SolidWorks 2011 Parts Bible - Matt Lombard [98]
To sketch on a standard plane or reference geometry plane, you can Ctrl+click the border of the plane with the sketch entity icon active, or double-click the plane. The space handle moves, indicating that newly created sketch entities will lie in the selected plane.
Defining dimensions
Dimensions in 2D sketches can represent the distance between two points, or they can represent the horizontal or vertical distance between objects. In 3D sketches, dimensions between points are always the straight-line distance. If you want to get a dimension that is horizontal or vertical, you should create the dimension between a plane and a point (the dimension is always measured normal to the plane) or between a line and a point (the dimension is always measured perpendicular to the line). For this reason, reference sketch geometry is often used freely in 3D sketches, in part to support dimensioning.
Using 3D sketch summary
Three-deminisional sketches are extremely powerful for many different applications. The problem is that they are also limited in some of their capabilities, and they do not work exactly like 2D sketches. You will benefit from knowing how to use 3D sketches at some point, even if it isn't every day.
Tutorial: Editing and Copying
This tutorial guides you through some common sketch relation editing scenarios and using some of the Copy, Move, and Derive tools. Follow these steps to learn about editing and copying sketches:
1. Open the part named Chapter6 Tutorial1.sldprt from the DVD. This part has several error flags on sketches. In cases where there are many errors, it is best to roll the part back and go through the errors one by one.
2. Drag the rollback bar from just after the last fillet feature to just after Extrude3. If Extrude3 is expanded so that you can see Sketch3 under it, drop the rollback bar to after Sketch3. If a warning message appears, telling you that Sketch3 will be temporarily unabsorbed, select Cancel and try the rollback again. Figure 6.19 shows before and after views for the rollback.
Figure 6.19
Rolling the part back to Extrude3
3. Edit Sketch3 and deselect the Sketch Relations display (View⇒Sketch Relations). Relations with errors will still be displayed. Click Display/Delete Relations on the toolbar (the Eyeglasses tool), and set it to All in This Sketch. Notice that all the relations conflict, but only one is unsolvable: the Equal Radius relation. This appears to be a mistake because the two arcs cannot be equal.
4. Delete the Equal Radius relation. Select the relation in red and click the Delete button in the PropertyManager. (You can also press the Delete key on the keyboard.) The sketch is still not fixed.
5. Click the green check mark icon to close the Display/Delete Relations PropertyManager.
6. Right-click the graphics window and select SketchXpert; then click Diagnose.
7. Using the double arrows in the Results panel, toggle through the available solutions. All the solutions except one remove sketch relations. Accept the one solution that removes the dimension. This is shown in Figure 6.20.The sketch no longer shows errors in the graphics window, but it still does in the FeatureManager.
Figure 6.20
Using the SketchXpert to resolve an overdefined sketch
8. Close the sketch. Notice that the error flag does not disappear until the sketch has been repaired and closed.
9. Use the rollback bar to roll forward to after Extrude2 and Sketch2. Figure 6.21 shows the tool tip message that appears if you place the cursor over the feature with the error. With time, you will begin to recognize the error messages by a single keyword or even by the shape of the message text. This message tells you that there is a dangling relation — a relation that has lost one of the entities.
Figure 6.21
A tool tip gives a description