SolidWorks 2011 Parts Bible - Matt Lombard [21]
Figure 1.29
Sketching a circle
8. Deactivate the circle by clicking its toolbar icon or pressing the Esc key on the keyboard. Now click and hold the cursor on the circle, then drag it to change the size of the circle. The center of the circle is locked to the Origin as the Coincident icon near the Origin appears. The radius is undefined, so it can be dragged by the cursor. If the centerpoint were not defined, the location of the center of the circle could also be dragged.
9. Activate the 3 pt Corner Rectangle. To find it through a menu, choose Tools⇒Sketch Entities⇒3pt Corner Rectangle.
10. Click the first point inside the circle, click the second point outside the circle, and click the third point such that one end of the rectangle is completely inside the circle. Use Figure 1.30 as a reference. Avoid making any two points vertical or horizontal from one another. You will learn in Chapter 3 about how to control automatic relations in more detail.
Figure 1.30
Sketching a three-point rectangle
11. Activate the Centerline tool by choosing Tools⇒Sketch Entities⇒Centerline. Click and hold the left mouse button first at the Origin; then at the midpoint of the far end of the rectangle release the mouse button, as shown in Figure 1.31. When the cursor gets close to the midpoint of the end of the rectangle, it snaps into place. Press Esc to turn off the Centerline tool.
12. Select the centerline and Ctrl+select the line with which it shares the midpoint relation. After making the second selection, do not move the cursor, and you will see a set of options in a popup context toolbar. Click the Make Perpendicular icon, as shown in Figure 1.32, and the rectangle becomes symmetric about the centerline.
Figure 1.31
Creating a midpoint relation between a centerline and a line
Figure 1.32
Making the rectangle symmetric about the centerline
13. Drag one of the corners of the rectangle from inside the circle and drop it on the circumference of the circle itself. The point here is that you want the corner of the circle to be right on the circle always. A coincident relation is created by the drag-and-drop action. Now when you move either the circle or the rectangle, the other may change in size. Try dragging the circle itself, a corner point of the rectangle, or a line of the rectangle. Try dragging the centerline and the free endpoint of the centerline. Notice that the result of moving each different sketch entity is different from any of the others.
14. Click the Smart Dimension tool in the Sketch toolbar or choose Tools⇒Dimensions⇒Smart. Click the outside end line of the rectangle, and move the cursor away from the line. You can align the dimension one of three ways: measuring the horizontal dimension of the line, the vertical dimension, or the dimension aligned with the angle of the line. When the dimension is aligned with the angle, as shown in Figure 1.33, click the RMB. This locks in that orientation and enables you to select a location for the dimension without affecting its orientation. Click to place the dimension. If the dimension does not automatically give you the opportunity to change the dimension, double-click the dimension and change it to 0.5 inch or 12 mm. If this is larger than the diameter of the circle, notice that the circle changes to accommodate the new width.
Figure 1.33
Placing a dimension on an angled line
15. Drag the endpoint of the centerline around the center of the circle to see how the sketch reacts. Notice that the dimension added to the rectangle keeps it a constant width and makes it react more predictably.
16. Put a dimension on the circle. Click the circumference of the circle with the Smart Dimension tool, and then place the dimension anywhere on the screen without clicking any other geometry. Notice that diameter values of less than the dimension created