Dimension to Background Lines in a Section View
Dimension to Background Lines in a Section View
(OP)
Quick question: Does it violate standards to dimension to a background line in a section view?
In my view, it's bad practice, but I'm not sure that it's explicitly disallowed by any standards. We do our drawings in accordance with ASME Y14.5-1994. Unfortunately, I don't have my copy with me at present.
Thanks for the help.
In my view, it's bad practice, but I'm not sure that it's explicitly disallowed by any standards. We do our drawings in accordance with ASME Y14.5-1994. Unfortunately, I don't have my copy with me at present.
Thanks for the help.





RE: Dimension to Background Lines in a Section View
"Good to know you got shoes to wear when you find the floor." - Robert Hunter
RE: Dimension to Background Lines in a Section View
I can't remember where it says about not dimensioning to hidden lines, if not in 14.5 I think it's in 14.3 but I don't see it now.
What is Engineering anyway: FAQ1088-1484: In layman terms, what is "engineering"?
RE: Dimension to Background Lines in a Section View
RE: Dimension to Background Lines in a Section View
What is Engineering anyway: FAQ1088-1484: In layman terms, what is "engineering"?
RE: Dimension to Background Lines in a Section View
RE: Dimension to Background Lines in a Section View
RE: Dimension to Background Lines in a Section View
I'm sure there are situations where it makes sense to do otherwise so long as it isn't disallowed, but I find it clearer to limit dimensions in section views to features in plane with the section cut.
RE: Dimension to Background Lines in a Section View
If someone has changed their outlines from hidden to solid, that same someone should get their a$$ kicked.
RE: Dimension to Background Lines in a Section View
I still don't fully understand what you mean by background lines.
It sounds like maybe background lines are lines of geometry not actually visible, what would normally be 'hidden lines' if shown at all.
Dimensioning to hidden lines is not allowed per ASME drawing standards, I just can't remember the exact reference.
If this is the case then I lean towards what CBL says.
"Is there a 3D software that will allow you to turn off these background lines?" Depending what we mean by 'background lines' then yes, most software I've ever seen gives you control over what I'm used to seeing called 'hidden lines'.
What is Engineering anyway: FAQ1088-1484: In layman terms, what is "engineering"?
RE: Dimension to Background Lines in a Section View
"Is there a 3D software that will allow you to turn off these background lines?"
In Pro/E & I assume other CAD programs there is the ability to toggle a section view between "total" which shows the back lines and "area" which eliminates them. I normally do "total" unless the back lines are excessively busy or confusing in some way.
RE: Dimension to Background Lines in a Section View
"Good to know you got shoes to wear when you find the floor." - Robert Hunter
RE: Dimension to Background Lines in a Section View
They're not hidden lines, simply lines from the background of the section cut (i.e. out of plane). UG & Pro/E let you turn them off... not sure about other software. In the case pictured, the section cuts through a center hole and features visable in the background (i.e. not in the plane of the section cut) show up.
My stance is, you take the section through specific features, and (in general) only those features should be dimensioned in that view. That way, it's more explicit what's being shown.
Perhaps it's not disallowed to dimension to background features, but that doesn't mean it's best practice.
RE: Dimension to Background Lines in a Section View
RE: Dimension to Background Lines in a Section View
I suggested that the hidden lines be turned on in the parent view as that would greatly help in clarifying just what those features are. If that was understood, I can think of no reason to require another section to add the dimensions in question. The goal is generally agreed to be creation of a clear, concise drawing.
"Good to know you got shoes to wear when you find the floor." - Robert Hunter
RE: Dimension to Background Lines in a Section View
If that is the case, the dimensions shown are OK. However, showing the slots as hidden detail in the main view would avoid confusion and very simply explain what is being shown.
RE: Dimension to Background Lines in a Section View
What is Engineering anyway: FAQ1088-1484: In layman terms, what is "engineering"?
RE: Dimension to Background Lines in a Section View
Here's the other view showing the slots (been revised since last time).
The slots pictured show up in the background of the section cut (shown in my earlier post). Since they're out of plane of the section, I think it's less clear to dimension to them in section A-A.
From the responses above, it sounds as if it's not illegal, but I still feel that it's best practice to only dimension things that your section explicitly cuts through in your section view.
Actually, I think that it's the most clear to turn off the background lines entirely so the section is the only thing visable.
RE: Dimension to Background Lines in a Section View
RE: Dimension to Background Lines in a Section View
Of course, if time and drawing space is available, you could add an individual section through the slots to show their depth, but I feel that it would be more of a luxury than a necessity.
If additional time and/or efort isn't available for another section, I still recommend showing the hidden lines in the section parent view. This would help in a clearer understanding of just what features are being referred to.
"Good to know you got shoes to wear when you find the floor." - Robert Hunter
RE: Dimension to Background Lines in a Section View
From the sound of things, the initial detail wasn't illegal. Still, I think that it's much clearer this way.
RE: Dimension to Background Lines in a Section View
However, if within context of the whole drawing it could be confusing then that should over ride matters and may give cause to either crank the section line through the slot or add an extra view. Like ewh kind of said.
What is Engineering anyway: FAQ1088-1484: In layman terms, what is "engineering"?
RE: Dimension to Background Lines in a Section View
RE: Dimension to Background Lines in a Section View
Really, though, it sounds like a matter of preference and style, rather than one of standards.
RE: Dimension to Background Lines in a Section View
"3.6.1. Visible Lines. Visible lines behind the cutting plane are generally shown. Selected lines may be omitted if greater clarity is gained."
I haven't found anything in any standard related to dimensioning of "background" features in cross-sections, but IMO this is acceptable and very often indispensible practice.
The only situation (that I can imagine at the moment) where I would not go for such dimensioning is for features that are visible in a background of cross-section but are not in the same projection plane as cutting plane.
RE: Dimension to Background Lines in a Section View
I have seen cases where turning tangent lines either on or off makes a view more clear but I don't think I've ever seen a case where removing lines representing actual features did more good than it caused confusion. I always expect any view to accurately represent what the part will look like. I agree that excessive dimensions in one view can make a cluttered print but that's not the case here.
If you look at the parent view in the first print you provided, there is no dimension for the OD, ID, or counterbore. Will turning off the lines to those features in your parent view make the drawing more clear since those lines aren't "adding information"? To me, it would be a much more confusing print. I just don't think it's a good idea to turn off lines depicting features. I'm sure there are some cases where it makes perfect sense but this isn't one of them. I think that hiding feature lines should be more the exception instead of the rule.
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