parallelism tolerance 2

[waqasmalik]

If i have a cylinder of length 20 plus minus 0.2 mm. We all know that flatness of both faces will be automatically controlled within 0.4( Total size tolerance) if produced at LMC and Rule 1 is not violated.We also know that both controls of 0.4 will exist at the same time.Now I want to ask that how much automatic parallelism control is for both faces of a cylinder?
Thanx and apologies for anything quoted wrongly...

 

[pmarc]

If we arbitrarily select one of the side faces as a reference surface, the second face won't be out of parallel by more than 0.4.

 

[asmeY145Manswer]

But what if you are more than .4, and the parallel jaws of a caliper tell you that you are within +/- .2. That parallelism will never be checked if you don't call out a parallelism control.

Which is fine if it is not important to you. But in reality, yes you could be more than .4. And it all depends how it is measured, and that is arbitrary now to anyone who has to measure it.

 

[asmeY145Manswer]

You said this was ok. Right? Because that's how it gets measured. As long as you are happy with that, then I think it is OK too! Fine with me!

 

[asmeY145Manswer]

fyi

 

[gabimo]

asmeY145Manswer,
I don't really know what the inspection method has to do with the parallelism tolerance.
pmarc was trying to explain the mechanics of the tolerance zone and the DEFINITION by the Y14.5 standard.
Caliper rule and other inspection methods has little or no relevance in what was the OP question.
Y14.5 states very clear:
"NOTE: The figures in this Section use measurement techniques to
explain the tolerance zones. It is neither the intent nor within the
scope of this Standard to define measurement methods"

 

[pmarc]

Thank you, gabimot.

You are right, I was not thinking about any particular inspection method.
0.4 of actual parallelism error between both sides is the absolute maximum allowed regardless of inspection method chosen (of course if we are following Y14.5 standard and Rule #1 is in charge).

So replying to asmeY145Manswer's statement...

"But in reality, yes you could be more than .4."

... I would say:
Yes, in reality you could be more than 0.4, but only if the feature in question was manufactured out-of-spec or if it was not subject to Rule #1.

 

[gabimo]

Due to the obscene language used by one of the member some replies were removed.

It will be much better to keep the discussion here technical and polite. Our degrees, work experience, membership on standards committees, etc lend no weight to an argument. Only the technical merit of our assertions and the support we provide for them has merit. We are all learning. (Thank you Dean)

Some deleted comments were a blatant attack on members. Please refrain from personal attacks. We completely respect your knowledge and experience and sincerely appreciate your opinion and contribution to the forum, but we will not tolerate attacks on individuals.

OP question: “how much AUTOMATIC parallelism control is for both faces of a cylinder?”

Answer: If we arbitrarily select one of the side faces as a reference surface, the second face won't be out of parallel by more than 0.4. (Thank you pmarc)

Comments:
Can you add a parallelism tolerance bigger than 0.4? Yes you can, but will add no value and will show lack of GD and T literacy. (Y14.5 standard implied, size tolerance and rule#1)

Any questions / comments are welcome.

 

[waqasmalik]

Thanx pmarc and gabimot