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Involute cutter identification.

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  • Involute cutter identification.

    Can you identify the pressure angle of an involute cutter from the DP and depth as marked?

    A No2 cutter, 12DP, depth marked as .1798 - I need a 20PA cutter.
    Peter - novice home machinist, modern motorcycle enthusiast.

    Denford Viceroy 280 Synchro (11 x 24)
    Herbert 0V adapted to R8 by 'Sir John'.
    Monarch 10EE 1942

  • #2
    'fraid not

    Probably not. Thet are usually either 14 1/2* or 20*

    This is how it is marked on the cutter:


    http://en.wikipedia.org/wiki/Milling...te_gear_cutter

    Comment


    • #3
      No....

      The DP (Diametral Pitch)is based on the diameter of the pitch circle and the No. identifies the range of gear teeth that the cutter is able to cut.
      if u do a search here for cutting gears u will see there's been considerable discussion on the topic.
      The PA determines the profile of the teeth based on the angle of contact of the meshing teeth. it usually says on the cutter what the PA, DP and No. is.
      I spent most of my money on women and booze, the rest I just wasted.

      Comment


      • #4
        Bugger

        The PA is not marked on the cutter. Is there no other way to tell?
        Peter - novice home machinist, modern motorcycle enthusiast.

        Denford Viceroy 280 Synchro (11 x 24)
        Herbert 0V adapted to R8 by 'Sir John'.
        Monarch 10EE 1942

        Comment


        • #5
          Usually if they are not marked they are 14.5 degrees, but that's not 100%
          .

          Sir John , Earl of Bligeport & Sudspumpwater. MBE [ Motor Bike Engineer ] Nottingham England.



          Comment


          • #6
            That one sounds like a 14.5 degree one, the full depth of a 14.5 degree tooth is 2.157/pitch, for 20 degrees it's 1.800/pitch.

            Joe

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            • #7
              Right-o, thanks. Saved me finding out the hard way
              Peter - novice home machinist, modern motorcycle enthusiast.

              Denford Viceroy 280 Synchro (11 x 24)
              Herbert 0V adapted to R8 by 'Sir John'.
              Monarch 10EE 1942

              Comment


              • #8
                Pa = 14 1/2*

                Originally posted by Peter.
                Can you identify the pressure angle of an involute cutter from the DP and depth as marked?

                A No2 cutter, 12DP, depth marked as .1798 - I need a 20PA cutter.
                Depth of cut for 14 1/2* PA = 2.157/DP = 2.157/12 = 0.1795"

                Depth of cut for 20* PA = 2.25/DP = 2.25/12 = 0.1875"

                The cutter PA is 14 1/2*

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                • #9
                  Okay, so who's right ? Optics Curmudgeon or Old Tiffie ?

                  Comment


                  • #10
                    Both,
                    Works out the same.
                    tiffie has just repeated what Joe said earlier.
                    .

                    Sir John , Earl of Bligeport & Sudspumpwater. MBE [ Motor Bike Engineer ] Nottingham England.



                    Comment


                    • #11
                      Okay, color me stupid here, but 1.800/12 = .150 Not .1875. What am I missing here ?

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                      • #12
                        Tiffie's got the right 20 degree number, I was looking at the stub tooth table on that one.

                        Joe

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                        • #13
                          Nearly.

                          I can vouch that its (too?) easily done Joe.

                          I've caught myself nearly doing the same as you did several times.

                          Comment


                          • #14
                            Thanks to both of you. I really appreciate it. I have cut a few gears, but not many, using an involute cutter and a dividing head. I've even repaired a metric gear using an American cutter. My set-up probably wasn't correct, but it worked. So I was happy.

                            Another thing I was wondering is which is the most commonly used.....the 14.5 or the 20 degree PA ?

                            Comment


                            • #15
                              Originally posted by Terry L
                              Another thing I was wondering is which is the most commonly used.....the 14.5 or the 20 degree PA ?
                              Up until the 60's, 14.5° was most common. Now, 20° is most common.

                              14.5° pressure angle will mesh quieter and with less vibration, but 20° PA has a stronger tooth.
                              "Twenty years from now you will be more disappointed by the things that you didn't do than by the ones you did."

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