TIPniques: First Look at AutoCAD 2010

November 27th, 2010

It's that time of year again when Autodesk starts to unleash its latest versions of AutoCAD and other products. Being right on top of things, AUGI Hotnews "TIPniques" will begin a series on the new features and enhancements in AutoCAD 2010.

Overview
Of the many new features in AutoCAD 2010, the three that Autodesk is strongly promoting are Freeform Modeling, Parametrics, and PDF Support. That being said, there are so many more enhancements and additions that even without the aforementioned new features, AutoCAD 2010 would still have much to offer. Here is a partial list of some enhanced features:

* User Interface
* Application Menu
* Ribbon
* Quick Access Toolbar
* Parametric Drawing
* Measure Tools
* ' Spline/Pline Tools
* External References
* PDF Support
* Drawing File Format
* 3D Printing
* Autodesk Seek
* Free-Form Design
* CUIx Files
* Action Macros, and more

Again, this is only a partial listing of the new enhancements available in AutoCAD 2010. I want to start with the one of two most significant updates: Free-Form Modeling and Parametrics. It will take some time to cover these two in detail. I will begin by reviewing Parametric Constraints. Next month, Melanie Perry will cover several of the other enhancements in AutoCAD 2010.

Parametrics
AutoCAD 2010 offers something for both worlds—2D and 3D. The free-form modeling feature is a 3D modeling enhancement while the new Parametrics features are used in 2D design. Parametrics are nothing new to CAD software or to Autodesk. They are, however, new to AutoCAD, making it an even more powerful design tool. Parametrics allow the designer to constrain drawing elements based on their intent and design purposes. There are two types of Parametrics, Geometric and Dimensional, and both can be found in their own panels on the Parametric Tab in the ribbon.

 

Figure 1: The Parametrics Tab in the Ribbon. It can be found in the 2D Drafting and Annotation workspace.

Geometric constraints
The Parametric Constraints help to ensure design objects remain dimensionally and geometrically intact as the design changes. Geometric Constraints prevent design relationships from being altered geometrically. This is accomplished by applying one of several different types of constraints. Some of the constraints possible are: Coincident, Parallel, Tangent, Collinear, Perpendicular, Smooth, Concentric, Horizontal, Symmetrical, Fixed, Vertical, and Equal. These choices will make sure your drawing objects act the way you want them to, no matter what.

Dimensional constraints
Dimensional Constraints ensure that objects are set to specific values. For example, if you want a line to be 50 units long, then constrain it dimensionally to 50 units. If you rotate or move that line, it will remain 50 units long unless you edit the constraint. Similar to the geometric constraints, there are several dimensional constraints to choose from. They are Linear, Aligned, Horizontal, Vertical, Angular, Radial, and Diameter. With these constraints, you can make sure an arc has a set radius and that its center point is a specific distance from wherever you need it to be.

There are some values that you can't constrain such as Arc Length, but that is what AutoCAD 2011 is for, right? Dimensional Constraints have two forms, Dynamic and Annotational. While both constrain measurements, they serve different purposes. The annotational versions look just like dimension objects and are managed the same way. Dimension styles are applied to them, too. They have all the same properties as Dynamic Constraints, but can be displayed for plotting as if they were dimensions.

Dynamic Dimensional Constraints are not meant to be plotted or annotation. They are there to manage the measurements of objects. Their display settings are not managed by dimensional styles, but by their own set of variables.

 

Figure 2: Dimensional Constraints applied to linework. Note the Parametrics Manager on the left.

User-defined parameters
A sort of third type of Constraint, the User-Defined Parameter, allows you to create formula or value for a variable to be applied to other dimensional constraints. This is done through the Parametrics Manager. Click the Creates A New User Parameter button on the top left of the manager. Give it a name, expression, and value. For example, the name could be X, the expression d1-1, and the value would be calculated accordingly. In this case, if you alter the value for d1, then the value for X would update. In Figure 2 above, d1 equals 24, so X would equal 23. Now you can make D2’s expression X and it would equal 23. If you don't want to use X, then in D2’s expression, type in D1-1, etc. This is but one application of User-Defined Parameters and Dimensional Parameters.

Using constraints
Constraints can be applied in countless ways. Combinations of dimensional and geometric constraints can be very powerful. Constraints can be used to make certain specific values and relationships are held and can also be used to demonstrate different design values. You apply dimensional constraints just as you would dimension objects. Geometric constraints can be applied one at a time or you can use the Autoconstrain command to constrain your objects. There are settings where you can adjust what constraints are applied and in their order of importance.

 

Figure 3: Constrained Dimensionally and Geometrically. Note the constraint icons.

When selecting an object (as in Figure 3 above) it will be highlighted as usual, but any constraint icon that applies will also be highlighted. Also (as seen in Figure 3) any associated constraint icon will be highlighted, showing you which objects are parametrically connected. The two circles shown are constrained so that whatever value is given to RAD2, both circles will have a radius of that value. When RAD2 is changed, both circles will update because the circle on the right is dimensionally constrained by RAD2 and they are both geometrically constrained to be equal. The arcs at the ends of this bracket are also set to be equal, so if we change the radius of one, both will update and be equal.

From time to time you will find that you are trying to constrain a drawing that cannot be constrained in that way. You will receive an error message similar to that found in Figure 4.

 

Figure 4: This error window is displayed when trying to constrain objects that cannot be constrained any further.

When you receive this message, you have several options: make the dimensional constraint a dimensions, try again, or cancel. This message might appear because it will conflict with other constraints or it will over-constrain the objects and they cannot work properly. Keep in mind that when you constrain a drawing, there has to be a dimension where the geometry can change. If every possible dimension is locked in, the drawing cannot be edited and other constraints cannot adjust as needed. There has to be room to grow, in other words. There are many examples I could show to demonstrate this, but you will find what can and cannot be done as you use the product.

Constraints in dynamic blocks
Dynamic blocks have been around for a while now and many of us use them every day. They have been enhanced to take advantage of constraints in many ways. Remember Look Ups? Well parametrics can make these so much easier to apply. Get your linework done and add constraints, both geometric and dimensional. The dim constraints can be used for lookup variables or use the new BTable. It is a command that creates a table based on the variables you choose. You can then enter the wanted values for those in a spreadsheet-like table. And, if you have a spreadsheet with data in it already, just select the fields, copy, and paste them into your new block table and you are finished! Very fast.

Parameter manager
I mentioned the Parameter Manager earlier, but I want to elaborate. The Parameter Manager allows you to manage the dimensional parameters and user-defined parameters. If you select a parameter in the manager, the constraint in your drawing will be highlighted. This makes managing them easier. You can open the manager by selecting the Parameters Manager, or type PARAMETERS on the command line.

Eventually there will be several parameters within the manager. This makes managing them difficult. A good practice is to give each constraint a descriptive name. The names cannot have spaces in them. If a group of dimensional constraints relate to each other, then give them similar names. For example, brktop (for the dimension for the top of a bracket), brkbot (bracket bottom), brkleft (left side of the bracket), and so on. The parameters are sorted alphabetically, in ascending or descending order. Use your Layer Manager experience for this.

 

Figure 5: The Parameter Manager

Conclusion
There are many new additions and enhancements in AutoCAD 2010. AUGI Hotnews will spend the next few issues reviewing them and exploring them in depth. AutoCAD 2010 isn't due to be released until March of this year, but it isn't too late to start reviewing what the product has to offer. Parametric Constraints is one of the major set of features new in AutoCAD 2010. They will aid designers in maintaining dimensional and geometric relationships and design intent.

 

Brian C. Benton is a CAD technician and designer located in Fort Myers, Florida. Brian has been working with AutoCAD since release 10 in the mechanical, structural, and civil engineering fields. He has been a detailer, drafter, designer, IT assistant, CAD software manager, protector of standards, and proverbial "Help Desk." Brian is currently one of Cadalyst magazine's "Tip Patrollers." He can be reached at bbenton@cad-a-blog.com. His blog can be found at: http://CAD-a-Blog.com
 

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