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I have improved mine somewhat, at least it's the same no matter the pick order. Still working on a better method for correct centerline. Looks pretty close most of the time and should work with LWPolylines and Old Style Polylines and should handle bulges. I finished this at work, so untested on AutoCAD 2000i at home, so just AutoCAD 2026. ;;; Draws a centerline between two polylines. | ;;; | ;;; https://www.cadtutor.net/forum/topic/98778-hybrid-parallel/page/3/#findComment-677003 | ;;; | ;;; By SLW210 (a.k.a. Steve Wilson) | ;;; | ;;;=======================================================================================| ;;; DrawCl.LSP | ;;; Create centerline between two polylines | ;;; on layer Centerline, color Blue, and linetype Center | ;;;=======================================================================================| (vl-load-com) ;;; ------------------------------- ;;; Vector midpoint ;;; ------------------------------- (defun v-mid (a b) (list (/ (+ (car a) (car b)) 2.0) (/ (+ (cadr a) (cadr b)) 2.0)) ) ;;; ------------------------------- ;;; Distance squared ;;; ------------------------------- (defun dist2 (a b) (+ (expt (- (car a) (car b)) 2) (expt (- (cadr a) (cadr b)) 2)) ) ;;; ------------------------------- ;;; Nearest point ;;; ------------------------------- (defun nearest (pt lst / best d cur) (setq best nil d 1e99) (foreach cur lst (if (< (dist2 pt cur) d) (setq d (dist2 pt cur) best cur))) best ) ;;; -------------------------------------------------- ;;; Get polyline vertices (LWPOLYLINE or old POLYLINE) ;;; -------------------------------------------------- (defun get-poly-pts (ename / elist pts cur) (setq elist (entget ename)) (cond ((= "LWPOLYLINE" (cdr (assoc 0 elist))) (mapcar 'cdr (vl-remove-if-not '(lambda (x) (= 10 (car x))) elist))) ((= "POLYLINE" (cdr (assoc 0 elist))) (setq pts '() cur (entnext ename)) (while cur (setq elist (entget cur)) (cond ((= "VERTEX" (cdr (assoc 0 elist))) (setq pts (cons (cdr (assoc 10 elist)) pts))) ((= "SEQEND" (cdr (assoc 0 elist))) (setq cur nil))) (if cur (setq cur (entnext cur)))) (reverse pts)) (T (progn (princ "\nEntity is not a polyline.") nil))) ) ;;; ----------------------------------------- ;;; Polyline length (sum of vertex distances) ;;; ----------------------------------------- (defun polyline-length (pts / total i) (if (< (length pts) 2) 0 (progn (setq total 0.0 i 0) (while (< i (1- (length pts))) (setq total (+ total (sqrt (dist2 (nth i pts) (nth (1+ i) pts))))) (setq i (1+ i))) total))) ;;; ------------------------------- ;;; Polyline selection helper ;;; ------------------------------- (defun select-polyline (pick / sel) (while (progn (setq sel (entsel pick)) (not (and sel (entget (car sel))))) (princ "\nPlease select a valid polyline.")) (car sel)) ;;; ------------------------------- ;;; Ensure Centerline Layer Exists ;;; ------------------------------- (defun ensure-centerline-layer (/ doc layers layerObj ltObj) (setq doc (vla-get-ActiveDocument (vlax-get-Acad-Object))) (setq layers (vla-get-Layers doc)) (setq ltypes (vla-get-Linetypes doc)) ;; Load CENTER linetype if needed (if (not (tblsearch "LTYPE" "CENTER")) (vl-catch-all-apply '(lambda () (vla-load ltypes "CENTER" "acad.lin")))) ;; Create layer if missing (if (not (tblsearch "LAYER" "Centerline")) (setq layerObj (vla-Add layers "Centerline")) (setq layerObj (vla-Item layers "Centerline"))) ;; Set layer properties (vla-put-Color layerObj 5) ; blue (if (tblsearch "LTYPE" "CENTER") (vla-put-Linetype layerObj "CENTER")) layerObj ) ;;; ------------------------------- ;;; Main DRAWCL command ;;; ------------------------------- (defun c:DRAWCL (/ e1 e2 pts1 pts2 ref tgt mids coords arr doc ms pline closest closed layerObj) (vl-load-com) (princ "\nStarting DRAWCL centerline routine...") ;; Select polylines (setq e1 (select-polyline "\nSelect first polyline: ")) (setq e2 (select-polyline "\nSelect second polyline: ")) ;; Get vertices (setq pts1 (get-poly-pts e1)) (setq pts2 (get-poly-pts e2)) (if (and pts1 pts2) (progn ;; Determine longer polyline as reference (if (> (polyline-length pts1) (polyline-length pts2)) (setq ref pts1 tgt pts2 eRef e1) (setq ref pts2 tgt pts1 eRef e2)) ;; Compute centerline midpoints (setq mids '()) (foreach pt ref (setq closest (nearest pt tgt)) (setq mids (cons (v-mid pt closest) mids))) (setq mids (reverse mids)) ;; Ensure Centerline layer and linetype exist (setq layerObj (ensure-centerline-layer)) ;; Create centerline polyline in model space (if (> (length mids) 1) (progn (setq coords (apply 'append (mapcar '(lambda (p) (list (car p) (cadr p))) mids))) (setq arr (vlax-make-safearray vlax-vbDouble (cons 0 (- (* 2 (length mids)) 1)))) (vlax-safearray-fill arr coords) (setq doc (vla-get-ActiveDocument (vlax-get-Acad-Object))) (setq ms (vla-get-ModelSpace doc)) (setq pline (vla-AddLightWeightPolyline ms arr)) ;; Match closed/open status (setq closed (= 1 (logand 1 (cdr (assoc 70 (entget eRef)))))) (vla-put-Closed pline (if closed :vlax-true :vlax-false)) ;; Assign layer (vla-put-Layer pline "Centerline") (princ "\nCenterline created successfully on layer 'Centerline'.")) (princ "\nNot enough points to create centerline."))) (princ "\nFailed to get polyline vertices.")) (princ) ) Most Civil software has this in it and works pretty good AFAIK most of the time, it's not using LISP. It might be the harder, but maybe for new AutoCAD using CENTERLINE command with automated trimming and Join and Close if needed might be best for accuracy.

Good morning, I found this website searching for tutorials to guide me on this Structural Drafting assignment with Penn Foster. I have read through a few of the current threads, and some were helpful, but with visuals being shared that are not correct vs a lack of what it should look like, I am still lost. I wish I had known about this website during Oelson Village, I did pass that with a B on that one. However, that was easier for two reasons.. it is my daily life working with architectural plans for custom homes, so a site plan was not a stretch for me, and also it gave me a visual/goal to finish towards. I could auto-correct myself from step-by-step directions that left quite a bit out. Now I am onto the Structural Drafting assignment and am struggling more.. I was able to get to the point (of my attached images) due to some visuals and threads previously posted on here. However, when I switch to side (3D) views, it looks way off, and I am failing to see how this is all going to connect. Can anyone help me by showing me a visual of the end product that I am building..(I do not want the file, I want to build this and learn.) but a end visual of the front/side of what I am turning in helps. Or am I too soon into the steps, and should not freak out because it will all come together further along? Am I missing clear aspects like 3D measurements..details that are keeping these girders/beams I have built not architecturally correct. Please let me know if I am missing a key dimension, where I should enter that. I am taking a course to learn AutoCAD, but being asked to jump into 3D structual building after only ever doing a site plan in AutoCAD is rough. I get it..I learned a lot in the Oelson Village assignment, just by being thrown into it, but this Structural Drafting assignment is confusing for me. Thank you in advance to anyone jumping in, and sorry if you are repeating yourself. It is easy to get lost in other threads and go down a rabbit hole.

Nice @BIGAL . If you don't mind, I added a few lines of code to yours to make it work properly. ; https://www.cadtutor.net/forum/topic/98797-looking-for-a-lisp-to-evenly-space-polylines-from-their-end-points/ ; paralelle lines change ; offset a pline by an amount ; by AlanH Nov 2025 (defun c:wow ( / co-ord len1 len2 lst off off2 pt1 pt2 pts) ; Checking if pline is CW or CCW and set to CCW ; Orignal idea by Kent Cooper, 1 August 2018 Offsetinorout.lsp ; Modified By Alan H July 2020 (defun AH:chkcwccw ( ent / area1 area2 dist obj objnew pointmax pointmin) ;; remove "lst" from local variables (setq obj (vlax-ename->vla-object ent)) (setq lst (vlax-get obj 'coordinates)) (vla-GetBoundingBox obj 'minpoint 'maxpoint) (setq pointmin (vlax-safearray->list minpoint)) (setq pointmax (vlax-safearray->list maxpoint)) (setq dist (/ (distance pointmin pointmax) 20.0)) (vla-offset obj dist) (setq objnew (vlax-ename->vla-object (entlast))) (setq area1 (vlax-get objnew 'Area)) (vla-delete objnew) (vla-offset obj (- dist)) (setq objnew (vlax-ename->vla-object (entlast))) (setq area2 (vlax-get objnew 'Area)) (vla-delete objnew) (if (> area1 area2) (progn (command "pedit" ent "R" "") (setq lst (vlax-get obj 'coordinates)) ) ) lst ;; added this line to get a list of coordinates as "output" (princ) ) (defun replace-nth (lst n newVal) (cond ((null lst) nil) ((= n 0) (cons newVal (cdr lst))) (T (cons (car lst) (replace-nth (cdr lst) (1- n) newVal)))) ) (setq oldsnap (getvar 'osmode)) (setvar 'osmode 0) (setq off (getreal "\nEnter offset value ")) (while (setq pt1 (getpoint "\nPick 1st point outside ")) (setq pt2 (getpoint pt1 "\nPick 2nd point inward ")) (setq off2 (/ off 2.0)) (setq pts (list pt1 pt2)) (setq ss (ssget "F" pts '((0 . "LWPOLYLINE")))) (repeat (setq x (sslength ss)) (setq plent (ssname ss (setq x (1- x)))) (AH:chkcwccw plent) (setq len1 (distance (list (nth 0 lst)(nth 1 lst)) (list (nth 2 lst)(nth 3 lst)))) (setq len2 (distance (list (nth 4 lst)(nth 5 lst))(list (nth 6 lst)(nth 7 lst)))) (if (> len1 len2) (progn (setq lst (replace-nth lst 0 (+ (nth 0 lst) off2))) (setq lst (replace-nth lst 2 (+ (nth 2 lst) off2))) (setq off2 (+ off2 off)) ) (progn (setq lst (replace-nth lst 6 (- (nth 6 lst) off2))) (setq lst (replace-nth lst 4 (- (nth 4 lst) off2))) (setq off2 (+ off2 off)) ) ) (vlax-put (vlax-ename->vla-object plent) 'coordinates lst) ;; added here "(vlax-ename->vla-object plent)" instend of "obj" ) ) (setq lst nil) ;; added this line of code to "release" variable "lst" (setvar 'osmode oldsnap) (princ) ) Best regards.

As for the code from my first attempt, I suppose the least I should do for any “child of mine” is to make sure it can have a functional life, no matter how cross-eyed it was born: you never abandon a child. So here I leave a new version of “GLAVCVS’ cross-eyed child”, fresh out of the hospital. ;| G L A V C V S C R O S S - E Y E D C H I L D - o - ************************* G L A V C V S ************************* *************************** F E C I T ***************************|; (defun c:creAxis (/ e e1 e2 l i? l1 l2 lr p p0 p1 p2 px pm abis lii pmi pmf pi1 pi2 pf1 pf2 pc1 pc2 li1 o dameInters+Prox ordena decide sustituye damePuntos) (defun dameInters+Prox (p0 a lp / p1 px pt1 pt2 dmin d pf) (setq pt1 (polar p0 a 1e8) pt2 (polar p0 (+ a PI) 1e8)) (foreach p lp (if p1 (if (setq px (inters pt1 pt2 p1 p)) (if dmin (if (< (setq d (distance px p0)) dmin) (setq dmin d pf px)) (setq dmin (distance px p0) pf px)) ) ) (setq p1 p) ) pf ) (defun ordena (po px pm / p0 lr) (foreach p lii (if (and p0 (inters po px p0 p)) (setq lr (append lr (list pm))) ) (setq p0 p lr (append lr (list p))) ) ) (if (and (setq e1 (car (entsel "\nSelect FIRST LWPOLYLINE..."))) (= (cdr (assoc 0 (setq l1 (entget e1)))) "LWPOLYLINE") (not (redraw e1 3))) (if (and (setq e2 (car (entsel "\nSelect SECOND LWPOLYLINE..."))) (= (cdr (assoc 0 (setq l2 (entget e2)))) "LWPOLYLINE") (not (redraw e2 3))) (progn (setq lp1 (reverse (foreach l l1 (if (= (car l) 10) (setq lr (cons (cdr l) lr)) lr))) lr nil lp2 (reverse (foreach l l2 (if (= (car l) 10) (setq lr (cons (cdr l) lr)) lr))) lr nil ) (cond ((= (rem (cdr (assoc 70 l1)) 2) 1) (setq lp1 (append lp1 (list (car lp1) (cadr lp1) (caddr lp1)))) ) ((equal (car lp1) (last lp1)) (setq lp1 (append lp1 (list (cadr lp1) (caddr lp1)))) ) (T (setq pmi (mapcar '(lambda (a b) (/ (+ a b) 2.0)) (car lp1) (setq pc1 (vlax-curve-getClosestPointTo e2 (car lp1)))) pmf (mapcar '(lambda (a b) (/ (+ a b) 2.0)) (last lp1) (setq pc2 (vlax-curve-getClosestPointTo e2 (last lp1)))) ) ) ) (cond ((= (rem (cdr (assoc 70 l2)) 2) 1) (if pmi (progn (foreach p (append lp2 (list (car lp2))) (if (or (equal p pmi 1e-4) (equal p pmf 1e-4)) (setq l (if l (not (setq lr (append l (list p)))) (list (list p)))) (if l (setq l (append l (list p)))) ) ) (setq lp2 lr lr nil l nil) ) (setq lp2 (append lp2 (list (car lp2) (cadr lp2)))) ) ) ((equal (car lp2) (last lp2)) (if pc1 (progn (foreach p lp2 (if (or (equal p pc1 1e-4) (equal p pc2 1e-4)) (setq l (if l (not (setq lr (append l (list p)))) (list (list p)))) (if l (setq l (append l (list p)))) ) ) (setq lp2 lr lr nil l nil) ) (setq lp2 (append lp2 (list (cadr lp2)))) ) ) ) (redraw e1 4) (redraw e2 4) (foreach lp (list lp1 lp2) (foreach l lp (if p1 (if p2 (setq abis (+ (/ (+ (angle p1 p2) (angle p2 l)) 2) (/ PI 2.)) px (dameInters+Prox p2 abis (if o lp1 lp2)) lr nil pm (if px (mapcar '(lambda (a b) (/ (+ a b) 2.0)) p2 px)) lii (if o (if pm (ordena p2 px pm) lii) (if px (append lii (list pm)) lii)) p1 p2 p2 l ) (setq p2 l) ) (setq p1 l) ) ) (if pmi (setq lii (append (list pmi) lii (list pmf)))) (setq p1 nil p2 nil lr nil o T) ) ) ) ) (entmake (append '((0 . "LWPOLYLINE") (100 . "AcDbEntity") (67 . 0) (8 . "0") (100 . "AcDbPolyline") (70 . 0) (60 . 0)) (list (cons 90 (length lii))) (mapcar '(lambda (a) (cons 10 a)) lii))) (princ) )

Hopefully I can get back to my LISP today. I did do some experiments with CENTERLINE command in newer AutoCAD (not sure when it was first available), if just Polylines/lines, it gets the center very accurately, good for checking a LISP IMO. This is really a job for Civil 3D/ArcGIS or similar software.

I also think this thread has been stimulating. The final result should be useful for other users in the future. Regarding your approach, I agree; it's the best way to achieve an axis with perfectly centered segments. All that remains is to write the code that can do all of that without Express Tools.

Any one out there that Has LT2024+ etc can test the small bit of code that allows Excel to control CAD would like to know if it works.

Finally had some time to do something, give this a try. (defun c:numblk ( / atts bname ent grp lst lst2 num numstr obj ss) ; ; groupby provided by Dexus (defun _groupBy (fun lst / itm old rtn) (while lst (setq itm (fun (car lst)) rtn (if (setq old (assoc itm rtn)) (subst (cons itm (cons (car lst) (cdr old))) old rtn) (cons (cons itm (list (car lst))) rtn) ) lst (cdr lst)) ) (mapcar 'cdr rtn) ) (setq bname (cdr (assoc 2 (entget (car (entsel "\nPlease slect a block for block name ")))))) (prompt "\nPlease select blocks") (setq ss (ssget (list (cons 0 "INSERT")(cons 2 bname)))) (setq lst '()) (repeat (setq x (sslength ss)) (setq ent (ssname ss (setq x (1- x)))) (setq obj (vlax-ename->vla-object ent)) (setq atts (vlax-invoke obj 'Getattributes)) (setq attext (vlax-get (nth 2 atts) 'textstring)) (setq lst (cons (list attext ent) lst)) ) (setq lst (vl-sort lst '(lambda (x y) (< (car x)(car y))))) (setq lst2 (reverse (_groupBy (lambda (e) (car e)) lst))) (setq num (getint "\nEnter start number eg 1 ")) (foreach grp lst2 (cond ((< num 10)(setq numstr (strcat "00" (rtos num 2 0)))) ((< num 100)(setq numstr (strcat "0" (rtos num 2 0)))) ((> num 99)(setq numstr (rtos num 2 0))) ) (foreach ent2 grp (setq obj (vlax-ename->vla-object (cadr ent2))) (setq atts (vlax-invoke obj 'Getattributes)) (vlax-put (nth 1 atts) 'textstring numstr) ) (setq num (1+ num)) ) (alert "Type numblk to run again ") (princ) ) (C:numblk)

Another version just drag over the plines left and right. https://www.cadtutor.net/forum/topic/98797-looking-for-a-lisp-to-evenly-space-polylines-from-their-end-points/ ; paralelle lines change ; offset a pline by an amount ; by AlanH Nov 2025 (defun c:wow ( / co-ord len1 len2 lst off off2 pt1 pt2 pts) ; Checking if pline is CW or CCW and set to CCW ; Orignal idea by Kent Cooper, 1 August 2018 Offsetinorout.lsp ; Modified By Alan H July 2020 (defun AH:chkcwccw (ent / area1 area2 dist lst obj objnew pointmax pointmin) (setq obj (vlax-ename->vla-object ent)) (setq lst (vlax-get obj 'coordinates)) (vla-GetBoundingBox obj 'minpoint 'maxpoint) (setq pointmin (vlax-safearray->list minpoint)) (setq pointmax (vlax-safearray->list maxpoint)) (setq dist (/ (distance pointmin pointmax) 20.0)) (vla-offset obj dist) (setq objnew (vlax-ename->vla-object (entlast))) (setq area1 (vlax-get objnew 'Area)) (vla-delete objnew) (vla-offset obj (- dist)) (setq objnew (vlax-ename->vla-object (entlast))) (setq area2 (vlax-get objnew 'Area)) (vla-delete objnew) (if (> area1 area2) (progn (command "pedit" ent "R" "") (setq lst (vlax-get obj 'coordinates)) ) ) (princ) ) (defun replace-nth (lst n newVal) (cond ((null lst) nil) ((= n 0) (cons newVal (cdr lst))) (T (cons (car lst) (replace-nth (cdr lst) (1- n) newVal)))) ) (setq oldsnap (getvar 'osmode)) (setvar 'osmode 0) (setq off (getreal "\nEnter offset value ")) (while (setq pt1 (getpoint "\nPick 1st point outside ")) (setq pt2 (getpoint pt1 "\nPick 2nd point inward ")) (setq off2 (/ off 2.0)) (setq pts (list pt1 pt2)) (setq ss (ssget "F" pts '((0 . "LWPOLYLINE")))) (repeat (setq x (sslength ss)) (setq plent (ssname ss (setq x (1- x)))) (AH:chkcwccw plent) (setq len1 (distance (list (nth 0 lst)(nth 1 lst)) (list (nth 2 lst)(nth 3 lst)))) (setq len2 (distance (list (nth 4 lst)(nth 5 lst))(list (nth 6 lst)(nth 7 lst)))) (if (> len1 len2) (progn (setq lst (replace-nth lst 0 (+ (nth 0 lst) off2))) (setq lst (replace-nth lst 2 (+ (nth 2 lst) off2))) (setq off2 (+ off2 off)) ) (progn (setq lst (replace-nth lst 6 (- (nth 6 lst) off2))) (setq lst (replace-nth lst 4 (- (nth 4 lst) off2))) (setq off2 (+ off2 off)) ) ) (vlax-put obj 'coordinates lst) ) ) (setvar 'osmode oldsnap) (princ) ) (c:wow)

I have enjoyed the discussion of this thread. As I gave the task more thought and anaysis it became more clear that the task was not simple. As it appears that there is still no satisfacory solution I thought I would offer the following. The first goal for me was to create a function that would create a midline between two non parallel lines. The mid-lines extents should be a function of the given line segments. This function could then be used in a program that would step through the line segments of one of the polylines and search the other polyline for relevant segments. The function "midline" accepts four points. The first two points, A1 and A2, are the ends of one line sement while the thrid and fourth points, B1 and B2, are the ends of an opposing ilne segments. The diagram below details the variables in the function. The program uses vectors as I prefer them over angles which present, for me, a variety of problems. uA = unit vector in the diection from A1 to A2 uB = unit vector in the direction from B1 to B2 uBisector = unit vector in the direction of the angle bisector of uA and UB The ends of the two lines are projected onto the bisecting line defining 4 points, A1M, A2M, B1M, B2M. I debated which of the points to output for the line to be drawn. I first used the closest and furthest points from the intersecttion point ABIntr but I found it more helpful to use the two intermediate points (A1M and A2M in the example above). Here's an example of the results after manually steppng alone the polyline. Looking at the area circled in red we find: To fill the gap we need a curve that starts with a radius of 0.1514 and ends with a radius of 0.1693. This can be done with a spline or you may find it acceptable to extend the two lines to the point of intersection. The best way to create the spline is to use the Control Vertex Method and use the two endpoints and the imaginary point of intersecton for the middle CV. This ensures tangency to the two lines. As can be seen below the distance to a random point along the spline (red) agree! Run the program "test" and specify the end points of a line segment on one of the polylines, then the endpoints on a line segment on the opposing polyline. I have found the results very accurate and although it may not be used for creating the complete "hybrid " polyline it is helpful in finding the correct line for a specific segment.

My one should find the centre between the shortest lines from polylines point to the other... not perpendicular so should give a reasonably curve.

And, VERY IMPORTANTLY, it should return the same result regardless of which reference polyline is processed first. In my opinion, this is the first requirement for the method to be consistent.

15 years later I am annoyed by this effect too and This is one of the first links that shows up when searching for a solution. The system variable is MTextFixed. Changing it from 2 to 1 disables it.

Thank you @Steven P The problem with creating the centerline using perpendiculars is that even in straight sections, the centerline is not equidistant perpendicularly from the reference polylines (unless the reference polylines are parallel). This is the method I used manually, but I didn't achieve this goal.

We used to have a 3rd party PDF printer - it also worked with all the office applications for example. Worked just the same as adding any other physical printer, might be a solution. However I thought LT had a PDF plotter as a part of the package

I looked at the Autodesk site and as far as I know only AutoCAD for MAC (LT) 2026 is compatible with Tahoe which was just released September 2025. Can you print to an image file, that may work, or just see if Fedex/Kinkos can print the drawing file.

Oops again. Didn't know '@' is the same - my bad. Still the offset of it amazes me.

BTW this is also included without a command initialize, just wish I new what/how to access that as with (getvar 'lastpoint)

Never before knew AutoCAD saved this info.. Please test as I'm still A2K.. Key "0" to get last point picked when asked by command where to start.. which also includes: *ANY.point.on.screen. Any other number [understood as 'from'] changes this location as offset.from that <dist+angle> toward the current mouse position. Another is to click on a live vertex, hit esc, now that point is the saved/usable coord as mentioned. Similar to the second point of command which is used as 'dist.from.lastpoint' toward mouse as you press 'enter'. ... Still learning so I'll contact here. This is certainly useful once you add it to your mental tools.of.trade. * ANY.point.on.screen also includes non.entity,bare loc.

Need a Plan dwg showing the line work etc this will give some clues about the extra points that you want highlite those points in the Plan dwg, to really get an proper answer need a full CIV3D dwg not just a output setcion so a CIV3D user can run the make long and cross sesctions.

"so that it works for "Y" direction movements as well." I did think about what happens if the objects are drawn on an angle, There may be a way by using work out the new points using a 90 angle off the existing points. Suddenly busy so not sure when will have time to do something.

I need to print a PDF so I can take the file to be printed at Fedex/Kinkos. I have AutoCAD LT 2021 for Mac. Computer recently upgraded to Tahoe OS. In trying to fix this I found that I seem to have two versions of the app: AutoCAD LT 2021 and AutoCAD LT 2021F. The 2021F, I think I understand, is the new version created by the upgrade to Tahoe. In the Plot window, the Print drop-down does not have the option for printing to PDF. There are only physical printers listed. The Save to PDF button at the bottom creates an Acrobat error and will not print. Export to PDF does not work. In addition, the Plot Style is set to Print As Displayed. I am not using .ctb because I can’t get one loaded at this point. The drop-down options for Plot Style are New, Import, Reveal in Finder. These are not working. (I want them to work eventually, but I have to get the PDF printed as soon as possible.) So setting the Plot Style to other than Print As Displayed can wait for now. I’m thinking this is a file path issue, but I have no idea how fix it. But maybe that's wrong. Thank you for any help.

Use OVERKILL to remove the overlaps.

Edited Not quite there yet, will draw points at the mid points between each coordinate in the polylines and the closest point in the other. Draws a poly line connecting most of them... but not quite... Something odd if you select the polylines in the wrong order. Results are similar to what others have. No account taken for arcs yet (defun c:PolyMD ( / acount MyPoly1 MypolyEnt1 MyPolyVert1 MyPoly2 MypolyEnt2 MyPolyVert2 pt pt1 pt2 PtList1 PtList2 pnt NewPoly NewPolyEnt) ;;; Sub functions ;;;;;; ;;https://www.cadtutor.net/forum/topic/87445-help-add-vertex-to-polyline/ (defun add_vtx (obj add_pt ent_name / sw ew nw bulg) (vla-GetWidth obj (fix add_pt) 'sw 'ew) (vla-addVertex obj (1+ (fix add_pt)) (vlax-make-variant (vlax-safearray-fill (vlax-make-safearray vlax-vbdouble (cons 0 1)) (list (car (trans (vlax-curve-getpointatparam obj add_pt) 0 ent_name)) (cadr (trans (vlax-curve-getpointatparam obj add_pt) 0 ent_name)) ) ) ) ) (setq nw (* (/ (- ew sw) (- (vlax-curve-getdistatparam obj (1+ (fix add_pt))) (vlax-curve-getdistatparam obj (fix add_pt))) ) (- (vlax-curve-getdistatparam obj add_pt) (vlax-curve-getdistatparam obj (fix add_pt))) ) bulg (atan (vla-GetBulge obj (fix add_pt))) ) (vla-SetBulge obj (fix add_pt) (/ (sin (* 4 bulg (- add_pt (fix add_pt)) 0.25)) (cos (* 4 bulg (- add_pt (fix add_pt)) 0.25)) ) ) (vla-SetBulge obj (1+ (fix add_pt)) (/ (sin (* 4 bulg (- (1+ (fix add_pt)) add_pt) 0.25)) (cos (* 4 bulg (- (1+ (fix add_pt)) add_pt) 0.25)) ) ) (vla-SetWidth obj (fix add_pt) sw (+ nw sw) ) (vla-SetWidth obj (1+ (fix add_pt)) (+ nw sw) ew ) (vla-update obj) ) (defun add_vtx@point (ename lst_pt / n ename obj dxf_10 pt_brk l_tst) (setq obj (vlax-ename->vla-object ename)) (setq dxf_10 (mapcar 'cdr (vl-remove-if-not '(lambda (x) (= (car x) 10)) (entget ename)))) (foreach el (mapcar '(lambda (x) (trans x 0 ename)) lst_pt) (setq pt_brk (trans (vlax-curve-getClosestPointTo ename (trans el ename 0) nil) 0 ename)) (setq l_tst (vl-member-if '(lambda (x) (and (equal (car x) (car pt_brk) 1E-08) (equal (cadr x) (cadr pt_brk) 1E-08))) dxf_10)) (if (and (equal pt_brk el 1E-08) (not (eq (length l_tst) 1)) (not (eq (length l_tst) (length dxf_10))) ) (progn (setq lst_brk (cons pt_brk lst_brk)) (if (zerop (length l_tst)) (add_vtx obj (vlax-curve-getparamatpoint ename (trans pt_brk ename 0)) ename) ) ) ) ) ) (defun mAssoc ( key lst / result ) (foreach x lst (if (= key (car x)) (setq result (cons (cdr x) result)) ) ) (reverse result) ) ; end Massoc (defun midpt (p1 p2) (polar p1 (angle p1 p2) (/ (distance p1 p2) 2.) ) ) (defun LM:Unique ( l ) (if l (cons (car l) (LM:Unique (vl-remove (car l) (cdr l))))) ) (defun LM:intersections ( ob1 ob2 mod / lst rtn ) (if (and (vlax-method-applicable-p ob1 'intersectwith) (vlax-method-applicable-p ob2 'intersectwith) (setq lst (vlax-invoke ob1 'intersectwith ob2 mod)) ) (repeat (/ (length lst) 3) (setq rtn (cons (list (car lst) (cadr lst) (caddr lst)) rtn) lst (cdddr lst) ) ) ) (reverse rtn) ) (defun MakePoly (PtLst PolyClose / ) (princ "Close: ")(princ PolyClose) (entmakex (append (list (cons 0 "LWPOLYLINE") (cons 100 "AcDbEntity") (cons 100 "AcDbPolyline") (cons 90 (length PtLst)) ;; (cons 70 PolyClose) ) (mapcar (function (lambda (p) (cons 10 p))) PtLst) )) ) (defun MakePoint ( pt / ) (entmakex (list '(0 . "POINT") '(100 . "AcDbEntity") '(100 . "AcDbPoint") (cons 10 pt) )) ) (defun MakeLine (pt1 pt2 / ) (entmakex (list '(0 . "LINE") '(100 . "AcDbEntity") '(100 . "AcDbLine") (cons 10 pt1) (cons 11 pt2) )) ) ;;;;;;; end sub functions ;;;;;;; (setq MyPoly1 (car (entsel "\nSelect Outer Polyline: "))) (setq MyPoly1Ent (entget MyPoly1)) (setq MyPoly1Vert (mAssoc 10 MyPoly1Ent)) (setq MyPoly2 (car (entsel "\nSelect Inner Polyline 2: "))) (setq MyPoly2Ent (entget MyPoly2)) (setq MyPoly2Vert (mAssoc 10 MyPoly2Ent)) (foreach pt MyPoly1Vert (setq pt2 (vlax-curve-getclosestpointto MyPoly2 pt)) (setq PtList1 (cons (midpt pt pt2) PtList1)) ) ; end foreach (setq NewPoly (MakePoly PtList1 (cdr (assoc 70 MyPoly1Ent)))) (setq NewPolyEnt (entget NewPoly)) (foreach pt MyPoly2Vert (setq pt1 (vlax-curve-getclosestpointto MyPoly1 pt)) (setq NewLine (makeline pt pt1)) (setq PtList2 (cons (midpt pt pt1) PtList2)) (setq pnt (car (LM:intersections (vlax-ename->vla-object NewLine) (vlax-ename->vla-object NewPoly) acextendnone))) (setq pnt (list (car pnt) (cadr pnt))) (add_vtx@point NewPoly (list pnt)) (setq NewPolyEnt (entget NewPoly)) (setq NewPolyEnt (subst (cons 10 (midpt pt pt1) ) (cons 10 pnt) NewPolyEnt )) (entmod NewPolyEnt) ;; (entupd NewPoly) (command "erase" NewLine "") ) ; end foreach (foreach pt PtList1 (Makepoint pt) ) (foreach pt PtList2 (Makepoint pt) ) ;;Work out if midpoints outside of exterior polyline (in case of complicated shapes) ;;Work out polyline bulges ;;If closed poly, add end vertex (princ) )

I follow your instructtion. and do the other test, flattened it befor running TICS ,make sure they are flat. but there are still some overlaping lines left . I am confused... lisp test-V2.dwg