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Distinguished Contributor
Posts: 110
Registered: ‎02-24-2009
Message 1 of 9 (628 Views)

Line not tangent

628 Views, 8 Replies
06-18-2012 06:09 AM

Working on Acad2012 3d Civil. I draw a circle of 4000' radius and another one of 2000' radius. I put a tangent line between the two circles and I do see the tangent symbol but when I zoom in real close, it's not. So now I can't trim the excess radius of the two circle. I do have a trim line pasted the two supposedly tangent points. Is this a CAD issue or is their a variable to change that actually makes the lines tangent.

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wfberry
Posts: 1,610
Registered: ‎09-05-2006
Message 2 of 9 (622 Views)

Re: Line not tangent

06-18-2012 06:37 AM in reply to: falconbird

Draw your two tangent lines, use the Fillet command with the proper radius.  No problem.

 

Bill

 

Distinguished Contributor
Posts: 110
Registered: ‎02-24-2009
Message 3 of 9 (582 Views)

Re: Line not tangent

06-19-2012 06:16 AM in reply to: wfberry

I am not sure how to implement the filter command with a line to make it tangent to the circles

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AllenJessup
Posts: 5,614
Registered: ‎05-21-2003
Message 4 of 9 (578 Views)

Re: Line not tangent

06-19-2012 06:30 AM in reply to: falconbird

Are you working at high coordinate values, like state plane? As accurate as autocad is, when you work in a large coordinate system it can lead to small errors that will prevent trimming. The usual advice to test for this is to move the entities close to zero and try the operation again.

 

Allen

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sjg
Posts: 518
Registered: ‎09-29-2010
Message 5 of 9 (576 Views)

Re: Line not tangent

06-19-2012 06:40 AM in reply to: falconbird
Whats your VIEWRES set to, I have mine set to 20000. If your zoomed in close with it set to a smaller number, it might not appear to be connected but is. You could also try to get a distance from the end of the tangent to the end of the arc. If it is zero then they are connected.
Steve Goessling
Land Consultants
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Distinguished Contributor
Posts: 110
Registered: ‎02-24-2009
Message 6 of 9 (556 Views)

Re: Line not tangent

06-19-2012 10:10 AM in reply to: AllenJessup

I think that is it. Thanks for the heads up.

Employee
Posts: 707
Registered: ‎08-25-2009
Message 7 of 9 (550 Views)

Re: Line not tangent

06-19-2012 10:39 AM in reply to: falconbird

A REGEN typicall will clear up the graphics as well if you zoom in tight and things don't look tangent or round.

 

Cheers,

 

Peter Funk

Autodesk. Inc.



Peter Funk
Autodesk, Inc.

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LeafRiders
Posts: 294
Registered: ‎09-28-2010
Message 8 of 9 (521 Views)

Re: Line not tangent

07-13-2012 09:39 AM in reply to: peterfunkautodesk

"Are you working at high coordinate values, like state plane? As accurate as autocad is, when you work in a large coordinate system it can lead to small errors that will prevent trimming. The usual advice to test for this is to move the entities close to zero and try the operation again."

 

Seriously... You don't think people work in world corridnates? Extend and Trim for a circle drawng tangent and tangent, has no extend or trim point. I've set the VIEWRES to 20000, I've moved my UCS to the site. Still no results. This is a major issue that from what I can tell, has been an issue since 2003.  What is the workaround or fix for this issue. It's haunted me for almost a decade and still nothing resolved by the wonderful minds at Autodesk.

 

... and please don't suggest I use the fillet command, really?

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AllenJessup
Posts: 5,614
Registered: ‎05-21-2003
Message 9 of 9 (514 Views)

Re: Line not tangent

07-13-2012 10:37 AM in reply to: LeafRiders

You replied to Peter but quoted me. So I'll take a stab at it. Yes. I do think people work in State Plan. Almost everything I do is in State Plane or a local system based on State Plane.

 

But State Plane coordinates aren't all tied to a similar base point. So depending where you are you may have larger coordinate values. Also metric systems are lower values than foot based systems, unless there is a much higher base point coordinate assigned.

 

I didn't suggest moving the project closer to 0,0. Just the linework that was not working out. As I said, this was to test the theory.

 

A workaround that many people say they use is to truncate the first few digits from the State Plane coordinates. That way the coordinate values are smaller. See User Project Coordinate in WORKING WITH GRID COORDINATES. Thanks to Sinc.

 

The first time I remember encountering this problem was in R12, so 1992±. Moving the linework closer to 0,0 solved the problem. Another option with basic Autocad linework is to draw closer to 0,0 or in a new file at low coordinates and them bring the linework to where it need to be. I haven't had to do any of this for quite a while. Our state moved us to metric about 10 years ago. So with smaller coordinate values I don't have a problem to often. Now we're going back to Imperial so I may have to deal with it again.

 

I don't see this a a Fault in the software. But it is a Limitation. AutoCAD was the first CAD program that could calculate as far out as it can now. Maybe it's time to look at finding a way to increase it again. But you know that will mean even more computer resources will be needed if everything is calculated out to 24 decimal places.

 

BTW. Having a UCS based at the site won't change anything. The coordinates in the drawing remain the same. Only what AutoCAD reports them as and treats input differ.

 

Allen

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