# How to set constraints and measure distance tangentially between 2 splines

#### giangnguyen

##### New member
Hi everyone,

I just have small questions. Let's say I am designing a pair of wheel fairings (it is the airfoil) for the small race car and I want to measure distance between (in this picture) the highest point on the outermost line and the lowest point on another outermost line.

In reality this pair of fairing are not symmetric like this simple example; the constraint in reality is the distance between the outer edges of these fairing, i.e the outermost point of line A and line B.

Therefore, I would like to ask if you know which tools in CATIA allow me to do this.

I attach here the picture and the drawing file for your reference.
https://www.dropbox.com/s/3xpotvlpdmjcl4p/Setup a pair of fairings.CATPart?dl=0

Thank you very much.

#### Attachments

• 5.2 KB Views: 3

#### MrCATIA

##### Super Moderator
To get the greatest distance between the two curves, use MEASURE BETWEEN and choose the MAXIMUM option.

Choosing MINIMUM will measure the shortest distance.

Last edited:

#### giangnguyen

##### New member
Dear MrCATIA,

I have tried the "maximum distance option" but I got the unwanted distance. I attache the picture here. What I want is the distance between the two outermost lines, but what I got is the distance between one outer line and one inner line, which is the translation distance as well.

So I would like to ask if I forget choosing any other options?

#### Attachments

• 18.7 KB Views: 4

#### MrCATIA

##### Super Moderator
A couple other ways to get that distance if Measure Between doesn't work:

1. Split the splines into two halves then measure the top half to the bottom half

2. Change the selection mode to Picking Point and select the splines close to the top and bottom for an approximate distance

3. Add two tangent lines parallel to X axis, and measure the distance between the two lines

Last edited:

#### kiran1992

##### New member
Hi,
If you have the feature called EXTREMUM in wireframe toolbar you can explore the option (i dont know if its available in student version)

using this you can create the points at your extreme min or max position in any curce and then measure it