I have created two perpendicular lines. The first one is 20mm long with the middle define on the center of the sketch. The second line is draw at the top of the first line and is also 20mm long. When i change the second line, the first line is moved to the left and does not stay on the center. If i try to move the first line back in the center, the second line is nomore perpendiclar and the dimension of the first line change so the center is nomore on the axis.

For the issue with the lines not staying perpendicular, select both lines and apply the Perpendicular constraint.

Hello,

I did this but i but it does not solve all my problems. See following pictures. I try to dra a line from X=0Y=-15 to X=0Y=15 (30mm length line). The center of the line being at the 0,0 of the coordinate system visually. If i change the length of the line to 40mm, the middle point of the line change by 5mm. I did not find the way to coincide the middle of the line with the model zero. The only way is to redraw the line with the good value. There is no coincidence option in the list of contrains

This bring a lot of questions about editing a sketch.

Vincent Brouillet

Try selecting each endpoint and moving it half the distance youâ€™re trying to extend the line.

Since there is a dimension constrain on the line it is not possible to move end points

Vincent Brouillet

I believe you need to â€ścloseâ€ť the sketch tools and that will allow you to use the â€śmoveâ€ť tool.

Hello! In this case, the most accurate way is to create a horizontal line and lock it just for a reference. The midpoint of the vertical line can be snapped to the endpoint of the horizontal one, then the two endpoints of the vertical line can be constrained to be symmetrical to the horizontal one to make sure the midpoint will always stay in the same place

Thank you Peter. Your method work quite well.

Now is it possible to define a constrain on an axis and is it possible to define a constrain between an axis and the center of a circle for example or do i need to create lines every time i want to set accurate dimensions

Vincent Brouillet

Hi Vincent, I would say additional lines for construction are the best way to achieve accurate results