From FreeCAD Documentation
- Normal : If one circle is selected Normal not modify the radius of circle (Default)
- Adapt Rad. : If the button Normal' is pressed, the button change to Adapt Rad. the spring is adapted to the detected radius (If a radius is detected )
- Point Mouse : If the click mouse is on one face the spring is created on this point (Default)
- Center Face : If the button Point Mouse is pressed, the button change to Center Face, the spring is created on the center face selected
- Position Position : If two object are selected (First axis, Second the spring (or other object)), this checkBox is enabled and you can modify the placement object 2 (spring) along the on object 1 (axis), if this Position is checked the "Position" option is enabled for use
- Circle : If three points click mouse are selected the Circle button is enabled and it possible to create a circle which can serve as a base for a spring