Following the SolidWorks overview, sketch and extrude series, this article continues the tutorial on making revolved extrusions in the SW2008 and 2009 versions.
So, you have mastered the sketch construction, and the extrude process in the new SolidWorks 2008. You have also studied the Revolved Boss/Base feature and used it to create parts that have a cross-section rotated about one of the parts axis. But what if the part is more complex – and the axis of rotation is not one of the sketched lines? For example – a ring:
This detail is almost impossible to construct by a simple “Extrution" feature (although it is achievable by creating a “square ring" and applying fillets to achieve the round one – but this is, of course, not a way to work with CAD program). So, using the “Revolved Boss/Base" is a must here. However, the part is not rotated about one of its sketched lines…
In fact, the would be no straight lines in sketch at all… Nevertheless, as always in SolidWorks, we start by constructing a sketch:
Click on any of the principle planes, and draw a circle profile. Set the circle dimension – this is your ring “wire" diameter. Now, click on “Line" option in the sketch features. Instead of solid line – pick the “Center Line" – dashed.
Next, draw the line (its length is not important), and set the dimension between the line and the circle – this would be the “Mean" diameter of your ring. Remember, it is actually a radius – so you have to divide the intended mean diameter by 2:
Exit the sketch, and use the “Revolved Boss/Base" feature
e to create a ring – specifying the dashed center line as the rotation axis. Unlike the previous example of Revolved Extrusion, this time we have no need in full circle rotation. Thus, pick the mid-plane option and create a symmetric “C-profile", leaving an angle of 20 degrees.
Notice, that the edges of the “C" opening are not parallel but rather compliant with your specification of the revolution. It is obvious, that this “Revolved Boss/Base" feature is very useful for creating various parts that have a constant cross-section and an axis of rotation – either if it is “part" of the body or a “virtual" line and either it is a full-circle of a partial one!