setdesigner

Hello, I am new to Vectorworks. I want to attach the exterior line of a wall to a grid line. I am trying with the constraint tool but the only way it works it point constraint from the end point of the grid line to the mid point of the wall. But it snaps to the wall's mid line. Colinear constraint does not works. The purpose is to adjust only the grid lines, and have the walls follow. Any clues ?