DN Staff

May 17, 1999

7 Min Read
Mechanical CAD gets easier

The best mechanical engineer is not necessarily the best CAD operator and vice versa. The reason is that solids modeling today is not simple to learn or use. Solids modeling is powerful in achieving the next level of engineering productivity but still complex. Companies pay a big startup price in terms of the time and cost of training and, more importantly, longer cycle times. Since cycle time is so critical to satisfying the demands of customers and beating competition to the market, this is a high tax to pay.

We are about to enter a phase of solids modeling where programs will become dramatically easier to learn and use. But, before I cast my predictions for the future, it is best to look first at where we are now. Today, users tell me about the following pain points:

CAD takes too long to master.

  • There are too many things to remember.

  • Functions are too hard to discover. Even when you discover something once, it may take you a month to find it again.

  • Error messages make no sense.

  • Help files are not much help as key-word searches often come up with no result. These files are also disconnected from the application. Often users forget what the help menu said as soon as they close the window.

Once you have mastered a system, even more problems arise. You have to stay at the top of your game. Many engineering managers tell me they want to be once-a-week users. That is impossible with current CAD systems.

In addition, engineering is solving function before form, but CAD systems often force you to solve the form problem first. This often forces you to accept something less than the desired solution. One fourth-year design-engineering student at the Rochester Institute of Technology does all his design work with "anything except the CAD system." He tells me he turns to CAD when he is done with his design and wants to make a 3D model. The CAD software gets in the way of his "creative design process."

Together, these two images of the Aquajack Water Pump from Rajesh Mirajker of Mirajker Design in India illustrate Mirajker's approach to his design challenge. Instead of using a CAD system, Mirajker used paper and pencil to create his design. After completing his sketch, he used the CAD system to turn his design into a 3D model.

Engineers are constantly getting trapped in the assembly "relationship" quagmire. They go so far and get stuck, and then have to start all over. Many customers that use certain systems create relationships that are so complex, they can't remember what their intent was with designs they worked on just a month earlier.

And if all of this were not enough, a design created by one engineer can't be passed on or easily understood by another engineer!

Changes made to such complex assemblies as this progressive spline broaching machine 10 station turret, designed by Jeff Wymer of Autodesk for the General Broach Div. of Utica Engineering, can be a challenging and time-consuming task with today's CAD programs.

To find the answer to why the world is still struggling to learn and use solid modeling systems, one needs to look no further than the cognitive part of our brain. Solving design problems is a decision-making exercise based on processing information in a designer's head.

Dave Ullman writes in his book, The Mechanical Design Process, that the key to understanding our capacity to work in either 2D or 3D lies in our short-term memory. This is the main information processor in the brain, and it can process information very quickly. Unfortunately, short-term memory can deal only with approximately seven pieces of information at one time. Worse, the older we get, the more of our short-term memory we lose! Up until now, 3D systems have required users to remember too many rules, modes, and constraints. This quickly fills up most of the "slots" in a person's short-term memory, leaving little room for the creative design process.

So far, the industry's answer to these issues has been wrapping a solids modeling system with a Windows operating system. While file-management and preference functions look alike from one Windows product to another, the underlying technology of 3D systems can still be incredibly complex.

A new paradigm. The world needs a new paradigm where the designer can concentrate on the design, not the CAD system. In order to achieve this, I believe that following pieces must be put in place:

1. Direct object manipulation. The best way to understand this is to think about how children begin using a software game. They don't take it out of the box, read the manual, and then take a three-day training program. They install the software and learn it by "poking around."

Just as the children's game and educational software industries had to design with this kind of demanding customer in mind, so do makers of CAD software. In the past, there has been a disconnect between the way CAD software vendors developed their user interfaces and the way CAD users would prefer them. CAD vendors are often meticulous about presenting all of the possible options, while ignoring the fact that one choice is used 90% of the time.

The industry needs a new "intuitive" system, with significantly fewer--and significantly smarter--commands. User interfaces must be designed with the user in mind. Something I call user-centered design principles should affect every part of the product. Modes will disappear, and the tedious process of understanding complex software relationships will virtually disappear.

All of this means that users will have single-day productivity and will be able to use the systems effectively, even if they are once-a-week or once-a-month users.

2. Function before form. Users need an environment where they can solve their assembly-centric design problems with a minimal amount of geometry. Being forced to model everything before you can tell if it will work takes too long and forces too many compromises later in the process. For example, no CAD system today tells you the optimum place to place a sprocket when you are designing a new bicycle. Systems of the future will. Problems will be solved significantly faster and will result in better designs.

3. Assembly-centric flexibility. Assembly modelers today treat parts as rigid bodies that are glued together. Future modelers have to work differently. Changes need to be accommodated freely across the entire design, making changes in complex designs easy.

4. Design intent. The ability to capture and reuse design intent is still a need that has not been met. Just producing another "geometry-only" modeling system would not add that much value to the world of engineering. The ability to capture and reuse design process "know how" in an engineering department is a huge leap forward. The paradigm of reusable design intent will also facilitate tying a customer directly to the engineering process.

5. Active learning environment. A new paradigm in "just-enough" and "just-in-time" learning must be available to users. Active coaching will offer suggestions based on what an engineer is designing. An example is an environment where the system will tell a user the valid range for the size of the fillet, instead of the user blindly doing trail and error. Help files will be deeply integrated into the application. End users will be able to drive the application from inside the help system. No forgetting what you read in the help file by the time you get back to the application!

Future CAD systems that incorporate these five key technology improvements will enable engineers to concentrate on the design rather than the CAD system.

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