SOLIDWORKS Fit Spline Explained

Article by Kaden Sumsion on Mar 15, 2023

In  SOLIDWORKS , have you ever noticed hard edges at conjoining surfaces, surfaces intended to be one continuous bend? Digitally, these are not a hindrance to our work, but these hard edges can appear on manufactured products, especially products made on a CNC machine or through plastic injection molding. 

Using the Fit Spline Command in SOLIDWORKS

Fit Spline is a tool in SOLIDWORKS that can help clean up these edges to produce a single, smooth surface. Fit Spline takes two different lines, curves, or splines and smooths the junction to a continuous unbroken line.

Remove Hard Edges in SOLIDWORKS Using Fit Spline

Removing Hard Edges in SOLIDWORKS

How to use Fit Spline

To access Fit Spline, go to Tools > Spline Tools > Fit Spline. 

Once a basic shape is created using lines, arcs, and/or splines, Fit Spline can be used to edit the shape and remove the hard edges. 

Access SOLIDWORKS Fit Spline Command

With the Fit Spline command open, select the geometry in which to alter. In this example, the geometry we want to alter is the sketch the body is extruded from. When the geometry is selected, Fit Spline shows a preview; we can then adjust the Tolerance. If we increase the tolerance, Fit Spline will smooth out the hard edge as cleanly as the tolerance allows. 

Adjust Tolerances Using SOLIDWORKS Fit Spline Command

Different Uses of Fit Spline

Above we discussed how to use Fit Spline, and as an example, we smoothed out the hard edges of a closed loop sketch. Fit Spline can also be used on Open Loops.

For example, Fit Spline can be used to clean and smooth out the hard edges on a revolve. In the revolved part below, we can see there is a hard edge on the model that could show up in manufactured parts.

Revolved Part in SOLIDWORKS

Edit the sketch of the revolve, select the geometry to alter, and then open the Fit Spline tool. 

On an Open Loop sketch, ensure that the Closed Spline option in the Fit Spline tool is not selected; otherwise, it will automatically try to close the loop. 

SOLIDWORKS Fit Spline Command Used with an Open Loop Sketch

Fit Spline between 3D Geometries

Another use for Fit Spline is to automatically connect two different 3D geometries with a spline. 

To do so, select two geometries and then open the Fit Spline command. Similarly to the other uses, we can adjust the Tolerance of the Fit Spline and edit the additional options. 

Use SOLIDWORKS Fit Spline to Connect 3D Geometries

SOLIDWORKS Connect 3D Geometries Using Fit Spline

This will automatically generate a spline to fit between the two geometries. 

SOLIDWORKS Fit Spline Between 3D Geometries

SOLIDWORKS Fit Spline Demo

For more information on the Fit Spline tool, watch the video below for a demo on using this tool. 


Learn More About SOLIDWORKS Splines

Ultimate Guide to SOLIDWORKS Splines

SOLIDWORKS Tutorial: Edit, Create, & Convert Style Splines

Using the Curve Through XYZ Points Tool in SOLIDWORKS

Introduction to Continuity and Curvature in SOLIDWORKS (Part 1)

Managing External References in SOLIDWORKS Assemblies



About Kaden Sumsion

Kaden is a SOLIDWORKS Technical Support Engineer at GoEngineer.

View all posts by Kaden Sumsion