Gear cutters

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Gear cutters

Home Forums Beginners questions Gear cutters

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  • #197823
    Roger Hulett
    Participant
      @rogerhulett83124

      Do gear cutters come in different sizes?. This is not a silly question. For example I have a gear cutter No 3 12DP 14.5pa. It has an outside diameter of 62.5mm.

      Are all gear cutters of the above spec 62.5mm or is it possible to get for example a No3 12DP 14.5pa with an od of 35.00mm ??

      The reason I ask is that I have to copy a gear set up which consists of one gear 92.5mm od and one gear 37.5mm separated by a shaft 20mm long. (This is all one piece of metal) With the gear cutter having a radius of 31.25mm it will not cut the smaller gear wheel without fouling the large one.

      The original gear set up was made in 1921,and appears to have been turned on a lathe judging by the tooling marks and not cast as a whole.

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      #7714
      Roger Hulett
      Participant
        @rogerhulett83124
        #197827
        Michael Gilligan
        Participant
          @michaelgilligan61133

          Roger,

          There is no reason for the cutter to be a particular size, or to have a specific number of teeth.

          You could [and perhaps they did] cut the gear using a single tooth fly-cutter … or, alternatively, by a planing process.

          MichaelG.

          Edited By Michael Gilligan on 24/07/2015 16:05:53

          #197829
          Tim Stevens
          Participant
            @timstevens64731

            Or you could make the two gears separately and bolt them together (or use a shaft with a key, etc).

            Cheers, Tim

            #197830
            KWIL
            Participant
              @kwil

              Some gears are cut by a planing action and not by a rotary gear cutter, therefor you can cut to a shoulder. Some are a single point tool and on larger tooling the tool itself can be curved to suit.

              #197833
              Rufus Roughcut
              Participant
                @rufusroughcut

                Hi Roger try here

                http://mikesworkshop.weebly.com/making-gear-cutters.html

                or search gear cutters in these forum subjects

                Regards

                Rufus

                #197837
                KWIL
                Participant
                  @kwil

                  Rufus.

                  Those would work on a planing machine for the OP's need, he has a gear cluster which does not allow it to use the rotary milling machine approach shown on the link.

                  #197839
                  JasonB
                  Moderator
                    @jasonb

                    Kwil, if the cutters were made less than 40mm dia that would allow them to run out at the end of the cut on the small gear into the 20mm gap without hitting the large one.

                    This is a planing machine which was probably used on the originals, the small cutter moves up and down like a slotting machine.

                    Or for bigger gears the cutter move shorizontally, you can just see the straight cutter behind the gear

                    J

                    Edited By JasonB on 24/07/2015 16:57:39

                    #197853
                    Phil P
                    Participant
                      @philp

                      Jason

                      The top photo shows a Sykes machine where the cutting process is continuous with both the cutter and blank rotating as the teeth are planed.

                      The lower photo is a Sunderland machine. The cutter will move vertically with respect to the gear it is cutting as well.

                      The blank rotates one, two or maybe three teeth while the cutter follows it to generate the involute profile.

                      The blank is then indexed and a few more teeth are cut.

                      I have photo's of my Alexander Milling machine set up to do the Sunderland process if anyone is interested.

                      Phil

                      #197854
                      Roderick Jenkins
                      Participant
                        @roderickjenkins93242
                        Posted by Phil P on 24/07/2015 19:10:16:

                        I have photo's of my Alexander Milling machine set up to do the Sunderland process if anyone is interested.

                        Yes please,

                        Rod

                        #197871
                        Anonymous
                          Posted by Roderick Jenkins on 24/07/2015 19:17:26:

                          Posted by Phil P on 24/07/2015 19:10:16:

                          I have photo's of my Alexander Milling machine set up to do the Sunderland process if anyone is interested.

                          Yes please

                          +1

                          Presumably the Sykes machine cutter is essentially a gear with an involute form appropriate to the number of teeth and with relief on the cutting edges? However, for the Sunderland gear planer the cutter looks like a short section of rack, and therefore is simpler to make?

                          Andrew

                          #197872
                          JasonB
                          Moderator
                            @jasonb

                            Bailey's have video of the two machines in opperation on this page

                            #197917
                            Phil P
                            Participant
                              @philp

                              Here are the photo's

                              I cannot claim it was my own idea though, my late father was responsible for rigging it up.

                              He cut a set of Myford change wheels going up in increments of ONE.

                              The photo below has been stitched together from multiple images so ignore the wonky bits.

                              stack of gears.jpg

                               

                              alex-01.jpg

                               

                              alex-02.jpg

                               

                              alex-03.jpg

                               

                              alex-04.jpg

                               

                              alex-05.jpg

                               

                              I still have all the kit to do this, but I also have a Mikron hobbing machine which does most of my gears, so this is probably not going be rigged up again any time soon.

                              I think you will agree that my dad was a clever bloke when it came to gear cutting. He did this after he had sold most of his workshop due to ill health just for something to keep his mind active.

                              Phil

                              Edited By Phil P on 25/07/2015 08:45:27

                              Edited By Phil P on 25/07/2015 08:49:19

                              #197923
                              Bazyle
                              Participant
                                @bazyle

                                That looks like the X axis is geared to the rotation so cutting a spiral not a gear, so is that a way to curve the flank? Definately ingenious dad.

                                Not seen a GHA mill before. I'm sure I once saw a lathe by them being scrapped at work but never found any reference of them making anything other than engravers. I suppose the Deckel lookalike is logical what with their die sinkers.

                                #197925
                                Roderick Jenkins
                                Participant
                                  @roderickjenkins93242

                                  Most impressive. Lovely mill.

                                  Thank you

                                  Rod

                                  #197961
                                  Phil P
                                  Participant
                                    @philp

                                    Just in case anyone fancies having a go, here are my dads words to go with the pictures.

                                    gear-cutting-procedure-1.jpg

                                    gear-cutting-procedure-2.jpg

                                    step-back-calcs.jpg

                                    He actually designed an attachment for a Myford lathe to generate true spiral bevel gears, but that is another story.

                                    Phil

                                    #198011
                                    Roger Hulett
                                    Participant
                                      @rogerhulett83124

                                      Thankyou to all contributors to this thread. not having a planing machine leads me toward the fly cutter solution. However that gives me another problem. I only have a horizontal mill.I cannot see a supplier of fly cutters for horizontal mills in UK. Also the articles on gear cutting with a fly cutter indicate that the cutting tools are at right angles to the holder, so, not only have I to find a fly cutter for a horizontal mill it has to have a right angle tool !!!

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