Dynamic Blocks and Constraints

[Anonymous]

Trying to make a dynamic block. How do I use constraints such that when I stretch the plate (marked (P)) to the right and/or down, my basepoint (Position 1) will remain at the intersection of the right edge of the plate and the centerline (Intersection shown circled in blue below). 

Someone please help. 

Thank you, 

Brian

[Anonymous]

Clarification: Position 1 is not a basepoint but a position parameter which I want to assign a move function to. 

I created a point and used coincident constraints to keep it at the intersection of the two lines. Now I just need to figure out how to link the position 1 parameter to this point

[Libbya]

Unless there is more to the block including some other difficult action (e.g. arcs) then I wouldn't use any constraints at all.  I would use dynamic parameters and actions as their behavior is much more direct and consistent.  Dynamic parameters/actions are like pulling a cooked spaghetti noodle.  Constraints are like trying to push it from the back.  Post the actual block for better assistance.