How to creating a proper engineering drawing? 5

[JimboJones21]

Hi, I have a new job where I need to take CAD models and create manufacturing drawings for the parts.

Are there any books that teach how to make a manufacturing drawing? I have a copy of the ASME standards, but they don't teach how to make a "nice" manufacturing drawing.

I don't want to bother the senior engineers with my questions about what needs dimensioning and what needs GD&T...

Anyone know of any books or resources I can use to help me??

Thanks.

 

[ewh]

Try here -> forum1103


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

 

[drawoh]

JimboJones21,

Bother the senior engineers.

If they want this thing done their way, they are going to have to help you. They understand your company's requirements. Hopefully, they have had the sense to talk to your fabricators, inspectors and assemblers, and there is knowledge to be passed on to you.

There is no sympathy for know-it-alls who screw up.

JHG

 

[SnTMan]

Study existing drawings

Regards,

Mike

 

[rb1957]

don't most CAD packages have a "print 2D drawings" option ?

 

[ewh]

Find a good, general text book to start with to get a foundation of why a good drawing looks as it does. Something similar to those written by French & Vierck. Used hardcovers are 32 cnts plus shipping on Amazon. This will give you a foundation from which you can then study the various applicable standards.

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

 

[Cockroach]

I would contact SolidWorks or AutoCAD and find out when and where they offer tutorial classes. Might as well do it right, right from the start. You can also find classes in the evening and weekends at your local technical college. Heck, I've even seen some online through websites. So there is no shortage of sources.

I would interprete "looks good" to mean "functional". I only have one rule: if the machinist needs to stop the equipment, pull up an alternate source like the Machinist Handbook, ask a question or make a phone call, then the drawing has failed. Tell the man what you want and not how to do it!

I've found some really excellent textbook references in antique book stores, some dated back to 1897. I buy them just out of curiosity and see the history and development of the machining practice. Some pretty amazing stuff. Still, machines such as shapers and methods in hobbing gears are practical in today's age. Old book stores would be another avenue you could investigate.

Good luck with it, stay focused on functionality of the print.

Regards,
Cockroach

 

[mcgyvr]

Solidworks/Autodesk do NOT offer classed on how to make "proper drawings".

You bother the senior engineers..You study the companies existing drawings. You need to at least know design intent from the engineers. How the heck are you supposed to know what tolerances need to be applied/where,etc.. (hopefully this is in the models already..it should be)
You need to know how the parts will be made so you can put the correct information on the parts.

 

[MadMango]

Creating industry/coporate standard drawings and "...questions about what needs dimensioning and what needs GD&T..." are two entirely different things.

For the first, as suggested, review existing drawings. Chances are you will find an existing drawing that covers something new. Get to understand what the general notes mean, why they were used. Talk with those that will build from your drawing, get their input in case you need to add clarification. Rise, repeat.

For the second, you'll have to pick senior brains, no way around it, unless you designed it yourself. The application of proper GD&T is covered in forum1103.

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


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

 

[MintJulep]

Drawings need to completely and unambiguously define the geometry of a part.

To accomplish that, every feature needs to be located in three dimensions.

So step 1 is make sure that every feature is fully located.

The dimensioning and tolerancing scheme required has to do with how the part need to function.

[simplified example]If the relative location of two features is important, then the distance between them should be directly dimensioned, don't dimension them both to an unimportant feature just because it's easier to draw.[/simplified example]

So step 2 is understand how the part needs to function.

Drawings should define what you need. Not how to make it. However, it sure is useful to understand how things can be, and are likely to be made.

So step 3, go talk to machinists - good ones. If you don't have machinists, at least try to find a good estimator who understands how things are made.

Modern CAD tools all have "dimension shot guns". At the click of a mouse you can very easily scatter random dimensions over the entire drawing. This will result in a really crappy drawing.

 

[ewh]

Drafting software does not a drafter make.

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

 

[rb1957]

sorry, but are we talking about designing or about drafting ?

 

[ewh]

"proper engineering drawing" seemed like drafting to me.
Models already exist and the OP takes them and makes drawings, thus I think it is safe to say that drafting does apply.

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

 

[bigTomHanks]

Think in your mind "what information do I need to make this part?" This is how you make a good drawing for manufacturing and then have the seniors check your work for awhile so they can point out things that only experience can teach you. As others have said look at some of the other existing manufacturing drawings and try to see what they did and try to think about the "why" of each dimension and call out.

 

[chicopee]

I would suggest go to a local institute for a drafting program that can put you on a fast track or get private lessons from an academy instructor, otherwise, you may not have that job for long. Also explain to your boss of what you are doing.

 

[rb1957]

i thought it was a drafting question, too ... but he got a bunch of what seemed to me to be design answers.

and we should note his field, electrical, so he probably hasn't had much drafting instruction (if mech's get that these days).

GD&T would be a good place to start.

 

[Cockroach]

Yeah agreed. Seems to be more design related answers than "drafting". Sure hope that doesn't answer the question!

Regards,
Cockroach

 

[ewh]

You should be able to correctly project views, extract details, understand differing line weights and fonts and other basics (such as "dimension and extension lines should not cross), before you tackle more design oriented tasks, such as GD&T.

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

 

[chicopee]

Well the OP seems to indicate a lack of knowledge about drafting practices.

 

[Walterke]

"JimboJones21 (Electrical)"
I guess that says it all.

P.S.: I didn't know "OP" was used here.

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