Could someone tell me please how do I draw this spiral-alike object in AutoCAD 2014?Thank you

How exactly does the shape need to match?  This is a simple Polyline with all 180° arc segments, easily drawn with Snap turned on appropriately:You can fiddle with the proportions, how close the loops are to each other, etc.A Spline could do the same but achieve a closer approximation to the nature of the curvature in your image.  Again, have Snap turned on and experiment with the spacings in both directions of the defining points.

Can you show me please step-by-step as a 2D GIF animation of the process of constructing this spiral-alike object?

The Polyline version:The green dots and dashed dark grey where-it's-headed path are for visual reference -- in this case, the ends of the larger upper arc segments are 13 drawing units apart, and the ends of the smaller lower arc segments are 6 units apart.  Snap is turned on at 1 drawing unit.You could also just draw Arcs and Copy or Array them, then join them into a Polyline.

Kent Cooper2024-07-10 19:34:50

Can you show me the 2D GIF animation step-by-step of drawing this spiral-alike object as similar possible as the one shown on the image at post #1 using a spline? Can you also show me the grids of it?dery2024-07-11 00:49:06

For the Spline version, more defining points are appropriate than for the Polyline of all half-circle arc segments.  These are the spacings/proportions I used:to do this:Then I did this in Properties to get the end directions to look better:

Kent Cooper2024-07-12 15:11:18

As I can see on the symbol, does the Start and End Tangent Vector Y in inch unit?

[QUOTE=dery].... does the Start and End Tangent Vector Y in inch unit?[/QUOTE]  It's in whatever drawing units are current in your drawing settings, as all entries in the Properties palette always display things.  Just make the start and end tangent vector Y settings equal in value but opposite in sign.  The start-positive and end-negative in mine are appropriate to the direction I drew the Spline, but the opposite would be needed if drawn up-side-down, and if the whole thing runs vertically, use X instead of Y, etc. -- you'll figure it out  It doesn't need to be 1 unit, but that made a good "look" for me at the size of my spiral -- the best appearance could be a very different value depending on the size of things.  You can even play with both X and Y if you don't want the ends springing vertically off the "base" line, to match the fact that in this configuration the Spline doesn't quite cross the base line exactly vertically at intermediate crossings.


Kent Cooper2024-07-12 14:35:47

Mr. Kent Cooper, why I can't find the "Start and End tangent vector Y" in my AutoCAD 2014 Properties?

Show us what your Properties palette has in the Misc category when you have a Spline selected.Are you perhaps working with a closed Spline?  They don't have those properties.

This is the properties menu of my AutoCAD 2014 looks like.

It must be related to this confusing aspect in your image:That should say Spline in the light blue box, or if you have more selected than just the Spline, it should say All with a number in parentheses of the quantity of selected objects, and a breakdown under it showing how many of each type of object are in the selection.  Yet it looks like you do have the Spline selected, with all its grips showing -- whether also anything else, I can't tell.  If you can figure out why that what's-selected box is empty, maybe that will help with getting to the end tangent vectors.
Kent Cooper2024-08-19 19:35:14

[QUOTE=Kent Cooper]If you can figure out why that what's-selected box is empty, maybe that will help with getting to the end tangent vectors.[/QUOTE]I have no idea of why the selected-box is empty.What should I do then?dery2024-08-20 09:42:58

Maybe this will give you some help.  I have no other suggestions.

Unfortunately, after doing your suggestions, still not working. Can it be done by using command?

It can be done with entity data.  If edata is the entity data list of a Spline [extracted with (entget)], this will make the start tangent [the 12 entry] upward and the end tangent [13] downward:(entmod (append edata '((12 0.0 1.0 0.0) (13 0.0 -1.0 0.0))))Play around with the value of what's 1.0 there [both positive and negative] to adjust the "strength" of the directions.

How do I do that? Could you tell me please the step-by-step procedure? It's better if you show me by gif animation.

In simplest terms, paste this in at the Command: line:(defun C:STE (/ spl sdata) ; = Spline Tangencies at Ends  (setq    spl (car (entsel "\nSpline to have end tangent directions forced: "))    sdata (entget spl)  )  (entmod (append sdata '((12 0.0 1.0 0.0) (13 0.0 -1.0 0.0)))))Then type in the command name STE.  It can be made more sophisticated, such as to verify that you selected an open-ended Spline.Note again that this particular version forces the starting tangency to be upward, and the ending tangency downward, as appropriate to the images in this topic.  Different versions could be made for different orientations.  Or it could be made to ask, or possibly to determine something from the configuration of the selected Spline, and/or to figure out the "strength" of the directionality based on something about the Spline, and so on.If you paste it into a plain-text editor such as Notepad, and save it to a file with a .LSP filetype ending, you can use APPLOAD to load it into any drawing.  If you would use it often enough to justify this, it can be made to automatically load in every drawing you open, so it will always be available.

I got this message after paste-ing the code you sent to me and execute it by typing STE:"Spline to have end tangent directions forced:"What should I do?

Pick it.  Maybe I should have made the prompt more long-winded:"Select Spline to have end tangent directions forced:"