Solids or surfaces?
It’s a choice that has been in place since the very first day of SOLIDWORKS in 1995. When beginning your CAD journey with SOLIDWORKS, it’s common to choose solids. This seems to be an obvious choice as “solid” is in the name of the software. But if you want to take your modeling to the next level, you need to add surfaces.
Using surfaces is like a cheat code to unlock next-level modeling. When it comes to being a power user with SOLIDWORKS CAD, you will need not solids or surfaces, but rather both solids and surfaces.
If you want to get better—or even get started—with surface modeling in SOLIDWORKS, this is the crash course for you. You will be on your way to becoming a surfacing expert in less than 10 minutes.
Why Should You Care About Surface Modeling?
Surfaces are a way to help you create solid geometry. Most industry experts describe surfaces as a means to the end goal of solid geometry. The official SOLIDWORKS help file even describes surfaces as “reference” geometry.
But surface models are an incredible tool to help you create solid geometry. Look around to see everything that would be almost impossible to model without surfacing. I am looking at my mouse, microphone and monitor stand that will be far easier to model with surfacing. Honestly, I wouldn’t consider modeling them without surfacing, and you shouldn’t either.
So, here are the surfacing hacks you need to know to get started modeling with surfacing in SOLIDWORKS.
What are Surfaces?
Surfaces are geometry with zero thickness or volume. Surface modeling is different than solid modeling in many ways, but it also has similarities. For one thing, they share a lot of the same terminology. This alone shows just how connected they are.
The first hack is, therefore, to leverage your existing solid modeling experience to get started. You will still use familiar operations such as sketch, extrude and cut paired with graphical modeling. Sure, it’s different than solid modeling, but don’t be intimidated because it’s not impossible.
Going Beyond the Basics
Beyond the basics of surfacing, there are a baker’s half-dozen tools we could call “hacks” to help you instantly improve your surface modeling.
Are You Working With Surfaces?
First, we need to know if we are working with surface geometry. Even an Elite SOLIDWORKS Application Engineer with decades of experience will have this rather inelegant way to check: visual inspection. Look at the graphics area or the feature manager for signs of surface geometry. Here’s what to look for:
Graphics Area: In the graphics area, look for blue edges. Blue edges indicate you have open surfaces; these need to be closed. They will show up as black when turned into a solid.
Feature Manager: In the Feature Manager, see what is listed in the surface bodies folder. In the image below, you will see what it looks like when you are or are not working with surfaces.
By default, these “body” folders only show when their values are greater than zero. That’s why you don’t see the Surface Bodies folder at all on the image on the right above. If you want to change your system options to always show these folders, you can right click in the Feature Manager and select “Hide/Show Items” and change the folders from the default “automatic” to show.
1. 3D Sketching
3D Sketching is not just for surfacing, it’s a must-have for any SOLIDWORKS power user. Like most SOLIDWORKS users, the first time I learned 3D sketching was for creating weldments. But it’s incredibly useful for quickly creating complex shapes. Think of 3D sketches like a 2D sketch that isn’t tied to any one plane. You still use the same tools such as lines, points or splines, but instead of preselecting a plane you can just click and create the geometry. This gives you the flexibility to create complex and compound shapes.
To create a 3D sketch, you click the dropdown button under Sketch on the sketch ribbon, and click “3D Sketch.” The trick to easily manipulating a 3D sketch is to look next to your mouse for a clue as to what reference direction you’ll be sketching. The direction will be indicated via planes like XY, YZ or ZX. To change to a different direction, just hit the tab key to cycle through the referenced directional plane.
I find that 3D sketching is critical to creating support or reference geometry to help create complex or compound shapes. When working with surfacing, you’ll start to notice that it’s not as straightforward as simple solid modeling—there are a lot of intermediate steps required to create the shapes you want.
2. Projected Curve
Think of project curves like a projector, but instead of projecting an image on a wall or screen it projects a 2D or 3D sketch onto a face. It’s an incredibly powerful way to take a flat 2D sketch and turn it into useful 3D geometry.
It can be like a magic step that takes something incredibly easy to create (a 2D sketch) and applies it to a complex shape. Just be mindful of the potential distortion that could happen when applying a 2D shape to a 3D surface. The option of “Direction of Projection” helps you have a little more control on this.
3. Face Curve
Face curves, also known as iso-parametric or UV curves, are a web of sketches that trace the curvature of a surface. Think of it as a curvature mesh but with each line of the mesh turned into a 3D Sketch entity. In other words, usable geometry to continue to modify your complex surface geometry.
To make a face curve, click the face you’d like to trace and then define a mesh density. When using the mesh method, you control the density by specifying the number of evenly spaced curves along and across the geometry.
You can also define the curves by means of specifying a position. This gives you granular control over the curves that will be created by defining a specific location.
When the curves are created, you can see that each one of them is added as sketch geometry. This means each curve is now usable for various surfacing tools or even direct editing capabilities. This is useful enough to be declared a lifesaver at times—like when you need to work to modify dumb solids imported from other CAD systems.
4. Offset Surface
The Offset Surface tool creates a new surface from an existing surface or solid face. It’s a way to create a copy of the geometry offset by a distance. If the offset distance is zero, you will make an exact copy of the surface. In fact, that is the only way to make an exact copy of a surface, now that there is no longer a “Copy Surface” command.
A common use of the Offset Surface command is to start fresh with existing geometry, such as when you’re working on a complex shape or cleaning up imported models. The offset surface tool will clean the slate for your modeling.
5. Offset on Surface
The “Offset on Surface” tool is similar to the offset entities tool you’re familiar with from 2D sketching but it’s powerful enough to be able to offset entities and project them onto a complex 3D surface.
Remember to define the way the length of the offset is calculated. Because you are working on complicated 3D shapes, you have the option to take the curvature into account or to ignore the curvature. A geodesic offset will take the curvature into account when calculating the offset. This defines the offset distance along the surface. A Euclidean Offset defines the offset distance linearly, in that it does not account for the curvature.
6. Trim
The Trim command is the workhorse of surfacing commands. You can use Trim to trim or cut intersecting surfaces. This will save you a lot of time in surfacing when you are adding extra geometry, as using Trim will let you easily remove excess geometry and clean everything up.
Let’s look at all the settings and options available to you with this incredibly useful and powerful command. You can use it as a standard trim, which is nothing more than using one surface or sketch as a tool to cut another. Or you can use the Mutual Trim option, which enables you to trim multiple surfaces using the surfaces themselves as the tools. This way you just graphically pick which entities you want to remove or keep.
7. Thicken
Thicken is our last stop on the surfacing journey. If you still think of surfacing is a means to a solid, Thicken is your command.
Click your surface and give a thickness and, like magic, you have a solid body. To be sure you only need to check the feature tree and there you will see the bodies folders are updated to reflect the change from surface body to solid body.
Conclusion
There you have it—the baker’s half-dozen of surfacing tools you need to add to your toolbox. You are on your way to becoming a surfacing expert. There may be many more nuances to surfacing, but I hope you consider these hacks a good start.
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