Center line callout symbol placement 2

[lb125]

I recently started a new job and a co-worker and I are having a debate about if the center line symbol (C&L)should be placed on the line or not. Is there a standard for this or not? I've attached a example. Thanks in advance for any help.

LaMonte B.

 

[KENAT]

It's my understanding that the 'CL' symbol you show is no longer used. I recall seeing it in ASME Y14.5M-1994.

Per ASME Y14.5M-1994 2.7.3, just showing items aligned etc. implies no relationship/tolerance, which I believe CL was often assumed to imply.

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(probably not aimed specifically at you)
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[KENAT]

Oops, should be "I don't recall seeing it in ASME Y14.5M-1994"

Posting guidelines faq731-376

http://eng-tips.com/market.cfm?

(probably not aimed specifically at you)
What is Engineering anyway: faq1088-1484​

 

[ewh]

It seems to be redundant information; the line font alone indicates that it is a centerline. The only use I know of it is when you note what component/feature it is a centerline of (CL ITEM X for example).
As far as location, I wish I had such issues to debate. ;-)

"Good to know you got shoes to wear when you find the floor." - [small]Robert Hunter[/small]

 

[fcsuper]

I was taught in Drafting school that when the centerline symbol is used, it should always be overlapping the centerline it belongs to. Some engineers and other types of CAD jockeys (who never learned drafting formally) cringe at this thought for some reason and I've never been able to figure out why. In my experience, any old examples (board drawings and older ACAD drawings) always have overlapping the centerline.

OK, now to the next topic. The CL is no longer a standard symbol. It's not disallowed by the standards, but it is also not supported by the standards. If you intend to use the CL symbol (or any symbol not supported by the standards) at your company, a definition should be stated somewhere that everyone can find. At my last company, we defined all special symbols in the general notes when they appeared on the drawing.

Is CL needed? Sometimes, it helps, but it is never really needed. Why does it sometimes help? Because you may have a drawing view with many centerlines (through various features that lend themselves to the use of centerlines), and you may wish to identify the centerline that represents the center of the part itself. You can use CL to do that.

Finally, your drawing looks like a SolidWorks drawing. (It doesn't matter if it is not...I'm just going to use SolidWorks as the example.) For horizontal lines, just use the CL as is. But for vertical lines, you may wish to rotate the CL about -20degs (an option available in the PropertyManager for the annotation note). This will avoid having the vertical line in the L disappearing on the centerline.

Matt Lorono, CSWP
Product Definition Specialist, DS SolidWorks Corp
Personal sites:
Lorono's SolidWorks Resources & SolidWorks Legion

 

[11echo]

I've worked in the design/drafting profession for over 35 yr.s, and I've seen it both ways. However I'm betting it's more discipline oriented as to where it's "properly" indicated. In piping design world, as I said, I see it both ways. In the machine world I'd bet it's on/in the centerline itself.

 

[ewh]

I have seldom seen it in the mechanical world. I have also been taught drafting formally, and this issue was not an issue. In situations such as that mentioned by fcsuper, I have always found it produces a better drawing to eliminate superfluous cenerlines that tend to create more clutter than clarity. A primary directive of drafting is the creation of a clear, concise drawing, and centerlines through everything do little to achieve that end. Just because features may lend themselves to the use of centerlines does not mean such centerlines are required or desireable.
I do agree with his recommended placement though, if the symbol is going to be used.

"Good to know you got shoes to wear when you find the floor." - [small]Robert Hunter[/small]