Here we assume you already have a sketch, as for instance described before. Extrusion is the process by which solid bodies are “magically” build out of a flat contour. Basically, the software understands that a base rectangle, or circle or some other shape will then be “raised” along an axis (most of the time) perpendicular, as if you pile say plates, one on top of each other. Or, as you compute the volume of such bodies, by “slicing”.
So to build something out of a sketch, such as the one we just built in the previous lesson, we ask SolidWorks to extrude it. To do that, we need to go in the ‘Features’ section of tools, by clicking on it (observe now that the top toolbox has changed accordingly):
So what we want is an ‘Extruded Boss/Base’. Ok, let us assume the sketch from the previous lesson is now “sideways”, somewhat like so:
This is just for you to be able to follow this — it does not matter how the view is in order to start an extrusion.
So, we can go click on the ‘Extruded Boss/Base’ tool from the top menu, to build the base. Again, SolidWorks is asking us to select what to extrude (also observe the red X, which means ‘Cancel’, or ‘Nevermind’, in case we change our mind midway).
Like in the previous dialog, we go and hover until the sketch becomes orange, and then we click on it, and things start to happen:
This is a preview of what is going to happen if we click the green checkmark, to validate everything. We are in a mode where we can adjust parameters, such as the dimension to extrude along. We prefer to work with mm, grams and seconds as units (as selected from the lower right corner), so that’s why the left bar shows us 16mm as proposed length. We can go and edit that number, or literally drag the middle arrow from within the yellow prism being build (it will first become orange, when we hover, then, if we click, it will go up or down). Here’s even more: we can even rotate the whole thing while we are deciding about all these parameters. Watch it here, and see how the left 16mm changes when we click on the arrow and lengthen or shorten it:
Also observe that from time to time, a mouse icon with a check mark appears: this is a validating shortcut — clicking the right mouse button tells SolidWorks that we’re done, the same way as when we click the green checkmark in the left bar. So we can go and validate something of the order of 2cm (20mm).
Now let us look at the left bar — it now contains a new item we added, and it is named by its type:
We can however change its name to something more appropriate for us, by clicking on it, as we said before.
Now that we have the base, we can build a cylinder on top of it. How do we do that ? The same way ! So, we need to make a sketch. We can do that either on existing planes, or on planes we geometrically define (more on that later), or on faces of existing solids, such as those extruded. Thus, we can sketch something right on top of this box we just built! We can thus simply click on the Sketch tool, we will again be asked where we want to sketch, and we will select the top face. Let us see all that in detail in the next lesson.