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Understanding Drawings
26

Understanding Drawings

Understanding Drawings

(OP)
Hey,
I have diificulty reading drawings, my understanding is improving the more I look at them but I was wondering if anyone has any methods or tips that helped you when you started?

RE: Understanding Drawings

Hi AndrewMech

What sort of drawings are you trying to understand?

desertfox

 

RE: Understanding Drawings

(OP)
It's mainly labyrinth seals and valves,
but help or tips on just general drawings would be greatly appriciated.

RE: Understanding Drawings

2
I find that the way most people are able to grasp the nuances of drawing interpretation is by redrawing it.  Sit down with a couple of drawings in your spare time in front of a computer and redraw the things.  You will gain a wealth of knowledge.

Dan

www.eltronresearch.com
Dan's Blog

RE: Understanding Drawings

2
Or better yet, take some parts and try laying out the views required to machine it (hand sketches).  Seems you have a hard time translating a flat drawing into a real object, so perhaps by doing the revers you will get a better feel for the drawings in the future.

"Art without engineering is dreaming; Engineering without art is calculating."

Have you read FAQ731-376: Eng-Tips.com Forum Policies to make the best use of these Forums?

RE: Understanding Drawings

2
Of course it may not be you.

It seems that the capability of producing a good drawing is a lost art.

 

RE: Understanding Drawings

2
Glad Andrewmech you asked a question. that is the first tip.When in doubt ask? Do not assume,for in your later career,you might commit grave errors by wrongly interpreting drawings. Also study the drawings,by placing them on a large table,brightly lit and a lens to go with. I have made some mistakes for not following these tips.

As you are concerned with valves,these are pretty simple have some old drawings and place them against the valve and start reading the drawing,slowly you will begin to understand the details. I too learnt the very hard way.   

Learn the rules,so you know how to break them properly.
Dalai Lama

_____________________________________
 

RE: Understanding Drawings

2
You are in a great position to learn to read drawings.  I learned the same way, by having to make parts from drawings.  Really helps when one is later in the position of making drawings.

Practice!  Practice!  Practice!  Don't be too quick to jump to conclusions.  Give the whole drawing a look before you start cutting.  Start by getting the big picture (especially how views are related to one another) and work down to details.

Your efforts to learn will be hindered by drawings created by people who have less than a full clue about how to properly draft.

RE: Understanding Drawings

2
This is a can of worms! You didn't mention which side of the manufacturing process you are on.

You may be reading poorly drawn drawings. Today's manufacturers have little time allocated for proper drawings: the old 'draw it and get it out the door as fast as you can' mentality of apparant cost effectiveness creates ripples of confusion all the way down the manufacturer/installtion/application lines. Expert draghtsmen (women) are becoming a rarity, especially those with board experience.

You may have a spatial block on your thinking: can you visualize in 3D? Can you move, change, rotate your visualizations? Most people cannot; every expert designer and drafter can. In this case you might research improving your spatial skills, visualiztion and such.

It could just be experience: you have not had enough exposure to drawings and their real world results. If you have access to a shop, assembly plant or supplier plant then walk around (if allowed) and look at what the assemblers, fabricators or workers are producing from what drawings (examine both).

Modern schools of engineering place little emphasis on drawings yet they are the fundamental link between the mind of the designer and the the real world result. Overcomplicating drawings with useless information creates too many questions and so, confusion. Too little information has the same effect. Experience is the teacher here. If you have access to many drawings then start studying the older designs and their parts in hand (if available) and you will see the cause-effect at work (or not).

Good luck.

RE: Understanding Drawings

2
Andrew

follow the advice of all these good suggestions.

Is there some one helping you?
do not try this alone,
Ask for help if not sure what the drawing is requiring.
there is no shame in asking. there will be if you make a mistake.

Look a previous made parts & review it with drawings.
this will help. It is hard even for some season machinist or sheet metal guys to under stand what has to be accomplished. so they ask for assistance.

It will take lots of Instruction from more experience persons & lots of patients. do not rush since you are an
apprentice.
Take Blue print reading & drafting classes this will help.
Having a mentor will make your training & Job much easier.

Take Care

RE: Understanding Drawings

Really great answers above.  

My ruled of thumb is that spoken communication is maybe 25% effective.  (The listener hears and understands about ¼ of what the speaker meant.)  Communication with drawings properly done to a standard convention may hit 90%.

Also, if you are in a project and someone objects when you ask questions, get out of the project as soon as you can.  

Happy Thanksgiving,

tom
 

Thomas J. Walz
Carbide Processors, Inc.
www.carbideprocessors.com

Good engineering starts with a Grainger Catalog.    

RE: Understanding Drawings

Many people struggle with reading drawings when they first start out.

An old trick taught to me many years ago was to cut out or trace the views from the drawings and transfer them to some thin card and make a model with the aid of some masking tape or even model it up out of a piece of plasticine, you can always add bits on that way. It soon becomes second nature to "see" what is going on.
 

RE: Understanding Drawings

AndrewMech (Mechanical)
A simple learning tool you can make yourself, take a piece of 1" square bar stock cut it 2" long, cut one end off at 45 degrees, you will now have a piece 1"x 2" on one face, 1"x1" on the other and a sloping side on the other two faces. Paint every face and end a different color.
You can now use this to visualise different views as you would see them on a drawing.
B.E.

RE: Understanding Drawings

Our organization required a 3-dimens miniature on dwgs to aid visualization. This was for details as well as assys. It would have helped you.

Taking a course in free hand sketching was one of my foundations in visualization. Spatial visualization is important to building engineering conceptions.  

RE: Understanding Drawings

(OP)
Hey,

Just wanted to say thanks for all of the suggestions and im going to give as many of them as i can a go. Ive found this forum extreamly helpful and will hopefully be using it regularly.

Thanks again

Andrew

RE: Understanding Drawings

Are you looking at plan view drawings as such as construction or blueprint drawings, or are you having difficulty with isometric/machine drawings?

Project Engineer
http://www.cognidyn.com/
 

RE: Understanding Drawings

Quote:

Modern schools of engineering place little emphasis on drawings yet they are the fundamental link between the mind of the designer and the the real world result.

The reason is because the professors, mostly with little real world experience, expect draftsmen with a 2 year degree to be creating drawings from your designs.  I was lucky enough to have people mentor me at my previous employers of the importance of a proper drawing.  You learn quickly that red ink is your friend.

RE: Understanding Drawings

To add to the mostly good stuff above...

There are 'industry standards' for drawings.  Now while not everyone (anyone?winky smile) sticks to them 100% many of the general ideas in them apply to all but the most poorly done drawings.  If in the US you want to look at the ASME Y14.100 series of standards, 14.3 & 14.5 will probably be most useful, if your employer doesn't have them maybe the library or somewhere will.  Even if the library doesn't have them it may have drafting books based on them.

They will lay out some of the fundamental rules/ideas behind projection of views etc, define common symbology and most other major drawing conventions.

So when I started, I asked lots of questions, I'd also spend time (much of it my own) looking at the drawing standards and one of my colleagues drafting books.

There are also some other forums on here that may be of more specific help such as:

forum1103: Drafting Standards, GD&T & Tolerance Analysis
forum281: Machines & Machining engineering

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What is Engineering anyway: FAQ1088-1484: In layman terms, what is "engineering"?

RE: Understanding Drawings

Murphy's Law;
There are lots of dimensions on a drawing, except for the one You need.

RE: Understanding Drawings

Ahh..., the mistake of not taking care of basics & fundamentals in the modern engineering curriclum. Whatever happened to Drafting and Engineering Graphics & Technical Communications? Oh yeah! The computer took over and now it's supposed to do everything. One problem, "garbage in equals garbage out".

Time too return to basics and the Professional Engineering Degree Program in the Universities instead of the simplified B.S. Programs.  

 

RE: Understanding Drawings

I had trouble interpreting a drawing when working at "Commercial Machinery Fabricators" corporation. I am a degreed engineer with a background as mechanic, machinist and machine builder as well... between jobs at the time, I was hired as a welder, then moved to the lathe when the lathe operator had a heart attack.

"Cut these shafts" said the stuporvisor [sic]... "here's the drawing."

3" dia. steel about 18" long, to be turned down on the end to.... get this...

2.500" +/- 0.000"

I kid you not.

I laughed and laughed. The stuporvisor tried to insist that the drawing was correct, and to follow it. I tried to explain that machining to a tolerance of "zero" is not even possible, but if one were lucky enough to get one part to measure exactly on spec within  0.0005" then after removing it from the machine and cooling it, the dimension would differ to outside the "spec".

Good grief.

Examining the pile of parts left by the usual operator led me to the conclusion that the actual dimension was 2.500 +0/0.020" or so. Basically, to fit into the wheel bearing w/o too much slop, er, "clearance."

RE: Understanding Drawings

KNOW - and even more important !! - fully understand the the way we (engineering and draftsmen) define the section views, plan view, elevation and detail views.  

EVERY one of those little arrows and "notes" and letters and numbers and abbreviations on the piece of paper you are looking at has a meaning.  The "intelligence" of the whole comes from how you integrate those details together (looking from the left side towards the right, looking from "above down" in one view and then loooking from the "right side" of THAT section view to "see" what is in the tird view of the assembly.  

Also: the missing dimension is often on the manufactoring or prefab drawing, but is not repeated on the final assembly drawing you are looking at.  A forged piece may get many of its dimensions from the orignal "casting" drawing, then the forged piece gets machined (with many hundred other dimensions),  then parts get added to the machined piece on a third or fourth "level"  of the drawing.  So the actual dimension for length overall (LOA) may be on any of several earlier drwaings.

Also - notice that there always seems to be another "also" ??  - there are very specific rules for naming and displaying and plotting these projection views: but those "specific" rules for drawings are exactly OPPOSITE each other in Europe and in the US.  This is NOT the metric/ANSI/inches/gage/pipe/steelshape/threads/sheetmetal/wire/plate/rebar measurement problem, but that European-drafted plots will be present the "opposite" side of the machine than what you are trained in if you started in the US.  Alternate: they see our drawings and will produce "mirrir-image" parts because they have been properly trained in the opposite methods.

RE: Understanding Drawings

Quote:

but that European-drafted plots will be present the "opposite" side of the machine than what you are trained in if you started in the US

Do you mean the PROJECTION according to which a drawing is produced??  Any competent organisation will ensure that their standard drawing border will include the projection in words, with the standard 'conical frustum' icon or both.

And it's a mistake to think all those on the East of the Atlantic draw in the same way.  We standardised on third angle more than 50+ years ago because it made more sense (and maybe something to do with WW2).  Of course the Germans all seem to OBEY the DIN standards

RE: Understanding Drawings

The best drawing should be easily understood by everyone, in any place, without the need of interpretation beyond basic knowledge on the object been presented. Too often, we are forced to guess a piece of work by its origin, trade standards, covnentions ... What a waste.     

RE: Understanding Drawings

2D engineering drawings have always needed conventions.  Without them who would know what was the meaning of the different line styles!

RE: Understanding Drawings

Legend.

RE: Understanding Drawings

Sorry cntw1953, I'll have to disagree slightly.  At least in my little part of the mechanical world, to create a drawing that captured all the requirements, without relying on various drawing and dimensioning conventions set up in standards that the average joe on the street wouldn't understand would be almost impossible much of the time.

There should be little or no guessing in drawing interpretation, if you don't know, ask.  To assume ...

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What is Engineering anyway: FAQ1088-1484: In layman terms, what is "engineering"?

RE: Understanding Drawings

Don't meant to argue, but how do you like to see a civil engineering plan without N/S arrow?

Prints made in 19xx
Company out of business
Author unknown

Popular Convention:
A - North to the left
B - North heads up
C - North follow flow direction

Sure it finally gets figured out, just a little time and some frustration.

Just a few days ago I realized I have interpreted the stock up and down in a completely reversed manner by looking the color of the number indicated in China website:

Red - DOWN (in US), UP (in China)
Green - UP (in US), DOWN (in China)

Glad I didn't throw any money in the trap.

Best practice - provide some consideration to readers...
Maybe I am asking too much, but that's the way I do.

RE: Understanding Drawings

Just remember, it's called detailing for a reason. If any piece of geometry is not explicitly defined on the drawing (or in a specification referenced by the drawing), then the drawing is wrong.

Luckily, there are a lot of great tools to help an engineer or designer communicate exactly how parts should look and fit together available in ASME Y-14.5M-1994 (newer standards are available, but 1994 is quite widely referenced). It's 250 pages long and explains how to use Geometric Dimensioning and Tolerancing quite well.

Nonetheless, it may be a bit difficult to pick up off of the bat. If you'll be dealing with drawings extensively, you may consider taking an ASME class. ASME offers some good online classes that will get you up to speed on working with drawings. Good luck!

RE: Understanding Drawings

For those of you who commented on Engineering Schools lack of education with regards to reading and generating drawings, here's a little food for thought.

The modern Bachelor of Science engineering program is literally stretched to the limit.  Most schools have reached the required credits limit allowed for a bachelors degree (I think it's 128 credits) and are now having to make very difficult decisions about what to cut back, or cut altogether.  There is simply too much information to teach a normal high school graduate in 4 years, especially now that humanities (core class) requirements are increasing.

The decision to cut some of the drawing generation and interpretation classes is a pain, but at least it is something that can be picked up quickly with a little encouragement from an angry machinist!

RE: Understanding Drawings

cnw, aren't you arguing against yourself?  Surely if the drawing had followed some convention, and what convention was clearly stated, it would have been easier?

"but at least it is something that can be picked up quickly with a little encouragement from an angry machinist"

Sadly not, or the drawings round here wouldn't have been so bad for so long.

Even in the UK where they don't have the same humanities requirement at least on my degree very little time was spend on design communication or whatever you want to call it.

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RE: Understanding Drawings

In the USA there needs to be more apprenticeship programs in the engineering, & metal fabrication fields. An Engineer graduates from college/Trade now put him or her on an apprenticeship for 4 years.
During which the Engineer, Machinist or Metal Fricator,  is making a living.

Other countries have excelant such programs.

RE: Understanding Drawings

2
I think this discussion is turning into one about apples and oranges.  It seems that cntw1953 is approaching the subject from a civil viewpoint, while many of the others are approaching it from a machinery viewpoint.  On a machinery drawing, legends are seldom used and industry standards are usually specified.  Projection method is also usually indicated, which should avoid problems like that mentioned by racookpe1978.  While necessary dimensions may inadvertently be left off, other "end" dimensions are left off because they are not required to fabricate the part being detailed.  It is poor practice to include dimensions that are the result of previous processes, and if they are included they should be reference only.  A good drawing is a concise drawing.  

"Good to know you got shoes to wear when you find the floor." - Robert Hunter
 

RE: Understanding Drawings

ewh:

"...and industry standards are usually specified.  Projection method is also usually indicated, which should avoid problems like that mentioned by racookpe1978."

True, the lack of above in many otherwise excellent drawings is disappointing, it causes confusion and frustration. (A personal experience after few years dealing with mech drawings from different vendors/regions)

KENAT:

Sorry I didn't make it clear. I meant when you have to "guess" from those non-consistent country/regional/company conventions, it frustrates.

The other example has occurred a few times somewhere in the forum - one mistakenly interpretated the thickness left out by the other was in "mm" because "m" & "kg" were repeatly mentioned in the post. Wrong! It turned out to be "cm", a regional practice/standard of the poster.

I believe most of us here wouldn't make the same mistake. But "never"? Especially when we accross disciplines around the globe.

 

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