General Software

27 May, 2009 By: Bill Fane

### The times, they are a-changin' — and when it comes to new 2D parametric drawing, change can be very, very good.

Your boss comes out of a meeting with an important new client. As the two pass your desk, your boss hands you a marked-up printout showing seven changes to the client’s design that must be implemented before they get back from lunch.

 The boss wants a few changes to a client’s design.
Before the two can finish putting on their coats, the printer spits out a revised drawing.

Your boss looks at the printout and says, "How would you like to join us for lunch?" -- making a mental note that you had even picked up on the revisions to the R2.000 and 4.500 dimensions that were necessary to match the revised diameter.

 Roughly 10 seconds later, you are finished with the changes.
Are you a magician or a time traveler? No, but you are smart enough to have updated to AutoCAD 2010. AutoCAD now includes 2D parametric drawing functionality so anatomically correct changes are made to the drawing pretty much as quickly as you can enter new dimension values.

In case you are unfamiliar with the terminology, let's start with a couple of explanations.

Parametrics involves two basic functionalities: geometric and dimensional constraints.

Geometric constraints. Geometric constraints effectively are sticky object snaps. Assume that you are drawing a line in standard AutoCAD, then object snap it to be tangent to an existing circle. The line only knows about the circle for the brief instant that it takes for AutoCAD to calculate the tangency point, and the circle never knows the line exists. On the other hand, if we apply a geometric constraint to the two objects, they both remember that the other object exists and that they must always remain tangential to each other. If you move the circle, the line will also move to remain tangent.

The twelve available geometric constraints include fun ones such as collinear, parallel, symmetrical, and equal. The equal constraint can be applied to line lengths or to circle or arc radii. Horizontal and vertical constraints can apply to points as well as lines, so the center of a circle will always be located vertically (same y coordinate) as the center of an arc or the end of a line.

Dimensional constraints. Dimensional constraints are the opposite of AutoCAD's associative dimensions. In regular AutoCAD, if you change the length of a line, the dimension will update to reflect the new size. On the other hand, if you change the value of a parametric dimension, the line will change length. Meanwhile, all the geometric constraints remain active so that changing a single width dimension will update all drawing views that appear or are related to the revised object. The changes reflected in the first two figures above took less that 10 seconds to complete, and most of that time was spent typing in the new values.

Believe it or not, there’s more, and it’s even better. A dimension isn't limited to containing a specific value but can contain a formula that links it to one or more parameters. The formulas can include a full range of mathematical operators such as logarithms, exponents, and trigonometric functions, so drawings can include intelligence and design intent. A single drawing can represent a full range of model variations. Simply enter a model number, and things such as wall thickness, shaft, and bearing diameters will update. My favorite mathematical operator for design work is the random number generator.

The first drawing above was created without using a single temporary construction line, turning line, or object-tracking snap point. I simply sketched the basic shapes quickly, then used collinear and equal length constraints to align and link the objects between views. The left edge of the front view always is collinear with the left edge of the top view, and the depth of the top view is always equal to the width of the side view, and so on. To further simplify things, you can elect to just select a set of objects and AutoCAD 2010 will automatically apply the most logical constraints.

Similarly, I didn't use any form of precise or direct distance entry while creating the objects. I just applied dimensional constraints, then added my precise values later.

I have observed that most design projects start out as a quick sketch on a coffee shop napkin -- which I call napkin-aided design (NAD). The new parametric functionality now lets us recreate this directly in AutoCAD. Simply do a quick sketch first, constrain and dimension it, then play with the dimension values. That first drawing took about 15 minutes to create.

In the design process, the most constant thing is change. Show me a designer who claims that nothing changed from the first sketch through to production, and I'll show you a liar or a fool. With parametrics, we can play what-if scenarios all through the design process.

Making a Mesh of Things
Over the years, the CAD industry generally had morphed through a variety of processes for representing 3D objects, and AutoCAD has included pretty much all of them. This evolution started from simple elevation-and-thickness specifications on standard line, circle, and arc objects through a variety of 3D faces and all the way to true 3D solid models.

AutoCAD 2010 adds new 3D surface functionality. At first it seems to be a retrograde step; why model a balloon when you are designing a bowling ball? The answer comes in the freeform design tools that Autodesk gives users to edit the surface models. This functionality is particularly applicable to the styling of consumer products such as cell phone cases, computer game controllers, hair dryers, and so on.

Instead of boring you with a detailed description of the capabilities, I'll simply wow you with a sequence of illustrations that just begin to hint at the power that lies within AutoCAD 2010's new 3D mesh functionality. The figure captions alone are sufficient explanation.

 Use grip-edit faces, edges, and vertices to drag the box into a new shape. …

 Add smoothing to refine the shape …

 … and add even more smoothing. …

 … and it’s as smooth as it gets.

 Perform more grip editing on the smooth mesh …

 … and turn the 3D mesh into a regular AutoCAD 3D solid.

 Finally, perform normal Boolean operations on the resulting solid.

We sure came a long way from a simple box, didn't we?

In the Beginning
Now that I have covered the headline-grabbing new features of AutoCAD 2010, let's look at many of the other new or revised tools in this version.

The first thing you notice when starting AutoCAD 2010 for the first time is the new Initial Setup dialog box.

 The new Initial Setup dialog box in AutoCAD 2010.

This dialog box is the first of three pages used to select any one of seven different industry groups, to optionally add one or more additional workspace tools, and to set your default template file and units. These settings are intended to optimize the tool palettes, ribbon, and new drawing setup to match your typical use of AutoCAD 2010. After initial set-up, this dialog box doesn't appear again at start up but can be accessed later through the Options command whenever you want to change settings. You can also elect to skip this step, in which case AutoCAD will apply its default settings

Ins and Outs of AutoCAD 2010
AutoCAD 2010 includes enhanced PDF support for both output and input.

The enhanced PDF output functionality includes layer support. This functionality becomes significant when a PDF file is attached as an underlay, which now is possible. The two most significant features of the new PDF functionality are that it is now possible to snap to objects within the PDF underlay and to control the visibility of layers within PDF underlays. For example, an HVAC consultant now can access accurate, usable data from an architectural drawing without an architect having to relinquish control over the original drawing file.

Another output enhancement in AutoCAD 2010 is that it now supports 3D printing more directly. You can print to an STL file or you can connect online directly to one of several 3D printing service bureaus, which will print your model and ship it back to you. The matter replicator is alive and well.

Chip off the New Block
Two major enhancements improve the current block editor functionality.

First, dynamic block definitions can include the new parametric functionality, including the fact that dimensional constraints can be linked through formulas. For example, if you stretch the length of an insertion of a dynamic block, its width can automatically vary proportionally.

The other really big improvement to the block editor is that it now includes a preview mode. You can check and test the various controls and relationships without having to actually insert a block into your drawing.

Details, Details
AutoCAD 2010 has many additional enhancements. The fact that most can be covered in a single sentence or two does not mean that they are insignificant. Here are some of the best productivity enhancers:

• The Purge command will now purge zero-length objects and empty text objects.
• A viewport can be rotated within a layout.
• The fading intensity of xrefs can be set. A previous clumsy workaround was to assign lighter-gray colors to the xref's layers.
• It is now possible to reverse the vertex sequence of lines, polylines, splines, and helixes. This function can have a significant effect on the outcome of commands such as Divide and Loft.
• The new MeasureGeom command is similar to the Area command, except that it will also measure distances, volumes, angles, and radii.
• Splines can be converted to polylines and vice versa.
• Grip editing now can be used on nonassociative hatch areas.
• If the Hatch command fails, it now highlights the boundary gaps that caused the failure. The highlights remain after the command closes so you can easily find and repair the problems.
• The new Seek command lets users share and search for design content on the new Autodesk Seek web site.

Do You See What I See
The big question in any new release is that of file compatibility. With AutoCAD 2010, Autodesk has stuck to its previous pattern of only introducing a new file format at every third release. The slightly bad news is that it's AutoCAD 2010's turn to be the new one. Therefore, earlier releases won't open an AutoCAD 2010 file.

The good news is that as expected, AutoCAD 2010 will let you Save As back to earlier releases.

I was able to test back to versions 2007, 2008, and 2009, and the really good news is that files survive a round trip. I created a file in AutoCAD 2010 that contained both parametrics and 3D meshes. I saved it back into '07-'09 format and opened it in AutoCAD 2008. The only minor issue was that visual styles did not react to the 3D meshes, which always displayed as wireframes. I did some generic editing such as creating a few lines and circles and saved it. When I opened it again in AutoCAD 2010, the parametrics and the 3D meshes had survived the round trip.

AutoCAD 2010 LT can use parametrics and 3D meshes but can't create or edit them.

Tie a Brand-New Ribbon
The ribbon menu first appeared in AutoCAD 2009. The 2010 version has been extensively modified and now contains context-sensitive tabs. As you invoke certain commands, additional tabs that present appropriate options will appear at the right end of the ribbon. Their labels have a light-green background to indicate that they are context-sensitive.

Finally, AutoCAD 2010 brings a couple of changes that I don't particularly like.

First, it would seem that Autodesk is determined to push us into using the ribbon, no matter what.The problem is that the ribbon is getting very complex and full of a large number of tiny icons. In the 2D Drafting ribbon, the Home tab alone contains 50 icons, not counting the ones in drop-down tabs.

Second, you no longer can right-click in the Quick Access toolbar to get a list of the other toolbars. You can still right-click in any toolbar to get a list from which you can turn any other toolbar on or off, but the problem is that AutoCAD 2010 out of the box does not display one single toolbar other than Quick Access. You need to use the cumbersome Toolbars or CUI command to turn on at least one.

Finally, the big red A button in the upper-right corner has been greatly reduced and simplified. It no longer contains a replica of the menu bar.

Notwithstanding my grumblings, however, AutoCAD 2010 adds some amazing capabilities that will revolutionize how we create and edit drawings. The 2D parametrics alone are well worth the price of admission. Highly Recommended