Arcs

Degree

Specifies the degree of the curve. The values range from 2 to 7. The default is 6.

Spans

Specifies the number of spans in the curve. The values range from 1 to 14. The default is 1.

Note: The sum of the degree and number of spans cannot exceed 16. When creating rational geometry, as set in Preferences > Construction Options , the Spans option is not available.

Draw a three-point arc

1. Select the Arc (three point) tool .

2. Click the start point of the arc, or type a 3D coordinate to place the point exactly.

   

   If you click the endpoint of an existing keypoint curve, the new arc attaches itself to the end of that curve. Dragging the common endpoint moves both curves.

3. Click a second point to lie on the arc, or type a 3D coordinate to place the point exactly.

   

   • Click the to add the point freely.
   • Click the to align the point horizontally to the first point.
   • Click the to align the point vertically to the first point.

4. Click the end point of the arc, or type a 3D coordinate to place the point exactly.

   

   • Click the to add the point freely.
   • Click the to align the point horizontally to the first point.
   • Click the to align the point vertically to the first point.

   As you drag the end point, the Arc (Three Point) tool displays the radius of the arc in current linear units.

Draw a two-point arc

1. Select the Arc (two point) tool .

2. Click the start point of the arc, or type a 3D coordinate to place the point exactly.

   

   If you click the endpoint of an existing keypoint curve, the new arc attaches itself to the end of that curve. Dragging the common endpoint moves both curves.

3. Click the end point of the arc, or type a 3D coordinate to place the point exactly.

   

   • Click the to add the point freely.
   • Click the to align the point horizontally to the first point.
   • Click the to align the point vertically to the first point.

4. Click the center point of the arc, or type the radius of the arc and press .

   

   As you drag the center point, the Arc (Two Point) tool displays the radius of the arc in current linear units.

What if...?

• I want to edit the coordinates or length after I create a line?

  Choose Windows > Information > Information Window and change the parallel distance or angle.

  The relationships between keypoint curves are maintained until you manually reshape one of the curves.

• I want to draw arc segments at a different angle to the last line segment?

  Arc segments always project “forward” from the previous line. You cannot create concave arcs with the Line-arc tool.

  To get concave arcs, you must go back and edit the curve after creating it.

• I want to export keypoint curves to IGES?

• Key lines are exported as entity 110 (line).

• Key arcs are exported as IGES entity 100 (circular arc).

Draw an arc tangent to a curve

1. Select the Arc Tangent to Curve tool .

2. Click the start point of the new arc on the curve it will be tangent to.

   

3. Click the end point of the arc, or type a 3D coordinate to place the point exactly.

   

   • Click the button to add the point freely.

   • Click the to align the point horizontally to the first point.

   • Click the to align the point vertically to the first point.

     As you drag the end point, the Arc Tangent to Curve tool displays the radius of the arc in current linear units.

Draw an arc concentric to another arc

1. In the Curves tool palette, select Keypoint Curve Tools > Arcs, then click the Concentric Arc tool .

2. Click the arc from which the new arc will be offset.

3. Click the start point of the arc, or type a 3D coordinate to place the point exactly.

   

   As you drag the start point, the Concentric Arc tool displays the distance between the two radii.

4. Click the end point of the arc, or type a 3D coordinate to place the point exactly.

   

What if...?

• I want to create a concentric arc of more than 180 degrees?

  Concentric arcs are usually drawn in the direction that will create the smallest sweep angle.

  To draw an arc in the opposite direction, choose Windows > Information > Information Window. Open the Attributes section and click Complement.

• I want to create a concentric circle?

  Choose Windows > Information > Information Window. Set the Angle/Sweep attribute to 360.