Thread depth in a pocket & slot GD&T callout 2

[i2xtreme]

Are thread depths the same as counter bores in there interpretation?

Is either slot callout correct?

Please view the attached pdf and let me know which are the correct callouts.

 

[dingy2]

In the positional tolerance of the slot, B, is correct. A references the slot with a diametrical tolerance zone but the feature of size is not round. B is absolutely correct.

I also like B in the dimensioning the depth of the thread since it came from a base line rather than chain dimensioning.

Dave D.

http://www.qmsi.ca

 

[weavedreamer]

ASME Y14.5M-1994 1.8.11 (Fig. 1-37) should answer the first portion.
5.10.1 (Fig. 5-47) illustrates an example of a slot.

 

[ewh]

Re: Fig. 1-37
I never realized that a depth callout of "3" is to be interpreted as "13".

The Edge... there is no honest way to explain it because the only people who really know where it is are the ones who have gone over. - [small]Hunter S. Thompson[/small]

 

[dingy2]

ewh:
You misinterpreted 1-37. It means that the largest counterbore of 10 mm has a depth of 3 mm.

Dave D.

http://www.qmsi.ca

 

[ewh]

OH!! (As the light hits my eyes)
Now I understand. Thanks!

The Edge... there is no honest way to explain it because the only people who really know where it is are the ones who have gone over. - [small]Hunter S. Thompson[/small]

 

[CoryPad]

Threads are the same as counterbores for interpretation. B is correct for the threads - as dingy2 said, it avoids chain dimensioning and it simplifies inspection because you measure from an easily accessible feature (the large outer surface).

Having said that, the actual numbers on your example make no sense. The two counterbore depths equal the thread depth, so there is no available material to make the threads.

Regards,

Cory

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

 

[dingy2]

Cory is correct on the dimensioning conflict.

Dave D.

http://www.qmsi.ca

 

[KENAT]

What dingy & cory?

B is most correct interpretation on the thread callout given top left however, Counterbore symbols would probably be needed to clarify the callout, there is no dimensioning conflict. The Depths for round holes are measured from the surface UOS.

The depth dimension of a blind hole is the depth of the full diameter from the outer surface of the part.

This is illustrated for C'bores in figure 1-37 mentioned above.

The first c'bore has a depth of .125 from surface, second is .250 from surface, thread is .375 from surface so you end up with .125 of thread (.375-.250).

For the slot B is more correct though you may want to consider adding 'BOUNDARY' - see the reference weavedreamer gave.

KENAT,

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[CoryPad]

I retract my previous statement regarding no material available for the threads. I was thinking about chain dimensioning, not paying attention, so thanks KENAT for correcting me.

After closer scrutiny, the axial thread engagement is approximately equal to the thread diameter, which is a common ratio used for joints that have similar materials for the internal and external threads.

Regards,

Cory

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

 

[dingy2]

Kenat:

Yes, I agree with you on the dimensioning. Looks like Cory and I must have had the same breakfast.

Dave D.

http://www.qmsi.ca

 

[i2xtreme]

Thanks for all your help, this is leading to what I expected, and KENAT nicely leaded into my next question. To me the standard can be a bit fuzzy so your help is much appreaciated.

Quote (ASME Y14.5M-1994 1.8.9 of ):
"The depth dimension of a blind hole is the depth of the full diameter from the outer surface of the part."

So with that said please view the attached pdf for my next question to clarify for me what precisely is intended by the standard. A or B

"Outer surface of part" means precisely what?

 

[MechEng2005]

While I certainly don't have the knowledge of the other individuals that have been posting (or access to standards for that matter)...

From my understanding of what was said, for "problem 2", neither of your variations is correct. The depths would both be measured from the surface. The 1.50 dia. hole would reach a depth 0.03 from the surface, and the 0.25 diameter hole would extend an additional 0.22, for a depth from the surface of 0.25.

Of course, I could be wrong. I'm not as knowledgeable as the others that will surely arrive shortly to correct me. Perhaps since the callouts are not in the same note it is different.

-- MechEng2005

 

[KENAT]

In this case I'd say it's ambiguous and the section or equivalent should be shown.

...Where the depth dimension is not clear, as from a curved surface, the depth should be dimensioned...

KENAT,

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[ewh]

I would interpret this differently than the previous situation (hey, I've had my coffee and am aware again), and consider the "outside" surface to be the bottom of the .03 pocket, as these features are not related as the others are. KENAT has it right though, if there is any question in interpretation, show a detail.

The Edge... there is no honest way to explain it because the only people who really know where it is are the ones who have gone over. - [small]Hunter S. Thompson[/small]

 

[ringster]

It would seem that symbols serve a purpose. However, there are cases such as we have here where it might be preferred to dimension directly in the sectional view as applicable. I would ask though, why is it necessary to control the depth of the thread to plus or minus .010? Why not just a min depth?

 

[MadMango]

I was always told to take thread depths from the bottom of the spotface when designing hydraulic manifolds, which follows the logic of ewh.

 

[CoryPad]

Your A and B are showing the same thing, not different things. A has the dimensions chained together, B shows them with a common starting point. B is preferred.




Regards,

Cory

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

 

[i2xtreme]

MechEng2005 - you are correct, I made a mistake in my illustration for question 2... option "B" should read .250 NOT .280… my first mistake of the year, dang

I personally would say for question 1 B and B are the more correct answers as most agreed. But to know what is 100% correct is key, yes there are ways around using the depth by using sectional views etc, but when you have a part that looks like swiss cheese doing 15 different section views becomes just as confusing as the standard it’s self. Supplying a depth attached to the original feature is easy to find and no depth “hunting” required

For question 2 I would say “A” is correct. I am in agreement with ewh.

All I (we?) need is the next generation of the standard is to clear up these interpretation questions. Who do we email these types of questions to? Is a new standard ever going to come out? I know my book for the standard was $165 bucks. $165 x ~50,000 copies is about 8 million bucks! I feel it is a bit over priced for what you get.

When a vendor makes a part wrong due to interpretation, I can’t say yup flip to section x.xx and there it is. Some things are clear but the standard to me is 1/3 as thick as it should be. I hope on the next version there are a lot more illustration with perhaps a few example of parts which are fully dimensioned.

There’s nothing worst then arguing with a vendor on a standard that is not clear, when you thought it was clear when you put the symbol there in the first place

Is black ice clear? ;-)

 

[KENAT]

i2xtreme for your question 1 I believe the standard is perfectly clear as per the extract I give and the reference weavedreamer gives. I don't see the confusion, although arguably the callout you give for the holes in your first question isn't perfect due to not using C'bore symbol.

On your second question I believe it's inherently ambiguous and would be difficult to come up with a refined definition in the stndard that corrects this. Arguably referencing them back to a datum may clarify in some situations but perhaps not all.

As to who to contact it says it in the standard in the penultimate paragraph of the Foreward in ASME Y14.5M-1994 on page v.

KENAT,

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