Drafting Techniques

## Drafting Techniques

Contributor
Posts: 13
Registered: ‎07-29-2007
Message 1 of 10 (8,063 Views)

# Drawing a line tangent to two circles

8063 Views, 9 Replies
02-11-2013 01:14 PM

If I have two circles of unequal diameters and I want to draw a line tangent to them. How is this done?

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Registered: ‎12-05-2005
Message 2 of 10 (8,057 Views)

# Re: Drawing a line tangent to two circles

02-11-2013 01:36 PM in reply to: ronaldseto

Line command, using the TAN osnap, pick one circle to start, and the second circle to end the the line.

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Registered: ‎03-25-2009
Message 3 of 10 (8,043 Views)

# Re: Drawing a line tangent to two circles

02-11-2013 05:58 PM in reply to: ronaldseto

Please find the correct anser in the question of 'How to draw a line tangent to two circles?'

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Registered: ‎12-05-2005
Message 4 of 10 (8,033 Views)

# Re: Drawing a line tangent to two circles

02-12-2013 05:26 AM in reply to: 3wood

That's an .... "interesting" way to do the task, but its' also a lot more steps that using the tools built into the software to do it simply, with one command, one osnap, and two picks.

Contributor
Posts: 13
Registered: ‎07-29-2007
Message 5 of 10 (8,014 Views)

# Re: Drawing a line tangent to two circles

02-12-2013 11:52 AM in reply to: 3wood

Mr 3wood, Your solution worked, although a bit lengthy. I thought there may have been a shorter way to do it Others said to use the line command with osnap tangent; click on one circle for start and on the second circle for finish. I tried this, but it doesn't work.

*Expert Elite*
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Registered: ‎04-10-2005
Message 6 of 10 (8,009 Views)

# Re: Drawing a line tangent to two circles

02-12-2013 12:20 PM in reply to: ronaldseto

Type out the steps you are doing.

LINE <enter>

TAN <enter>

Pick the first point

TAN <enter>

Pick the second point

<enter>

Works like a charm here.

To comment on the OP's answer below:

There is no need to turn off running OSNAPS to acheive this. Just use the Snap: TAN while in the Line Command and a line to tangent will work as needed.

Contributor
Posts: 13
Registered: ‎07-29-2007
Message 7 of 10 (8,008 Views)

# Re: Drawing a line tangent to two circles

02-12-2013 12:21 PM in reply to: ronaldseto

I just tried it again. I realized that I have to pick only the tangent snap to use with the line command. All other snaps have to be disabled.

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Posts: 969
Registered: ‎03-25-2009
Message 8 of 10 (7,992 Views)

# Re: Drawing a line tangent to two circles

Not sure this method works in early AutoCAD versions? It works great in AutoCAD 2012 though.

*Expert Elite*
Posts: 1,924
Registered: ‎12-05-2005
Message 9 of 10 (7,979 Views)

# Re: Drawing a line tangent to two circles

02-13-2013 05:38 AM in reply to: ronaldseto

It's worked in versions af Acad as far back as I can recall.  Oddly though, using the PLINE command rather than the LINE command does not. work the same way, and will only be tangent to one of the circles.

dunno if it's fair to call that a bug, poor software design, or what, but it does not work as one would expect it to.

Contributor
Posts: 25
Registered: ‎04-16-2012
Message 10 of 10 (7,715 Views)

# Re: Drawing a line tangent to two circles

04-12-2013 02:17 PM in reply to: ronaldseto

ronaldseto wrote:

I just tried it again. I realized that I have to pick only the tangent snap to use with the line command. All other snaps have to be disabled.

You can force a temporary over-ride of your current object-snap settings by typing in "TAN<enter>" when prompted for any coordinate input. Doing so will, for that input only, disable all other object-snaps, and only look for Tangents. Much faster than manually going into the object snaps dialog every time.

This also works for other object-snaps:

...and my favorite, M2P!

Typing "M2P<enter>" at a coordinate input prompt will prompt you to pick *TWO* points, and uses the midpoint between them as the single input.

And yes, you can stack snaps inside M2P. For example, you could pick a point that is Midway between 2 Points, one being the virtual INTersection of two non-touching lines, the other being a point that is the CENter of an arc.

...Or you can use it to find the midpoint of the midpoint between two points!!! (AKA the 1/4-point)

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