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Is that all there is....


Bill Tillman

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Okay, at the risk of offending certain people and at the risk of finding out that I'm just doing something wrong I'm going to make this bold statement. Having watched AutoCAD users from the sideline for many years now I finally ventured in myself. Especially into the 3D drawing arena. And like I found out at the age of 15 when this very wordly woman of 19 popped my cherry I'm kind of left feeling, "is that all there is".

 

For years now I have heard of the 15 decimal place accuracy of AutoCAD...

 

Well I have drawn up a set of residential stairs for a customer in order to build him a glass and aluminum handrail system. I am trying to fillet or connect lines which I swear are in the same plane. I look at the properties of each line and the Beginning and Ending X values are exactly the same for each line to the 1/16". Still when I try to fillet them or extend or trim, AutoCAD 2009 says they are not coplanar. I fiddle around with the UCS and sometimes that solves the problem...sometimes it doesn't.

 

So I ask, is that all there is. That I can expect AutoCAD to only be just a little bit short of very accurate or am I doing something wrong?

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Yep, I think you did something wrong otherwise you wouldn't be getting the error message. Try again is all I can say. Unless of course you care to post a subsection of the drawing here for forum members to have a look at. Sometimes it is the obvious we have the most trouble seeing. No offense meant. Just an observation from a one-eye-blind CAD user.:wink:

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The reason AutoCAD is likely saying the objects are not coplanar is that...well...they're not coplanar. If your drawing units are to the 1/16" the lines are probably off by a little less than that. Change your drawing units to decimal and take the decimal places out to 8 or so. Highlight both lines and look at the properties, specifically the starting and ending coordinates.

 

If the lines are coplanar along the z-plane the properties should look similar to this:

 

Start X | *VARIES*

Start Y | *VARIES*

Start Z | 0.00000000

End X | *VARIES*

End Y | *VARIES*

End Z | 0.00000000

 

If they all say *VARIES* your lines are not coplanar, overwrite the fields which should match with the proper values. I would also recommend you not work in fractional or architectural units if you're working in three dimensions, decimal inches are the way to go. If you have trouble remembering your fraction/decimal conversions, print out a chart like this one (http://www.alpiindustrial.com/images/inch-fraction-to-decimal-conversion-chart.gif)

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Just had another idea on this. If the lines are on a bias in the octants of the world UCS, editing start and end points may not work, but, if the are connecting at a 90 degree angle you can use the UCS command in 3pt mode to draw a new UCS. Select the intersection of the lines as the new origin and then select the endpoints of each as your x and y axes. Then choose perpendicular for the z value. The lines should now fall along the XY plane and should fillet with no problem. If these don't take care of it you could post the drawing and I'll take a look. I love rooting out the cause of strange little oddities like these. Chicks dig guys who do 3d linework in AutoCAD.

 

***Disclaimer: Chicks do not dig guys who do 3d linework in AutoCAD. If you know of any who do...please have them contact me immediately so I can verify this aberration***

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Thanks everyone for the great pointers. I admit there must be something wrong in my method, but again, ACAD says the lines are coplanar by the properties. The Beginning X and the Ending X values are the same, the Y values differ and the Z values are all 0. But I did draw this using Architectural units....duh, I'm doing an architectural drawing.

 

So this morning I'm starting the layout again from scratch and will be using decimal units. I'll post back if that resolved the problem.

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Wait a second...if the only values which are different are the y values then your lines aren't just coplanar...they're parallel. And that means by definition they will never intersect, so extend won't do anything for them. Fillet works for me on parallel lines but only gives a curve with a radius half the distance between the lines, the only solution in that situation. Can you expand a bit more on what you are trying to do specifically? Or can you select those two lines and wblock them into a sample file to post here?

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