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The Geneva Hours Clock from Digital Machinist

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  • The Geneva Hours Clock from Digital Machinist

    Here is my latest project, running in the pages of Digital Machinist magazine.

    I call it Geneva Hours because I used a Geneva mechanism to advance the hour hand. The clock also uses a 60:1 worm drive to get from seconds to minutes.

    Although I used CNC for many of the details, I designed the clock so that it could be built using manual machines.

    The clock uses the same circuit board, with a few parts added, that I designed for the Magnetic Gear Clock.

    The series will run 3 issues for the important details and possibly a fourth dealing with surface finishes.

    As a service to readers of Digital Machinist, and with George's approval, I am again offering circuit boards, kits and assemblies.
    Bare circuit board $15.00
    Electronic parts + board $40.00
    Assembled & tested $55.00

    I also offer coil winding service, where readers mail me their machined bobbins and I wind the coils and add lead wires, and then mail them back. The cost is $40.00 for the four coils.

    All prices are postpaid in the U.S.

    I can be contacted by PM on this board or e-mail at [email protected].


    Weston Bye - Author, The Mechatronist column, Digital Machinist magazine
    ~Practitioner of the Electromechanical Arts~

  • #2
    That is a beautiful piece of work Weston! I hope to someday build one of each kind if I can ever find the TIME. I really like the magnetic one, using magnets for gears.
    Kansas City area

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    • #3
      Originally posted by Weston Bye View Post
      ...and possibly a fourth dealing with surface finishes.
      Ding, ding, ding! "Yes," is my vote if George is reading. I find finish work is a largely overlooked topic in machinists' literature.

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      • #4
        Nice work Wes, will see it at the next NAMES! right? I take it that the 60 to one seconds to minutes means the minute hand moves once per minute? Looks like more than one Geneva in there to me. Bob.

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        • #5
          Bob, the clock was on display at NAMES this year, and I'm sure that this one or one like it will be there next year. The seconds are read out on a ring that rotates with the vertical shaft above the rotor. Above that, a 60:1 worm gear drives a horizontal shaft that carries the Geneva pinion that drives the 12:1 Geneva wheel for the hours, and a 1:1 spur gear to drive the minute hand. I will post a closeup photo later today.

          Arthur, I probably mis-spoke myself a little. While I will deal somewhat with surface "finish", I also plan to explore surface "treatment", involving patinas and such. I agree that it is a neglected area of the hobby. What I present will necessarily be limited to the immediate application and certainly not the last word on the subject.

          Idea for Prospective Authors: If you are pretty good at some aspect of surface finish or treatment, and can present it in such a way as to be understandable and achievable by the rest of us, I'd like to see it.
          Weston Bye - Author, The Mechatronist column, Digital Machinist magazine
          ~Practitioner of the Electromechanical Arts~

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          • #6
            As promised in the previous post, here is a closeup of the "clockworks".
            ..a 60:1 worm gear drives a horizontal shaft that carries the Geneva pinion that drives the 12:1 Geneva wheel for the hours, and a 1:1 spur gear to drive the minute hand...
            Weston Bye - Author, The Mechatronist column, Digital Machinist magazine
            ~Practitioner of the Electromechanical Arts~

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            • #7
              Electronic Circuit Board & Coil Winding Service

              Post 1 has been edited to include electronics offers for the clock.
              Weston Bye - Author, The Mechatronist column, Digital Machinist magazine
              ~Practitioner of the Electromechanical Arts~

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              • #8
                In the article you mention you have a book coming out, any idea when that will be available?

                Also, is the worm gear purchased or do we make it as part of the build?

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                • #9
                  Sky,
                  I am told that the book is well along, but the date has not been determined.

                  The worm and worm wheel are machined as part of the build. The worm is a simple threading operation and the worm wheel is just slightly more difficult than a common spur gear.

                  If you want a sneak preview, the spur gears I presented in the Spring 2014 issue of DM were used in this clock.
                  Weston Bye - Author, The Mechatronist column, Digital Machinist magazine
                  ~Practitioner of the Electromechanical Arts~

                  Comment


                  • #10
                    Drawing Error Alert!!

                    It has been reported by a reader that, after having built the details for the clock as described in the Summer 2014 issue, there is an interference between the rotor and the bobbin faces.

                    I went back and checked dimensions, comparing the drawings with the actual prototype that has been running merrily with no such interferences, as well as reviewing the assembly in CAD.

                    Sure enough, I mis-dimensioned the bobbin drawing: the overall length of the bobbin, drawn as .850", should be .750". Correspondingly, the .650" dimension of the winding window should be reduced to .550".

                    I apologize to my readers who may have been inconvenienced by this error.
                    Weston Bye - Author, The Mechatronist column, Digital Machinist magazine
                    ~Practitioner of the Electromechanical Arts~

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                    • #11
                      For those of us who have already made the bobbins (I mailed them last week to you for you to wind them, they should show up Monday or so), could we just move the mounts out a little bit? I know this might mean a bigger base, but I started with the bobbins as that looked like the most fun so it's the easiest for me.

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                      • #12
                        Moving the mounting locations outward radially would indeed be a solution for those who have not started the base yet, and would have no adverse effects on operation.
                        Weston Bye - Author, The Mechatronist column, Digital Machinist magazine
                        ~Practitioner of the Electromechanical Arts~

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                        • #13
                          As I have already made bobbins and wound them and made the base in fact everything is a smaller rotor in order?

                          Ian

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                          • #14
                            A smaller rotor is possible, but might deliver slightly less torque (smaller lever arm). A slightly closer spacing of the poles of the rotor may suggest narrowing the tips of the pole pieces where they emerge from the bobbin.

                            From my own perspective, I would find it easier to machine new bobbins and transfer the magnet wire (the wire being the most costly part of the assembly) from the oversize bobbins, particularly if the rotor was already made.
                            Weston Bye - Author, The Mechatronist column, Digital Machinist magazine
                            ~Practitioner of the Electromechanical Arts~

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                            • #15
                              Here is the corrected drawing for the bobbin.

                              George
                              Traverse City, MI

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