TechDraw Section Examples

Introduction
The TechDraw workbench made a big step forward regarding the generation of section views. To not overload the reference pages this page's intention is to give examples and supply proper naming for the performed tasks.

I'm doing my best to find the correct terms, but since I'm not a native speaker it's your turn to fix my mistakes if you find one.

Sections
Sections or section views are used to look inside an object to show details that are invisible or hard to recognise from views with hidden lines enabled.

Usually there is a projection group showing a simple object from at least 2 directions for a complete graphical description; complex objects require more views to describe each detail, the hardly visible and the oddly positioned ones.

One of the existing views will be used as a base view where you draw a section line to define how to derive a section view. That is the way for manually drafting and how it is done by most CAD software. FreeCAD does not work like that yet!

The FreeCAD way
It is not yet (version 1.0) implemented to draw a section line in a 2D view and transfer information such as position and angle back into 3D space.

Instead FreeCAD provides a Set View Direction widget in the Task panel plus either a Section Plane Location widget for simple sections or an Object Selection widget and a Projection Strategy within the Section Parameters for complex sections. (see Simple section and Complex section)

Example Object
This object has no use at all except to describe the different kinds of section representations.
 * (BTW, I rather use the word object than part to avoid confusion with a Std_Part.svg Std Part)



Simple sections
Simple sections use a single section plane to cut through the whole object. Any section view requires a base view ( property) to position a section plane when using Insert Section View for simple sections. The vertical axis of the section plane is always the normal of the base view and the horizontal axis of the section plane is parallel to the section line. Usually the section view is oriented with its horizontal axis also parallel to the section line. The angle between section line and the base view's horizontal axis is controlled by widgets of the Set View Direction area:



The View Direction as Angle combo-box allows to set an arbitrary angle and the four buttons are used to cut the object at preset angles perpendicular to the horizontal and vertical view axes:

90°, 270°,  180°,  0°

Horizontal section
Section A-A (section up)





Section B-B (section down)





Vertical section
Section C-C (section left)





Section D-D (section right)





Arbitrary section
Section E-E (section at an arbitrary angle)





By default the section plane goes through the global origin (3D) which means the section line goes through the origin of the view. To get an offset section line (and plane respectively) we can change the values within the Section Plane Location widget.



Auxiliary view
FreeCAD is lacking a specific tool to derive auxiliary views from base views, but Insert Section View can handle that, too:

Using Section E-E from above and changing the mentioned values to X = and Y =  the section line/plane doesn't cut the object anymore and the section view turns into an auxiliary view. (Be careful when you change the values. Large steps tend to crash FreeCAD!)

The label was edited manually. The section line and one arrow have to be hidden in followig steps since one single arrow is enough to properly define an auxiliary view.

Single Section
If there is only one section view on a drawing and it is plain to see that the object is cut along a center line, the section line including the arrows and the view title may be omitted.



Internal section
A section view may be integrated into the basic view. This case doesn't need arrows and title as well.



Complex sections
Coming soon...