SI units tol 5

[ctopher]

How do you read these tolerances?
Not sure how to add this symbol here, but "<_" is "less than or equal to".

x<_10, +/-0.1
10<x<_100, +/-0.15
100<x<_500, +/-0.25
500<x, +/-0.5

If a dimension is 165 or 22.5, what tolerance is used?

I have never used this type before.
Thanks.

Chris
SolidWorks 10 SP5.0
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[pmarc]

This is a very typical tolerancing scheme used in ISO world.
Its based on assumption that for certain manufacturing methods accuracy of dimension becomes smaller (tolerance is wider) as the nominal size gets bigger.

If the dimension is 165 the limits are 164.75 - 165.25.
If the dimesnion is 22 the limits are 21.85 - 22.15.

 

[ctopher]

So, the number falls within the range (x) it's that tolerance.
Seems odd to me, but I understand it.
Thank you!

Chris
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ctopher's home
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[MintJulep]

More like

If the number (x) falls within the range...

 

[ctopher]

MJ,
Thanks, I typed too fast without checking.

Chris
SolidWorks 10 SP5.0
ctopher's home
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[Belanger]

I don't think it's just for ISO; I've seen it on prints that use ASME. I've heard it referred to as a "graduated" tolerancing scale or method.

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

 

[ctopher]

Thanks John.
Of all my years of drafting/eng/etc, this is the first I have seen this.

Chris
SolidWorks 10 SP5.0
ctopher's home
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[fsincox]

Limits and Fits have been defined with a similar system for quite a while by ANSI B4.1-1967. Why other linear tolerances should be excluded would have been more the question im my mind.
There was an ANSI or ASME standard on metric tolerancing that proposed the ISO style, (DIN German) system it appears to have been withdrawn now.
Frank

 

[KENAT]

This kind of tolerance is also common in the design guides of castings, moldings etc.

Posting guidelines faq731-376

http://eng-tips.com/market.cfm?

(probably not aimed specifically at you)
What is Engineering anyway: faq1088-1484​

 

[powerhound]

This looks like graphing restrictions or inequalities. I thought I had seen the last of these in Trig.

Powerhound, GDTP T-0419
Engineering Technician
Inventor 2010
Mastercam X5
Smartcam 11.1
SSG, U.S. Army
Taji, Iraq OIF II

 

[CheckerHater]

The standard was ANSI/ASME B4.3-1978(R2004) General Tolerances for Metric Dimensioned Products; so it’s more than 30 years old.

It was happily reassured in 2004 but later decision was made to transfer it from B4 committee to Y14 committee to become “drafting and tolerancing” standard.

As a result it was successfully “missing in action”. Copies are still around. One may be surprised, how much it resembles ISO 2768.

 

[fsincox]

Thanks CH, I knew I had seen it before.
Frank

 

[Madhu454]

It is very easy to assign general tolerances for the drawings which are dimensioned with Inches as dimesioning units. The preeceding zeros represents the toleance value.
Example; 14.0
14.00
14.000

General Tolerances
.X = +/- .01
.XX = +/- .001
.XXX = +/- .0001

Above shown is just an exapmple. You might be familiar with this.

If you use milimeters (mm) in the drawings then the whole numbers should not be preceeded by zeros as per the satandard. You dont have provision to assign general tolerances as the example shown above. Since ISO standard uses mm as the dimensioning unit. it has to go for other methods for mensioning the genereal tolerances. The general tolerancing scheme you mentioned in your post is very coomon in ISO.

 

[fsincox]

Madhu454,
Do you work with the ISO system much, yourself?
Frank

 

[ctopher]

Madhu454,
I am very familiar with the scheme you mention.

Chris
SolidWorks 10 SP5.0
ctopher's home
SolidWorks Legion

 

[fsincox]

Sorry ctopher, Your initial question would not imply that to me. I am interested in a discussion with people who have used this system2 for a period of time and had to live with it.
Frank

 

[pmarc]

Frank,
What are your doubts/concerns about ISO system?

 

[Madhu454]

Hi Frank,
Yes, I wrk on ISO system. We use Geometrical Product Specification (GPS) in our drawings. GPS is based on ISO standard constisting of more than 150 standards to completely define the part. It is very similar to GD&T,(but there are few differences compare to ASME standard). In our companey we dont use general tolerances in drawings. But I have seen many drawings created as Chris mentioned in his post.

 

[fsincox]

pmarc,
Thanks, I think you know I have been interested in it for some time. I do not feel I know enough about it to have my own "doubts".

Madhu454,
Thanks, I sounds like you do not use the part we have been discussing here, I have been interested in issues like the stack up of these implied tolerances.

Frank

 

[pmarc]

Frank,
Yes, I noticed that you are really interested in the ISO GD&T language, or as Madhu454 said - GPS. And I also noticed that you sympathize with some (or most?) of the ISO's approaches to the tolerancing of parts.

I also remember that you already started some threads about the topic on the forum. The most recent one was about cummulation of tolerances for two round holes, right? Could you give any other example showing your concerns? I think it would be a best starting point for further discussion.