Work/Life Balance: Making the Most of Regeneration Time

By Larry Pitts, PlugPower

If you’re like me, you’re getting sick of all these “best practice” and “CAD standards” articles littering our favorite design magazines. Everyone is so concerned with making robust Pro/ENGINEER models that regenerate flawlessly and efficiently. There seems to be a written procedure for every keystroke and mouse-click a Pro/USER could make. 

To this I say, “Standards shmandards.” It’s time to have more fun at work. All you have to do is learn the fine art of regenersurfing. What is this new technique? Well, let’s see what Webster says… 

regenersurfing (rê·jen·er·sir·fin). The act of creating long CAD software regeneration cycles with the intent of browsing the World Wide Web while "waiting." 

Think about it. What could be better than casually surfing the Internet while giving the illusion that you’re doing something constructive? Your boss thinks you’re intensely working on some complex assembly when you’ve actually spent your day poking around the likes of eBay and NFL.com. 

Luckily for you, I’ve spent years perfecting this art and I’m going to share that experience with you. The key to regenersurfing is employing design methods that confuse Pro/ENGINEER. So, just for you, I’ve assembled a list of surefire ways to slow down regeneration time and speed up your surfing performance.

Tip #1. Spin and leave dimensioning.

If you were in a hurry, which of the following two equations would you rather solve?

.50/.125 or .4999987/.1250012

If you picked the second one, you’re either a glutton for punishment or a math geek with lots of time to kill. 

You may be thinking to yourself, “This is a computer calculating the answer, not a human brain.” You’re right; computers are extremely fast. But consider the massive amount of calculating Pro/ENGINEER has to do to make a slightly complicated feature. These equations add up and can really take a toll on your regeneration speed, especially when combined with a wacky accuracy setting. 

So the next time you’re in sketcher mode, instead of typing in an easily divisible three-digit value, grab the modify dimension wheel and give it a whirl. For extra fun, I like to take it out to seven decimal places and embed a friend’s phone number into sketch dimensions. For example, .8675309 would be perfect if you have a friend named Jenny.

Tip #2. Circle the wagons with circular references.

Have you ever heard the statement, “You can't be your own mother…if you manipulate time, you might accidentally disappear”? 

In biology, that claim holds true for just about every life form except amoeba and other one-cell protozoa. Fortunately for those wanting to expand Pro/ENGINEER regeneration time, a component can be its own parent with a little performance-killing blunder known as the circular reference. 

A circular reference typically results when you redefine a feature’s or component's references to another feature or component that was created after it. In other words, it‘s a confused parent-child relationship. When regenerating the assembly, Pro/ENGINEER has to loop around redundantly to confirm placement. It’s the CAD world’s version of the chicken-and-egg problem. 

Of course, understanding what a circular reference is, is one thing. Knowing how to make them is another. Here are a couple dependable ways to create an assembly Woody Allen would be proud of.

(2a) Pick at will. Model tree confusion is key to slow regeneration, so you want to reference as much unrelated geometry as possible. When working in an assembly, keep the parent-child relationship in mind. Drive intent from peer objects at different levels in the assembly structure without using logical shared geometry features such as External Copy Geometry. The beautiful thing here is that you don’t have to try to make a circular reference. It’s easy. Just let your mouse run amuck, and before you know it, you’ll have a nice long .crc file. 

Don’t forget: the more loops in a circular reference the better. Try to make the components involved in the problem the parents of as many child components as you can. Don’t be afraid to go up and down a few assembly levels. Eventually your model tree will resemble a bowl of spaghetti, and you will be on your way to bringing Pro/ENGINEER to a standstill. 

(2b) Restructure recklessly. Another way to create circular references is by carelessly using the Restructure tool. While not a consistent performance-killer, restructuring can really mess things up if used improperly. 

First, you can easily create unintended external references if you don’t pay attention to the selection query. It’s simple to lose track of what’s related to what. Later, when you change something, KABOOM!!! The assembly becomes unstable. 

Second, you can get references "climbing up the tree" and forming all kinds of bottom-up relationships that slow down regeneration. With a bottom-up model structure, the system may need entire assemblies in session that it would not otherwise need. This can cause problems for users trying to work concurrently on models. It can also end up monopolizing top-level assemblies, and even cause problems with Pro/INTRALINK in the form of circular dependencies. Use this technique to really undermine top-down design practice.

Tip #3.  Sweat the small stuff.

Features like helical sweeps, used to make threads, extruded text, and advanced rounds, are good for representing visual aspects of a design. As a result, most designers will either make a simplified rep to remove the features from memory or use a cosmetic representation such as curves. 

These features are your special friends because they take a really long time to regenerate. Since you’re trying to decrease performance efficiency, it’s good idea to model these unneeded features as often as possible. In one brilliant application of this technique, I saw a salty old regenersurfer model woven screen mesh.

Tip #4. Leave your mark.

Last but not least, take the time to let people know this is your mess. Put your personal touch on your parts. Leave old features such as shared data, unused datums, and other garbage in your models. Go ahead and be a pack-rat. Leave old ideas in the form of suppressed features and components. 

One of the most effective techniques you can use is to hide buried features inside of other features. For example, model a helical sweep normal to a complicated datum curve and then make sure it’s completely encompassed in the body of your part. 

Although most of these efforts won’t show up in your graphics window, they are working hard behind the scene to really bring down regeneration speed.

Reality Check

You’ve probably realized by now that this is all a joke. Call it what you will—engineering satire, design comedy, or nerd humor—laughter may be the one thing that gets you through another day of failure resolution and corrective tolerance stack-ups. Like anything else in life, these tribulations can actually be entertaining if you lighten things up with humor. 

The fact is, Pro/ENGINEER users can develop bad habits that drive their colleagues crazy. They may cut corners when faced with an impending deadline, or display a complete disregard for standards. The impact of these bad design practices becomes crystal clear when you introduce the ridiculous idea of intentionally messing things up.

But if you don’t think this is funny, you may be in need of more help than you know. Think of this as an intervention. Just have an open mind and ask yourself, “Do I do this?” If the answer is yes, you’re probably causing more problems than you realize.

Larry Pitts is a design engineer at Plug Power Fuel Cell Company, where he has worked with PTC products such as Pro/ENGINEER, Pro/INTRALINK, PDMLink and Pro/MECHANICA since 1998. Larry has spearheaded using data-sharing techniques to generate robust, complex parts that require frequent design change. He is also a advocate for user education and participates on the CAD Steering Committee. This article is based on his award-winning presentation at the PTC/USER World Event 2006. You can find more of Larry’s humor at www.baddesign.us.