Hi,I have got a problem with my file, from beginning it meant to be used for 2D purpose and one of the time I worked on it, I relised that the lines are strech on the Z axiz which make the file heavier and imposible to export. is there a way that I can flat the line so that all the lines will equel to 0 on the Z Axiz ?

Use the FLATTEN command.  You must have Express Tools installed.

That depends on what you mean by objects [considering also the possibility of things other than Lines] being stretched on the Z axis.  If, when you select a Line, the Properties box shows a "Delta Z" value of zero, but it's "tall" into the Z direction when viewed from a direction other than plan view, then it must have non-zero Thickness [not to be confused with Lineweight, or with Width in Polylines -- Thickness is "up off the page" in the Z direction].  Other entity types show it differently than the Delta Z value for Lines, but like Lines, they will all have a non-zero value in the Thickness slot in the Properties box.  FLATTEN is not needed to fix that [though it will] -- just change their Thickness to 0, either in the Properties box or with the CHPROP command, to flatten that kind of extension in the Z direction.  And unlike Flatten, this approach will leave things that should remain at different elevations [such as contour lines] where they are, instead of taking them all to the 0 level in the Z direction.Kent Cooper2014-09-09 16:14:49

Hello everybody, I have this old method working on all the AutoCAD releases ( I suppose ).
 
With an UCS set on WORLD: move all the objects from point 0,0 to 0,0,1E99 then move all the objects from 0,0,1E99 to 0,0,0.
this should be checked with a 3D viewpoint that you find in : View, 3D point of view, SE or an other.
 
Amaona, please tell us what you have done, succeeded or not, etc...

[QUOTE=philippe JOSEPH].... move all the objects from point 0,0 to 0,0,1E99 then move all the objects from 0,0,1E99 to 0,0,0.
....[/QUOTE]
 
[That will "zero out" the Z coordinates of things, but will not change entity Thickness, if that's the issue, to zero.  The Flatten command will do both, if that's what's needed.]Kent Cooper2014-09-10 15:17:44