How to Get the Distance and Angle Between Two Points In Autocad

Here is another useful autocad trick that can help you obtain the distance and angle between two points in autocad :

1. Type command DIST. You can also click on menu Tools, then click on Inquiry and then click Distance.

2. When autocad prompts for the first point, click on the first point.

3. Then click on the second point and hit enter.

4. At this point, autocad command line should show you the distance and angle between the specified points.

How to Replace an Dimension Text with a New Text in Autocad

If you want to modify or replace the existing text in an autocad dimension text object with a new text then do the following steps:
1. Type command DDEDIT. You can also go to Dimension menu, then click Object, click on Text and then Edit.
2. Autocad will prompt you to select the dimension text to edit. Just select the dimension text wherein you want a text to be replaced or edited.

3. A text editor will appear. In it replace or edit the dimension text with a new one.

How to Override a Dimension Style in Autocad

In order to override a dimension style, you must first set up a dimension style overrides and then apply the dimension stye overrides you just created.

Here's how to set up the style overrides:

1. Type command DIMSTYLE. You can also go to menu Dimension and then Click on Dimension Style.

2. The Dimension Style Manager dialog will show up. Under the styles, select the dimension style for which you want to create a dialog and then click Override.

3. The dialog box Override Current Style will appear. There are several tabs in this dialog box, click on them and make the appropriate changes for your override dimension style. Then Click OK.

5. You should see the dimension style override you've just created in the dimension style name list. Click close to exit the dialog.

Now that you have created the style override in autocad, you can now apply the dimension style overrides.

To apply the dimension style overrides, do the following steps.

1. Type DIMSTYLE.

2. This shows up the Dimension Style Manager dialog. Click Override.

3. The Override Current style Dialog will appear. Here, enter the style overrides and then click OK.

How to Rotate Dimension Text In Autocad

Many times we need to rotate a dimension text in autocad. Rotating a dimenstion text in autocad is an indispensable procedure that every autocad draftsman should learn. We need to rotate a dimension text to clearly label the dimensions of our drawing objects. The following are the steps on how to rotate a dimension text in autocad.

1. Type command DIMEDIT. You can also go to the menu Dimension, click on Align and then to Angle.

2. Autocad will prompt you to select the dimension object to edit. Just select the dimension text you want to edit.

3. Finally, enter the angle for the dimension text.

Moment of Inertia Area and Perimeter using Autocad

This tutorial will teach you how to get the moment of inertia, area and perimeter of a drawing entity in autocad. Ok, well as you might already know not all kinds of drawing objects or entities can be extracted with moment of inertia, area and perimeter. What we are talking about here are closed figures such as rectangles, squares, trapezoids, circles and any irregular shapes that are closed or closed polygons to be specific. However, before can we can get the properties mentioned above these drawing objects must be first converted into regions.

To convert a drawing object into region, do the following:
1. Type "region" in the command prompt.
2. Select the drawing object and press enter. The drawing object should be an autocad region at this time.
3. However, if your drawing object has a hole inside, say a pipe which must be composed of inner and outer circles, you must convert each circle into a region and then subtract the inner circle region from the outer circle region. To do this, type "subtract" in the command prompt, press enter and select first the outer circle and then the inner circle. By this time, you should already have a pipe region. Now, there is still one more important thing that you need to do. You must verify that you have indeed created the pipe region. Point your cursor into the outer circle. If both the outer and inner circles highlight, then you have successfully created a pipe region otherwise you need to start over.
Now that you already have a region, you are now set to get its moment of inertia, area and perimeter. The magical command here is "massprop" which stands for mass properties. Here are the steps:

1. First, you need to get the centroid of the region and then use that property to set the the User Coordinate System (UCS) to zero. Type in "massprop", press enter and select the region on your autocad screen and press enter again. By this time, Autocad will show the properties Area, Centroid (x, y), Perimeter and Moment of Inertia among others in the command prompt. To get a complete view of these properties scroll down the command prompt or adjust the command prompt window. The Area and Perimeter properties are final however the moment of inertia is not.

2. To get the correct moment of inertia, you need to set the origin of the UCS into the current centroid of the region. To do this, get the value of centroid (x,y) you obtained in step 1. Type "ucs", press enter, type "m", press enter and then type in the centroid values in this format x,y ( say 12233.0230,323.9441 ) and press enter. The origin of the UCS should now be at the centroid of your region. Type "massprop", press enter, select the region and press enter again. Autocad command prompt should now show the correct moment of inertia. As a check, if you have done everything right the centroid values you obtain this time must be 0.00,0.00 otherwise you made a mistake in entering the centroid values from step 1 into step 2. If this happens, just start over from step 2.

Autocad Custom Commands and Autocad Plugins

Just like any software plugin, an autocad plugin is a computer program that extends the capability of the autocad software. In windows softwares, plugins are computer programs that have an extension '.dll' which stands for dynamic link libraries. In autocad, autocad plugins have extension '.arx' which stands for Autocad Runtime Extension.

Actually, '.arx' programs are also dynamic link libraries. In fact when these programs are compiled from C++ programming language, the compiler outputs a default file with '.dll' file extension. Autocad plugin programmers are encouraged to replace the extension with '.arx' to distinguish the program as an autocad runtime extension. These autocad plugins are also called ObjectArx programs.

There are actually other types of computer programs that can extend autocad capability aside from ObjectArx programs. These are the LISP and VB programs. However, these programs don't have as much power as the ObjectArx programs. In fact, these programs are not called plugins but simply autocad automation scripts. Though they can also be compiled into
binary files, their script form is more than enough to serve its purpose. ObjectArx applications are strictly in binary file because they must be written in C++ language and therefore must be compiled into binary files.

Autocad plugin programmers use the Microsoft Visual C++ IDE to write and complile their plugins. They also have an above-average level of mastery of the C++ language. Most importantly, they master the ObjectArx API (application programming interface) which contains the classes and functions needed to control autocad and add more powerful functionality to it.

So what are the capabilities that an autocad plugin add to an existing autocad software? Well, it simply adds custom commands to your favorite autocad command list. How long does it take you draw a grid of horizontal and vertical lines





that vary in spacing? Using the primitive command, you will draw a line, type offset command, enter distance, offset, enter distance, offset...you do this long, boring and tiresome routine over and over. With an autocad plugin, you just type the custom command (say 'cells' for the superdraftsman_commands.arx found in this blog/website) of an autocad plugin and enter the different dimensions and you are done!. The grid lines with varying spacing are on the screen just like magic! Do you want to draw a window elevations? Just type custom command 'window' of an autocad plugin, enter the required dimensions and voila your window elevation appears right there on the center of your computer screen! The amount of time and effort save is so big that instead of spending time on drafting, you will now spend more time on your design!

Developing autocad plugins is not only limited architectural or drafting applications, structural autocad plugins can also be developed for the use of structural engineers or architects who want to check their drawings for structural integrity. As you might already observed in the superdraftsman autocad plugin (see my previous posts to know more about this plugin ) that I have developed, most of the custom commands added on it are intended to automate drawing tasks such as pipe, grids/cells, windows, sections etc. These custom commands simply draw objects on your autocad program fast but they don't help you determine if these objects, which represent real structural sections or members, can withstand a specified load.

In order to take the development of autocad plugins to the next level, I am planning to add structural custom commands to the superdraftsman making it an official structural autocad plugin. The following are the structural custom commands I plan to include:

1. comstren . One of the structural custom commands will let you calculate the strength of given section or structural member. After a section is drawn using the previously developed custom commands of the said plugin, a new structural custom command "comstren", short for compressive strength, will be entered into the autocad command line. The program will then ask for the kind of material to be used: steel, concrete or aluminum. Since this command calculates the axial compressive strength of a structural member, it asks for the unbraced member length. After this dimension is provided by the user, the autocad plugin calculates the axial compressive strength using the appropriate design codes (see below).

2.tenstren. This is short for tensile strength. This structural autocad custom command will calculate the tensile stength of a section drawn using the superdraftsman autocad plugin. When a section is already created, you will simply type the command "tenstren" , you will be prompted to pick the section and enter the type of material. Then, the plugin will calculate the tensile strength of the section. Note that this time, the plugin will not ask for the length of the member since tensile strength is independent of this parameter.

3.benstren. This is short for bending strength. This autocad custom command will calculate the bending strength of a structural member using a given section. Assuming that the section is already drawn on the autocad window, you type the command "benstren", enter the laterally unbraced length, enter the uniform load throughout the member length and select the section to be used. Then, the plugin will calculate the bending strength using the applicable design code below.

AISC(American Institute for Steel Construction) 2005 for Steel
ADM(Aluminum Design Manual) for aluminum
ACI (American Concrete Institute)

That's all for now. But I am planning more structural custom autocad commands to be added in the plugin.