Often it is necessary to use the measurement of one object as the input for a calculation. This can be easy if you are grabbing the value from a sketch constraint but a little more difficult to use from a random object edge.
To understand this we will use two cubes. The first will be the reference the second one will be set based on the measurements of the first.
We will set the length of Cube Blue from the dimension displayed on on the Draft Dimension.
I have named the dimension A_Length
First lets look at the property as displayed in the property tab.
We are interested in the A_Length.Distance property.
This value can be used in the Length property of Cube_B
To place the value in the Length we will use the Function editor. When a field is selected, can be calculated a small blue circle with f(x) will be shown. This triggers the “Formula Editor”
While you are typing you may get autocomplete options. Not all parameters are represented by the autocomplete. Until you finish with an actual valid property you will see the red “not found error”
FreeCAD can be finicky, this time it decided to autocomplete
When the full paramter is entered and valid, the result will reflact that value.
Once you click Ok change the length of cube A will update the Dimension line and the length of Cube B
The key for to get auto completion working for me in 0.19 was to start the formula with “<<".
Did not even occur to me to try that, thanks! I think this might have been added in 0.19. I am now wondering which objects in FreeCad to which this applies.