Create Controlled Curves in Adobe CS5 Illustrator
Adobe Creative Suite 5 (Adobe CS5) Illustrator allows you to create controlled curves. Controlled curves are objects which are built with a great degree of precision.
Create a new document and then choose View→Show Grid to show a series of horizontal and vertical rules that act as guides.
If it helps, use the Zoom tool to zoom in to the document.
With the Pen tool, click an intersection of any of these lines in the middle area of the page to place the initial anchor point and drag upward.
Let go but don’t click when the direction line has extended to the horizontal grid line above it, as shown in Figure a.
Click to place the second anchor point on the intersection of the grid directly to the right of your initial point.
Drag the direction line to the grid line directly below it, as shown in Figure b.
If you have difficulty keeping the direction line straight, hold down the Shift key to constrain it.
Choose Select→Deselect to deselect your curve.
Congratulations! You’ve created a controlled curve. In these steps, we created an arch that’s going up, so we first clicked and dragged up. Likewise, to create a downward arch, you must click and drag down. Using the grid, try to create a downward arch like the one shown in Figure c.