00:00In this FreeCAD tutorial, you learn how to draw different types of B-splines in the Sketcher workbench.
00:10When a new document is created, select the part design workbench, then create a new sketch with this button.
00:18Select a plane, it does not matter which one in this tutorial.
00:22Click on the small arrow on the B-Spline tool button to see which types of B-splines there are.
00:30If you cannot find it, click right mouse button on a toolbar and make sure Sketcher B-Spline tools is checked.
00:42Let's start with a B-Spline defined by control points.
00:45Each time you click left mouse button, a control point will be created.
00:56Click right mouse button to apply the spline.
01:02Here you can check Periodic, but this only works when you are drawing or create another spline.
01:10Now start drawing another spline, and check the Periodic box.
01:15The spline is a closed loop now.
01:20Draw more control points and click right mouse button to apply the spline.
01:25All lines in a Periodic spline are tangent.
01:32Start drawing another spline.
01:35When you press the F key, you can undo the last point you created.
01:39You can even undo the first point you created.
01:51Now select Periodic B-Spline by control points.
01:54This is actually what you did before when you checked the Periodic box.
02:05You see that the box is already checked now.
02:08Finish the spline and click right mouse button to apply.
02:11So these dotted circles are the control points.
02:21And the other vertices are created within a Periodic spline.
02:24Select the line and press Delete to remove the whole spline.
02:28Now draw another B-Spline defined by control points.
02:38Each time you clicked, a control point was created.
02:40Select the Dimension tool, and click on a control point to define its position.
02:52It's the same as dimensioning a normal vertex.
02:57Click right mouse button to exit the Dimension tool.
03:01You see, one control point is fixed now.
03:03Delete this spline.
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03:15Now select a B-Spline by knots.
03:21Each time you click, a vertex on the spline itself will be created.
03:24Click right mouse button twice to apply the spline and exit the tool.
03:41You clicked four times so a start and end point and also two other knots were created.
03:46Select the Dimension tool and click on a knot to define its position.
03:50Click right mouse button to exit the Dimension tool.
04:00Knots are better when you want a more precise path of the spline.
04:10Also delete this spline.
04:13And select a Periodic B-Spline by knots.
04:16Try creating a spline and undoing some points to get used to it.
04:29The four points that were created are the knots you see as vertices on the line.
04:33Delete this spline and create a B-Spline defined by control points again.
04:47Now you see, each time you clicked, a control point was created instead of a knot on the line itself.
04:55Control points are perfect for less precise shapes.
04:58You might also want to check out my 3D printing channel. See you there.
