Request for Recommended Approaches for Determining Projection Type in Engineering Drawings 2

[Jupshaw]

Dear Engineer's,
I'm reaching out to seek your expertise on a challenge I've encountered in interpreting certain engineering drawings.

In some instances, I've come across drawings where the projection type (first or third angle) is not explicitly mentioned in the drawing or accompanying notes. To address this issue, I've been employing a workaround by redrawing an established view in Solidworks 2D. By manipulating the drawing, I can visually confirm which oriented view aligns with the original drawing.

While this method has proven helpful, I'm curious if you or your team have encountered similar situations and devised alternative approaches to confirm projection type. I'm particularly interested in learning about any methods that may provide more definitive results or streamline the process.

If you have any insights or recommendations to share, I would greatly appreciate your input. Your expertise in this matter would be invaluable in enhancing our approach to interpreting engineering drawings effectively.

Jay.

 

[Garland23]

The easy answer would be to say that the projection symbol (a cone) should be on every drawing.
But the official answer might depend on whether you are using the ASME or ISO standards for drawings/dimensioning.

 

[Jupshaw]

@Garland23
Yes, agreed but in my situation, there was no symbol or interpretation that indicated if it was Third or first.
From your response, are you suggesting that depending on if its ISO or ASME standard will also determine the angle projection type?

 

[CheckerHater]

are you suggesting that depending on if its ISO or ASME standard will also determine the angle projection type?

Yes. In ASME-land third angle projection is practically a law. The ISO-world is leaning towards first angle projection.

And I have seen sending out drawing without cone symbol and getting back mirror image of what you were expecting.

Strangely even after that the cone symbol was not added to the title block.


"For every expert there is an equal and opposite expert"
Arthur C. Clarke Profiles of the future

 

[ctopher]

I agree, it should be on the dwg, and on the templates.
Also, others should be taught how to interpret dwgs. I have seen too many times parts made wrong because people don't understand how to look at views (top or bottom?).


Chris, CSWP
SolidWorks
ctophers home

 

[3DDave]

Adding a reference trimetric view of the part will remove significant amounts of ambiguity, even better than the cone.

 

[Jupshaw]

@3DDave
Yes, importing a reference trimetric view reduced confusion or uncertainty about the part shape and dims which is how I confirmed the non-conformity of part. My now question would be, are there any other strategies that would confirm my assessment that has not been mentioned above?

Also Thank you for the advice guys!

Jay.

 

[jassco]

Hi, Jupshaw:

What you did is a band aid approach. You need to correct your sheet format(s) per ASME Y14.1M. See section 8.1 - Angle of Projection Block. See also Fig. 1.

Best regards,

Alex

 

[geesaman.d]

I would get a statement from the customer that states which projection is to be assumed if no projection is clearly indicated.

My company is like many others; our drawings from years ago were done for our shop or the vendors down the street. ANSI drafting practices were barely in place, we were all taught by the same schools to do things about the same way. Only when we started cross-pollinating our drawings to global suppliers and vice-versa did projection angles become a question.

One brand new drawings there isn't much excuse for a customer to not indicate projection as a note or cone symbol. Older drawings can be a real challenge - if I had a dollar for every time a management type has declared 'revise all of the drawings' but didn't know how to answer 'which of all 150,000 drawings should we revise first?'... So that's why it's reasonable to have the customer at least put a blanket statement in writing about the not-specified condition.

David

 

[3DDave]

"What you did is a band aid approach."

A trimetric is an approach that nearly guarantees understanding. People can overlook the cone symbol very easily; the equivalent of telling people the traffic light is red or green when there are color blind drivers.

The bandaid was the cone symbol when creating a trimetric view was costly or difficult. Except for those stuck in 2D, hand projection land, there is no excuse not to have a trimetric.

 

[CheckerHater]

People can overlook the cone symbol very easily

People can mistake ISO tolerance with thread pitch and complain about it being "too small".

I've seen it, but it's not an excuse. People working with drawings must be thought to read the drawings.

Just my ¢2

"For every expert there is an equal and opposite expert"
Arthur C. Clarke Profiles of the future

 

[3DDave]

Surgeons should just keep track of what they are doing, but they still make a nurse count the sponges anyway.

Life is full of little surprises and experts should never make mistakes, but that isn't an argument for not making obvious that which might be overlooked.

 

[jassco]

Hi, 3DDave:

I agree that a trimetric is an approach that nearly guarantees understanding. In fact, I use it all the time myself. But angle of project block is required per ASME Y14.1M.

Best regards,

Alex

 

[Burunduk]

If that's such big issue, you can just avoid both types of orthographic projections, and dimension everything on trimetric views.

 

[3DDave]

Only on drawings prepared in accordance with ASME Y series drawing standards is it required. Another antiquated excess.

 

[jassco]

Hi, 3DDave:

I disagree with you on this one. If you were to have a dispute with your vendor and you did not indicate angle of project on your print, you would not have a case at arbitration court. Angle of projection needs to be explicitly stated.

Best regards,

Alex

 

[3DDave]

Hold up the part. Hold up the trimetric. Ask the court if the handedness of the part matches the handedness of the trimetric.

I would be more pleased if ISO, et al, would drop first angle projection completely. Fire up the trash burners and feed every 1st angle drawing in.

 

[MintJulep]

The cone is the accepted way to explicitly state the projection of the drawing on the drawing.

Yes, a trimetric or isometric view certainly helps the viewer understand the part, but this requires the viewer to make a deduction of the projection used.

[sarcasm]This is just like how every book explicitly states its language on the cover. Otherwise the reader would need to attempt to read the book and deduce if they understand the language that it's written in.[/sarcasm]

Many years ago I was commissioning a machine in Turkey - a first-angle projection country. I needed the facility's machine shop to make me a simple part, so I made a sketch in third-angle projection and took it to the machine shop.

Many confused squints and hand gestures from the shop foreman trying to interpret my pretty simple sketch.

After a few minutes I understood the cause of the confusion. I drew the third-angle cone on the sketch and immediately got a big smile and thumbs-up from the foreman, and got my part a few hours later.

 

[3DDave]

I'm sure a cone can fix it, if people are by default always examining the cone. In your case, you were there to specifically clarify it. But for a 3, 3, 3, 3, 3, 1, 3, 3, 3, 3, 3 with 100 3rd angle and 1 1st angle getting to the floor, I bet the 1st angle will choke the process, particularly if it would result in a valid 3rd angle part.

Just creasing the paper to show that the projection is back rather than front might have done the same as the cone.

Quoting myself: "Except for those stuck in 2D, hand projection land, there is no excuse not to have a trimetric."

 

[Jupshaw]

@3DDave,
could you direct me to the link and a snippet of the ASME Y standard where it mentions that the angle projection symbol or interpretation should be present on the title block or anywhere on the drawing.

Jay.