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Thread: Understanding machine screw sizes

  1. #41
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    Quote Originally Posted by Doozer View Post
    As a mechanical engineer, I designed on some drawings for some high voltage standoffs with
    a 1-41/64" x 16 TPI thread because the lathe machinist would not adhere to the drawing that
    specified a 1-5/8" x 16 TPI thread, even when I called out the major, minor, and pitch diameters
    on the print. The thread size with a 64th made him look real close at the drawing, and not just
    cut the same old threads, devoid of reading the actual dimensions. I did this only after repeated
    phone calls could not get the message to the guy on the shop floor that I actually expected him
    to actually follow the drawing if he wanted us to pay the bill. I have to say that it did work in the
    end. I got my 1-5/8" x 16 TPI with .015" over on the pitch diameter. Crazy what you have to
    sometimes do to manage stupid humans.

    --Doozer
    Huh, that's nuts. Way I learned it, the drawing is The Word of God and you better have a good reason to make a shop floor change. Having said that, I've had the ill fortune to work with a *lot* of numbnuts who discount any kind of "book learning" because it isn't "real world" and fly by the seat of their pants.... they had no respect for the Engineering Dept. whatsoever. Its always fun to get hard numbers out of those types, and get them to explain *why* something works, or doesn't work.... made me get old fast and pull my hair out to deal with them.

  2. #42
    Join Date
    Feb 2012
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    Metcalfe, Ontario, Canada
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    Quote Originally Posted by andywander View Post
    #12 was pretty common "back in the day". Rather than saying it didn't catch on, you might say that after a time it "caught off".

    But, even today, 12-24 screws are used to mount servers and other IT equipment to racks. 10-32 is the other common size used for this purpose. There's also a metric standard, but I forget what it is....probably M5 x something or other....
    If it is M5 then it would most likely be M5.

    Apparently it is a faux pas to add the pitch for a standard metric coarse thread.

  3. #43
    Join Date
    Jul 2011
    Location
    Medford MA
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    632

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    Quote Originally Posted by Doozer View Post
    As a mechanical engineer, I designed on some drawings for some high voltage standoffs with
    a 1-41/64" x 16 TPI thread because the lathe machinist would not adhere to the drawing that
    specified a 1-5/8" x 16 TPI thread, even when I called out the major, minor, and pitch diameters
    on the print. The thread size with a 64th made him look real close at the drawing, and not just
    cut the same old threads, devoid of reading the actual dimensions. I did this only after repeated
    phone calls could not get the message to the guy on the shop floor that I actually expected him
    to actually follow the drawing if he wanted us to pay the bill. I have to say that it did work in the
    end. I got my 1-5/8" x 16 TPI with .015" over on the pitch diameter. Crazy what you have to
    sometimes do to manage stupid humans.

    --Doozer
    !

    A long time ago I was part of a committee wroting some documents setting some standards for the Internet. I was the document editor. I had a strong suspicion that people were not reading the document ... just arguing based on preconceived notions and expectations. So I put several pages of Shakespeare right into the document - not in a separate section or anything like that, right between two letters of a word, line “this is soRomeo oh Romeo, wherefore Art Thoume text of the document”.

    No one commented on it, or asked about it.

    It is in the final version that’s been published

    AND the guy who picked it up and did a follow on version just left it there.

    So it’s not just machinists who can be blind, thick skulled and dim witted :-)

    Frank

  4. #44
    Join Date
    Dec 2012
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    499

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    The metric rack screw size is M6 x 1.0

  5. #45

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    Quote Originally Posted by RB211 View Post
    F it, I'll just use metric hardware!

    Sent from my SM-G950U1 using Tapatalk
    One may make any sized metric threads in an effort to confuse someone in the future, there is no reason you can not make for instance M25-2.1 threaded components (-: Doing so will likely cause considerable head scratching in the future.

    Most threads are made on CNC machines these days and are not dependent on a gear train, simply enter the lead to 4 or more decimal numbers.

    It is fun

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