GD&T question for European Drawing 2

[Rooster67]

I am trying to establish the correct meaning of the GD&T symbols used in a dutch drawing.
I'm not sure how old the drawing is, but the GD&T symbols don't seem to follow the current ISO 1101 standard.
Can anyone help me interpret the GD&T correctly?

 

[KENAT]

File doesn't apper to open, doesn't have a . extension which may be problem.

KENAT, probably the least qualified checker you'll ever meet...

 

[Rooster67]

One more try

 

[MadMango]

Still not working, can you describe the symbols?

"Art without engineering is dreaming; Engineering without art is calculating."

Have you read faq731-376 to make the best use of Eng-Tips Forums?

 

[CorBlimeyLimey]

Rather than keep posting non-working attachments, try downloading it in when in the preview. If it doesn't download there it won't download here.

 

[CorBlimeyLimey]

Just testing the attachment function.

It works!

How are you selecting the file to upload?
Are you just typing in the location from your machine or using the "...or upload your file to ENGINEERING.com" link?
The latter one works.

 

[Rooster67]

Sorry to mess you all about, but I've finally managed to upload the file.
Just for future reference it was the file name that was stopping it, I had called it GD&T and the upload didn't like the & bit.

Anyway, can anyone help me interpret the GD&T correctly?

 

[ja500]

The drawing attached dosnt have any GD&T.
It seems to have lots of linear dimentions in both metric and imperial.

what have you dificulty in interpreting?

jason

 

[KENAT]

OK, so the drawing doesn't use the current standard symbology for GD&T, at least that I'm familiar with from the UK (BS/ISO) & US (ASME). However it does appear to have fcf with letters.

I'm guessing the letters are meant to be instead of symbols. Not sure if it was an old dutch thing, or maybe a software translation error.

I will say this, datum B dosen't appear to be a valid datum, at least it's not called up how I believe it's meant to be.

The 'c' looks like it might be flatness, but that's just a guess.

The 'f', no idea. I was thinking position but I don't think that works.

Sorry.

KENAT, probably the least qualified checker you'll ever meet...

 

[weavedreamer]

CATIA maps 'f' as parallel, and 'c' as flatness.
That happens when the font is substituted, which occurs when you do not have the identical font loaded on the system the document is opened on.

Caution: While most GD&T fonts use the same keyboard mapping, it is not standardized that I am aware of. One of the fonts I have has 'b' as perpendularity and 't' as total runout, where the other (Catia) list's 'b' as square and 't' as perpendicularity.

 

[Rooster67]

Thanks to all of you with helpful comments, the dimensions have been changed to question marks "???" on purpose as I didn't want the original dimensions released into the public domain.
However it's interesting to find out about the CATIA mapping process, which makes sense about how these feature control frames may have ended up with letters not the normal symbols.
What I would like your opinions on now are:-
If indeed the 'c' represents flatness and the 'f' represents parallel then would the drawing "work" from a common sense point of view.

Thanks once again to everyone for you're continued help.

 

[KENAT]

So the flatness 'c' is pretty self explanatory I think, basically that surface which is used to make datum A needs to be flat within .002.

Now all of the presumed parallel constraints are less clear. In fact I'd go so far as to say that I don't think they are really valid GD&T.

My best guess of the intent is that the 2 'peaks' are meant to be equidistant from A to within .002 of each other.

KENAT, probably the least qualified checker you'll ever meet...

 

[KENAT]

Sorry hit submit by error.

As regard the 'f' with regard to datum B I have a couple of thoughts.

I think datum B is meant to be the plane thorough the 2 holes. Really I think this should have been called out more like fig 4-8 of ASME Y14.5 -1994 with a sligthly different, but more correct, definition per para 4.4.3 (b).

In this case what I'd guess they want is for the centerlines of the 'peaks' to be parrallel to B. Even if I'm right though I'm not sure this is the best way to achieve it, it may not even really be valid application of GD&T.

I did wonder if they were trying to make the 'peaks' symetrical about datum B but I don't that's what they're trying to do although with the dimensioning scheme the way it is they probably need to.

Hope this helps, fundamentally though if possible I'd suggest you go back to whoever gave you the drawing and ask for clarification. Anything else will be just a best guess/estimate which may not match what they intended.

KENAT, probably the least qualified checker you'll ever meet...

 

[weavedreamer]

Parallel is a refinement of a limit dimension.
Fig. 6-16 illustrates it used as a refinement of a profile tolerance.

The limit dimension would be centered around datum B considering Kenat's observation. It makes sense the ribs parallel to B, yet the positioning of that parallelness strikes me as ambiguous. Clarification would be prudent.

 

[fcsuper]

Is that finish callout legit...something looks funny about it?

Matt Lorono
CAD Engineer/ECN Analyst
Silicon Valley, CA
Lorono's SolidWorks Resources
Co-moderator of Solidworks Yahoo! Group
and Mechnical.Engineering Yahoo! Group

 

[powerhound]

If the drawing is to the ASME standard then the datum on centerline is wrong. ISO allowed this at one time but no longer does.

It could be that the pattern of holes is used as a datum but that would require a FCF under the hole dimension. The only other option is the make the centerplane of the OD datum B and position the holes to it.

This is likely the AIGDT font. If it is then "f" is parallel and "c" is flatness. this would also mean that the callout between the two peaks and in the detail is incorrect.



Powerhound, GDTP T-0419
Production Supervisor
Inventor 2008
Mastercam X2
Smartcam 11.1
SSG, U.S. Army
Taji, Iraq OIF II

 

[powerhound]

The closed triangle on the surface finish means that material removal is required but being that the rest of the print is apparently in inches, a 0.8 is an incredibly fine finish. Because the 0 precedes the value, and 0,8 is a common metric callout, I would be inclined to believe that this is a metric callout (micrometers) on an inch print. The 0.8 would be about a 32 finish in inches.

Powerhound, GDTP T-0419
Production Supervisor
Inventor 2008
Mastercam X2
Smartcam 11.1
SSG, U.S. Army
Taji, Iraq OIF II

 

[Rooster67]

Thanks again to all of you who took the time to reply with helpful comments and suggestions, these are greatly appreciated.
Out of interest the original drawing was metric, but who ever drafted the original was somewhat misguided in their application of the GD&T.
The discussion has given me the confidence to believe that the original design intent was probably meant to mean 'flatness' & 'parallel', but that the font mappings have got lost in translation.
The drawings will now be redrafted to the following standards:-
Drafting - BS 8888:2006
GD&T - BS EN ISO 1101:2005
Thanks again to all of you for the help.
Best Regards,
Rooster67

 

[KENAT]

Rooster, if I recall correctly BS8888 calls up that ISO.

Definitely look at how datum B should really be specified/what it should be. I'm pretty sure that it's wrong to the standards you are now re-drawing to.

KENAT, probably the least qualified checker you'll ever meet...

 

[fcsuper]

Good catch, Power, but I was actually talking about the other finish callout. I've never see finish callout point to a regional-like reference circle. What feature/surface is meant to have the 0.1 finish applied to it? (also, is 0.1 correct?) The P view is not very clear as far as I can tell.

Matt Lorono
CAD Engineer/ECN Analyst
Silicon Valley, CA
Lorono's SolidWorks Resources
Co-moderator of Solidworks Yahoo! Group
and Mechnical.Engineering Yahoo! Group