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What does a circle with a slash through it mean?

  1. Jul 21, 2016 #1
    I am reading European engineering publications, and the circle with a slash shows up about half of the time in front of length measurements. For example, Ø15 x 1.12 mm. What does this mean?
  2. jcsd
  3. Jul 21, 2016 #2


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    Staff: Mentor

  4. Jul 21, 2016 #3
    Makes sense, thanks.
  5. Jul 22, 2016 #4


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    Could be a representation of digit ZERO.
  6. Jul 22, 2016 #5
    Diameter is probably correct in your case but Ø is often used to distinguish zero form O. I have also seen it used for the greek letter phi on occasion.
  7. Jul 23, 2016 #6


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    The format would make sense if it described a 15mm diameter bolt, threaded with a 1.12mm pitch thread.
    But 1.12mm is not a standard metric pitch.
  8. Aug 6, 2016 #7
    It is a left-over from ancient computer programming practice. Back when data was entered by writing on paper than having it keypunched (are you old enough to know what a keypunch was?) and all alphabetic data was upper case, you needed some convention to distinguish O (letter) from 0 (zero) They look the same on paper, on the punch card, and on many printers. That goes back 50 years - I still do it out of habit.
  9. Aug 7, 2016 #8


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    ... and to add to the confusion: Ø is a Norwegian/Danish character, (Oe ligature) equivalent to the Ö in German and Swedish.
  10. Aug 7, 2016 #9
    this means a disc of diameter 15mm and thickness 1.12mm
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