# 3D Math Data, GD&T and FAI - My issue lies more with Profiles

S

#### satsoe

Roundness question

Hello All,
I might be dumb with this question?, but anyways it is better to ask rather being silent? I have a roudness callout of .0013(mm) in our print and supplier provides a result of .00039. I was told this dimension is out of print. Could somebody explain the logic behind this?. I am under impression smaller is better?

#### Stijloor

Super Moderator
Re: Roundness question

Hello All,
I might be dumb with this question?, but anyways it is better to ask rather being silent? I have a roudness callout of .0013(mm) in our print and supplier provides a result of .00039. I was told this dimension is out of print. Could somebody explain the logic behind this?. I am under impression smaller is better?

Before getting wrapped up in the numbers, is your and your supplier's interpretation of "roundness" or circularity the same? ASME Y14.5M-1994 Par 6.4.3.1 (page 162) defines the circularity tolerance zone as the radial distance between concentric circles.

Also the method of measurement may have an impact.

Just some thoughts....

Stijloor.

S

#### satsoe

Dear Stijloor,
Thanks for the reply. Supplier and us use same gaging technique .

#### Miner

##### Forum Moderator
Re: Roundness question

Hello All,
I might be dumb with this question?, but anyways it is better to ask rather being silent? I have a roudness callout of .0013(mm) in our print and supplier provides a result of .00039. I was told this dimension is out of print. Could somebody explain the logic behind this?. I am under impression smaller is better?

Is the supplier's result in mm or in inches? If in inches, it is out of spec.

S

#### seamus26

This is an old thread, but I'm in the midst of a discussion about reporting profile per ASME standard, and for the life of my I can't find anything.

My issue is this. Say you have a profile tolerance of .010. You have min max readings within the profile of +.007 and -.004. Nobody disagrees that this part is out, but by how much? Apparently - and I quote another forum - according to ASME :

Note that no single actual value may be calculated for comparison to the tolerance value in the feature control frame, except in case of unilateral profile tolerances.

Conventional wisdom has always told me to double the worst case reading (either + or - material) giving this part a profile of .014. Or is it? This is in keeping with ISO, which apparently says :

Bi-lateral and unequally disposed profile tolerances have a single actual value that can be compared to
the tolerance in the feature control frame to make a conformance decision. Single actual value =
largest deviation (amongst plus and minus material directions) x two.

Using the doubling method I am OOT by .004 (.014-.010). Or, if profile of .010 is the same as BASIC ±.005, does my .007 put me OOT by only .002 (.007-.005)?

If someone has some clear direction from Y 14.5, please share. This could be important when explaining my results.

TIA

#### Stijloor

Super Moderator
This is an old thread, but I'm in the midst of a discussion about reporting profile per ASME standard, and for the life of my I can't find anything.

My issue is this. Say you have a profile tolerance of .010. You have min max readings within the profile of +.007 and -.004. Nobody disagrees that this part is out, but by how much? Apparently - and I quote another forum - according to ASME :

Conventional wisdom has always told me to double the worst case reading (either + or - material) giving this part a profile of .014. Or is it? This is in keeping with ISO, which apparently says :

Using the doubling method I am OOT by .004 (.014-.010). Or, if profile of .010 is the same as BASIC ±.005, does my .007 put me OOT by only .002 (.007-.005)?

If someone has some clear direction from Y 14.5, please share. This could be important when explaining my results.

TIA

You have a profile tolerance of .010. The default interpretation for profile per ASME Y14.5M-1994 and ASME Y14.5-2009 is that the tolerance zone is "equally disposed about true profile." The permitted deviations are .005 above true profile and .005 under true profile. Because one deviation is .007 above true profile, you are out of tolerance (OOT) by .002.

Hope this helps.

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