10 CAD Rules to Live By

August 28, 2018


cad tips, nx cad



10 CAD Tips to Live By

Marginal, at best.
This article is merely the ramblings of an old CAD soldier rather than a specifically focused expose’ on the latest NX CAD tips and functionality. I’d like to just lay out some common sense considerations for the benefit of the grass roots users and corporate decision makers alike. It comes after, well, more than 34 years of working with “.prt” files. And it seems common sense has vanished from so many places nowadays.


10 CAD Tips to Live ByThis tool we call CAD (I’m not EVEN going to spell that out if you don’t know what it stands for) has been a long time in the making. The internet will tell you (and we all know if it’s on the internet, it must be true) that the beginnings of CAD can be traced to 1957 when a Dr. Hanratty developed a commercial numeric-control programming system called PRONTO. I had never heard that until I just started writing this article. I mean… who knew?

So how did we get to where we are today, viewing multiple 4k screens driven by graphics cards costing $1000’s, processing data so fast, the NASA equipment of those old moon landings couldn’t keep up, and, via wifi, opening a CAD assembly from our division’s database in India that contains iterations of parts defined in a family all driven from spreadsheet data that prompts us for changes to a deformability parameter because it sensed a change in an automatically loaded WAVE linked part which conflicts with a Design Requirement that spawns a KF routine which solves the overconstraint which, in turn, updates the attributes that will populate the Title Block automatically and, when finished, save it somewhere in “the cloud” so our downstream applications in 3 southern states can then get updates to their associative manifestations? One step at a time, my friend, one step at a time.

A Little Background

I started my journey in those backward times when all design was developed by either using trial and error on prototypes or capturing the part shapes in orthographic representation in a 2D medium called drafting (or draughting, if you’re more of a crumpet type… you know, an English Danish!). Engineering drawings were the gospel of product development and nobody did nuttin’ if it wasn’t on the drawing. I remember jobs where we had to distribute 7 copies of the “blueprint” when we released a design to production so that everybody in the company would have the latest revision of the design.

Hah… blueprint… that’s a good one! In high school I actually made REAL blueprints by blasting blinding light onto my graphite-on-vellum drawing behind which we positioned special light-sensitive paper for a minute or two, then rolled that special paper up into a tube that we put onto the “developer”. This was a simplistic ventilation chamber that blew ammonia from a sealed tank through the tube which chemically converted the coating on the special paper from bright yellow to dark blue. The blue coating remained only behind the lines and lettering on the drawing during the “exposure” step because the blinding light photosynthetically evaporated it everywhere else. Therefore, I had a “copy”! And now you know why they call it a blueprint.

A little later in life, when I was employed as a drafter, designer, drafting designer, engineering designer, design draftsman… (oh whatever! just pay me the money and skip the title!), the companies I worked for started investigating and comparing CAD systems, circa 1980. In all honesty, they were just electronic drafting programs. You first had to buy the software and the custom hardware that it worked on, which, for the most part was equipment marketed by the software developer but usually manufactured by one of the main computer companies like Digital, HP, IBM, etc. Then you had to get some expertise help you set it up and install it. Setting it up was actually harder because the equipment barely fit on an 8-foot long lunchroom table and weighed more than the users themselves! And the cables and adaptors and power converters and… well, suffice it to say, it was a weekend project, literally.

Once the system was operational and the base data had been installed, along with the font sets and language converter (programming format, not nationality) and all the additional modules (no literally… plug in electronic modules that contained certain data or command routines based on the software package you purchased), you were ready for employee training and the development of your new engineering business processes to accommodate the new electronic file format. Standards had to be developed, documented, proofread and checked, distributed to everyone in the company. They then would wonder what in the world this “CAD” system was. And how much did it cost. And what the big benefit was going to be. What was the big benefit of all this high technology expense and logistics??? Why, prettier drawings, of course!

In 1984, I was designated as a lead designer and assigned to the new CAD development project. The system was a product of McDonnell-Douglas called Unigraphics II, version 4 and was capable of creating 3D wireframe models and 2D curve based drawings. I was a member of a team chartered to develop the practices and CAD Standards document in addition to the backup and storage processes for the data. I learned many, many things in those early days, including the practice of preparing 2D views that were to be added to the drawing. This was an arduous practice of erasing all the 3D curves that were “hidden” by other curves in front of them or that were normal to the view… one curve at a time! I know this is starting to sound like I had to walk to school in the snow uphill both ways but to be honest, creating the drawing was ten times the work it took to create the 3D curve model.

The software wasn’t inadequate back then. It was state-of-the-art. It had superior surfacing capability and the ability to create sections and intersections of them to derive integrated curve profiles. In fact, it was and still is the best CAD system I’ve ever used. And, yes, I’ve used other CAD systems. But the truth is, what’s the best CAD system…? It’s the one you know.

But let’s move on from the reminiscent ramblings of this old man to my advice to those using and managing a CAD system.

10 Rules for Common Sense CAD Applications

1. Employ just one CAD system.

Ok, two if you really have to.  Seeing the hassles and logistics at the hundreds and hundreds of companies I have taught at and provided services for, they pay a substantial price for providing multiple CAD platforms for their users. Here are some things to consider.

    1. Regularly repeating software version installations – once/year minimum,
    2. Maintenance and patch updates – multiple times/year,
    3. Separate training processes and resources,
    4. Separate business processes,
    5. Compatibility with operating systems, hardware, and downstream applications.
    6. Translations and the loss of design intent across systems,
    7. Yes, you have an alternate system to rely on if one of them ceases to exist but predicting the direction and focus of the providers is more than most feasibility studies can realistically project. But consider… people said in the 80’s that EDS was vulnerable. In the 90’s, they said Unigraphics and UG Solutions and UGS, et al were all in a risky transitional state. In the 2000’s, PLM Solutions was overextended and too diversified. Today, what are they saying? Simply put, you need to look at the consistency of the software and it’s value to you and stop spending resources on fear and speculation.
    8. Adding to the frustration levels of your users – something most managers and business owners don’t consider. Studies show that users who must memorize the different functions, processes, options, hot keys, data formats, and usability and keep up with the constantly changing enhancements are less productive and generally have lower morale than those with a consistent, role using a single CAD system
2. Always assess the return on your human resource investment.

Do not establish obstructive or nonproductive standards and practices.

    1. At one of the companies I worked at employing Unigraphics, the standards were so stringent, requiring users to actually change the color, font, and width display of every object in the model, it took twice as long to create and were often rejected by the work flow process, adding to the delays with needless transfer between folders and status assignment.
    2. Don’t use the software to accomplish counterproductive, conflicting tasks. Have you ever seen a demo on PMI where the presenter is trying to promote the MBD approach (Model Based Definition) and ends up demonstrating how to import PMI onto a drawing? Wait… what was the point of all that again?
    3. On the other hand, prevent the “Weird Harry’s” in your user group from overcomplicating the CAD data and doing things weird so that others have a hard time working on it or can’t work on it at all. (Usually for the erroneous purpose of trying to establish their own irreplaceability.) These users exist in every environment and every time I talk about Weird Harry in class, the fellow colleagues in the room smile at each other, identifying a certain fellow user!
3. Keep your users trained and well aware of the capabilities of your system.

Do not rely on your users advancing their knowledge and understanding on their own. Trust me –most users are just trying to “get by” with as little stress and personal attention as possible. They will lay low and abide by the old saying, “When people suspect your ignorance, do not speak and remove all doubt.”

4. Promote user interaction and universal understanding of the best practices.

Managers assume that whatever their power users know, the others will follow and emulate the same practices. Ohhh contrayer! (I don’t know French. Except for Jacques Cousteau and Peanut Buster Parfait.) In fact, I guarantee that even your worst users know something that your power users don’t know. I’ve been teaching and supporting this software to literally 1000’s of users for decades and it never ceases to amaze me how one of them teaches me something nearly every class I teach. I preach that they should get up and walk around to not only aid in their ergonomic health (eyes, neck, wrist, etc.) but to go watch a fellow user. I guarantee within 5 minutes they’ll say, “Wait! How did you do that?”

5. Avoid redundancies in the modeling approach.

Through the years, I have reviewed many models and the practices with which they were created, both in my classrooms and at customer sites in their databases and archive folders. I would estimate that 50 to 70 percent of users create redundant Datum Planes and Sketches, ignoring the obvious Datum CSYS tool that Siemens created in the model template files. If a Sketched profile is needed in the same plane as an existing Sketch, why not add those curves to the existing Sketch? The Selection Intent/Curve Rules provide all the options necessary to include only the curves needed for any given swept feature. At a certain aerospace company, the wing support ribs for its jets are created by a dozen or more Extrude features, one or both directions, some with draft, some with offsets, some united, some subtracted, BUT ALL OF THEM FROM THE SAME SKETCH. This allows constraining of the curves very easy because they can all be constrained off each other within the same Sketch and not off of many, many other objects all over the model. When an edit is needed, there is only one Sketch to activate. It’s one-stop shopping!

6. Schedule regular investigation of improved practices and methodologies for your industry and product design.

One of the companies I taught at had published a document for the best practices to duplicate the repetitive geometry in their common parts. These practices reduced not only the time to create parts and the time to open, update, and save parts, but also reduced overall part memory and improved graphics performance substantially.

7. Get a clue.

Understand that if you are not doing the same things that other companies are doing and have been doing for years and you still aren’t doing it, maybe they might know something you don’t. If you’ve been using NX for decades and still don’t use Assemblies and Components, you are stuck in the 80’s and need to get out of that rut! If you go to PLM World or a training class and see impressive functionality but say to yourself, “Well, that’s pretty kul but we don’t use that.” Instead, have you ever thought, “I wonder why they are presenting that?”

8. Get another clue.

You should realize that when Siemens comes out with functionality like Synchronous Modeling, Assemblies Constraints, WAVE linking, and Borders, Zones, and Title Blocks on drawings, just to mention a few, and have consistently enhanced them for over a decade now, you ought to consider looking into it a bit deeper to see if there’s an advantage in there for you. They don’t do that to deceive you with things that don’t work.

9. Don’t force your users to battle with software defaults based on ignorance.

Allow your users to drive the standards, preferences, and Customer Defaults where possible. Provide an occasional pizza lunch on Friday and encourage some interactive dialog about common practices and find out what annoys your users about the software defaults. If a majority agree that a new Reference Set named “PARTING-PLANE” ought to be in the template part so they don’t have to keep creating it themselves, get your CAD admin or IT group to accommodate them. In a non-intimidating way, get users to voice what frustrates them or forces them to do things the long, hard way because they just don’t know the smart way to do it.

10. Be your own checker.

Bear with me while I daydream about yesteryear just one more time. In my early years as a designer, companies employed people (actually called checkers!) in the company that verified the work of others, scrutinizing every line, looking for missing crosses to T’s and dots to I’s on the drawing to ensure quality and avoid mistakes getting released to production. They were a real and measurable value to the engineering effort. But, as has been the practice in business ever since those days, short-sightedness justified the monthly bottom line being more profitable at the risk of lower product quality in the long run, and those positions were eliminated. As a user, verify that what you create is correct and usable for your downstream users with confidence. Just because a CAD system is accurate to the Nth degree (NX can calculate to 100 decimal places if you prefer), creating a surface without the required G3 continuity is just as bad as making a .1 radius .01. Measure it!

11. KISS.

Google it.

So there’s your Top 10 Rules for staying sane in a CAD environment and getting real results. OK, that’s actually 11 but how many times do you actually get what you pay for nowadays much less get a bonus? Number 11 is my little “KISS” to you today!


We hope this article provides some tips that your company is able to benefit from, even if it’s just to avoid some common pitfalls that others fall prey to. Use the knowledge available to you. One of the worst assessments you ever want to hear is that your CAD application is “marginal, at best”.

Post by Garrett Koch

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