Position tolerance of the opening which is in distance from the datums 5

[michal77]

Hello,

In my daily work I deal with drawings where position tolerance is marked in
the way like on the attached example 1 - please take a look on doc file where I combined all examples.

In my opinion, this way of dimensioning is incompleted. According to
example1 I understand this tolerance like on the pic no. 1

The shape of the tolerance zone is a cylinder which is perpendicular to
datum A, lies on axis between opposite walls (datum B) and is 40mm away from
datum C. But we don't control a 'height' from datum A. So we cannot mark
dimension 25 as a basic.

I spoke about this with other guys and I received a tip that you cannot
treat a tolerance zone, in this case, as a cylindrical zone but you have to think
about tolerance zone as a sphere which is connected to the upper, or lower,
side of the axis of mentioned opening.Then we control the 'height' and we
can mark dimension as a basic dim. I'm not fully convinced that it's right.
Please take a look on attached pic no. 2

There is also third theory, that the tolerance zone is a cylinder like on
the attached pic no.3

Mentioned cylinder is on specified position in 3D and you can control
everything. I don't agree with this theory.

Finally, I can show you my way of dimensioning stuff like this. Please take
a look on attached pic no. 4 and example 2.

The shape tolerance controls mentioned 'height' so 25 can be marked as
basic, the rest remains the same.
I know that it's complex post but I wanted to avoid creating a lot of posts
which wouldn't be connected to each other.
I hope that I was clear for you and many thanks for your any remarks.So ..... what do you think about it ? which way is correct ? Or maybe there is also another way how to solve this problem....

Best regards
Michal77

 

[KENAT]

Off topic, your written English is very good michal, it's just even us native English speakers sometimes confuse ourselves on here by misunderstandings of the written word, especially some of the specific GD&T terminology.

I'm pretty much self taught but have got to work with a few people, one in particular, who are very good.

By the way, if still in Poland are you using ISO drawing standards. Most of the contributers here mainly work with ASME and their are some differences in certain areas, though as Powerhound said probably not this specific case.

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

 

[michal77]

Thanks KENAT

Normally in Poland we use ISO standard, but sometimes like for example in my case, we make drawings according to ASME. I assume that it depends on country from which company is. My automotive company is from Canada, so it's probably a reason of my adventure with ASME. Hmmmmm I assume that I know main differences between these two standards.... but it's only my assumtion
This situation is also better for me from completely other point of view. In case of ASME, everything is included in one book (I mean ASME from 1994, I’m not sure about the latest editions), in case of ISO you also have one standard (should be ISO 1101.... I don't remember right now) but it's some kind of summarization and for more detailed info you have to go to linked substandard, which is not so easy in daily work.

PS – I due to your knowledge of ASME, I assume that you are from US or Canada. Am I right?

Best regards
Michal

 

[KENAT]

UK originally but now US. I've worked both systems but didn't get into GD&T in much depth till in the US.

ASME Y14.5M-1994 is still the current version, there's supposed to me a new one out soon. 14.5 has all the toleranceing and dimensioning but there are lots of other drawing standards/rules etc. in other Y14.100 series documents.

Not remotely relevant but we actually have some Polish interns here at the moment.

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

 

[michal77]

Y14.100 series sounds interesting, I'll check out this....
I've been once in UK during my business trip, very interesting country.
I'm going to create a new post, because there is still some questions which should be figured out by me, so I hope we'll be in touch.

Best regards
Michal

PS - say hello to my countrymen.

 

[Brandy7]

Michal, on the last Drawing the 40 Dim. on Datum "B" should have a tolerance applied to it somewhere or just remove the Basic and give it a +-Tol. also the 10 Dia. should have a Tol. for the mating rivet. RFS is o.k. for Hole mating with Rivet.

 

[michal77]

Hi Brandy7,

In both cases you are right, it was done by accident. I was so concentrated on position tolerance of the opening, that I missed this....