Pneumatic tube is the form generated by an axis (line in 3D) and a circular cross-section of constant radius.
At the moment, WinTess3 finds form of only closed pneumatic tubes.

When we use the menu File | New | Pneumatic tube, the program displays the parameter window of the tube.

First of all, we must enter the axis of the tube, by importing a 3D closed polyline that was previously saved on WinTess layer of a DXF file.

The parameters that define the pneumatic tube are:

1. Diameter: Tube diameter
2. Points per ring: Although sections of the pneumatic tube at the vertices are actually ellipses, when there are many sections, these ellipses come closer to a circle. The more points the circle has, the softer the patterns and, therefore, the obtained final form.

Here we have some buttons:

1. Polyline points: In that case, the patterns are defined by the polyline. Each segment between two vertices of the polyline is a pattern. If the vertices are far apart and the curvature of the tube is important, the sections of pipe in these vertices are clearly ellipses.
2. Number of patterns: The user sets the number of patterns to build the tube. The program is responsible for dividing the axis of the tube in the same number of sections. Therefore all patterns will have approximately the same width.

Finally we have two lines of information:

• The length of the central axis that generates the pneumatic tube.
• The approximate width of the pattern, obtained by dividing the previous value by the number of patterns. Obviously, if the patterns have been produced directly from the points of the polyline, this value is informational only and may differ very much in reality.