# Need a help in catia surface

#### lakku12

##### New member
Hello All,

Created a outer profile. How to create center axis passing through form all the profile.

#### MrCATIA

##### Super Moderator
Is each profile a circle?

#### lakku12

##### New member
profile is not circle. its uneven profile. Example; the contour of bone at different plane.

#### Bouta

##### New member
Circle or not - create a power copy. Fill each "circle" with Fill operation. Then plant a "Point on Surface" with the coordinates 0 - they should land more or less in the center of the circle as the circles appear to be very irregular. Then connect the points. If the spline becomes very twisted you can reduce the number of points.

#### lakku12

##### New member
Circle or not - create a power copy. Fill each "circle" with Fill operation. Then plant a "Point on Surface" with the coordinates 0 - they should land more or less in the center of the circle as the circles appear to be very irregular. Then connect the points. If the spline becomes very twisted you can reduce the number of points.

View attachment 2262
Thank you very much. It works !!!

#### PLM Technology

##### Member
Bouta +1
Great idea, it will take a bit of time, but it will work 100% sure

#### Bouta

##### New member
Alternatively, you can also make a powercopy using a point contructor formula. This approach will give you the exact center of gravity for each (irregular profile).

centerofgravity(`Geometrical Set.1\Sketch.1` )

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This is a very elegant approach but I can't understand what does the "centerofgravity()" formula result in? Where do you put that formula? Do I need to pull out the X, Y and Z coordinates from the center of gravity formula accordingly? Can you put more screenshots? Thanks.

#### costinruja

##### Newbie
The idea is that you can define geometries (point, line...) as parameters and assign them a formula. The output of this so called parameter is a geometrical entity (point, center of gravity in your case).

You can see in the box for formula definition the required inputs and outputs.

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