Tolerance and significant digits 2

[Brad1979]

Let's say I have a print with +/- 0.003" tolerance on a dimension. Typically with 3 significant digits, one would round numbers like 0.0034 down to 0.003. My question is should a +/- 0.003" tolerance be interpreted as +/- 0.0034" due to significant digit rounding?

 

[drawoh]

Brad1979,

Where does .0034" come from?

The ASME Y14.5 standard states that a tolerance of .003" means .003000000 etc. If you measured something .0034" out of specification, it should be rejected.

--
JHG

 

[KENAT]

What drafting standards do you use?

All limits are absolute. Dimensional limits, regardless of the number of decimal places, are used as if they were continued with zeros.

Examples:
12.2 means 12.20...0
12.0 means 12.00...0
12.01 means 12.010...0

To determine conformance within limits, the measured value is compared directly with the specified value and any deviation outside the specified limiting value signifies non-conformance with the limits.

So no you don't round in the way you're suggesting, at least to ASME. +/-.003" equates to +/-.00300000000000000000000...0. +.0034 would be out of limits.

Posting guidelines faq731-376

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

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

 

[Brad1979]

Thanks guys. I was not aware of that section of Y14.5M. That's what I was looking for.