Straightness callout over a set distance 2

[Norse1957]

Hi all,

I've come across a drawing that someone did for a very simple part that is just a 42" long, .63" dia. aluminum rod, with a straightness callout. The question I have is I've never seen straightness called out this way, if you look at the attached image, where they're saying it needs to be straight within .015" per every 12"... Has anyone ever seen it done this way? I suspect that whoever did the drawing, didn't know of a way to properly show this, and they just did their own thing, rather than following proper GD&T practice. That being said, the only way I know would to just have a note written under the straightness callout?

Jack

 

[3DDave]

That symbol is the correct way to use that. If overall straightness is important a limiting FCF is used, but at 42 inches long it's not going far with that amount of allowed variation and if it isn't required it's not used.

 

[dgallup]

Yes, I've done straightness per unit length many a time for a long part like a bar.

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The Help for this program was created in Windows Help format, which depends on a feature that isn't included in this version of Windows.

 

[SeasonLee]

If the FCF associated with a FOS dimension, the diameter symbol Ø cannot be omitted on the straightness callout.
It looks like an ISO print for me.

Season

 

[Norse1957]

Can you show me where in the Y14.5 this is shown to be an acceptable practice? I can't find anything that shows an example of the "/" being used in the FCF.

 

[3DDave]

Which version? In '2009 it's in figure 5-4, but it's the combined, limiting composite FCF. It has the "/" in the lower section to refine the zone.

 

[SeasonLee]

Per Y14.5 2009 version

Season

 

[Norse1957]

Thank you very much guys!

 

[jassco]

It is called "local straightness" or "local flatness". I saw a video clip on "local flatness". Someone moved around a coin (disk) on a flat plate. I think Prof. Don Day did it.

Best regards,

Alex