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Technical Drawings

Technical or Reference Drawings

Unlike patent drawings, technical drawings are great for reference. Before we had 3D printers or CNC machines, machinists, fabricators, building contractors (and the list goes on), would rely on technical drawings to create an accurate project. Every angle was explained, hidden lines were essential and the cut-away, or detailed view, gave much needed information. This still holds true today however, with the introduction of CAD/CAM into the manufacturing process, the technical drawings become less necessary in some instances.

Don't get me wrong, without technical drawings, some projects could never be completed. You can't put a large metal tubular frame into a CNC machine. A welder or fabricator must have technical drawings in order to build what the engineer or designer has outlined. Technical drawings are still very much alive, well and necessary. What's changed is that the CAD files, in certain applications, can minimize the need for drawings. Notice I said, "In certain applications....", that's the key phrase.

For those of us who used to draw technical drawings with a pencil on paper before there was CAD, we can appreciate that the 3D model we create in CAD, will now produce the drawings simply by importing the model into the drawing environment. You can create your different views with little effort. If you make a change to the model, it will update in the drawing environment, in all the views, instantaneously. It's really amazing.....for those us old enough to remember, that is.

Not to Change the Subject but, What's a CAD File ?

Today, the 3D printer and CNC machines read files (three dimensional files) that then create parts. If you have a flaw on the virtual model, it’s duplicated in the CAD file.  There’s no machinist to back you up by finding your flaw and giving you a call. That flaw will get produced and, produced very well I might add.

When parts don’t fit, it’s usually too late. The 3D printers or CNC use whatever parameters they’re given, period.  So it’s very important to get the model right. Computer aided design has given us the tools to fit parts with exact clearances needed. The computer can’t do all the work though. You have to know what clearances are acceptable or appropriate for the materials that are being used. Also, heat, loads and the type of materials used, have a lot to do with what clearances are necessary.

Virtual model using CAD
So What's a Technical Drawing Good For Then ?

So what’s the point of engineered or technical drawings then? If you make the drawings on a CAD program, you can use them for dimensional insight, into the model. You can “check” the model by looking over the drawing. If you find a problem, you can go back into the model, make your changes, then reboot the drawing and the changes are reflected in the drawing.  If you were around before there was CAD, then you remember that entire projects were built from drawings.  Drawings are invaluable for creating parts and assemblies when manufacturing equipment isn’t applicable.  Such is the case of building a house.  Houses are built from drawings and so far, they don’t have a 3D printer big enough for a house so, for now, we’ll refer to drawings.  CAD makes the drawings and the management of them, much easier than in the days of pencil and paper.

In CAD, you have a feature that will check for interference between parts during motion. But technical drawings are a way to look at the 3D model through dimensions.  Looking at dimensions can orient you quickly to the scale of your project. The advantage of CAD is that it can create virtual models and allow to test them through generators in the software that help diagnosis potential problems in assemblies such as stress failure through dynamic simulation or flow rate through ducting.

Are There Any Other Uses ?

Another, off the subject use for technical drawings is that they look great for posters and flyers. I know, I know. I like ’em though. You can make some really cool views. You can change the materials of your model to give the model a new appearance. Some parts can be shifted to transparencies, sectioned views and the list goes on.

So, in summary, technical drawings and CAD files each have their own unique uses and one couldn’t replace the other. Then, different from both the CAD file and the technical drawing is, of course, the patent drawing.

Dimensional Reference Drawings

A note on engineering drawings; the drawings shown here are a good example of what the USPTO will not accept for patent drawings. They look great, are wonderful reference but a computer can’t read them and the patent office won’t accept them. That’s not to say they’re not useful, just that they have their limitations. Now don’t let yourself get confused like our friend on the right here. Patent drawings are actually easier to make than these.

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Caution

“Whatever you can do, or dream you can, begin it…Boldness has genius, power and magic in it.”  Goethe