Creating Symbols (From the Trenches AutoCAD Tutorial)

Make symbols that withstand multiple use.

When I first came to work at Frankfurt Short & Bruza, we used Autodesk Building Systems and Architectural Desktop 2004 in conjunction with Project Navigator to coordinate drawings with the other disciplines. We now use Architectural Desktop and Autodesk Building Systems 2006, and we plan to jump to 2007 versions and possibly Revit.

We started to have problems: symbols were disappearing when drawings were bound and exported. I was selected as the CAD tech representative to figure out a solution to the problem. The following fix works for Exporting from Autodesk Building Systems. This process is strictly for the Export feature, and users will have problems if they perform too much clean up on a drawing by using Aecobjexplode or other commands. This type of cleanup could compromise the drawing before export. These smart devices can also be exploded one time to just a block reference, which makes things easier as well. Note also that these blocks are intended for export into 2004 format.

Rules of the Road
Before we get started, here are some rules of the road:

1. Don't use a block to create a block. Make sure to start with objects and line segments. Using a block to create another block is bad because when you go to bind this block, it will be turned into a little dot or may not even be able to be bound.
2. Don't use hatch patterns inside of these blocks; they will not bind. Use solids and lines!
3. Use layer zero to create blocks. Later, we'll review using layer keys to assign to devices.
4. Make sure 0, 0 is at the insertion point wanted to use to insert the block into drawings. I will explain the process of making symbols to use on a tool palette.

Step-by-Step

First, create a symbol using linework.

Now make sure that 0,0 is at the point of where the symbol will be inserted. This point will be the same point used to place and rotate the symbol.

After creating the symbol and locating 0,0, you can create the block.

Select the linework and then go to Format / Blocks / Block Definitions on the pull-down menus.

The next part of this process is to name the created block. Start the name using (somting reconizable_).

After creating the block, go back to the pull-down menu Format / Style Manager. Select Electrical Objects / Device Styles. Right-click on Device Styles and select New.

The name used in this column will be the name that appears on the pallet.

Now select the Design Rules tab. On this tab, set the Type of device and the Layer Key. On the Wire Clean up radio buttons, select Trace Geometry.

Most 2D blocks only need Three Views and only one block. This is a single-pole switch.

Notice the important parts: View Name, View Block (the block created for this view), Display Representation, View Direction and Scaling. It's important to make sure these are set up correctly.

To add a view, just click the Add button on the side of the View Name box.

It names this view, "New View." You can select a representation of the block in the Display Representation box.

#1 Model. In this view, you can locate 3D blocks. Notice the Display Representation, View Directions and the Scaling box.

#2 Plan. In this view, locate 2D or Plan, Top View blocks. Please note the Display Representation, View Directions and the Scaling box. In the Scaling box in the Plain View, it's important to check the box Use Annotation Scale. This setting is needed only for devices, don't turn it on for lighting devices.

#3 Reflected. Use the same block as used in Plan. The steps for this process should mach the Plain view details. This view is mainly for other disciplines to use the Reflected View Port settings.

You should make an additional View for text objects apart from the original block. In the case of the dimmer switch or any other block that has text outside of the original block, don't change the 0, 0!

The text must be made into a block using the 0, 0 point of the block for which the text is meant to be used. Notice the 0, 0 point for this text is located on the insertion point of the original block.

If the original block has any text or if the text needs to always stay upright, you can keep the text horizontal by selecting Keep Text Horizontal. In this example, when I select Keep Text Horizontal, the text in this block for the text "S" that is related to this block keeps it's rotation as the Block is rotated.

Finally, save the symbols you created back to the file-source drawing that the tool palette reads from.

NOTES FROM CADALYST TIP PATROL:Cadalyst had its intrepid Patrollers review this month's "From the Trenches." Our Patroller agrees that this is a valuable solution and has a few additional comments about the author's block rules that were set out at the beginning of the story.

In regards to not using a block to create a block, the Patroller says, "Unfortunately, I've seen innumerable blocks within blocks coming from architectural firms for the past five to ten years. When I receive DWG files I like to clean them up."

He also agrees that you should use layer zero "as it makes the blocks take on the color of the layer they are placed on. When a building changes from 'proposed' to 'as-built' status, it can go through a change in layer color so that they can appear to exist by making use of the screening attribute within the setup of a CTB file's colors. CTB files are what I normally find being used, in the CE firms I've been employed by.

And finally, our Patroller agrees that there should not be an insertion point offset when you place the blocks within your DWG file. He shares, "And I normally take the time to align the CE Block so if it is going to be used in conjunction with a street's curb or centerline, I then rotate it so that it 'faces' a Zero Rotation angle. In this way I can then spend less time rotating it to match it perpendicularly to the street's centerline or curb. See image below. Also note that I revise the color of my backgrounds so that I don't lose the double and triple digit AutoCAD colors ending with 6 through 9."