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Journal 4.0 Types of Drawings that Engineers Use

Dizzy’s Journal Entry (Napkins to CAD)
[Two full weeks until Practice Day event]
The build team started work on the few parts that the whole team agreed are Very unlikely to change. The rest of us are making final decisions in the Embodiment Design phase. Eve and I are a little behind because we should have had engineering sketches for our design by now…


All season Coach has been telling us to keep a record of EVERYTHING we do, say, or think regarding the project…as Coach says, “Keep everything from napkin sketches to brainstorming worksheets to detailed drawings…”

Well I took a peek at Gadget’s design journal this morning. There were actually sketches of an automated napkin dispenser!!! Gadget had completely misunderstood Coach’s reference to “napkin sketches.”   …we were all ROTFL, especially Roomba!

Of course, Coach thought it was a good chance to review the different types of engineering “drawings”…so, here we go.

Class notes on…



“Napkin” Sketches

These are any quick doodles to convey or capture a basic idea. They are quick and rough. What does an engineer do when sitting at a donut shop and a grand epiphany pops up? Grab a napkin and scribble it out! Coach says these are gems that need to be guarded like treasure because they get easily lost in the shuffle. I’ve learned to just staple them in my design journal instead of copying them. It is amazing how often a little detail in the idea gets lost in the translation to a formal sketch. Going back to the napkin sometimes reminds me of the more creative parts of the idea.


When they are used most? To capture general ideas quickly and then move on.





Engineering Sketching

engr sketch

These things take a little more time than scribbling on a napkin…but, they give you a lot more information about the design.  Some pictures look “3D” and others are just plain 2D picture (ha! a pun). Though the 3D pictures make a lot more sense when studying a part, the 2D are actually easier to draw…go figure.

Sketching is generally done without drafting “tools” other than pencil and paper. But, there are specialized grid-papers available to make it a lot easier. (Square grid is used for 2D drawing and triangular grid is used for 3D drawing.) Basic variations in types of lines can be used to indicate center lines and hidden lines. Only overall dimensions are included when essential to communicate the general idea.

When they are used most? Leading up to prototyping or quick design reviews.



Okay, imagine the part and draw what you see one line at a time. This much I can do. But, what about the other side you can’t see? And, how do you know how thick each piece is if all you can see is the front?

Apparently, someone figured out this cool way of representing a real 3D object using only 2D pictures on a page. It’s called Orthographic Projection (truthfully, only “third angle orthographic projection” makes any sense to me).

Coach datalinked some videos to the team’s collective net…I’ll review them later.

Engineering Drawing

This is where most people think “CAD” (or computer aided drawing) because the details can get scary. But, “engineering drawing” is more about “what” is in the drawing than “how” the drawing is produced. Like a sketch, an engineering drawing includes information about geometry and dimensions. But it also may specify tolerances, materials, and finishes. There might also be a lot more different types of lines to tell different things about the part…this is certainly made easier with a CAD program (huh? is this computer aided drawing or computer aided design?)


Because every company tends to have a different way of doing everything on their drawings, our team created our own company “drawing policy”:

  • standard paper size to use
  • format for title block information
  • types of lettering and font to use
  • where to use flag notes
  • how to name and number drawings so we know how parts fit together


This is the first draft of the brush holder…we don’t know if the acrylic or the PVC (flattened from the sewer pipe) is going to be easier to bend into shape.

When they are used most? To impress the BEST notebook judges (ha!).

This article differentiates types of “drawings” which engineers rely on

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