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Product Design

Autodesk Inventor 7 and 8

31 May, 2004 By: Bill Fane

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Rapidly evolving solid modeler adds 2D drafting and document management tools

A BIG PROBLEM WITH writing reviews on the latest version of Autodesk Inventor is trying to keep up. The company churns out new releases every six months, so while I'm here writing about releases 7 and 8, release 9 will be out by the time the magazine hits your desk (see Related Links below).

Historically Speaking

Inventor falls into the general product category of parametric solid modeler, along with other programs such as Mechanical Desktop, Pro/ENGINEER, SolidWorks, Solid Edge, thinkdesign, and IronCad. You create a 3D solid model, and the program then generates the 2D drafting views. If you change the value of a dimension, the size and shape of the 3D model changes parametrically, and the 2D drafting views update accordingly. You can then create assemblies from these parts, and if a part changes, the assembly updates (figure 1). These products are aimed primarily at mechanical designers.

Although Inventor is an Autodesk product, it's not AutoCAD. Instead, it was written from the ground up as a parametric solid modeler intended for mechanical design. It was not the first in this market, and the frequent releases reflect Autodesk's desire to catch up and surpass everyone else as quickly as possible.

In the beginning, Autodesk's initial focus was on getting the basic modeler to work properly. The bells and whistles would come later. Do you really care how many drink holders your new car has if the engine doesn't run properly?

Inventor has evolved into one of the best parametric solid modelers, but earlier releases came up short in the 2D documentation department. As mentioned earlier, it isn't AutoCAD. In fact, at one point SolidWorks claimed to have better AutoCAD compatibility than Inventor did.

Release 5 added a great deal of AutoCAD compatibility, but even so, Mechanical Desktop remained better at the finer points of 2D drawing production. You might expect this, of course, because Mechanical Desktop runs within AutoCAD.

The big news in Inventor Release 6 was weldment modeling.

Lucky 7

The big news in Release 7 is that there is no really big news. Well, it does include the Vault along with Pipe and Tubing, but technically these are separate items, not parts of basic Release 7.

Figure 1. Inventor is a parametric solid modeler, which means that if changes are made in one part, all parts and assemblies associated with it are updated to reflect the changes.

A lot of programming effort went into Release 7, but unfortunately not a lot shows on the surface. Some users grumbled that it should've been called 6.1 because it doesn't seem to be a full new release.

Release 7 coincided with AutoCAD 2004, which means that its AutoCAD compatibility had to be completely overhauled to match the new AutoCAD file format. This was not a trivial job. In addition, the AutoCAD Mechanical 2005 functionality within the Inventor Series has been greatly enhanced for those 2D projects.

Figure 2a. Inventor’s Tube and Pipe module, introduced in Inventor 7 Professional, automates tube and piping design. Here I defined a piping run made from soldered copper with fittings. Inventor automatically creates a 3D path.

The Vault

In my review of AutoCAD 2005 (May 2004, p. 26, www.cad alyst.com/acad2005.htm ), I said that Autodesk seemed to be at Phase 3 of CAD system design. In this phase, users are beyond the gee-whiz initial excitement and commodity drawing production. They are more concerned with managing and controlling the thousands of files they have on their systems. The new Sheet Set Manager in AutoCAD 2005 was an example of this.

Figure 2b. Once you specify the route, Inventor displays a simplified representation of the piping.

Over the years, many vendors have attempted to produce EDM (electronic document management) or PLM (product life management) tools. According to Autodesk, the problem with most of them is that they attempt to be all-encompassing, trying to cover all documents in all situations in all companies. This tends to make them very large, expensive, and unwieldy.

Figure 2a. Inventor’s Tube and Pipe module, introduced in Inventor 7 Professional, automates tube and piping design. Here I defined a piping run made from soldered copper with fittings. Inventor automatically creates a 3D path.

Autodesk's solution is the Vault. This is a Reader's Digest condensed version intended mainly for the engineering office. Its primary focus is CAD files, but it also controls other files such as Microsoft Office documents, DWG, bit-map files, and PDF files.

A Vault installation has two basic components. First, you must set up a server to hold the Vault (I named mine Pole). This contains user files and management tools.

Next, each user is set up as a Vault client. Managers can assign different access and security rights to different users. Users can then access the Vault server according to their rights.

The basic function of the Vault is sign-out and sign-in control. This means that a manager can assign a specific individual to edit a file. Other users can see the file, but can't modify it. The user to whom the file is assigned can't put the file back in the vault until the manager approves the changes.

Figure 2d. All parts are associative—if you change the style to threaded steel, everything updates.

So far this is pretty basic stuff, but the Vault includes a number of other useful functions. For example, it can maintain revision history archives. This doesn't just mean that you can save a copy of an earlier version of a single part before you edit it-you can also maintain assembly archives.

This means that you can go back later to see exactly which parts were included in a specific assembly revision, and in turn see the archive versions of those parts. An assembly might currently be at revision D, with a component part at revision C. The Vault lets you go back and see the assembly as it was at revision B, including the part as it was at revision A in that version of the assembly.

Another powerful tool is the Vault's ability to generate where-used data for a part. It's easy enough to delve into an assembly to see which parts it contains, but this function lets you go the other way. You may know that a certain part is used in an assembly, and you may know that you need to modify the part to make it work better in the assembly. It's nice to know that your modification to the part won't mess up other assemblies that use it.

Figure 2e. Again, when you change the style to glued PVC and change the route, everything updates..

The Professionals

My favorite definition of a professional is someone who does for money what everyone else does for fun. Autodesk stirred up a lot of fun when it introduced Inventor Professional Release 7. The problem is that its name implies that the standard version is somehow inferior. Autodesk should have called it something like: Inventor extra-cost module that provides extra functionality to specific people who need it, but you don't have to buy it if you don't need it. This is one of those lose-lose situations. If companies charge extra for specialized modules, they get accused of nickel-and-diming the customer. But if they include everything in a basic package, other users complain that they're paying for things they never use.

The two main modules so far are Tube and Pipe, introduced in Release 7, and Wiring Harness, new in Release 8. Interestingly, you can't purchase just one-Release 8 Professional includes all the modules.

Tube and Pipe. This is a cool module if you design anything that involves tubing or pipe made from almost any material to almost any standard.

Let's say you need to run a pipe that passes through three specific holes. You begin by specifying the type of pipe to be used. I chose soldered copper with fittings. Next, you specify the holes in sequence. Inventor automatically creates a 3D path that passes through the holes in the specified sequence and direction, following the rules for fitting sizes, minimum segment lengths, and so on (figure 2a).

When you finish specifying the route, Inventor updates to show a simplified 3D representation (figure 2b).

Now comes the fun part. When I tell Inventor to populate the route, it does so as shown in figure 2c.

But wait, there's more! Everything is associative. When I change the pipe specification to threaded steel, everything updates as in figure 2d. Figure 2e shows the result of changing the hole locations and switching the material to glued PVC. The 2D drawing views can also produce a full bill of materials list for each piping run.

The Cable and Harness module was introduced in Release 8 Professional. This has much the same functionality as Pipe and Tubing, but it applies to cables and wiring harnesses. You specify the type and locations for electrical control components such as switches, relays, motors, and so on, and you specify routing locations.

You then indicate where pairs of points are to connect, and Inventor draws the full wiring harness. To make it even simpler, it supports AutoCAD Electrical. You can use AutoCAD Electrical to create electrical ladder logic diagrams and then pass the connection list to Cable and Harness.

Straight 8

I'd like to believe that Autodesk has been listening to my comments about 2D documentation in Inventor, because that's the big push in Release 8. The program now includes a large number of features that increase the speed and versatility of 2D drawing creation and annotation. Even so, it doesn't quite have the full set of drafting features found in Mechanical Desktop.

Figure 3. When you load Inventor 8, you can also load Mechanical Desktop 2004 DX, which lets you create a New Companion file, a Mechanical Desktop 2D drawing within Inventor. Here’s a 2D Inventor drawing of a part.

The good news is that a new option gives you the full Mechanical Desktop drafting features. How? Simple! Read the fine print on the Setup screen when you install Release 8 for the option to install Mechanical Desktop 2004 DX. Many people miss it, because they already have Mechanical Desktop 2004 installed from their Inventor Release 7 installation. The DX version is different.

Mechanical Desktop 2004 DX has an extra option in the File menu. This option creates a New Companion File, which is a fancy way of saying that Mechanical Desktop can now attach to an Inventor part file. You can create your 2D drawing views in Mechanical Desktop using your Mechanical Desktop styles and standards. If you edit the 3D model in Inventor, your Mechanical Desktop drawing updates.

Figure 3 (p. 34) shows an Inventor 2D drawing of a part, while figure 4 shows the Mechanical Desktop 2D drawing of the exact same part, as derived from the Inventor companion file.

Three minor limitations apply to creating a Companion file in Mechanical Desktop. First, it works only with single parts, not assemblies. Second, it won't apply dimensions automatically-you must manually apply reference dimensions.

The third limitation is related to the second one. Because they are reference dimensions, they work only one way-you can't revise a 2D Mechanical Desktop drawing dimension and have it drive the Inventor model.

Figure 4. The same Inventor part file, but the 2D drawing was created in Mechanical Desktop.

Of all the 2D drafting improvements in Release 8, my favorite is that you can now open the part file for editing directly from within the 2D drawing file. Just right-click on its browser entry, then select Open. This works for single parts as well as for components within an assembly.

Until the Next Release. . .

With Release 8, Inventor continues its frantic pace to be the total modeling and documentation solution for mechanical design. There is a bit of contention associated with the Professional modules, but if you need their functionality, they are invaluable. Highly Recommended.