Use of the word "mil"
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    Default Use of the word "mil"

    Hello everyone. Today I was astonished to learn that, in America, the word "mil" is another term for a "thou". Is this really true? I can just imagine the problems this could cause for an immigrant machinist from a metric country mixing it up with a millimetre.

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    Yes, and "millwrights" are union job appointments to make sure all the lackys use the vernacular correctly!

    Now "circular mils" will have you running 'round like you were electrified.

    ;-) It's not what you say, it's how you say it.

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    Quote Originally Posted by Vincent Phipson View Post
    Hello everyone. Today I was astonished to learn that, in America, the word "mil" is another term for a "thou". Is this really true? I can just imagine the problems this could cause for an immigrant machinist from a metric country mixing it up with a millimetre.
    That's correct. It's pretty old school though, I've never really heard it outside of the context of specifying something like fabric or nitrile glove thickness where there's not too much room for confusion.

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    The one place the typical US citizen would see it most often in a non-machine-shop context is in the dimensions printed on boxes of plastic garbage bags or storage/freezer bags they would buy at the grocery store. This aligns with BoxcarPete's mention of plastic film thickness in stuff like gloves.

    If you really want ambiguous and possibly confusing, consider "points". In some applications, these are synonymous with mils and therefore thou. But in most contexts, they are something entirely different. In fact, in the US printing trade, a "point" could either be 1/1000" or 1/72", depending on whether you are measuring thickness or length.

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    I'm not sure I've heard the terms interchanged. Mostly just "thou" in our shop/industry. IMO, it could be an issue, but not if you're being clear with yourself and others which measuring system the part is in. If someone tells you in passing and you're not sure, ask for clarification. If the part has mixed Metric/Imperial dimensions and it's not clear where that "mil" is applied, ask for clarification.

    It's the same problem as when a carpenter asks you to take a "tenth" off a piece and they really mean .100, not .0001.

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    A “mil” is either a mL or a millionth of an inch. Any other use is archaic (nearly always in the “coatings” industry) and should not be propagated.

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    Quote Originally Posted by RC Mech View Post
    A “mil” is either a mL or a millionth of an inch. Any other use is archaic (nearly always in the “coatings” industry) and should not be propagated.
    If I recall correctly, the first time I heard the prefix "mil", it was when I lived back in ancient Rome. It was a popular addition to words to signify units of 1000. sort of like "cent" is to 100.

    Millennials might find difficult with the concept.

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    Quote Originally Posted by BoxcarPete View Post
    That's correct. It's pretty old school though, I've never really heard it outside of the context of specifying something like fabric or nitrile glove thickness where there's not too much room for confusion.
    Also common as dirt on garbidge bags and Vis-queen o/e plastic vapour barrier.

    Not to mention the fractional-cent rates on real-estate tax-rate percentages..

    Where's the "surprise?"

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    Quote Originally Posted by RC Mech View Post
    A “mil” is either a mL or a millionth of an inch. Any other use is archaic (nearly always in the “coatings” industry) and should not be propagated.
    *yawn* tell that to the food-storage and garbidge-bag / lawn leaf bag / "contractor clean up" bag AKA plastic sheet/film goods industry?

    Likely to get your ass laughed right outta the room?


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    First time I heard it was a friend of mine who works in PCB design for electronics. He said it's the term they use in that industry.

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    I was just pulled back into the world of printed circuit board design after a 30 year hiatus. Designed a board and got a prototype made. I noticed that here in the US the unit of mil meaning .0001” is pretty pervasive as a measurement unit in pcb layout dimensions.

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    Along with the others already mentioned, I've seen it used in paint shops for paint thickness, as well as plating shops.

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    all the above why its best to specify actual units, SI or otherwise, NOT ambiguous acronyms or abbreviations. such as "tenths" or "mills"

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    Quote Originally Posted by thermite View Post
    *yawn* tell that to the food-storage and garbidge-bag / lawn leaf bag / "contractor clean up" bag AKA plastic sheet/film goods industry?

    Likely to get your ass laughed right outta the room?

    No use telling the old-timers in that room they’ve been doing it wrong. It’s only liver-spotted tradition, you see.

    Not sure about the laughing, between the wheezing and COPD coughing fits one would have to dodge dentures falling to the floor.

    Moral of the story is not to use dumb-ass slang for measurements. Boomers and fossils be damned.

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    Quote Originally Posted by RC Mech View Post
    A “mil” is either a mL or a millionth of an inch. Any other use is archaic (nearly always in the “coatings” industry) and should not be propagated.
    Milli-amps are 0.001 amp.

    Deci is 1/10
    Centi is 1/100
    Milli is 1/100

    Sent from my SAMSUNG-SM-G930A using Tapatalk

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    Quote Originally Posted by RC Mech View Post
    No use telling the old-timers in that room they’ve been doing it wrong. It’s only liver-spotted tradition, you see.

    Not sure about the laughing, between the wheezing and COPD coughing fits one would have to dodge dentures falling to the floor.

    Moral of the story is not to use dumb-ass slang for measurements. Boomers and fossils be damned.
    It is only confusing to the uninitiated.

    Those who know, know.

    A simple way to weed out the pseudos.

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    "Dual Inline Package" (DIPs) integrated circuits were available in three common widths, 300 mil, 600 mil, and 900 mil, which referred to the distance between the two rows of leads (in industry jargon, "legs").

    The center-to-center distance between the legs in the rows was usually 100 mils, but there were DIPs with 50 mil leg spacing in the waning days of DIP packages.

    Personally, I prefer "mil" as jargon for 0.001 inch, and dislike "thou". I call the 0.001 meter unit a "millimeter", and prefer to spell out the words "millimeter" and "inch".

    I've seen, and probably committed, too many hand-written "mm" and "in" notations that could be either one.
    Last edited by John Garner; 06-29-2021 at 01:47 PM. Reason: Put the i in integrated, in the first sentence

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    Quote Originally Posted by Vincent Phipson View Post
    Hello everyone. Today I was astonished to learn that, in America, the word "mil" is another term for a "thou". Is this really true? I can just imagine the problems this could cause for an immigrant machinist from a metric country mixing it up with a millimetre.
    Sincere question? Does the term "mil" ever come up when describing unites of length in the "civilized/ metrified world?

    I've never heard mm being called "mils". MKS rules!

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    Most if not all of the PCB houses I've worked with, domestic and otherwise insist on operating in "mils" where they equal 0.001 inches. Why the overseas ones want to do that I'm not sure. I design the outlines in mm, but they Gerber out in inches because that's what everyone seems to want over by objections.

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    Quote Originally Posted by RC Mech View Post
    No use telling the old-timers in that room they’ve been doing it wrong. It’s only liver-spotted tradition, you see.

    Not sure about the laughing, between the wheezing and COPD coughing fits one would have to dodge dentures falling to the floor.
    Moral of the story is not to use dumb-ass slang for measurements. Boomers and fossils be damned.
    *yawn*

    Not so much dentures as shrapnel, actually. Wiki extract:

    The majority of combat deaths in the Napoleonic Wars, World War I, and World War II were caused by artillery


    Another "mil" - "slang term" for "milliradian".. is used to lay those guns...

    Milliradian - Wikipedia

    Or missiles.

    What with the MIM-14b Whiskey-three-one warshot yield at 20 Kilotons?
    The term "be damned" wudda been justifiable as well.


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