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  • Gears, gears and more gears

    Been working with Art Fenerty of Mach3 fame on his new gear-cutting program.
    Basically brought about because he wanted to do clock gears and then it got all out of hand with eccentric gears and all that artistic crap.

    Link to the site at www.gearotic.com there is a demo copy but the tutorials are worth watching.

    Anyway I wanted to get the program back to making mechanically perfect gears and bring in some ideas. Most of the cutting is for routers making thin gears with a vertical spindle but there is an option for doing spur and helicals travelling across the face.

    Now for the good bit even though CNC is needed the gears are cut with a conventional off the shelf $3 end mill and that end mill will cut any gear provided it can reach the root, don't believe it, watch the video.......

    http://www.youtube.com/v/qZJ95I3ZWro&

    Not a great picture, the white nylon doesn't help but I'll redo it later on brass or similar. Main thing is it shows the operation, the cutter blocks a slot out and then by using all 4 axis at the same time it moves away, raises the cutter and rotates the 4th axis so each pass is at a different angle and part of the involute. You have the choice of selecting how many passes per tooth.

    But because specials cutters are not needed it's now very easy to modify gears to fit an application. I cut two 14 tooth gears to text book specs, mounted then on two pins the required distance apart and they ran perfectly, I then made two more identical blanks but cut 13 on one and 15 on the other.



    You can swap these in any order and they run fine. Helicals are still a work in progress, they work but the tooth shape is not correct yet.



    Again simple tooling, in most of these cases the tool was a throw away FC3 3mm end mill costing £2.99

    [Edit]

    Forgot to add but the program will be a work in progress, if there is a demand for an application then it may be added if possible. Bevels are definitely on the cards but the program is for general release first.
    Last edited by John Stevenson; 09-25-2010, 05:43 AM.
    .

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




  • #2
    John
    Great work!!
    I will be sure and pick that program up....
    and it great to see a GOOD post here!! LoL
    eddie
    please visit my webpage:
    http://motorworks88.webs.com/

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    • #3
      Thanks John, its good to see some chips and a real worthwhile project and some fresh ideas! JIM
      jim

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      • #4
        Hi John,

        Looks great to me. The video is fine, just a touch out of focus or a touch to close in filming it. I would love to be able to make something like this.

        As always, thanks for sharing,
        -SD:

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        • #5
          Your back from the pub then.

          Dave
          Just south of Sudspumpwater UK

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          • #6
            "Your back from the pub then."

            He never left the pub. His wife dropped off the laptop and some extra money....got to love the gal

            eddie
            please visit my webpage:
            http://motorworks88.webs.com/

            Comment


            • #7
              Been back 10 minutes and playing with this program again.

              Because everything is done in software you can play "what if ?" to your little hearts content.
              Not quite what you want to fit in? How about a 18.5DP cutter or better still to get bang on a 18.67564 DP ?

              Sooooooo.

              I drew a 40 tooth XL series timing pulley up in CAD [ with the help of Mr SPI Industries ] and got some measurements off it.

              They went back to Gearotic [TM] and juggled some figures.



              So if we use 16.25 DP we get an OD of 2.5240, we need 2.5240, OK so far

              Then play with shift, stubbing and tooth width we get a total depth of 0.0571, we need 0.0550, 2 thou too deep, think I can live with this.

              Tooth width is 0.1242 and we need 0.1240, even closer.

              Now bung the dxf onto the original drawing and it's within a gnats left bollock.

              Only fly in the ointment is it says it wants a-0079 thou cutter but I reckon it can get away with a 40 thou cutter. I think this is all to do with going off standards on the shift and stubbing etc and I have asked Art to check this.

              It's still early days on this program but so was Mach3 at one stage and look where it is now.

              Once saved all that is needed to make any XL pulley is to change the number of teeth.

              .
              Last edited by John Stevenson; 09-25-2010, 05:51 PM.
              .

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



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              • #8
                That is one fantastic program. Imagine combining that with a 3D modeling program that uses parameters to punch out a model of any gear configuration that you could think of!

                Then again, maybe not. We could end up with some crazy engineer designing geartrains using completely non-standard gears. Bah.

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                • #9
                  Like this ?



                  .

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



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                  • #10
                    Just got home from the Gears model engineering show in Portland and a person there had a gear set with no "round gears" there must have been 8 or more gears. Interesting to watch a bunch of odd shaped gears running together.

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                    • #11
                      Got the new update from Art this morning and it's cured the screen problems and cutter size so a 47 thou cutter will fit.

                      Heres the comparison CAD file.



                      Purple is the true pulley, green is Arts program, by the time all the corners have been knocked off on a scotchbrite wheel it will be indistinguishable from original.

                      .
                      .

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



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                      • #12
                        Originally posted by John Stevenson
                        Like this ?



                        You, sir, can stay away from me.

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                        • #13
                          Helicals are go !!

                          Setup and did a 2.5Mod 11 tooth 45 degree helical today.



                          Came out perfect, checked it on the gear verniers and it was within two thou of where it should be.

                          51 minutes with a 3mm end mill running at 500mm/min - proof.



                          Elapsed time is next to the EStop button

                          Video here http://www.youtube.com/watch?v=OI8f6Lrwx00

                          Watch from 2.08 until 3.01 and you will see how it steps over in the Y and the 4th axis follows it to form the involute in a series of discrete steps.

                          Shout up if I'm boring you playing to an audience of one.
                          .

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



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                          • #14
                            Was playing with the demo a little yesterday and am looking forward to the non demo release being available for purchase.


                            I bet that e-stop button is hard to hit with the mouse cursor when that o-sh!t moment happens.

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                            • #15
                              how about intermittent gearing? I'm working on a project that requires intermittent rotary motion linked to a scotch yoke.

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