Should Number of Digits of Hole Size Match Feature Control Frame Tolerance number of digits?

[philyherb1]

If I have 6 holes located by basic dimension that are of size .XXXX +/-.XXXX,
should the positional tolerance within the feature control frame also be at .XXXX?
ASME Y14.5-2009 was not clear.

 

[chez311]

The text in Y14.5-2009 para 2.3 seems to suggest they should be considered separately. I do not believe that there is any requirement they have the same number of decimal places.

One of the first practical examples in the standard fig 3-29 shows this, the 8X 7.9-8.1 dia is accompanied by a 0.14 position tolerance. Another fig 4-4 has a 69.93-69.87 dia accompanied by a 0.8 position tolerance.

 

[drawoh]

philyherb1,

If your drawing is metric, you should delete the trailing zeros. Perhaps this solves your problem.

Consider the following positional tolerance (in inches)...

|[POS]|[DIA].0500|A|B|C|

What are the two trailing zeros accomplishing? Usually, we apply trailing zeros so that the title block note on tolerances applies. In the case of a positional tolerance, it is a tolerance.

--
JHG

 

[tz101]

No requirement whatsoever for these to match.

 

[SeasonLee]

You can get it from section 2.3.2 (d) on 2009 version

Season

 

[Belanger]

To clarify the OP's question: We're talking about comparing the number of digits in the hole's size tolerance with the digits in the FCF. The standard is indeed clear about comparing the number digits in the basic dimension with the digits in the FCF, but that's different than what was asked.
With that in mind, I would agree with chez311.

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

 

[SeasonLee]

J-P

I get this from James Meadows Textbook "Geometric Dimensioning and Tolerancing-Application, Analysis, & Measurement" page 15/16

Season

 

[philyherb1]

Thank you all for the info!
I was talking about a drawing in inches.

My 6X holes are .8782/.8764 Thru located with 3 place basic dimensions.
The positional tolerance attached to the hole size requested:
|[POS]|[DIA].0100|A|B|C|
|[POS]|[DIA].0010|A|

If 3 place basic dims used then this would be appropriate?
|[POS]|[DIA].010|A|B|C|
|[POS]|[DIA].001|A|

In other words I am not applying the positional tolerance to the "Hole Size"
but rather to the "Hole Location"

Thank you!

 

[tz101]

If 3 place basic dims used then this would be appropriate?
|[POS]|[DIA].010|A|B|C|
|[POS]|[DIA].001|A|

Yes. That will be appropriate, but so would 2 or 4 decimal places in the GD&T reference frame.

 

[Belanger]

Thanks for the clarification, Philyherb1. Your original post mentioned holes that are "located by basic dimension that are of size .XXXX +/-.XXXX."
That in itself is a contradiction, so I guess that's what threw me off.
(SeasonLee... I'm aware of that rule, but I interpreted the question as focusing on size, not location.)

Basic dimensions -- by definition -- can never have a +/- tolerance, so I presumed you were talking about the size of the holes (which would not be a basic dim). Either way, you got your answer.

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

 

[SeasonLee]

Either way, you got your answer

I always get my answer from this Forum too(edit), its a nice place to learn GD&T. Thank you all.

Season

 

[drawoh]

philyherb1,

Again, what information is provided by your trailing zeros. If your fabricator see fewer decimal places, they may quote a lower price for your parts.

In ASME Y14.5, .01 means 0.010000000000000000...

--
JHG