A New Look at MCAD
this nozzle assembly, the components are interdependent and the
cross handle is shown as an adaptive component. Inventor's Adaptive
Assemblies functionality allows users to make changes anywhere
in the model, not just in the order in which they created the
Autodesk is taking fresh aim at MCAD, the mechanical design
CAD market, with an entirely new software package, Autodesk Inventor.
Unlike the popular AutoCAD Mechanical Desktop, Inventor is not based
on AutoCAD itself. In fact, files created with the two packages are
not completely compatible. Autodesk started development on Inventor
in February 1996, two months before Mechanical Desktop first shipped.
The existing Mechanical Desktop is certainly a successful product.
In fact, with a half-million copies sold, Autodesk claims market leadership
in MCAD. But Autodesk has never claimed it is as robust as many of its
competitors, especially for big assemblies of 300 to 3,000 components
or more. Inventor, known to insiders by its code name "Rubicon" during
its three-year development cycle, is aimed squarely at that market.
In a round of private press briefings and demonstrations earlier this
summer, Autodesk emphasized three key features of Inventor:
- Ease of use. The interface is clean, there's an awesome sketch-into-entity
facility (much better than the one in other Autodesk products), and
a great help system that includes tutorial videos. Autodesk claims
designers can get used to it in a day or come back to it infrequently
and still be productive.
- The ability to design from the top down (starting with the design's
overall function, and plugging in parts to fit), or the way most other
packages work -- designing from the bottom up, one part at a time.
Designers can mix finished parts with schematic links, in 3D, to see
how everything might work before designing the final version of the
link part or parts.
- A new internal segmented database (it is a bit of an oversimplification,
but a CAD program can be considered nothing more than clever interface
to create database records, each record being a design entity) that
arranges things so you load only the detail and functionality of each
entity you need at the moment. Assemblies of 3,000 components load
in a matter of seconds instead of many minutes. Other programs might
appear to load views quickly, but this usually is done with lightweight
images of parts and assemblies. These images do not contain all the
information about the parts and may not reflect the latest version
of the assembly.
There are other goodies as well:
- An integrated "engineering notebook" that can record the
reasons you chose certain design solutions. The notebook can accept
data files, specification tables from a vendor catalog, or images
and even videos and sound.
- The ability to "associate" parts and subassemblies to one another
without a one-way dependency. This sidesteps the annoyance of parametrically
basing one part's dimensions on another that you've designed previously.
In that case, modifying a later part does not have any effect on the
earlier one; the modification destroys the parametric relationship.
In Inventor, modifying the later part will indeed have an effect upon
- Collaboration tools. Multiple team members can each work on a part
or subassembly. Inventor keeps track of who has what piece. Even those
without Inventor can track the design process.
- Super-fast pans and zooms. Inventor is the first 3D mechanical
design package to use the Fahrenheit 3D graphics technology being
developed by Microsoft and SGI. This adds detail as the drawing scale
changes, and also manages the on-screen drawing, avoiding time wasted
drawing areas that can't be seen on the screen.
here is a six-stage transfer machine for machining the cylinder
heads for an automobile engine. Inventor allows users to work
in the context of their entire design, however large the assembly
is, without sacrificing power or performance. Inventor can effectively
handle assemblies of 10,000+ components, and opens files two to
ten times faster than other competitive best-performing solutions.
In general, files from AutoCAD Mechanical Desktop can be read directly
into Inventor. Inventor is both an OLE server and client, so its 2D
and 3D data can be embedded into Desktop files. But Inventor files cannot
be read into Desktop while keeping their full intelligence. To put it
another way, 2D data moves in both directions, but 3D data moves cleanly
only from Desktop to Inventor. Desktop 4.0, early next year, will be
better at that.
The first release of Inventor, due this month, will lack some polish.
There are only limited tools for surface texture, for instance, and
no easy way to show exploded assemblies without reading the Inventor
file back into Desktop and handling the task there.
Autodesk claims to have spent $25 million developing Inventor. It has
filed for 17 patents on new technology created along the way. The database
technology itself is clearly a major advance in CAD -- probably the
biggest since object technology became truly useful a few years ago.
When you think Inventor, think SolidWorks on steroids. You simply have
to play with it, especially if you are involved in large projects with
thousands of parts. Also think about using it in conjunction with Mechanical
Desktop -- the products will co-exist for at least the next two or three
years. And think about digging deep into your wallet. The price will
be around $5,000.
S. Ross is an associate professor of journalism at Columbia University.
He has written several major design texts.
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