topic Re: how to align a line to be perpendicular to a arc at a specific point? in AutoCAD Forum

how to align a line to be perpendicular to a arc at a specific point?

Anonymous — Thu, 12 Oct 2017 19:11:18 GMT

I want to move a line to be perpendicular to an arc. I want to avoid draw a perpendicular line first.

Re: how to align a line to be perpendicular to a arc at a specific point?

user181 — Thu, 12 Oct 2017 19:17:17 GMT

Draw a line from the arc center to any point on the arc and that line is perpendicular to the arc. Or start the line command and use the perpendicular osnap and select the arc and then pick the second point for the line.

Re: how to align a line to be perpendicular to a arc at a specific point?

gotphish001 — Thu, 12 Oct 2017 19:56:22 GMT

You can pick the line, then pick the end point grip of the line, shift right click and force perpendicular snap, now pick the arc. It will snap to the arc perpendicular. It will shorten or lengthen the line though.

If you want to keep the lines length, you can use rotate command. Start the rotate command, select the line,pick the rotation point, then pick the reference sub command, reference the start and end of the line you, then as mentioned above force perpendicular snap and then pick the arc.

Re: how to align a line to be perpendicular to a arc at a specific point?

Anonymous — Thu, 12 Oct 2017 20:14:25 GMT

With the assumption that the existing line can be made perpendicular to the existing arc:

1. Move the line to the center point of the arc - Start the Move command, select any point on the line, and move to the center point of the arc (OSNAP)

2. Move a point on the line to the intersection point of the line and arc - Start the Move command, select a point on the line and move to the intersection point (OSNAP).

Re: how to align a line to be perpendicular to a arc at a specific point?

Vinayv4v — Thu, 12 Oct 2017 21:10:38 GMT

Hello,

Use this routine to draw perpendiculars according to your requirement.

COMMAND : PERP2ENT

For more details refer the link:

https://autocadtips1.com/2011/10/13/autolisp-perpendicular-to-entity/

Re: how to align a line to be perpendicular to a arc at a specific point?

Kent1Cooper — Thu, 12 Oct 2017 22:00:25 GMT

Here's a routine to draw perpendicular from a specified point on any entity with linearity: the (pf) function here. See Usage instructions at that Post.

@Vinayv4v's routine is really to draw things perpendicular to something, from multiple picked locations. But note the right end Line that isn't perpendicular, because it goes for the closest point to the [in this case] Arc, so when the Arc doesn't extend as far as where the Line would go if really were perpendicular, you get that kind of error.

Re: how to align a line to be perpendicular to a arc at a specific point?

beyoungjr — Thu, 12 Oct 2017 22:30:40 GMT

Lets all be careful with "Perpendicular". Is it actually "Radial" that the OP wishes to achieve? Also, do you want to bi-sect the arc with a radial line?

If so, create a line from center to midpoint of the arc... Radial and bisecting.

If you wish to align an existing line or other object to the bi-sect position just use Align and select the source/destination points in the order that you need for alignment. Then select "No" for scaling your aligned object/s.

Hope that helps,

Blaine

Re: how to align a line to be perpendicular to a arc at a specific point?

Kent1Cooper — Fri, 13 Oct 2017 12:59:54 GMT

@Anonymous wrote:

I want to move a line to be perpendicular to an arc. I want to avoid draw a perpendicular line first.

Looking at the original request again, I'm thinking --

Are you talking about a Line that is already drawn? If so, and if you don't want to change the direction in which the Line is drawn or its length, you can select the Line, grab any of its 3 grips, hit Enter to get into the Move option in grip-editing, and take that grip to the CENter of the Arc with CENter Osnap. If any point on a Line passes through the Arc's center, it will be perpendicular to the Arc. If you want it to touch the Arc at an end- or mid-point, grab the appropriate grip, Enter/Move, PERpendicular to place that point on the Arc.

If you don't mind changing the Line's direction and/or length, there are more options. An image or sample drawing would clarify what you want to do, exactly.