This gives us a different solid than the default settings. You can see in this preview the offset surface being made, but the Thicken command is normal to the selected planar face on the solid part (purple highlight), affecting both faces being offset from the surface body. Now look at the preview we get when we specify a direction vector:

You can see in the preview that the thickness surface being created is normal to the faces of the surface we are thickening.

Now, though, we can specify a direction for the offset created by the Thicken command.Ĭonsider the default behavior shown here: Until now, the calculation was based on surface normal, which is often what you want. Thicken takes a surface body (which has zero thickness) and makes it a solid (making it a volume) by specifying a thickness value and side to thicken. SOLIDWORKS 2020 adds a very nice option to one of my favorite surface-to-solid tools, Thicken.