

Point on Arc

Defines the arc by two end points and another point on the arc

Arc Length

Defines the arc by the arc length and specified chord length

Push/Pull

(3D views only)

Instantly extrudes the arc after creation; see Push/Pull mode of planar tools

Push/Pull Combine

(available with Push/Pull mode)

When the shape to be extruded is drawn on the face of a solid object, combines the two objects into a single solid addition or solid subtraction; when this submode is disabled, the new extrude remains a separate object, and the existing solid object remains unchanged

Either move the mouse to draw the arc or use the Data bar to enter an angle. Degrees start on the positive X axis (the "East" direction), and increase going counter-clockwise. ("East" is 0 degrees; "North" is 90 degrees; and "West" is 180 degrees.) To draw a quarter-circle arc beginning at 0 degrees and ending at the 6 o’clock position, enter -90 (minus 90) degrees. Enter 270 to draw an arc three-quarters of a circle around.

To create a NURBS curve, draw an arc and then select Modify > Convert > Convert to NURBS.

To edit an arc, click the middle handle with the Selection tool and drag to change the arc radius. Press the Option key (Mac) or Alt key (Windows) to change the arc’s size.

Arc by radius

Mode

Tool

Tool set

Shortcut

Radius

Arc

Basic

3

To create an arc by its radius:

Click the tool and mode.

Click to set the center of the arc.

Click the start point of the arc. Move the cursor until the desired arc orientation and size are previewed.

Click to set the end point of the arc.

Shapes101072.png 

Arc by three points

Mode

Tool

Tool set

Shortcut

Three Points

Arc

Basic

3

To create an arc by three points:

Click the tool and mode.

Click to set the start point of the arc.

Click to set the point for the arc to pass through. Move the cursor until the desired arc orientation and size is previewed.

Click to set the end point of the arc.

 Shapes101076.png

Arc tangent to line

Mode

Tool

Tool set

Shortcut

Tangent to Line

Arc

Basic

3

To create an arc by tangent:

Click the tool and mode.

Click to set the start point of the arc.

Click to define the line to which the arc will be tangent. Move the cursor until the desired arc orientation and size is previewed.

Click to set the end point of the arc.

Shapes101080.png 

Use tangent snapping to assist with drawing the arc tangent to geometry; see Snapping to a tangent (2D Only).

arctan_5.png 

Arc by center

Mode

Tool

Tool set

Shortcut

Center

Arc

Basic

3

To create an arc by two points and center:

Click the tool and mode.

Click to set the start point of the arc.

Click to set the end point of the arc.

As the cursor moves, the center of the arc is manipulated.

Click outside the arc to set the center.

Shapes101086.png 

Arc by specified radius

Mode

Tool

Tool set

Shortcut

Specified Radius

Arc

Basic

3

To create an arc by two points and a specified radius:

Click the tool and mode.

Click to set the start point of the arc.

Click to set the end point of the arc.

The Arc Radius dialog box opens. Enter the length of the radius.

arcradius.png 

Arc by point on arc

Mode

Tool

Tool set

Shortcut

Point on Arc

Arc_PointOnArc_mode.png 

Arc

Basic

3

To create an arc by two end points and another point on the arc:

Click the tool and mode.

Click to set the start point of the arc.

Click to set the end point of the arc.

Move the cursor until the desired arc shape and size is previewed, and then click to set the arc. To constrain the angle of the line between the arc endpoints, press the Shift key when drawing the arc.

Without the Shift key, the angle of the line between the endpoints (clicks 1 and 2) is unconstrained, and the chord defining the arc height is an unconstrained line drawn from the second endpoint

When the Shift key is pressed, the angle of the line between the arc endpoints (clicks 1 and 2) is constrained, and the chord defining the arc height is perpendicular to the center of that line

Arc by arc length

Mode

Tool

Tool set

Shortcut

Arc Length

Arc

Basic

3

To create an arc by arc length and chord length:

Click the tool and mode.

Click to set the start point of the arc.

Click to set the end point of the arc.

The Arc Length dialog box opens; set the parameters.

Click to show/hide the parameters.Click to show/hide the parameters.

Parameter

Description

Arc Length

The drawn arc length is displayed, and can be changed; this allows you to create several arcs with the same chord length and varying arc lengths

Specify Chord Length

Manually specifies the chord length, changing the arc endpoint

Chord Length

The chord length is the distance between the two end points of the arc; the arc length must be greater than the chord length

 

Arc into segments

Creating quarter arcs

 

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