Here’s a handy routine that lets you draw many perpendicular lines to any type of object. This can be done manually by using the perpendicular Osnap, but this routine lets you do this quickly.

Very handy for curved objects. As seen in the picture below, I used Splines, Polylines and an arc. One draw back is that the LISP routine looks for the closest part of the selected object.

Here’s how:

• PERP2ENT <enter> to start
• Select the object that you want the lines to be drawn to
• Pick points where you want the line drawn from

;; by sinc @ the Swamp 07/22/2004
;; Repeatedly draws a line from a pick point perpendicular
;; to a selected object
(defun c:perp2ent (/ entity pt)
(while (setq entity (car (entsel "\nSelect entity: ")))
(while
(setq pt (getpoint "\nSelect point to draw perpendicular from: "))
(entmake (list '(0 . "LINE") (cons 10 (trans pt 1 0))
(cons 11 (vlax-curve-getClosestPointTo entity (trans pt 1 0)))) ;_ list
) ;_ entmake
) ;_ while
) ;_ while
(princ)
) ;_ defun