Trimming

If anyone knows how to do triming I would love to know. I have read the book a few times and it doesn't make any sense

You mean trimming? That's easy. Start the trim command, then pick a line or circle that you want to be a boundary. You can have more than one or simply hit enter to select everything in the drawing. Then pick the objects you want to trim, but pick them on the side you want to cut off. See pictures below:

By selecting the circle as the boundry, pick inside the circle and it trims whats inside away. Pick outside the circle it trims that. Nothing to it.

(And no, I don't have 2 cursors on the screen, I faked that with a rectangle.)

What book did you read?

Look, all you should need is the AutoCAD Help file... Here's the Trim Command Reference.

Hope this helps!

Hello Renderman,

Yes that is the same thing I have in the Autocad 2011 book . You have to know you are dealing with an idiot here. I have been trying for a while and it doesn't work for me.

I have a large circle just touching two smaller circles and all I want to leave is the radius between the two small circle. I guess I should use an ARC. but I can't use an arc either.

No need for self-deprecating humor at this time... we'll get to that later, and I'll lead the way!

Now that you've provided more information, I can tell you that sometimes AutoCAD has a hard time trimming tangent arcs / circles. I sometimes need to draw a line from the center of one to the center of the other then use the resultant line / polyline to trim.

HTH

make sure everything is on the same plane and intersects one another, trimming a circle requires 2 trim boundries, so check that as well, if that isnt an option you might investigate the break command instead.

Sometimes if you've drawn your circles using the tangent osnap, they don't always quite touch. Autocad will display a decimal dimension to 8 decimal places but actually computes it to 16 places if I remember correctly. If they miss touching or intersecting each other by somewhere in that minute amount, the circles won't trim each other. If you're working in 3 or 4 decimal places, the rounding error could throw it off that much. The diagram below shows a way to make sure they touch. I've moved the circles far enough apart to make it easy to see. If you move the circles along the line as described, the intersections will overlap and allow the circles to trim. Just be sure to move the third circle towards the first two or you'll only separate the first two again and be back where you started.

Attach your file here? There could be something wrong with the geometry (like the lines not actually touching the circle).

Are are taking a class to learn this professional program, correct?

Where is the instructor?

If you email it sounds like you are doing kinda what is shown in the picture above? here are the commands i used to trim the circles

Just select your large circle and type trim in the command line, then touch the part of the smaller circles that are in the larger circle. if that doesnt work, sometime when autocad is acting funny i create a new drawing and copy everything into that drawing and it fixes it.

Thanks everyone!!

With your help I managed to trim the larger circle.

I need someone to explain layering . Many of the drawings I am making call for dotted or broken lines and I have read the book (Autocad 2011) on layering and feel I know less than I did before.

Thanks, The instructor has a lot of students that are now way ahead of me. I am just auditing the course so I don't have pressure to keep up. I won't even audit a summer course again, way too much material in too little time!

Thanks Jack.

My problem was having the two smaller circles and bringing the larger circle to touch the two smaller ones and then trim the same way you show in your drawing. I managed to get it once and with luck I will be able to do it again. Now I am trying to learn layering. very confusing. a lot of the drawings need broken lines and I just can't do it yet.

Up at the left top of the page under the CADTutor logo is a tab called Tutorials. Click on that and it will take you to a wealth of information about using AutoCAD and several other programs as well. If you work through a few of those, you'll be in a much better position to understand some of this, and the great part is, since many of them are videos, you can replay them as many times as you need to! And if there's something you still don't get, you don't have to go very far to ask a question!

Layering is a whole new question, and usually a new question equals a new thread. Very briefly though (some here will tell you that I don't know how to be brief LOL) layers can be used for many things. Basically its a way to separate various parts of your drawing so that you don't have to see or work on it all at once. There are many theories on how it should be done, but like everything else if you ask 100 people you'll get 150 answers. In architectural drawings, you could have a foundation layer, an electrical layer, one for plumbing, furniture, exterior walls, interior walls, hvac, etc. Many of the places I've worked that did mechanical drawing would have layers based on the different linetypes. They had a hidden layer, where anything using hidden lines lived, another for phantom lines, center lines, object lines and so on. Both usually had a dimension layer and one for text. By doing this, you can turn off the things you don't need to see and prevent accidental editing. (hmmm...the folks I mentioned earlier may be right!)

Here is a good link for Layers: http://www.autocadcentral.com/Tutorials/Lesson%207/lesson7.htm

just select a trim command tool or use trim command trim(); in command area at bottom of the AUTO-CAD and then select the broken line to trim area..

My problem was having the two smaller circles and bringing the larger circle to touch the two smaller ones and then trim the same way you show in your drawing. I managed to get it once and with luck I will be able to do it again.

This is not something you should try to do manually (read by eye), you're working with an incredibly powerful tool which can do all of the hard calculations for you. If you have two circles, and you want to draw a larger one which is tangent to both of the smaller ones with a specific radius, try this:

(defun c:CRR  ( / *error* oldCmdecho)
 (princ "\rCIRCLE: TANG->TANG->RADIUS ")

 (defun *error*  (msg)
   (and oldCmdecho (setvar 'cmdecho oldCmdecho))
   (cond ((not msg))                                                   ; Normal exit
         ((member msg '("Function cancelled" "quit / exit abort")))    ; <esc> or (quit)
         ((princ (strcat "\n** Error: " msg " ** "))))                 ; Fatal error, display it
   (princ))

 (and (setq oldCmdecho (getvar 'cmdecho)) (setvar 'cmdecho 0))
 (command "._circle" "ttr" pause pause pause)
 (setvar 'cmdecho oldCmdecho)
 (princ))

:wink:

Now I am trying to learn layering. very confusing. a lot of the drawings need broken lines and I just can't do it yet.

Jack's given you a good description of layering here... but if/when you start a new thread for this question, be sure to include information like what industry you work in, etc. (it can make a difference).

Can anyone help me chamfer a drawing I am working on.

Have you tried pressing the F1 key?

Have you read the prompts at the command line?

Command: [b]CHAMFER[/b]

(TRIM mode) Current chamfer Dist1 = 0'-0", Dist2 = 0'-0"
[b]Select first line[/b] or [undo/Polyline/Distance/Angle/Trim/mEthod/Multiple]:
[b]Select second line[/b] or shift-select to apply corner: