Creating Arcs

The Arc tool, which creates circular arcs of any angle, has seven modes. Create an arc by radius, three points, tangent, two points and center, two points and radius, two end points and another point on the arc, or by arc length and optionally, chord length. The Push/Pull mode is available in 3D views for instantly extruding the arc after creation.

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Arc_modes.png 

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 an arc by clicking two points and a center

Specified Radius

Defines an arc by two points and a specified radius

Point on Arc

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

Arc Length

Defines an arc by the arc length and specified chord length

Push/Pull (3D views only)

Instantly extrudes the arc after creation; available in 3D views

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 wall 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

arc_tool.png 

To create an arc by its radius:

  1. Click the Arc tool from the Basic palette, and select the Radius mode.

  2. Click to set the center of the arc.

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

  4. Click to set the end point of the arc.

Shapes100100.png 

Arc by Three Points

arc_tool00103.png 

To create an arc by three points:

  1. Click the Arc tool from the Basic palette, and select the Three Points mode.

  2. Click to set the start point of the arc.

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

  4. Click to set the end point of the arc.

 Shapes100104.png

Arc Tangent to Line

arc_tool00107.png 

To create an arc by tangent:

  1. Click the Arc tool from the Basic palette, and select the Tangent to Line mode.

  2. Click to set the start point of the arc.

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

  4. Click to set the end point of the arc.

Shapes100108.png 

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

arctan_5.png 

Arc by Center

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To create an arc by two points and center:

  1. Click the Arc tool from the Basic palette, and select the Center mode.

  2. Click to set the start point of the arc.

  3. Click to set the end point of the arc.

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

  4. Click outside the arc to set the center.

Shapes100114.png 

Arc by Specified Radius

arc_tool00117.png 

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

  1. Click the Arc tool from the Basic palette, and select the Specified Radius mode.

  2. Click to set the start point of the arc.

  3. Click to set the end point of the arc.

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

  4. Click OK.

The arc is created.

arcradius.png 

Arc by Point on Arc

arc_tool00118.png 

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

  1. Click the Arc tool from the Basic palette, and select the Point on Arc mode.

  2. Click to set the start point of the arc.

  3. Click to set the end point of the arc.

  4. 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.

 Shapes100119.png

Arc by Arc Length

arc_tool00122.png 

To create an arc by arc length and chord length:

  1. Click the Arc tool from the Basic palette, and select the Arc Length mode.

  2. Click to set the start point of the arc.

  3. Click to set the end point of the arc.

    4. The Arc Length dialog box opens.

    Click to show/hide the parameters.

  4. Enter the desired parameters, and click OK to create the arc.

Shapes100123.png 

Creating Extruded Arcs

A planar arc that has been created in a 3D view can be extruded immediately after creation.

arc_tool00126.png 

To extrude a created arc:

  1. Enable the Push/Pull mode in the Tool bar for the Arc or Quarter Arc tool.

  2. Create an arc using any of the modes in the Tool bar.

  3. With the arc still selected, click, move the cursor, and then click to create the extrude.

Shapes100127.png 

An arc can be extruded at any time with the Push/Pull tool. See Direct Modeling with the Push/Pull Tool.

The extrude height and radius can be changed with the Reshape tool (see Reshaping Extruded Objects and Solid Primitives), the radius can be modified from the Object Info palette, and the resolution can be adjusted through the 3D Conversion Resolution setting (see 3D Preferences).

 

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