Create a perpendicular line FROM A POINT on a line

[nicolas]

Hi,

 

Seemed possible to create a perpendicular line from a specific point on a line a few days ago but unable to do it again and I have looked countless places without any success. 

 

So far I can do so changing the UCS or using LINE, Shift+Right Click, Perpendicular, Click Line and move away from the line to next point and then move the line to desired position.  I have also read in a forum about a LISP that can do this but I believe there is a method using LINE and Perpendicular OS to do same.

 

Please advise. Thanks.

[BIGAL]

Try osnap set to perp only osmode 128 then can Line Near and a perp line should then appear and you can enter pick length etc. A lisp would do this as well. May also be able to use Cal.

[steven-g]

Use the UCS command to align the UCS with the line and then use ortho F8

[tombu]

For Civil 3D users there's a LINEPERPENDICULAR command for doing just that.

 

Lee Mac's Cursor Rotate lisp makes this easy though. http://www.lee-mac.com/cursorrotate.html

Pick the line to set snap angle and set Grade to 0 after you're done.

 

[eldon]

Amongst several different ways of drawing a perpendicular from a line, the one I use most of the time is to have Polar Tracking permanently on. As long as it is set up to measure the Polar angle relative to last segment, then I start from the line using Nearest OS, and then the guide lines show where perpendicular is. 

[nicolas]

Thank you all for your input.  I believe the idea is more likely perpendicular to line or perpendicular from line.  Creating the per. line from a specific position on that line through an intersecting arc, another line or a point is a second operation that can be achieved by many of the methods you mentioned.   I have noted that polar tracking with relation from last segment option really work when all the object snaps are off except the one needed namely endpoint, midpoint.  However if the particular position is pinpointed by an actual point and using NODE, polar tracking method does not work.  The point is not an integral part of the line.  Where an endpoint of the arc meet the end point of the line, polar tracking does not work if the cursor is exactly on the end point but it does work when the end point of the line is selected a bit away.  I believe this is due to two end point meeting and the software need to know exactly from which object to create the perpendicular line: the line or the arc. 

[eldon]

Yes, Polar Tracking does have its limitations. But as you seemed prepared to move a line after drawing it, you could construct the line (I favour the object snap Nearest) and then move the line to the desired position.

 

There is always the option to offset the line, then draw the line from the node or intersection to the perpendicular of the offset line. So many different ways to do it!

[nicolas]

@eldon I just tried your last tip.  It works just fine. Thanks for sharing. 

[BIGAL]

From a programming point of view its pretty easy, so when you say pick a point how is that worked out, the simplest is say mid, or shorthand like 1/4 and 3/4. Even a random point can be programmed and postive or negative offsets applied for which side. 

[SEANT]

On 7/24/2021 at 5:06 AM, nicolas said:

A Construction Line (XLine) has some enhanced capabilities regarding the ‘Perp From’ requirement.  (See Link for demo).  As with some other suggestions, additional work would be required to finalize a needed Line, in this case a Trim operation.  If nothing else - another option in the toolbox.

https://knowledge.autodesk.com/community/screencast/7af9ed57-f0b8-4a92-817f-b2db97b3ef09

 

[tombu]

Including lisp there are many options here and elsewhere.

https://www.cadtutor.net/forum/topic/62853-lisp-code-to-draw-a-line-perpendicular-to-another-line/

https://www.google.com/search?q=perpendicular line FROM AutoCAD Lisp