Trouble Trimming

[Steve_B]

Hi all I am having some trouble trimming a line using a circle as my cutting edge,the line falls short of the circle,I have tried changing EDGEMODE and still the problem persists!

[danellis]

It's *probably* a display thing, rather than an itnot working thing.

 

Try a regen to see if that improves it (display of circles in AutoCAD can be funny sometimes!)

 

dJE

[Steve_B]

It's *probably* a display thing, rather than an itnot working thing.

 

Try a regen to see if that improves it (display of circles in AutoCAD can be funny sometimes!)

 

dJE

 

Yes,it seems to pretrude by about a mill,but once regenerated it looks fine,Thanks.

[ReMark]

Do both pieces of geometry have a Z value of "0"?

[tonyj]

Do both pieces of geometry have a Z value of "0"?

 

What difference would it mean if they had different Z values?

[Dana W]

What difference would it mean if they had different Z values?

In the case of a drawing created with AutoCad LT, there probably is no chance of having a 'Z' value any different than zero since it cannot draw 3D. 'Z' is height, the third dimension.

 

If the "Z" value of the point on the line that appears to intersect the circle is different than any point on the circle, then the line and circle do not intersect. Objects must intersect (touch) in order to execute the trim command. In the case of the Extend command, there must be a point on the circle that will be intersected by the line once it is extended. The two objects don't have to be on the same plane to execute extend, but the line has to be pointed directly at some point along the circle or nothing will happen.

[ReMark]

"In the case of a drawing created with AutoCad LT, there probably is no chance of having a 'Z' value any different than zero since it cannot draw 3D. 'Z' is height, the third dimension."

Sorry but I disagree with this statement.

 

There have been a number of people who were using AutoCAD LT and had a drawing where some of the geometry had different "Z" values. If you don't believe me then do a search on the word "flatten" for starters. The usual answer to the problem involves a macro to give all objects a "Z" of "0". The macro has been posted here numerous times. Now, for how they accomplish this feat I can't say. Perhaps a few of them found and used the Change command with the Elevation option.

Edited March 22, 2013 by ReMark

[ReMark]

Here are two versions of the macro I was referring to. Why use a macro? Because AutoCAD LT does not support lisp and therefore the user does not have access to the Express Tools FLATTEN command.

 

[FlattenSel]^C^C_UCS;;_select \_move _p;;0,0,1e99;;_move _p;;0,0,-1e99;;

 

[FlattenAll]^C^C_UCS;;_move _all;;0,0,1e99;;_move _all;;0,0,-1e99;;_chprop;_all;;_thickness;0;;

 

[tonyj]

Hi Dana W. Actually I use autocad 2011 full version at work and autocad 2012LT at home. Anyway the point is, you can set your elevation to any value that you like in autocad LT and draw and place objects to these values.

Hi Remark, My question to you was 'what difference would it mean if they had different z values?' (and lets assume we are using autocad full version). You didn't answer this question.

[ReMark]

The difference in the Z value would mean that upon viewing from certain angles the geometry would either appear to extend too far or not far enough. It wouldn't necessarily mean the line was not the correct length.

[tonyj]

The difference in the Z value would mean that upon viewing from certain angles the geometry would either appear to extend too far or not far enough. It wouldn't necessarily mean the line was not the correct length.

 

Ah, now I see what you mean. I thought initially that you were implying that if the two objects had different z values, you would not be able to trim or extend them. Thanks for clearing that up.

[ReMark]

To be clear, I was not implying that at all. So we're in agreement.

[tonyj]

To be clear, I was not implying that at all. So we're in agreement.

Absolutely.

[welldriller]

tonyj: I noticed that no one has asked but could you possibly up-load the drawing to show what you are trying to do ?

My Autocad program is so old that I can not view a link to newer releases

[tonyj]

tonyj: I noticed that no one has asked but could you possibly up-load the drawing to show what you are trying to do ?

My Autocad program is so old that I can not view a link to newer releases

 

Welldriller,

It was actually Steve_B that started the thread. It seems like he must have got it sorted out.

[Dana W]

"In the case of a drawing created with AutoCad LT, there probably is no chance of having a 'Z' value any different than zero since it cannot draw 3D. 'Z' is height, the third dimension."

Sorry but I disagree with this statement.

 

There have been a number of people who were using AutoCAD LT and had a drawing where some of the geometry had different "Z" values. If you don't believe me then do a search on the word "flatten" for starters. The usual answer to the problem involves a macro to give all objects a "Z" of "0". The macro has been posted here numerous times. Now, for how they accomplish this feat I can't say. Perhaps a few of them found and used the Change command with the Elevation option.

Well, I probably was a little too adament with my statement. I suppose what I meant was "...creating a drawing in LT and sticking with normal practices, the "Z" will remain zero until brute force is used."

 

Oh, I believe you. The 10 or 12 times I have seen it, the drawings were created in full AutoCad, but drawn supposedly on the x/y plane. Now one can get stuff up off of zero "Z" in LT but one has to really work at it. The "Z" value can be changed in the properties sheet, and one can play in the 3D views options and put a world of hurt on the UCS.

[ReMark]

I think that the times we have seen this problem, as posted by LT users, is that they get carried away with manipulating the UCS and next thing you know their drawing is like a galaxy gone bad with bits and pieces of geometry scattered everywhere. It usuall boils down to OIE - Operator Induced Error. LoL

[Dana W]

I think that the times we have seen this problem, as posted by LT users, is that they get carried away with manipulating the UCS and next thing you know their drawing is like a galaxy gone bad with bits and pieces of geometry scattered everywhere. It usuall boils down to OIE - Operator Induced Error. LoL

Yup, and everything looks just peachy in LT modelspace until you go to pickpoint hatch a section view of a concrete window sill and AutoCad goes off for a while trying to fill the entire universe with ANS131 scaled at 2.

[welldriller]

tonyj Not sure what you are trying to do but this was done using the circle, line & trim command ???

 

trim a circle.dwg

[ReMark]

welldriller: I do believe tony solved his problem.