ISO Symmetrical Question 2

[SeasonLee]

Please ref to the symmetrical callout on the figure attached, its an ISO standard of a M14X1.5 Hex Flange Bolt. What's the meaning of T/2 on the FCF tolerance compartment?

Thanks for all helps

Season

 

[CoryPad]

I believe T refers to tolerance, see this example from ISO 4759-1.

 

[CheckerHater]

0.27 represents "radial" or maximum deviation in one direction, that is 1/2 of total tolerance zone, hence T/2.

Total tolerance zone will be 0.54. Why? I have no idea. Maybe it makes calculating tolerance stack-up easier - you can see quickly which tolerances should be split in half.

"For every expert there is an equal and opposite expert"
Arthur C. Clarke Profiles of the future

 

[ak762]

BTW SeasonLee's attachment displays the representation by GOST. CheckerHater;s interpretation with T/2 is absolutely correct.
Balloon n4 means particular marking method with reference in general note 4.

 

[CheckerHater]

Season, could you disclose where the drawing comes from?

I found mention of "radius" tolerance zone used alongside with "diameter" in GD&T on some Chinese factory site:

http://www.iron-foundry.com/geometric-tolerance-symbols.html

So, it looks like something very old and/or very local.

AK, you seem to know the most about it. What are the advantages of using "half-tolerances"?

"For every expert there is an equal and opposite expert"
Arthur C. Clarke Profiles of the future

 

[ak762]

The introduction in GOST 2.308-79 for the symmetry is the same as in ISO 1101 - "The tolerance zone is limited by two parallel planes a distance “T” apart, symmetrically disposed about the median plane, with respect to the datum."
“T/2” is radial value. It is true for Symmetry, Tolerances of Profile, Positional and special term Cross Axes. "T/2" usage is quite common for symmetry on the represented drawings according to GOST.
IMHO there are no any advantages of using "half-tolerances" except the confusions with symbol R applied for non revolved features.

 

[SeasonLee]

Thanks for all assists.

CH
OEM customer in Europe, the Note may be helpful for you, but I can't read it.

AK
Would you please re-post the general note 4, it looks upside down.

Season

 

[SeasonLee]

AK

Your post is right, the problem is I can't read it.

Season

 

[CheckerHater]

Should be something like this:

1. Steel 4140 or something very close, Class 10.9 Hardness HRC 32…39 per ISO 898-1
2. General tolerances: outside dim’s H14, inside h14, other +/- IT14/2
General tolerances of form ISO 2768-2 H
3. Coating: Phosphate dipping
4. Mark manufacturer ID and Class
5. Other requirements per ISO 4759-1-2009 grade A




"For every expert there is an equal and opposite expert"
Arthur C. Clarke Profiles of the future

 

[ak762]

I would like to write glad to help you Season but CH re-posted everything ahead
Just confirm the translation is correct. One comment regarding to general surface roughness, I guess you can see this symbol in upper right corner on the drawing.
The meaning is the same as general surface roughness max. allowed value unless otherwise specified.

 

[SeasonLee]

Thanks again for all helps from CoryPad, CH and AK.

Season

 

[dgallup]

For those of us who had no idea what GOST is, I looked it up.

http://en.wikipedia.org/wiki/GOST

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