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you how to continue building the part using the newly learned tools. By centering the sketch on the Origin and extruding by using a Mid Plane end condition, the initial block is built symmetrically about all three standard planes, with the part Origin at the center. In many parts, this is a desirable situation. It enables you to create mirrored features using the standard planes, and helps you to assemble parts together in an assembly later, when parts must be centered and do not have a hard face-to-face connection with other parts. Figure 4.7 shows the initial feature with the standard planes.

Note

When you create a feature from a sketch, SolidWorks hides and absorbs (consumes) the sketch under the feature in the FeatureManager, so you need to click the plus sign next to the feature to see the sketch in the tree. You can right-click the sketch in the FeatureManager to show it in the graphics window.

FIGURE 4.7

An initial extruded feature centered on the standard planes

The next modeling step is to create a groove on the back of the part. How is this feature going to be made? You can use several techniques to create this geometry. List as many techniques as you can think of, whether or not you know how to use them. Later, I will go through several techniques that work.

Tip

One of the secrets to success with SolidWorks, or indeed any tool-based process, is to know several ways to accomplish any given task. By working through this process, you gain problem-solving skills as well as the ability to improvise when the textbook method fails.

Figure 4.8 shows multiple methods for creating the groove. From the left to the right, the methods are a thin feature cut, a swept cut, and a nested loop sketch.

FIGURE 4.8

Methods for creating the groove

With a thin feature cut, you sketch the centerline of the groove, and in the Cut-Extrude feature, select the Thin Feature option and assign a width and depth. The option on the right is what is called a “nested loop,” because it has a loop around the outside of the slot and another around the inside. Only the material between the loops is cut away. The method in the center is a sweep where the cross section of the slot is swept around a path to make the cut.

Another potential option could include a large pocket being cut out, with a boss adding material back in the middle. Each option is appropriate for a specific situation. The thin feature cut is probably the fastest to create, but also the least commonly used technique for a feature of this type. Most users tend to use the nested loop option (one loop inside another).

Controlling relative size or direct dimensions

You can control the size of the groove as an offset from the edges of the existing part or you can drive the dimensions independently. Again, this depends on the type of changes you anticipate. If the groove will always depend on the outer size of the part, the decision is easy — go with the offset from the outside edges. If the groove changes independently from the part, you need to re-create dimensions and relations within the sketch to reflect different design intent.

Creating the offset

You need to consider one more thing before you create the sketch. What should you use to create the offset — the actual block edges or the original sketch? The answer to this is a Best Practice issue.

Best Practice

When creating relations that need to adapt to the biggest range of changes to the model, it is best to go as far back in the model history as you can to pick up those relations. In most cases, this means creating relations to sketches or reference geometry rather than to edges of the model. Model edges can be fickle, especially with the use of fillets, chamfers, and drafts. The technique of relating features to driving layout sketches helps you create models that do not fail through the widest range of changes.

To create the offset for your part, follow these steps:

1. Open a sketch on the face of the part. To create the offset, expand the Extrude feature by clicking the plus icon next to it in the FeatureManager