How to be Smooth in SOLIDWORKS – 3 Helpful Spline Tips

If you are a regular SOLIDWORKS user and looking for different options to create smoother splines in your sketches… you came to the right place. In this article I will take a deep dive into three of the advanced spline tools available in SOLIDWORKS. Perhaps you didn’t know they existed, or maybe you use them quite often in your day-to-day designing – either way I hope this will provide some useful information on some of the smoothest tools (heh, laugh with me) SOLIDWORKS has to offer.

Spline Basics

The spline tool is one of the many features in SOLIDWORKS which has improved with age. Over time the functionality and capabilities of this tool have enhanced plenty, but at its core the tool maintains its most basic features. There are two types of splines: B-splines and style splines. B-splines (basis splines) are most often used to create complex curves, and are defined by spline points, spline handles, and control polygons.

Spline Basics Chart

Style splines, on the other hand, are based on Bézier curves and are useful when your primary goal is to create a smooth curve. Style splines are defined by control vertices which form a control polygon. The only points on this curve are its endpoints.

Spline Basics Control Vertics

The advanced spline tools I’ll be diving into are an essential part of creating the smoothest splines imaginable. These include Simplify Spline, Spline Display options, and Curvature Combs.

1. Simplify Spline

The purpose of Simply Spline is to do just that – it simplifies your spline by decreasing the number of spline points defining the line. To access this tool you must be in an open sketch, and have the spline selected in the graphics area. Next, head to Tools > Spline Tools > Simplify Spline. In the dialog box you can either set a value for tolerance and click OK or click Smooth and watch SOLIDWORKS do its thing (always my preferred option).

Simplify Spline Chart

The tolerance in this case refers to the deviation of the new simplified curve from the original one. In the image shown above you can see the tolerance is set to 0.01in by default, which would result in a simplified curve with 34 spline points as compared to the original 35 points. If I click Smooth, it increases the tolerance to 0.02in and shows me a preview for a smoother curve using 30 spline points. Now you can go crazy and keep clicking smooth until only two spline points remain. The Previous option will cycle back through each sequence all the way to the original curve.

2. Spline Display Options

It is important to note that SOLIDWORKS offers different options for displaying information about your spline. Specifically, it is oftentimes helpful to display inflection points and the minimum radius of your spline to better understand and define its shape. Both of these display options are available by right clicking your spline while inside the sketch and selecting which you would like to see.

Spline Show Attributes
Spline Inflection Display Chart

3. Curvature Combs

Curvature combs provide a visual representation of the slope characteristics of your spline. To have the combs show on your sketch simply right-click the spline and select Show Curvature Combs. For splines, the combs cross at inflection points, and therefore they change shape as you drag and change the curvature of the spline.

Curvature Combs Visual Representation

Curvature combs can be extremely useful for the user to see small imperfections in their seemingly smooth line. For example, the image below shows a spline which, without the curvature combs shown, looks very smooth to the naked eye. However, the combs prove us wrong as we see bumps and indents in the overall comb pattern. (Pro tip here: turn on “Show curvature comb bounding curve” in Tools > Options > System Options > Sketch)

Curvature Combs Smoothness in Spline Graph
Modified Spline Inconsistence Chart

That wraps up my deep dive into some of the coolest tools, among many others, that can help smooth out splines. Next, I’ll be showing how I used these tools to help sketch the DP logo in SOLIDWORKS.

Let’s Put These Tools to the Test

I decided a fun way to apply these advanced spline tools would be to create the DP logo in SOLIDWORKS. First, I inserted a DP logo image into a new part file by Tools > Sketch Tools > Sketch Picture. Next, I created a first-pass sketch of the logo using rough splines, and later refined the splines using some of these tools in order to accurately sketch the lettering.

Design Point Initial Spline Sketch

I utilized the curvature combs of my splines on the rounded letters to determine the slope behavior of each spline – and improve the smoothness where needed.

Curvature Combs Smoothness in Spline
Modifying Curvature Combs in Spline

In addition, I took advantage of the Simplify Spline tool throughout the entire sketching process to ensure the bumps and indents of the splines were completely smoothed out. In the image below you can see how I used this tool to smooth the inner spline of the letter ‘d’. The simplified spline is shown in a yellow preview, where SOLIDWORKS calculated a 0.188in tolerance for my desired line smoothness.

Finally, I extruded the sketch and applied appearances to the model. The final product is shown below!

Want to see these tools in action? Check out our quick video!

Go ahead and try some of these techniques in your sketches – you might even find a couple of new spline tools you never knew existed! Feel free to reach out to us if you have any questions.