trailing zeroes and tolerances 3

[tk369]

I am in a quandry. I have a part 1660 mm long. My titleblock says, " Tolerance 1 place decimal +/- 1 "
Yet, I have a whole number per 1.6.1(b)of Y14.5.

Do I put 1660.0 on the drawing? Or leave it 1660?

Thank you in advance.


teddykaye

 

[KENAT]

You're going to have to look at what your local standards say.

Per ASME Y14.5M-1994 section 1.6.1 mm dimensions do not have trailing 0's so you can't simplistically use the type of block tolerance that varies by number of decimals.

What tolerance is required by function? Don't over rely on block tolerances just because they are there.

Mixing mm dimensions with inch tolerances also looks like a recipe for disaster.

Without knowing more information I'd be tempted to directly tolerance your part.

KENAT,

Have you reminded yourself of faq731-376 recently, or taken a look at posting policies:

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

What is Engineering anyway: faq1088-1484

 

[dgallup]

Many times ISO tolerance blocks are used with metric drawings. These base the tolerance on nominal dimension size so bigger dimensions get bigger tolerances. To me that makes more sense than the number of decimal places but we don't use either. We only have one default linear tolerance for the entire drawing. If you want a different tolerance you have to call it out on each dimension. At least it cuts down on errors.

As Kenat said, over reliance on tolerance block tolerances is a bad thing especially if they impose tight tolerances.

 

[drawoh]

tk369,

Systematically apply tolerances to metric dimensions. You will be surprised at how little extra time it takes. Your drawings and designs will all the better for you taking a few extra minutes to think things out.

JHG

 

[TheTick]

In the time it took to post the question, you could have added an explicit tolerance and moved on with your life.

 

[NomLaser]

Tick...you always have the best and most efficient answers

 

[sheevaraam]

If you want +/- 1 tolerance as per your drawing standard, then use one place decimal. If you wanted a looser or tighter tolerance then I would explicitly call it out e.g. 1660 +/- 2 or 1660.0+/- 0.5. Depends on how much deviation from the length you can tolerate on the part.

 

[looslib]

Well, we modified the Unspecified Tolrance block to say that 0/1 place dimensions have +/-.1 tolerance.
Sheevaraam, you cannot use decimal place holders for tolerance on metroc drawings like in your example:
"1660 +/- 2 or 1660.0+/- 0.5".
It would be:
1660 +/- 2 or 1660 +/- 0.5

You may also want to look at ISO standards for the metric classes of tolerance. A dimension of 5 would have a different tolerance than a dimension of 150 or 1660. Yet, they are all 0 decimal places. It does make sense if you think about it.


"Wildfires are dangerous, hard to control, and economically catastrophic."

Ben Loosli

 

[KENAT]

Don't bring up ISO 2768, I'm not sure I could take it today.

And appologies for my comment about mixing metric & inch, I realize now the " was part of the quotes not indicating inches.

KENAT,

Have you reminded yourself of faq731-376 recently, or taken a look at posting policies:

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

What is Engineering anyway: faq1088-1484

 

[fcsuper]

KENAT

Matt Lorono
CAD Engineer/ECN Analyst
Silicon Valley, CA
Lorono's SolidWorks Resources
Co-moderator of Solidworks Yahoo! Group
and Mechnical.Engineering Yahoo! Group

 

[CheckerRon]

I did a double take on that one too, KENAT, that is why we discourage using inch marks on mechanical (vs civil engineering) drawings.

 

[tk369]

i guess nobody uses quotation marks anymore! when i have a direct quote, i use them.
thanks to all for your comments. even the 'edgy' ones!

teddykaye

 

[CheckerRon]

That's OK, TK. You were gramatically correct. It was our own eyes that deceived us.

 

[fcsuper]

Don't think you "are" off "the" hook for the use "of" quote marks, mister"."

Matt Lorono
CAD Engineer/ECN Analyst
Silicon Valley, CA
Lorono's SolidWorks Resources
Co-moderator of Solidworks Yahoo! Group
and Mechnical.Engineering Yahoo! Group