Today a mentor and I were having a discussion about 2D Engineering Drawings. A few students were CADing a part that they had an engineering drawing for. The drawing is an assembly with separate pages with individual parts. Each individual part has only one sectional view on the page (the part is cut in half, but revolved). Given your expert opinion, what orientation (Top, Front, or Right side) would you say these parts are? Both of us had different answers and I would love to see what you all think.
I would say the convention of naming Top/Front/Right are so subjective and contextual that this would be an impossible question to answer.
The front view is traditionally the one that shows the overall contour of an object; where the important functional parts are; often the one that shows the longest dimensions. General rule of thumb is if somebody is asked to draw a 2D sketch of the item, the first inclination would be the “front” of it.
Where this gets tricky is if one is drawing, say, a school bus. 95% of folks asked to draw a school bus would probably draw the face showing the entry/exit door, the windows, the tires, etc. However, the actual front of the bus would be the headlight end, right?
To make orthographic projections on a landscape-oriented page, I would argue the “front” view of the bus would be the actual “side” of the bus, with the taillights on the left side and the headlights facing right. This would make the headlight end the “right” view, and the “top” view would be aligned with the long edge of the paper.
Similarly, round objects could be mounted in any orientation. For headlights, the circle is seen in the Y direction; for Andy Griffith-style police lights, the circle would be about the Z axis. But if I would make section views of them, they’d be oriented identically.
<.disclaimer> If a pile of engineers comes in and prove me wrong, that’s a lesson I’m happy to take. <./disclaimer>
Thank you both for your reply. I agree with both of you. It is a very weird drawing. We bought these shafts that build a gearbox assembly for an offseason project and this is the drawing that was downloaded for the shaft as they do not have any CAD models! Obviously this is a section view, so how would you guys CAD it? At this point, it is just for our curiosity how you guys would do it.
Front/side/top/whatever view is completely immaterial when creating a drawing. The drafter/designer/engineer should seek to create a drawing that fully captures the part(s) feature(s) with as few views and dimensions as possible while being as easy to read as reasonable.
I would add three other things:
Making good drawings is hard and requires a lot of focus and practice, and I encounter many bad drawings in my work.
Do not ever think that there is only one correct way to create a drawing or type of drawing.
You may run into someone(s) who tell you that drawings must be done a certain way and they are not always right.
Story time: I have worked for (sadly) a couple individuals who told James Meadows, to his face, that he was creating a drawing and GD&T in correctly. Now you may be wondering ‘who the heck is James Meadows?’
Here he is!
Here he is again!
Yeah… they told the guy who literally wrote the book on much of the modern drawing and dimensioning practices that he was wrong. (It was a shame because he’s a super nice guy and gives his email to all of his students so you can ask him questions in the future, which I have done several times.)
Suffice it to say that they were wrong, Meadows was right, and the drawings we make at my work suck a whole lot less now after some… heated discussions.
Yes, as I consulting/contract engineer, I have run into so many clients who have their way of arranging the dimensions, or standard views that only they use, and they get so indignant that theirs is the only right way.
Any drawing that contains all the necessary information for making and inspecting the part/assembly without being hard to read is a good drawing. Depending on the purpose of the drawing you might not even need to dimension all the features. It is common place in my industry to only show overall dimensions on sheet metal parts to be cut on a laser, and rely on the DXF or 3d model for actually cutting the part.
Spot on. I always have taught that the FRONT drawing should be the largest and most descriptive view of the object. Your bus analogy is perfect for understanding ‘front view’ for an orthographoc layout. I will be using this in my Mech Design classes here forth!
I have no idea where I saw someone’s “rules for design projects” but the gist of one rule is learn to draw because the best drawings are the ones that advance to prototypes. The first Saturday of the year and I suggest to students to take an extra minute to make a better sketch.
I have always been curious how infrequently, since my high school drafting class using blue printing, I’ve heard people use the terms isometric and orthographic. Search the terms on ChiefDelphi for example.
I agree with the others:
A good drawing or drawing set for something exposes adequate details to understand that thing. Exposes, as well, any details lost if as a matter of perspective or requirements it can not be illustrated.
If you present me a drawing set for a school bus it should be notable to me that said surface is the outside of an object that has cavities and other elements within it. That may seem obvious with a school bus, but it really does matter you communicate consistently and fully resolve important details in this process.
To extend this: if I give you drawings of 3D object to be printed on an FDM printer with a specific infill pattern in a specific orientation to the outer more solid surface (like a gear), it quickly becomes obvious why that detail should be acknowledged.
I don’t see the actual item being described, so I’ll leave my comment at this point.
My particular problem as a consulting engineer, is the companies that don’t give precise, thorough drawing standards, then complain that our drawings aren’t “right”. For reference I usually work with any given client on a single project for a few weeks or maybe months at the most.
For anyone out there looking to hire outside engineers for your projects, prepare detailed drawing standards or plan on altering the drawings in-house if you want more than any valid drawing containing necessary information. In my experience your going to spend a lot more time and money on emails trying to decipher your unwritten drawing standard than you would do your own corrections. (This would be different if the project contains many rounds of drawings over the course of a large project)