European Dimensioning Question

mochinist · Feb 22, 2006

Today one of my customers brought in some prints to have some parts made, the prints are all in French, since the machine they are for is French made. Anyways it had a symbol I had never seen before, for example one of the O.D.'s had a dimension of &#248 75 g6. The guy that brought it over didn't know what it meant either, so I called a engineer I work with frequently, and he said it was a way of calling out the tolerance of the diameter, he is going to fax over a copy of the chart that this reference's too, but I would like to know a little more about it. If any of you have a weblink with a chart or atleast a name of the standard so I can google it, I would really appreciate it.

Thanks
Don

Gary E · Feb 22, 2006

He's right... I would wait for his chart.

Here is a place to start..
http://www.kok.com/

RAS · Feb 23, 2006

Metric shaft and bore tolerance charts are in Machinery's Handbook. I'm not at work right now, so I can't help at the moment.

RAS

metlmunchr · Feb 23, 2006

g6 for 65mm to 80mm shafts is -10 microns/-29 microns

I can post a link to a chart if somebody can point me to something telling how to make a short link from one that's 3 feet long.

The only person here who hates pages that necessitate horizontal scrolling worse than Don T is yours truly

metlmunchr · Feb 23, 2006

Maybe this will work

http://tinyurl.com/ns95v

Dr. Rob · Feb 23, 2006

('scuse me, Mochinist...

Where'd you find that diameter symbol on your keyboard? And for that matter, what about things like degree symbols and whatever else people like us need? Is there some kind of extra font somewheres in the 'puter?)

franco · Feb 23, 2006

Dr Rob,

A lot of commonly used symbols are available by pressing the Alt key, and a numeric code on the numeric keypad.

eg Alt + 167 gives the º symbol, and Alt + 0216 gives Ø.

A list of other symbols can be found at:
http://www.lookuptables.com/
below the ASCII section.

franco

RAS · Feb 23, 2006

Dr. Rob,
When you are typing a post, or a reply, and need a special symbol, click on 'Start'/'All Programs'/'Accessories'/'System Tools'. There, you will find 'Character Map'. Open it, find the symbol you want, click 'Select', then 'Copy'. Come back to your message, right click where you want the symbol, and click 'paste: Ø

RAS

Dr. Rob · Feb 23, 2006

Okay, fellas. Thanks a-plenty.

Back to the subject at hand... those tolerance codes consist of a letter and a number. Lower case letters signify a tolerance on the minus side; upper case letters signify a tolerance on the plus side. Or, usually, shaft vs hole if you see it that way. The numbers depict magnitude. Most of these classes or codes are standardized and lookupable, but note that some larger industrial corporations have their own set of charts.

There isn't much more mystery to it really... Once you know the basic scenario, the rest is in the charts.

Chevy427z · Feb 23, 2006

We do a lot of work with German prints (in metric).

We have these little boxes called "Tolerators".

Just did a google on it and was surprised to find this:

http://www.mercateo.com/p/329-37912101/Toleranzenschluessel_Tolerator.html

The little wheel on the side is a handle that turns a tiny paper scroll inside. Took some getting used to those "foreign" tolerances, but once I did, it's easily understandable.... now what the engineers actually call out, that's something altogether different

Mark

Benta · Feb 23, 2006

Hi:
Metlmunchr: it's not microns, it's micrometers. At least in electronics, microns are 1/1000". That's a big difference.

Dr. Rob: "Lower case letters signify a tolerance on the minus side; upper case letters signify a tolerance on the plus side. Or, usually, shaft vs hole if you see it that way."

Wrong!!!!!! The ISO system describes fits.

Lower case letters are used for specifying shaft tolerance.
Upper case letters are used for specifying hole tolerance.
You can have shafts larger than holes if you want a "hard" interference fit.

mochinist: here are links to the data you need:

Hole tolerances:
http://www.tribology-abc.com/calculators/iso_holes.htm
Shaft tolerances:
http://www.tribology-abc.com/calculators/iso_shafts.htm

Regards,

Benta.

FranH · Feb 23, 2006

You will find that the standard dimensioning such as "g6" makes fits exactly what engineering designed. When you get the charts showing shafts and clearances everything is perfectly clear. Best thing since running water.

bcstractor · Feb 23, 2006

I don't think I have ever heard of microns being 1/1000" in "electronics" because "electronics" is all metric.

I think you are confused with mil which is the name for mm and 1/1000" in the US.

Chris P

Chevy427z · Feb 23, 2006

Hole tolerances:
http://www.tribology-abc.com/calculators/iso_holes.htm
Shaft tolerances:
http://www.tribology-abc.com/calculators/iso_shafts.htm

Just to add a bit of clarity to the links that Benta posted:

Bear in mind all the tolerances are three places. That is, when you read +6, you are actually looking at .006mm . When you read +335, you are actually looking at .335mm, and so on.

Mark

mochinist · Feb 23, 2006

Thanks for the help guys.

Dr I just used ascii codes as someone else pointed out.

mochinist · Feb 23, 2006

Bear in mind all the tolerances are three places. That is, when you read +6, you are actually looking at .006mm . When you read +335, you are actually looking at .335mm, and so on.

Yeah it took me a minute with the calculator to figure that out. I also found this http://www.metric4us.com/calculator.html

Chevy427z · Feb 23, 2006

Great link Don! Thanks for sharing.

My '03 Cavalier gets 6.031143162393162 l/100KM

Mark

Neil · Feb 23, 2006

I use MS Word and go insert>symbol and choose degree, etc...then cut and paste into whatever I am doing, usually it works...

Canyonman · Feb 23, 2006

Just a Quick THANK YOU for the ASCII Link and the Character Map reference.

Take Care,

Ken

metlmunchr · Feb 23, 2006

Metlmunchr: it's not microns, it's micrometers. At least in electronics, microns are 1/1000". That's a big difference.

Sorry, but we're not turning shafts from electrons. Google "definition of micron" and you'll find both micron and micrometer are defined as one millionth of a meter. Micron is sometimes incorrectly used as one millionth of an inch, but I've never seen it used as a thousandth of an inch. Micron is technically obsolete, having been replaced by micrometer. Be that as it may, I've never heard a machinist use the term micrometer because its easily confused with micrometer (the measuring device). Mil is sometimes used as one thousandth of an inch, but this too is confusing in a shop if both english and metric work is being done, as lots of machinists familiar with metric work will refer to a 40mm shaft as a 40 mil shaft.

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