SOLIDWORKS Boundary Surface

  • SOLIDWORKS Boundary Surface wasn’t added to SOLIDWORKS until 2008
  • It is a features that produces surfaces of much higher quality than other features
  • It has many advantages and special functions that help its users to create the best surface possible

The boundary surface features within SOLIDWORKS allows users to make surfaces that can be curvature or tangent continuously in both directions, i.e. every surface of the solid. This in many cases provides a much higher quality result than the loft feature.

The SOLIDWORKS boundary surface feature cannot be discussed however without mentioning the Loft feature. The Loft feature was in the very first release of SOLIDWORKS in 1995, and was just a solid feature at the time. It wasn’t until 1998 that surfacing functions were added to the software. Boundary surfaces and solid features specifically were not added to SOLIDWORKS until 2008, boundary surfaces are a much more commonly used feature, which is why this article is focusing on them.

Boundary surfaces quickly became the go-to feature when working with surfaces, as it possessed many advantages over its counterparts. It is typically the first feature that modellers will reach for when required to make a complicated shape. Some of these advantages were:


What some class as the main advantage of using Boundary ove Loft is the accuracy. The accuracy of the curves produced by the Boundary feature is much higher than those created by Loft and other features, with maybe the exception of Fill. It was a common complaint that surfaces generated by other methods failed to touch the specified profiles, which was a major problem.

Equality Between Direction 1 and 2

Boundary treats Directions 1 and 2 completely the same. Most surfaces in CAD are based on NURBS, which depends on a 2-directional UV mesh to function. In other features, such as Loft, one direction is called the profile and the other referred to as the guide curve. In Boundary you have Direction 1 and 2, and they both have exactly the same controls.

Arrangements of Curves

Boundary allows for a much wider range of curves compared to the other features. It needs two curves, but it doesn’t matter which combination of directions they go in, it could be Direction 1 and 2, two Direction 1, or two Direction 2.


Boundary also lets you use Connectors in both directions, in comparison to Loft only lets this happen in one direction. Connectors are quite powerful, and can be the difference between a BOundary working or not.

Special Functionality

Boundary has many special functionalities like:

  • Loft To Point
  • Degenerate Surfaces
  • Drag Sketch
  • Apply To All
  • Tangency Weighing
  • Curves Influence

Just to name a few! Not all of these options apply to every situation, their use depends on the specific application, but most projects will use two or three of these special functions. It is good practise to look through the special functions and see which might suit your project the best.


Despite the many advantages the Boundary has over features like Loft, there are some things that are present in Loft that you cannot find in Boundary. Some examples are:

  • Add loft section
  • Centerline Loft (similar to a multi-section sweep)
  • Closed Loop
  • Directional controls/separated tangency
  • Micro Tolerance

Have you used the boundary surface feature in SOLIDWORKS before? We would love to hear about your experiences in the comments below!

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