B-Splines

This documentation is a work in progress. Please don't mark it as translatable since it will change in the next hours and days.

This page describes how to use B-splines in FreeCAD. It gives also background information what B-splines are and for what applications they are useful.

Motivation

If you know already about B-splines and their application, you can directly continue with section??.

Let's assume you want to design a part that should be produced with a 3D printer. The part must have an edge this way:

You have to print the part in direction of the sketch's bottom to the top. Outer support structures might not be an option. Therefore you need to add a support directly to your part. What options do you have?

• Option 1: you could add a line from point (0, 20) to point (80, 40):

However this solution needs a lot of volume, thus weight and material.

• Option 2: you can connect the two points with an arc of a circle. To save volume, the arc should end tangentially in point (20,80). Then your solution looks like this:

OK. But at the bottom you don't need immediate support.

• Option 3: you could save some more volume if the connection between the 2 points is a circle that begins tangentially at (20,0) and ends tangentially at (80, 40). So this: