CAD and Design

There is a ring of discussions going on. One blogger commented on another, and some left comments on LinkedIn, and now I’m adding to the loop.

The arguments all seem to be made by people who aren’t directly involved in the process. Not sure I want to go to the length to call them all desk jockeys (or more famously typewriter jockeys) again, but you get the idea. The arguments all seem to be too close to one point of view to be able to see the whole thing, or too far from getting dirt on their mouse to understand the details.

Here’s the thing. CAD and Design overlap, and have some things in common, and some things that aren’t in common. Drafting is a quaint idea that I don’t really relate to. I’m not sure what relevance it has in today’s processes.

Product development is a process that starts with an idea, and that idea usually fills some need. The quality of the idea depends on the quality of the need. If the need is just to make more money, the idea usually turns out to be shallow and not very convincing. If the need is some way to better input data into a computer – then you’ve got a better chance. This, by the way, is why I think business types will always be shackled to needing to have real problem solvers  around them.

The idea leads to identifying a need, which leads to identifying a solution. To make the solution “real”, or more than just an idea, you have to plan. “Product development” in my eyes usually starts with this idea of a solution. Inventors are tasked with forming the idea of the solution. But inventors always need help going to the next step. The next step requires the task of “design”. The design, then needs to be documented so it can be understood by others. And then the documented design needs to be manufactured.

needinvention
design
analysis/engineering/prediction
documentation
manufacture

In my experience, these phases each overlap to varying extents. And they might even be iterative, where prototyping is actually a manufacturing phase, but it’s followed by iterations of the design or even the invention. Documentation is just the CAD work. It helps you communicate the idea. My day to day work involves tasks along the continuum from invention to documentation. Some days I design. Some days I just document the design. I even go back to the beginning to help solve the original need.

One of the arguments on one of the sites said something like “CAD happens too early”. I don’t believe this at all. It’s probably someone who can’t do CAD who is saying that. CAD happens as early as it needs to, because it can be used in a number of different ways. It can be used as a 3D napkin sketch. It can be used to convey concepts. It can be used for quantitative analysis. It can be used to help visualize. It can be used to prototype or manufacture. To say CAD happens too early is to misunderstand the process, and the role technology can play in it.

There seemed to be another argument against ease-of-use for CAD. My job is not threatened if an accountant can make a stack of blocks in 3D software. Or if a high school dropout can render mighty dragons in 3ds Max. It takes more than either of those to make real products.

My job, as a professional CAD jockey is to be able to translate between the language of design and the language of manufacturing. My CAD data has to be able to take into account everything that went before, and render it in a format that allows the manufacturing process to do what it does. This is not something you learn in college, or 2 nights a week in trade school. This is something you learn by osmosis working between people with the various skills you need. You have to work with a mold builder and probably make some stupid mistakes to learn what it takes to mold a plastic part with specific characteristics. You have to work with plastics designers to understand how, why and when to use a living hinge or a snap fit or vibratory weld or heat stake.

A professional CAD jockey isn’t just a guy who makes pretty pictures, and he doesn’t need to be a manufacturing expert. But he does need to know when he needs to ask questions. He might not even be an award winning designer, but he has to be able to understand design enough to make compromise decisions between design and manufacturing, as must always happen.

Maybe my type doesn’t exist that much. I’m a degreed mechanical engineer who does mostly CAD work. Many engineers might consider detailed CAD to be beneath them, but I like to think that I bring more than just drawing lines to CAD. I bring an understanding of the complete process. I can design, engineer, and I know what it takes to manufacture. The CAD work is just translating between those two worlds in a visual language backed up by math driven geometry. I know there are others out there who do the same thing as I do. If you “only” run CAD, and don’t understand the processes that happen before and after, you’d better work at a company that takes care of the rest of it for a while to learn the ropes. I’m not sure if there’s any such thing as a “freelance CAD operator”. You’ve got to bring more to the table than that.

15 Replies to “CAD and Design”

  1. I agree on the concept that doing 3d CAD without understanding engineering and design lead
    to problems. However some of the examples in this thread are pointing out that CAD tools are
    still difficult to use and prone to mistakes. There is plenty of room to create better CAD systems.

  2. There may not be such a thing as too early cad, but there definitely is such a thing as too early detailed cad. And the more complex the project, the worse of a nightmare this becomes.

    Managers tend to want to see 3D with all the nuts and bolts and all of the fillets as soon as possible, this makes effective engineering much too slow.

  3. @Glenn Schroeder
    Totally agree. I worked for an organization that actually took its new hire engineers (fresh out of school) and their first 6-months was working in the different manufacturing and proto-type groups before they sat down at CAD tube. You learn a lot about sheet metal when you have to bend it and about take your fingertips off because someone didn’t know there was a minimal flange length. Or that someone designed a simple part that required special tooling to make the bends in the part.

  4. Matt,

    I also agree with everything you said. I worked here on the construction crew for 10 years before learning SW and moving inside. That experience has been invaluable to me in my CAD work, and I’m sure that I’m a better draftsman than I would have been without the hands-on experience.

    I would like to expand on that theme if you don’t mind, and hopefully I won’t step on too many toes. Not only should CAD operators know more than just how to use the software, but engineers should know more than just how to run the numbers. I’m not one, so maybe I don’t have a right to comment, but it’s my opinion that they should have a year of experience in their field before working as an engineer. And I don’t mean a year working in the office, I mean a year of getting their hands dirty and actually working with the people who will be building or fabricating what they will design. Maybe then they’d consider things like cost and availability of materials before spec’ing them. And that’s just one example.

    Glenn

  5. @John
    I was called in by a company that had a problem with a sheet metal part. They had a $7,000.00 pile of scrap in the warehouse & wanted to know what happened.

    The SolidWorks drawing looked right but the parts were off. Turns out the designer had just changed the dimension in the drawing but not in the 3D SolidWorks model. The sheet metal supplier used the 3D model, imported into their sheet metal software, to make the parts.

  6. @Ken
    Yep, love that stuff. I had a composite drill jig to do recently for a different company. 8 bushings across a face about 20″ long. The radius of the face was nearly 70″, but the tolerances would have allowed a flat plate. What the heck, it’s only a nose cone. I’d get done a lot faster if it weren’t for ethics.

    That was the same part where they corrected the dimensions on the print, but NOT IN THE MODEL. Wow, did that make a stink when I asked which was right. Turns out the drawing was done in ProE, then imported into Catia. They made revs by just editing the dimension text. That may be my all time favorite.

  7. @John
    Got to love stuff like this:
    “The “Approved” prints I have to mill show dimensions to two decimal places, with tolerances ranging from .030″ to .003″.”

    Reminded me of the time a factory layout person laid out an angle on a sheet metal part to 90° when the nominal angle was 88° with a tolerance of ±2°. When asked why he laid it out that way, I got “Well it’s within tolerance and it’s easier to lay it out this way.”. Some people just do not understand, but yet they are getting a paycheck…

  8. I think this question of “Cad too early” has legitimate roots, if you remember not all Cad programs are created equal. A wise man once described Autocad as the greatest reverse engineering tool in the world. For those of us who started Cad in the 80’s, it was purely a documentation tool. It was so hard to edit complex designs that all the real work was done on the drafting table or napkins. Fast forward to today where I can doodle with SW more effectively than I can with pen and paper, as I have 3D .

    I think in a lot of companies Cad is still a handicap. Either by software choice or lack of skilled Cad jockeys (see Devons post), that phase is a burden that puts lag in the system, rather than adds value. I’m working on a part now, drawn in Catia by a major aerospace company. The “Approved” prints I have to mill show dimensions to two decimal places, with tolerances ranging from .030″ to .003″. Kind of a hint for things to come as i massage the model into something I can post. Machining time will be much less than the time wasted asking questions, fixing dumb solids (hello replace face tool), and getting design intent feedback. Cross training is the key to efficient design in todays world.

  9. I’m reminded of a company I consulted to in the medical device field. When I started there, I found this;

    1. A SolidWorks user that sat & stared at his monitor, trying to fix a problem in a part file, for about 2 weeks. I would walk by this guy’s cube on the way to the men’s room & kitchen. I believe he did nothing else at all during that time. I fixed it in 5 minutes(or less) and I suggested he might want to ask for help by others in the future.

    2. An Engineer that designed an injection molded part with over 300 features. He had spent about 3 months working on it. His method of “editing” the part was to add new features, NOT to edit existing features. He built features on top of features, over & over & over. The completed file was not editable and would usually crash when Opened. I’ve got a copy of this file around here somewhere. However I’m afraid to post it, I might bring down the entire Internet.

    3. A draftsman that created a 45 sheet drawing that referenced multiple large assemblies. He left the drawing file Open on his machine for over 2 weeks. He would come to me complaining about long rebuild times. He just kept adding more & more sheets and views, again the file was always left Open overnight day after day. When he finally Closed the drawing file, it wouldn’t ReOpen. He never could get it to Open, it would just crash.

    4. Finally at a different company; The CAD Admin was the last man in the PDM chain. He would make a pdf of the final approved SolidWorks drawing. Then he would put all the SolidWorks files for that drawing in a single folder and upload them to a network drive for “safe keeping” However…each time that a new folder was uploaded, it was created as a SUB-folder. When I arrived on the scene, he was gone and there were 1,204 SUB-folders on the network drive, all in in a parent-child chain. This was back in the days of Windows NT/XP. Because the path to the files in all these SUB-folders was more than 255 characters, none of these files would Open. It took me 4 weeks to restore order to the system and get the files to Open.

    So back in those days, I guess I was a CAD fireman, puttin’ out fires.

  10. Agree pretty much with all of the above, particularly the comments about mastering tools made by Jeff. If you aren’t a master of your creative tools (CAD, pen, sculpting tools whatever) you will be limiting your ability to create and communicate.

    I often run into the “no CAD early on” argument and it’s somewhat irritating (especially as my sketching skills are pretty poor – eyepatch on to get hand and pencil to behave and to be able to draw perspective correctly, med induced tremors). As ever, effective use of the medium is key and polishing rough / unfinished designs up as high quality renderings is asking for trouble.

    Finally, I have a bachelors in mechanical engineering, a masters in ID (both UK) and I am active at all stages of the product development process. I do spend the majority of my time on CAD (SolidWorks), though. Whenever I am asked what I do for a living I always have to pause, partly because I still haven’t decided to my own satisfaction and partly because I never know precisely how informed my audience is.

  11. @Jeff Mowry
    Right you are, Jeff. Your CAD software is just a tool, should be seen as a tool and used as a tool. Some tools are more efficient and/or easier to use than others and this is one of the differences between the drafting board and SolidWorks-like programs.

    Also do not forget that paper “accepts” anything. At least in a 3D modeling software you can check your model for interference (both static and dynamic), for weight, for function and can use it as input for analysis, including design optimization.

    Jeff, would you consider adding your point of view on the LinkedIn thread?

  12. When I was in college, I’d first write my papers by pen (manually). It worked better for me, since I actually had to dedicate a part of my mind to typing back then, remembering where the comma key was, etc.—too much mental overhead went toward typing, and my writing suffered. But after a while—a long time practicing typing over and over and over—that mental overhead faded away and instead typing turned into a conduit to more quickly write. I’m quite a fast typist now.

    Why’s that matter? Well, when I was a novice with the tool of typing, typing itself was much more of a burden than a lubricant for the task of writing. Since I can now type so much faster than I can write manually, writing by pen would now be a burden. Master the tool, and the tool can help you master your art.

    The same applies to all tools and all arts, similar to what Matt said above. If I weren’t a master at SolidWorks, SolidWorks would bog me down while hammering out design concepts. However, I’ve used SolidWorks since 1997 and consider myself a master. Instead of straining to figure out how to create certain forms of geometry with SolidWorks, I can instead create geometry quickly and really see what my muddled mental picture of a design looks like once the full context of the 3D assembly is added to the mix. It becomes a tools to more quickly establish the final design.

    I also saw a recent LinkedIn conversation regarding sketching vs. CAD, and it’s interesting to see the variety of comments on the topic. Perhaps the factor really is proficiency with the given tools?

  13. CAD comes too early only if it ends the discussion and freezes bad ideas. The concept parts may look too real and management might decide that no further design is needed. Engineers and artists need to overlap their skills and cooperate to find the best design.

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