Thread identification please.

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  • July 30, 2024 at 5:53 am #289539
    Monte NZ
    Participant

      International Member

      Could someone please  let me know the thread size of the three screws that attach the  starter pulley  on my 1924  2hp BNL Johnson…

      I believe it is an unusual thread size.

      Thanks in advance

      /

      Monte NZ

       

      July 30, 2024 at 8:09 am #289540
      The Boat House
      Participant

        Do an internet search for – screw size aomci. There is more than one oddball thread on those early Johnson’s.

        July 30, 2024 at 10:46 am #289542
        RICK EICHRODT
        Participant

          US Member - 2 Years

          Monte,

          I think they are 8x 30 thread size.  Chris Scratch has made some for me and I believe that is the size!

           

          Rick

          July 30, 2024 at 11:36 am #289543
          Steve D
          Participant

            A thread gauge tool like this has come in handy for me a number of times.

            thread-gauge

            July 30, 2024 at 6:36 pm #289545
            bkrsdoz
            Participant

              US Member

              Rick is correct. 8-30 thread size. You can find used ones from donor motors.

              I found some oval head slotted 8-32’s on EBay. They work as well.

              July 30, 2024 at 11:55 pm #289548
              joecb
              Participant

                US Member

                I think that it’s time to post the chart again. The old ASME screw thread standards.  Use caution when encountering a thread that appears to be a 1/4 inch, note on the chart that there are three screw sizes that are real close to 1/4 inch…. some unusual thread pitches also. A micrometer and thread pitch gage is your friend.

                Joe B

                1 user thanked author for this post.
                The Boat House
                July 31, 2024 at 3:41 am #289551
                Monte NZ
                Participant

                  International Member

                  Thanks  Tubs, Rick, Steve D, bkrsdoz and joecb for your help in sorting that problem and thanks to for the chart…..very handy…….I have printed it off for future reference.

                  Why they used such uncommon threads beats me!

                  As always, many  thanks for your input.

                  Monte NZ

                  July 31, 2024 at 1:10 pm #289555
                  joecb
                  Participant

                    US Member

                    Uncommon now – a- days, but optional “standards” back then. I believe that World War II industrial production boards did a lot to put the old standards to bed and introduce the current standards.

                    Joe B

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