Chapter 26 Introduction to Dynamic Blocks 795 Copyright Goodheart-Willcox Co., Inc. Assigning a Polar Stretch Action Figure 26-19 illustrates the process of adding a polar stretch action to the steel channel shape example. Access the Polar Stretch action option and pick the Depth parameter. Then specify a parameter point to associate with the action. Move the crosshairs near the appropriate parameter point to display the red snap marker, and pick to select. Alternatives include selecting the sTart point option to pick the start point of the polar parameter, or the Second point option to select the endpoint. If you plan to use grip editing to control the block, and added a single grip, specify the point with the grip. Next, create a window to defi ne the stretch frame. This is the same technique you apply when using the STRETCH command. See Figure 26-19A. Pick the objects to stretch, including the associated parameter. You do not need to use a crossing window, because the previous operation defi nes the stretch. However, crossing selec- tion is often quicker. See Figure 26-19B. Then select the objects to rotate, which are often the objects of a block. See Figure 26-19C. Press [Enter] to place the action icon. Test and save the block, and exit the Block Editor. The dynamic block is now ready to use. Using a Polar Stretch Action Dynamically Figure 26-20 shows the steel channel shape block reference selected for editing. The polar parameter grip appears as a light blue square at the far end of the channel depth. The insertion base point specifi ed when the block was created appears as a standard unselected grip. Select the parameter grip and stretch the channel depth to the new length and angle. Use dynamic input to view the stretch dimension and rotation angle, and enter an exact length value in the distance fi eld and rotation angle in the angle fi eld. You can also use the Properties palette to defi ne the distance and rotation angle. Ribbon Block Editor Action Parameters Polar Stretch Type BACTIONTOOL Polar Stretch polar stretch action: An action used to change the size, shape, and rotation of block objects with a stretch operation. Figure 26-18. An example of a portion of a motor mount with side views of different steel channel shapes that were created and rotated using a single block with a polar parameter assigned a polar stretch action.