Profile tolerance for outer rectangle surface

[Sa-Ro]

Hi

I need to control the outer surface of the rectangle wrt bore as shown in image.

Requirement: Outer surfaces to be equally located from bore center.

Does the drawing representation right?

Thank you

 

[3DDave]

4.1(l)

 

[Burunduk]

The CF in the second image of the 11 Sep 23 07:41 post is not necessarily non-conforming to the standard definition of a continuous feature. It is just not likely to function as one.

 

[Belanger]

3DDave, that paragraph 4.1(l) is only where center lines etc. are subsequently "located or defined by basic dimensions..."
So for the OP issue about coaxial holes, even that won't salvage things


John-Paul Belanger
Certified Sr. GD&T Professional
Geometric Learning Systems

 

[3DDave]

2018, the version OP is using.

 

[Belanger]

I misquoted.
But same idea: The implied zero rule only applies where "geometric tolerances establish the relationship between the features."
Thus, no dice for his coaxial holes.

John-Paul Belanger
Certified Sr. GD&T Professional
Geometric Learning Systems

 

[Sa-Ro]

Thank you

 

[3DDave]

J-P, if that is the interpretation it is clearly insane. That would require dimensions of [0.000].

 

[Belanger]

Not really. It simply means that we can't leave implied coaxial things without some sort of coaxial tolerance. Check out the 2nd and 3rd sentences in paragraph 5.8.3.

John-Paul Belanger
Certified Sr. GD&T Professional
Geometric Learning Systems

 

[3DDave]

J-P,

First, my reply was about centering the profile around the hole. I am not re-baselining my replies to the OP for distractions by other responders or further unrelated questions and squirrel darting by the OP. It's up to him to keep track.

Quote (3DDave)
standards are the rule book
I have ASME Y14.5:2018 book. But unable to locate the guideline for implied zero dimension for linear.

to which I replied

4.1(l)

Second, "geometric tolerances establish the relationship between the features" as the references to [A] appear in his later drawing as well, establishing what is required.

 

[3DDave]

To no surprise Y14.5-2018 1.4(l) says "For information on applicable tolerances for zero basic dimensions, see para. 5.1.1.4." which deals with angles and not coincidence of axes and planes.

5.1.1.4, on angles, says "For rules regarding implied 90° or 0° basic angles, see paras. 4.1(k) and 4.1(l)." but 4.1(l) doesn't deal with angles.

Seems like a great gotcha question for the GDTP test.

Create better rules rather than these inverted logic constructions. It is derivable that if features do not share a DRF or have a parent-child relation then any random measurement between them has no specified tolerance and should not be inspected. This restriction applies to 0 and 90 angles, but is not specified in (k). Why not?

 

[Burunduk]

This disccussion only indicates that the next version of the standard should eliminate the whole BS of the non-basic implied 0 mm/0 deg/90 deg dimensions "controlled" by the title block +/- tolerances. This stuff still being in the fundamental rules is a disaster.

 

[Belanger]

the next version of the standard should eliminate the whole BS of the non-basic implied 0 mm/0 deg/90 deg dimensions "controlled" by the title block +/- tolerances.

The fundamental rules allow that for implied 90º angles (j), but not for implied 0 linear relationships. The verbiage in (l) is always in regard to an implied basic dim that has a geometric tolerance.

John-Paul Belanger
Certified Sr. GD&T Professional
Geometric Learning Systems

 

[Burunduk]

Yes, but from my experience many folks will interpret the plus-minus in the block as applying to anything that is "implied". As long as the standard legitimizes this approach (j) the problem will not go away.

 

[3DDave]

B, you should take time and make an effort to educate them, as you have previously suggested should be done. If it is "many folks" I suggest you post a large number of laminated signs on this topic around the workplace and hold weekly brown-bag meetings to help your ignorant co-workers become fully informed.

 

[Burunduk]

3D, I actually do some of the things you suggested (laminated signs not included). You should know that it is not a one-company problem though. Misconception of this type are common in the industry, and standards being slow at getting rid of bad practices doesn't help.

 

[3DDave]

B, of course you are familiar with all companies on Planet Earth. I forget your omniscience.

 

[Belanger]

My apologies, folks, for giving fodder for these two to start going at it once again.


John-Paul Belanger
Certified Sr. GD&T Professional
Geometric Learning Systems

 

[Burunduk]

3D, does your reaction indicate you know otherwise and disagree that it's a common misconception in the industry?
Have you had previous jobs in the field, and are you in contact with co-workers, vendors, customers? For how long? If for long enough, I doubt you never encountered a design engineer who makes drawings and thinks the title block tolerance is good enough to cover for anything "not otherwise specified" including coaxiality variations.

 

[3DDave]

B, you made the claim. Show your proof.

 

[Burunduk]

Why do I need to provide proof when you do not even confirm that you disagree? Those who agree don't need proofs.