The rail curves allow you to change the shape of the body in between the profile sections. Here I show the same shape, but I’ve sketched a couple of 3D curves that I want to use to affect the resulting shape:īy using those curves as rail curves in the loft, this is the result you get: However, if you add a couple of rail curves, you can drastically alter the resulting shape. If you use Loft to create a shape between these 3 profiles, this is what you get: We’ll show a couple of views to make their relationship more clear: Here we have 3 rectangular profiles on parallel planes in space. What is a “rail curve”, and why is it needed in Loft? Rail curves in Fusion Loft allow you control the shape of the body as it transitions between Loft sections.

This article assumes that you already know the basics of using Loft to create solid or surface bodies between multiple sketch profiles.

This is not an exhaustive discussion of all the capabilities (though it is kinda long.) This post is an introduction to this subject, and gives some hints about to to best use this feature in Fusion.

I often see questions relating to the use of Fusion's Loft command, especially when using rail curves.

Fusion 360 hollow loft