Should I include all the details on the parts drawing 4

[Windback]

Hello everyone,

I have designed a steel part for machining and while drafting it, I fully defined all the functional surfaces as precise as needed. Then moved into other features but there are some features that I don't want them to fully dimension and restrict with tolerances because these features would be ok either way. The reason is that I don't want to deal with non-conforming parts at the end...

On the other side, ASME Y14.5 PARA 1.4b states "Dimensioning and tolerancing shall be complete so there is full understanding of the characteristics of each feature.". I got confused here, what should I do should I follow the standard or should I stick into engineering intent? What is the general practice for these situations. Any comment, advise and/or idea will be appreciated.

Thanks in advance.

 

[Jboggs]

"it's a steel part, not an assembly, and it's for the manufacture of said part and all its features"

OK. Here's another example. Drawings of machined castings or weldments are often created separately from the original casting or weldment drawings. The designer of the machining drawing will often have some very good reasons to include some of the basic dimensions of the original casting or weldment, simply for the machinist's information. These dimensions are not for the inspection of the machined part. They are to assist the machinist in handling and setup. As such they should have the REF callout in my opinion.

 

[3DDave]

Jboggs, Please stick to the original problem statement about which I had a queation instead of finding other areas that are off topic.

"I have designed a steel part for machining and while drafting it"

A steel part. Not a casting, not a weldment of many parts, "a steel part."

The OP says of that part there are features that don't matter what configuration or dimension they are. I want to know what the original problem submitter had in mind, not what you imagine someone else might have had in mind.

 

[Jboggs]

Sorry if you feel I wandered "off topic". I was just trying to give examples of dimensions that might appear on a drawing, any drawing, which might have some other purpose than strictly part definition. Even on individual part drawings, I have included REF dimensions which by strict rules would over-define the part, but were still useful for "reference purposes" by other users of the drawing.

 

[AZPete]

"...while drafting it, I fully defined all the functional surfaces as precise as needed. Then moved into other features but there are some features that I don't want them to fully dimension..."

You drew the lines. The machinist will have to replicate your lines. In order to QA the product, someone needs to know how much delta from Design to Actual is allowed, as all produced dimensions are some measure of deviation from perfect.

While you are OK with untoleranced features, the drawing remains mute on them. The machinist and inspector need to know where that line of demarcation of acceptable vs unacceptable is. There is always a line, even if it exists solely in your thoughts. You may as well express it in the drawing. It may be an overall tolerance, block tolerance, something, anything, just so long as the question is answered and a third party reviewer can adjudicate it clearly and repeatedly.

'On the other side, ASME Y14.5 PARA 1.4b states "Dimensioning and tolerancing shall be complete so there is full understanding of the characteristics of each feature."'

Imagine that you are an employee on an errand for the boss and you are instructed to go to HQ and give Envelope #1 to Executive So-and-So, Envelope #2 to Director Who-Knows, and Envelope #3 to some important employee but no one TOO important. Ugh. Clearly, the envelope has an intended destination, no? But, yet there is an open-endedness to it, but also subject to some arbitrary and unintelligible condition.

Specify completely. Be generous in your tolerancing to the point of your tolerance.