From:  Andrei Samardac
5759.9 In reply to 5759.8 
I know about this but it's not so fast as with lock cplain with view. And you have to make rectangle then rotate it on x and y or z to find the way you wanna cut, too complicated )
I did it another way, just draw 2 lines on each side and then conect them with loft to make rectangle and then subtract :)