Is there any specific way to learn how to check drawings? any books or website that you can provide? 4

[youngEngineer818]

Hello All:

I am a young engineer with 8 months of experience (in designing pressure vessel parts) and BSME degree. I am trying my best to learn as much as I can from my senior engineers. Basically. One of the task for them is checking drawings, dimensions, and see if anything is missing. I am learning how to check drawings from them at the same time to accelerate this process, can you give me some tips, advice, book's names that I can read to learn how to check drawings. I checked the drawings of my company and didn't find any ASME Y14.5 notes on it so I think we don't apply that code in our drawings. Its a general questions so please tell me as much as you can about this topic. My goal is to be a senior engineer and check drawings and sign them off. Thanks

 

[KENAT]

youngEngineer818

There have been numerous threads on this topic over on forum1103, might have been a better place for this question.

thread1103-193286
thread1103-305732 (I give a brief guide in this one for checking a drawing has all required dimensions)
thread1103-234444

As well as some others scattered around.

http://www.eng-tips.com/viewthread.cfm?qid=317633

What are you checking, everything; just basic format & nominal completeness; functional design, manufacturability... Drawing checking can cover quite a range.

Frankly you aren't experienced enough to do a very good job of full detailed checking thread1103-193286 but maybe some of these will help.

Gary Whitmire DESIGN TIPS Checking Drawings

http://www.roymech.co.uk/Useful_Tables/Drawing/Checking.html

http://www.draftsperson.net/index.php?title=Shop_Drawing_Checking_Guide

http://www.hillengineering.com/papers/How to Check a Drawing.pdf

Posting guidelines faq731-376

http://eng-tips.com/market.cfm?

(probably not aimed specifically at you)
What is Engineering anyway: faq1088-1484​

 

[MikeHalloran]

TIP: Check ALL of the drawing.

One of my early jobs involved checking system drawings for big boats. The prints measured 36 inches x ~35 feet. They were stored and transported rolled up. Every once in a while I'd find an image of an applique applied near the far end of the original, comprising a gross caricature of a human foot, annotated "Dimension A; 1 foot". It was a 'checker trap', of course, used to be sure that the minion assigned to check the print at least went to the trouble of unrolling the whole damn thing and looking at it before signing anything.

Your signature has to mean something.


Mike Halloran
Pembroke Pines, FL, USA

 

[Jboggs]

All your research should eventually end up in the form of checklists that can be applied to different types of drawings.

As for physical dimensions, my tips are:
1) Every required dimension should appear once, and only once.
2) It is usually, but not always, best if all dimensions can trace their source back to one vertical and one horizontal feature.
3) Dimensions should be placed according to the end use. If two holes mate to the same part, one of them should be dimensioned from the other, not from some other feature.
4) Minimize any overlapping or crossovers.
5) Stacked dimensions enhance clarity and minimize confusion.
6) If appropriate, ordinate dimensions are a very powerful tool. A great way to transmit information with minimum clutter.
7) Be aware of tolerances, both implied and specified, on every dimension.

 

[ZDR1985]

A good practice is to put yourself on the fabricator's shoes. If you clearly understood every bit of detail on the drawing (in a fabricators point of view), considering you are aware of the specifications of your product / project then you could be able to check the drawings properly and spot what is wrong, what is missing and what is not clear.

Consistency of units, spelling, titleblock completeness, neatness and presentation are the most basic drawing requirements which has to be checked by the drafter/engineer him/herself before handing it to the senior engineer.

 

[MadMango]

I've probably said this in the other postings, but it can be beneficial to review older drawings (pre-1980). A lot more "attention to detail" is present in older, pre-CAD drawings. It doesn't necessarily mean they are more correct (as standards did change over time), but they are usually/probably more complete and thorough than today's modern drawings.

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

Have you read faq731-376 to make the best use of these Forums?

 

[cry22]

My field is HVAC so it may not relate exactly to your trade. So, here are my two cents.

Before I check a mechanical system (HVAC), I look at the architectural drawings, I come up with my OWN concept and do my OWN Calculations (rough calcs of course) and then, and only then I look at the proposed design. I compare my concept with the proposed design, the rational is that my thinking is not influenced by someone's design.

 

[ornerynorsk]

Develop a systematic and methodical approach, and then follow it every time. An outline or checklist can be of great help.

It is better to have enough ideas for some of them to be wrong, than to be always right by having no ideas at all.

 

[KENAT]

Ah, checklists. I'm not going to say they can't help but a couple of thoughts.

To make a truly comprehensive checklist that covers every eventuality would be a tricky task and end up with a very long list. E.G. for mechanical machine design type work ASME Y14.5 is the relevant standard for dimensioning and tolerancing. To come up with a detailed checklist just for all the stuff in that one standards would be very challenging. Then there are other drawing requirements not explicitly in that standard, let along things like functionality and manufacturability checks etc.

Using an abridged checklist may still have merit but, you have to be careful that you don't just 'check to the checklist' but also keep looking for things not explicitly on the checklist.

Posting guidelines faq731-376

http://eng-tips.com/market.cfm?

(probably not aimed specifically at you)
What is Engineering anyway: faq1088-1484​

 

[1gibson]

Build it in your head.

1) Select the raw materials and determine a list of what you would need to order, and how much.
2) Cut the materials, see that they all fit together appropriately (does your flange bore match your pipe ID?)
3) Weld the materials (can you reach that to weld that after it's in there, or do you need to assemble in a different order?)
4) Machine the part if required (can you hit all the critical concentric areas in one setup, or do you have to flip the part? If you flip it, do you have something accessible to line up on?)
5) Inspect the finished product, with the instruments you have available. No easy way to measure from A to B? Add an additional dimension to a feature that can be reached by both. Yes, I said "easy way" for a reason. If it's not easy, it isn't going to get measured.
6) Check the GD&T for cleanup, and check the spelling
7) Make sure the correct initials are in the title block
8) Look for discrepancies. If it says 300# flange but is drawn with a 150# flange bolt circle, there are a number of things that can happen, and the least likely is that you get what you want.

If you're not sure on any of the steps, call somebody, or take a walk out to the shop. You can't ensure it is a good drawing unless you consider the perspective of everyone who will use it. If the fab shops comes back and says "how am I supposed to build that?" you better have an answer. Then when inspection says "how am I supposed to measure that?" you better be able to show them. Then when it's time to rework it, you get the picture.

 

[ornerynorsk]

Checklists are certainly not perfect. However, they are a good tool for the not-so-experienced to develop good habits, and develop muscle memory for the thought process. One thought on 1gibson's list, which is a good list . . . Number 6, make sure to involve the drafters with tolerancing issues. I've seen a lot of very professionally drawn prints in my day that can be made precisely to print, and have absolutely no chance of working properly 50% of the time.

It is better to have enough ideas for some of them to be wrong, than to be always right by having no ideas at all.

 

[1gibson]

And of course, I forgot the most important one. Gather every other relevant drawing that will interface with the one you are checking, and make sure they work together. Maybe your fabrication drawing is perfect by itself, but if you submitted something to a customer that shows a different nozzle location, you've still got a major problem.

 

[youngEngineer818]

Thanks to All who replied.
I have another question here. When do we use ASME Y14.5 codes? I see that our company doesn't use it. How does it effect? why do some companies use ASME Y14.5 and some not?

 

[ewh]

Y14.5 establishes a common definition, which is critical for proper interpretation. You can also use other standards, company or otherwise, as long as it is clear to all involved parties which standard is to be used to interpret the drawing.

"Know the rules well, so you can break them effectively."
-Dalai Lama XIV

 

[MikeHalloran]

Y14.5 is voluntary.

If your company chooses not to use it,
they may have their own standards,
or they may reference other standards,
on drawings or in contracts.

I they do none of that, expect to waste some time arguing with suppliers and customers over drawing interpretation issues. That is a business expense of unknown size.

Management is free to invest a little money in using standards, or to spend what is arguably more money to deal with the repercussions of not using them. That decision is typically above my pay grade, but I may politely point out the related opportunity from time to time.

I have never been good at pointing out management errors, so it has had career consequences for me.
Your mileage may vary.



Mike Halloran
Pembroke Pines, FL, USA

 

[drawoh]

youngEngineer818,

ASME Y14.5 is a language, not a process. If the note on your drawing states that you work to ASME Y14.5, the standard tells everyone how to interpret the dimensions, tolerances and symbols on your drawings. If you don't understand the standard, you don't know what you are telling your fabricators. You might be surprised.

--
JHG

 

[Regret]

Back in the day, and still happening in Germany (Hence Porsche, Mercedes, Audi, Bosch etc), people used to apprentice on draughtsmanship, then apply the detail design, yolerancing and design for inspection and manufacture they learned becoming a draughtsman in their becoming an engineer. My advice to you would be spend time drawing and learning under someone experienced and competent. As the Chinese are doing.

 

[gurkanc]

In addition to the above tips and advices, i may try to expand a bit.. If your company has a redlining system or an issue-management system (related to drawings), you could observe and gather an insight about what typical errors look like. Of course, this is an inverse approach (tells you the right thing by looking at mistakes and errors).