Autocad How to Draw a Tangent Line to Two Circles
I'm using Carlson Survey 2016 with IntelliCAD 8.1. I desire to draw a line that is tangent to two circles, similar this.
Tangent Snap works fine in drawing a line "to" a tangent, but non "from" a tangent. Is there an easy fashion to draw this?
Thanks.
Topic starter Posted : January 13, 2017 four:58 pm
Information technology's an piece of cake Calc to go the bearing and missing side. Utilise the sum of the radii as ane leg of an bending side side triangle...
Posted : January 13, 2017 v:10 pm
Kickoff the big circle in the radius of the small circumvolve. Describe a line from the eye of the minor circle to tangent to the inner large circle. The residue should be apparent.
Posted : Jan 13, 2017 five:35 pm
With the autocad engine in the cogo menu in that location is a simple routine "tangent line betwixt circles", great routine. Hopefully intellecad version has it.
Posted : January 13, 2017 6:01 pm
You're sketch is showing ane of the internal tangents. To get that, wait at the yellow lines higher up. I created a random radial on the large circle running SE, then I copied that radial to the pocket-size circle but ran it NW and connected the end points of the radials. Notice that the yellow line intersects the line betwixt the two centre points (blackness) at the aforementioned place where the 2 interior radials (magenta) intersect. One time yous accept that intersection point you can draw a line from in that location and snap tangent to i of the circles then extend the line to the other circle and it should exist tangent to both.
The external tangents are similar simply instead of making the two radials on reverse headings, make them parallel like the carmine radials above. Connecting the end points of the parallel radials and intersecting with a line running through the center of both circles volition create the outer intersection betoken in a higher place. Now you tin can draw a line from the intersection signal and snap tangent to the far circle and trim it at the virtually circumvolve.
I wish I could claim I knew this before you ask the question, but Google and Wikipedia are wonderful teachers.
Posted : January xiii, 2017 6:14 pm
The crossing of the magenta lines intersection is the key. It can be constructed a thousand ways considering of its symmetry!
Stephan's method has a weakness when the circles are almost the same size.
I continued the radius points, then constructed diameters of each circle perpendicular to that line (giving an "H" shape).
Drawing a line from one diameter extremity to the reverse bore extremity of the other circumvolve, in effect making an "X" out of the "H", gives one style to make the intersection. Then snap your tangents from there.
This method will piece of work fifty-fifty for equal radius circles!
Posted : January thirteen, 2017 8:32 pm
Years ago in ACAD, you just had to do the line command, type, tan, click on one circumvolve, then tan, click on the other, and it would draw the line tangent to both. I can't get that to piece of work in Carlson, with embedded ACAD, though.
Posted : January 14, 2017 7:sixteen am
Regular Autocad (I'thou in 2009 right at present) generates this geometry with the tangent functions on both ends.
Draw larger circle, then smaller circle.
Begin LINE command, and snap to TAN of larger circle, then the to point, snap to the TAN of the smaller circumvolve.
Tangent line betwixt circles is generated, that is identical to the one developed via Stephen Ward's method.
Does IntelliCAD not provide this functionality?
Posted : January 14, 2017 7:20 am
I know this thread is actually about how to get the software to do it for you, merely I wondered how to do it on a calculator.
d = distance between centers
R = one circle radius
r = other circle radius
a = distance from showtime circle centre to crossing point
And so from similar triangles you tin can chop-chop derive
a = d * R /(r+R)
With that it is like shooting fish in a barrel to solve the residual of the triangles.
-----
The first step in derivation is to note that the angles in each triangle are the same, so the sides are proportional.
a/R = (d-a)/r
and the rest is trivial algebra
Posted : Jan 14, 2017 7:45 am
epoch date, post: 409078, member: 485 wrote: Regular Autocad (I'm in 2009 correct now) generates this geometry with the tangent functions on both ends.
Does IntelliCAD not provide this functionality?
I believe this is some other small abrasive function cut out of the OEM version. AutoCAD may do it as a reminder that your non using the full version.
Posted : January 14, 2017 4:21 pm
It is sad that we have become an army of button pushers instead of thinkers. When did we stop learning how to exercise things get-go instead of expecting to get immediate answers with a few keystrokes.
This goes far beyond surveying and trigonometry. The answer to anything MUST BE easily institute on that magic wad of plastic and electronics that one tin can concord in their hand. Understanding whether or not the respond provided is reasonable has become passe.
Posted : Jan 14, 2017 6:48 pm
epoch date, post: 409078, member: 485 wrote: Regular Autocad (I'm in 2009 right now) generates this geometry with the tangent functions on both ends.
Draw larger circumvolve, then smaller circle.
Begin LINE command, and snap to TAN of larger circle, then the to point, snap to the TAN of the smaller circle.Tangent line betwixt circles is generated, that is identical to the one developed via Stephen Ward's method.
Does IntelliCAD not provide this functionality?
I run full AutoCAD, so ordinarily I just draw a line snapping tangent to both circles. My method above was just a workaround for those who aren't blessed with software that will describe information technology automatically.
Posted : January 14, 2017 half dozen:49 pm
Thanks, guys, for all your responses. There'due south more than one fashion to skin a cat!
As far as I tin can tell, IntelliCAD will non snap from a tangent, only to a tangent. It does have the "tangent line between circles" routine BK9196 mentioned.
I honey this place.
Topic starter Posted : Jan xiv, 2017 7:09 pm
Source: https://surveyorconnect.com/community/software-cad-mapping/line-tangent-to-two-circles/
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