Today’s featured routine is a gem if you need to make basic 3D Pipes. It does a couple of awesome thing: 1) It creates a pipe with an inner and outer diameter thus creating a true pipe. 2) Lets you specify the path of the pipe by selecting simple and complex objects such as polylines with arc segments, 3D polylines, arcs, circles, ellipses…3) Creates the pipe/tube as a 3D solid objects which will allow you to use the union and subtract commands if needed.

Here’s how:

• CURVE2TUBE <enter> to start
• Specify outer radius <enter>
• Specify inner radius <enter>
• Select object to define the path of the pipe

;;;===================================================================
;;; CURVE2TUBE -Gilles Chanteau- (gile)
;;; Extrudes a "donut region" along a curve(s) object(s).
;;;===================================================================
(defun c:curve2tube	(/	   AcDoc     Space     ext_rad
			 int_rad   ss	     obj       start
			 ext_circ  int_circ  ext_reg   int_reg
			 norm
			)

  (vl-load-com)

  (defun vlen (v)
    (sqrt (vxv v v))
  )

  (defun vxv (v1 v2)
    (apply '+ (mapcar '* v1 v2))
  )

  (defun vunit (v / l)
    (if	(/= 0 (setq l (vlen v)))
      (mapcar '(lambda (x) (/ x l)) v)
    )
  )

  (setq AcDoc (vla-get-ActiveDocument (vlax-get-acad-object)))
  (setq	Space
	 (if (= 1 (getvar "CVPORT"))
	   (vla-get-PaperSpace AcDoc)
	   (vla-get-ModelSpace AcDoc)
	 )
  )
  (if
    (and
      (setq ext_rad (getdist "\nExternal radius: "))
      (setq int_rad (getdist "\nInternal radius: "))
      (setq ss
	     (ssget
	       '((-4 . "<OR")
		 (0 . "ARC,CIRCLE,ELLIPSE,LINE,LWPOLYLINE")
		 (-4 . "<AND")
		 (0 . "POLYLINE")
		 (-4 . "<NOT")
		 (-4 . "&")
		 (70 . 112)
		 (-4 . "NOT>")
		 (-4 . "AND>")
		 (-4 . "<AND")
		 (0 . "SPLINE")
		 (-4 . "&")
		 (70 . 8)
		 (-4 . "AND>")
		 (-4 . "OR>")
		)
	     )
      )
    )
     (progn
       (vla-StartUndoMark AcDoc)
       (foreach	path (vl-remove-if 'listp (mapcar 'cadr (ssnamex ss)))
	 (setq obj (vlax-ename->vla-object path))
	 (setq start (vlax-curve-getPointAtParam
		       obj
		       (vlax-curve-getStartParam obj)
		     )
	 )
	 (setq ext_circ (vla-addCircle Space (vlax-3d-Point start) ext_rad))
	 (setq int_circ (vla-addCircle Space (vlax-3d-Point start) int_rad))
	 (setq norm (vunit (vlax-curve-getFirstDeriv
			     obj
			     (vlax-curve-getStartParam obj)
			   )
		    )
	 )
	 (vla-put-Normal ext_circ (vlax-3d-point norm))
	 (vla-put-Normal int_circ (vlax-3d-point norm))
	 (setq ext_reg (car (vlax-invoke Space 'addRegion (list ext_circ))))
	 (setq int_reg (car (vlax-invoke Space 'addRegion (list int_circ))))
	 (vla-Boolean ext_reg acSubtraction int_reg)
	 (vla-addExtrudedSolidAlongPath Space ext_reg obj)
	 (mapcar 'vla-delete (list obj ext_circ int_circ ext_reg))
       )
       (vla-EndUndoMark AcDoc)
     )
  )
  (princ)
)
;;;=======================================================================================