Why 3D CAD is a Designer’s Paradise
By Wayne Lundberg, CMfgE, June 2002
My favorite cartoon shows a king in the middle of a battle, his army fighting with spears and bows and arrows and a salesman trying to sell him a machine gun. And he tells his staff not to bother him, “Can’t you see I’m in the middle of a battle?”
This cartoon should be posted in every office and shop as it is typical of the way many new ideas are greeted. According to Dr. Ramachandran, there is a little biological valve at the base of our brain that does not allow any information which does not agree with our established models -- even for a second of consideration.
This is the problem with today’s 3D CAD-- a wonderful tool which would open the door to huge productivity improvements. If if it were only used the way it has been designed; to facilitate design and the communication of the design to the rest of the world – the machinists, process engineers, publicity, materials resource planners – and everybody else involved in the design.
Draw it once. Only once. Then send the data to the NC mill, to the graphics designer, to the buyer.
But most of the world has yet to accept this gift of technology. Traditionalists tie our hands and force us into contortions of orthographic presentations, drawn with exact line widths and dimensioning parameters, demanding exact crosshatching and alignments to show a tradesman exactly how the thing is to be built. The tradesman, on the other hand, must force brainpower into interpreting the three views (sometimes more) and put together an isometric representation; often sketching such a drawing on a piece of paper which was just unwrapped from his lunch sandwich.
Why on this green earth blessed with Infinite Intelligence must we conform to outdated, outmoded, ways of doing things – why ride a Model T Ford when a Boeing 757 is better, cheaper and faster?
Here is what the designer sees in their mind’s eye:
And here is what he had to send to the shop floor:
Of course fully dimensioned with tolerances and notes regarding finish, materials and the like.
Now, if this were in England or Europe one would assume third angle projection, and if in the United States it would be first angle projection.
Greek to most people including, I’d bet, a majority of readers of this article.
But let’s take it to the next step. Because in spite of understanding English and Metric systems, first angle and third angle, the tradesman would most likely produce something like the following:
Of course the error is exaggerated but only to illustrate what so often happens in real life.
Not because of any other reason than a failure to communicate between design gray matter and machine shop gray matter because of archaic methods used to communicate now, when the whole world is going graphic and true-life representations of almost everything.
The simple expediency of eliminating errors in communication would almost dictate that rational human beings use the state-of-the-art technology to avoid such errors.
But not only in avoiding errors do we get a huge advantage from putting our information into a real world (read 3D) environment, the effort is now used in every other department of the organization from configuration control to after sales service. One drawing. One drawing feeds the whole enterprise. From one drawing – the model in 3D – the whole company benefits.
What is the world waiting for?
Drawing a detailed component in orthographic views requires at least five times the number of command entries; most of them duplicates of others. In 3D one line will be used to establish the xyz location and then moved, copied, scaled or otherwise manipulated to make up an edge of the real model. Once the model has been constructed using real dimensions, an orthographic representation can be made in most CAD software packages by simply opening four windows; a top, front, side and iso view. Bingo! Alignment is automatic and in most cases dimensioning is also automatic by simply clicking the edges, or centers of what must be dimensioned. You then edit the tolerances based on traditional stacking technology based on shop capabilities.
But if you have been living your life fighting the traditional drafting machine, construction lines, line weights and the like it will be most difficult for you to imagine a world in which you simply tell the machine to put a line from xyz zero and increment it by 12 inches, then y by 6 inches, then x by minus 12 and close – no add a thick or extrude command for the z dimension and bingo, you have 11 lines made for you when you only drew 4. Now that’s magic!
AND – when it comes time to dimension all you do is tell the machine to put them where you want them since you are the one who told the machine the size, length and location in the first place. That information is now in the system for everybody to use for whatever reason they want. A jig, a mold, a drawing, a sketch, a fixture, an NC program… a rendered image for publicity, an assembly sketch, a warranty illustration. It’s been done once. For everybody.
Nothing else in the world of design comes this close to heaven for a designer intent on communicating their idea to the world at large.