Internal Planar Continuous Feature 2

[jnelson33]

Hey All,

Y14.5 R2018 permits the use of continuous feature on external planar surfaces now.

However, my engineer's drawing I'm reviewing has applied it internally.

Intrinsically, this makes sense in what it intends, but it's not explicitly explained from what I could read in our book so I prefer not to use it. (No salt please: I don't have a PDF where I can Crtl+F and search the whole standard quickly, and we all know the lack of an index in the book is a wild oversight)

Secondly, I didn't see anything about adding continuous feature to a basic dim either. It doesn't seem proper, but a profile tolerance is also applied (hence the points), so without a continuous feature symbol it would be ok with what I know.

Here's a picture of what I'm talking about:

There's a variety of methods I can use to convey what we want in the real world, but I know why my engineer chose this: Less dims and control frames to add to the drawing. I really wanted to open a discussion on this to see what others think.

If I present my design review correctly, this more complicated design will be eradicated, but I need some backup as there's no GD&T SME I can consult at our company.

Thanks!

 

[greenimi]

Maybe "your engineer" lacks proper standard (Y14.5) knowledge

 

[Burunduk]

As long as the planar surfaces are controlled by the same profile feature control frame, there is no need for the continuous feature symbol. The profile control will achieve coplanarity between the portions, within the profile tolerance.

 

[jassco]

Hi, jnelson:

This statement below does not make sense.

"Y14.5 R2018 permits the use of continuous feature on external planar surfaces now."

Continuous Feature exists before ASME Y14.5 - 2018. It can be applied to any features, external or internal.

There is nothing wrong to attach CF symbol to a BASIC dimension. I agree with Burunduk. There is no need for this continuous feature symbol if you have a profile feature control frame.

Best regards,

Alex

 

[Wuzhee]

We're still not seeing the profile FCF so anything is a guess from the start...
Make your questions unambiguous, else there'll'be a lot of unnecessary questions to answer.

 

[jnelson33]

Apologies for the lapse in replying.

CF was removed because I thought it was also redundant.

I added extension lines to the drawing to reduce assumptions.

This is a real part we're working on so I couldn't share the whole thing.

I also didn't have time to create a basic model to show what I was talking about.

Either way I appreciate the replies.

BTW jassco, I wasn't saying it didn't exist, only that 2018 allowed for it to be on planar features, not just turned features as I understood: gdandtbasics link

 

[Burunduk]

That gdandtbasics description in the link is not accurate. The symbol per the 2009 standard was not limited only to features of size, it is a common mistake. The confusion was caused by the standard not being clear enough about it. The defining paragraph in the symbology section (section 3) only referred to examples of FOS, but the definition itself did not indicate such limitation. The symbol was integrated incidentally in an example in the position section showing CF applied to a datum feature symbol related to an interrupted feature without size, replacing what is commonly specified by a note such as "2 SURFACES" for the datum application. But that was not the topic of the example and none of the paragraphs covering the meaning of CF referred to that example.

With that said, the application of the symbol in the OP image is incorrect. To make sense, the symbol must be placed next to some specification that treats the two portions as one. It could be a feature control frame for a geometric tolerance, or a datum feature symbol. For a feature of size, it could be a directly toleranced size dimension. The symbol shouldn't be called out as stand-alone or related to a basic dimension.