AutoCAD 2006 for CAD Managers, Part 527 Jul, 2005 By: Robert Green
Master new dynamic blocks and convert your old block library
Clarification: Dynamic Block Attributes
In the last newsletter, I stated that attributes can be used within dynamic blocks just as within any other block. Though my statement is technically accurate, it apparently confused a few readers. Let me clarify using two scenarios as examples.
Scenario 1 (conventional block): A conventional block called “36 INCH DOOR” is created with two attributes. The first attribute is called SIZE, and it has a preset value of 36. The second attribute is called COLOR and is not preset. On inserting the block in a drawing, a user is prompted by AutoCAD to specify the color of the door, but not the size. When attributes are extracted, the size always reports as 36, while the color varies.
Scenario 2 (dynamic block): A dynamic block is constructed that can represent many sizes of doors, depending on how you scale it when you insert it in a drawing. If you assign a preset attribute called SIZE to this dynamic block, as was done in the prior scenario, the size of the door will always report as 36. So you can specify preset attributes for dynamic blocks; however, doing so may not always reflect the physical reality of the block being modeled. Clearly a dynamic block will not always have a size of 36, so you should have made the attribute variable to require that the user input a size value.
The reader feedback I received concentrated on the second scenario. Many users expect the preset attribute of a dynamic block to react to scaling rather than remain constant. However, the behavior of preset attributes -- even within dynamic blocks -- is the same as it has always been in AutoCAD. That is, if you inserted a conventional block with the differing scaling factor, a preset attribute would not scale up or down -- and the same is true for a dynamic block. So rather than having a problem, we appear to have a wish list item for the next release of AutoCAD. I’m sure Autodesk has heard this issue before, judging by the e-mail I’ve received on the topic.
New Features Workshop
At this time I highly recommend that you take the time to really dig into the New Features Workshop topics on dynamic blocks, which can be accessed from AutoCAD 2006’s Help pull-down menu. Many lessons are available for dynamic blocks (figure 1). It’s not a bad idea to look at the Overview section, but if you read my last newsletter, you already know more about dynamic blocks than the Overview session will show you.
Figure 1. The New Features Workshop in AutoCAD 2006 offers many lessons on the topic of dynamic blocks.
The New Features Workshop gives you a visual show-and-tell you can’t get from a paper- or Web-based tutorial. The subject of dynamic blocks definitely adheres to the concept that a picture is worth a thousand words. Invest an hour of your undivided attention now so you’ll have a firm footing when you start creating your own dynamic blocks. Even if you normally have the attitude of, “Me, use the manual?” you’ll be well-served to actually see how the new block-editing environment works.
Now that you’ve worked through the New Features Workshop, let me recommend a plan of attack for creating your own dynamic block libraries.
1. Tackle the easier blocks first. Simpler cases such as blocks that stretch, mirror or simply scale up and down are the best places to start. Doors and windows are good examples. Recommend: New Features Workshop topics on moving, stretching and rotating. Also look at door and window blocks provided in AutoCAD’s sample tool palettes.
2. Tackle blocks that have tabular, or family-of-parts-type, properties. This will require that you become familiar with the Lookup Table functionality so you can generate the specific cases you want for any given block. Recommend: New Features Workshop topics on lookup tables. Also review the various nuts and bolts blocks provided in AutoCAD’s sample tool palettes. They are perfect examples of many, many blocks created by using one lookup table-driven dynamic block.
1. 3. Reserve for the absolute last the complex blocks that have multiple actions, such as stretching combined with rotating arrays. 1. Recommend: Lots of practice with simpler cases before attempting these more complex cases!
4. Test your new dynamic blocks on impartial users! Recommend: Take an assortment of power and novice users and let them try using the dynamic blocks you create. Evaluate for usability and ease of insertion. Remember that dynamic blocks will require more input from the user, so be absolutely sure you’ve made your dynamic blocks easy to use before rolling out a new library.
If you follow this gradual sequence of development and testing, you should be able to build your dynamic block skill set without too much frustration.
Now Build a Library
The challenge now is to decide which blocks you want to convert to dynamic blocks within your block library. This decision will be driven largely by when your company fully converts to AutoCAD 2006 (because dynamic blocks aren’t supported by earlier AutoCAD versions). The good news is you’ll have some time to get used to the block-editing environment. In the meantime, I’m sure we’ll also start to see dynamic block libraries popping up from third-party vendors.
Do your homework so you fully understand dynamic blocks before converting your block library. Dynamic blocks are complicated enough that you need to be confident in your ability to construct and debug them before they become an integral part of your drawings.
• Ellen Finkelstein’s Web site, http://www.ellenfinkelstein.com, has some cool examples of dynamic block creation under the AutoCAD tips sections.
• Autodesk offers white papers on the subject of dynamic blocks, at http://usa.autodesk.com/adsk/servlet/item?siteID=123112&id=5543837, including a detailed tutorial you can follow at your own pace.
I hope you've enjoyed my five-part look at AutoCAD 2006. I believe this new version of AutoCAD merits investigation because of the new flexibility and control it brings to the CAD manager. I encourage you to e-mail me with your implementation experiences and any questions about dynamic blocks. Until next time.