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  • clock winding ratchet

    how do I build one, the one i need has 14 div. with id of 1.000. i know this is not like a gear like this https://www.ebay.com/itm/11mm-REPLAC...-/400676485932

    So how is it done and what cutter I have never made one of these

  • #2
    How bout this and a dividing head? You can get them in various angles. Could even use an inexpensive router bit. JR

    dovetail cutter
    My old yahoo group. Bridgeport Mill Group

    https://groups.yahoo.com/neo/groups/...port_mill/info

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    • #3
      get just got that now how do i get 14 in to 360 = 25.7142857 for the div. I never have on this or a gear

      Comment


      • #4
        Originally posted by Brett Hurt View Post
        get just got that now how do i get 14 in to 360 = 25.7142857 for the div. I never have on this or a gear
        Can you plot that out on paper via the computer and use that as a guide with the dividing head? JR
        My old yahoo group. Bridgeport Mill Group

        https://groups.yahoo.com/neo/groups/...port_mill/info

        Comment


        • #5
          Originally posted by JRouche View Post
          Can you plot that out on paper via the computer and use that as a guide with the dividing head? JR

          Last edited by JRouche; 05-16-2018, 08:26 PM.
          My old yahoo group. Bridgeport Mill Group

          https://groups.yahoo.com/neo/groups/...port_mill/info

          Comment


          • #6
            Do you even have a dividing head? If not, what?

            14 divisions.

            A spin index, which has 360 divisions will not come out even (360/14 = 25.71...). But a winding ratchet does not have to be very precise so you could round to the nearest degree and it would work. In fact you would be hard pressed to notice the differences. Here is a table you could follow. The worst error is 0.43 degree.

            0
            26
            51
            77
            103
            129
            154
            180
            206
            231
            257
            283
            309
            334
            360

            If you have an indexing head or rotary table that has any gear ratio that is even (1:40 or 1:90 are common ones), then you can use any hole circle that has any multiple of 7 holes: 7, 14, 21, 28, etc. If you can provide the details, I/we can advise on turns and holes per division.

            If you have neither of the above, you can use a paper scale as suggested above. Any CAD program can compose and print a suitable scale. Again, for a winding ratchet, a lot of precision is not really needed.
            Paul A.

            Make it fit.
            You can't win and there is a penalty for trying!

            Comment


            • #7
              We are over - thinking this ! It's a simple ratchet not a cog wheel and in brass at that. How about a pair of dividers and a file.

              Joe B

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              • #8
                Yep, in fact that is how some of the old clock/watch makers would have done it. Scratch a circle. Set the dividers with a good (or bad) guess. Step around that circle and observe the error. Make a correction and try again. Repeat until you can not see any further error.

                Not super precise, but it will work.

                Stop worrying about it and just do it.



                Originally posted by JoeCB View Post
                We are over - thinking this ! It's a simple ratchet not a cog wheel and in brass at that. How about a pair of dividers and a file.

                Joe B
                Paul A.

                Make it fit.
                You can't win and there is a penalty for trying!

                Comment


                • #9
                  Originally posted by Paul Alciatore View Post
                  Yep, in fact that is how some of the old clock/watch makers would have done it. Scratch a circle. Set the dividers with a good (or bad) guess. Step around that circle and observe the error. Make a correction and try again. Repeat until you can not see any further error.

                  Not super precise, but it will work.

                  Stop worrying about it and just do it.
                  That is actually a pretty precise way to map out a bolt circle.

                  I was gonna suggest that but it seemed like Brett wanted to use another method. JR
                  My old yahoo group. Bridgeport Mill Group

                  https://groups.yahoo.com/neo/groups/...port_mill/info

                  Comment


                  • #10
                    https://www.youtube.com/watch?v=-we6ORrJgUI

                    Most spring winding ratchets don't have to be terribly precise. I've made one of these and used it to make plastic gears for my mini mill and mini lathe. It should be pretty easy to adapt it to a ratchet wheel using just a straight milling cutter set to mid point on the blank. Make shallow cut, turn blank, make next cut.

                    Comment


                    • #11
                      And it doesn't even have to be 14 unless you are restoring an antique. !5 is an easier number to divide and you probably have a multiple of that as one of the change-wheels on your lathe. If you have no kind of dividing head equivalent you can put an arbor holding your blank at one end and the index device at the other end and clamp it in a V-block.
                      If you don't want to buy a multitooth cutter you can use your mill's flycutter to hold a custom single point cutter. Just draw it all out large scale to work out the cutter shape and position of the blank.
                      Good to see you use both the popular forums I do. have you put the question on some more?

                      Comment


                      • #12
                        Originally posted by Paul Alciatore View Post
                        Yep, in fact that is how some of the old clock/watch makers would have done it. Scratch a circle. Set the dividers with a good (or bad) guess. Step around that circle and observe the error. Make a correction and try again. Repeat until you can not see any further error.

                        Not super precise, but it will work.

                        Stop worrying about it and just do it.
                        You can speed this process a bit by using the law of cosines to calculate the length of the required chord and using that value as your first setting.

                        C = R * sqrt (2 * (1 - cos(A)))

                        where:

                        C = chord length
                        R = radius of circle
                        A = 360/N
                        N = number of divisions

                        As a check, we know that this should reduce to C = R for N = 6 divisions...

                        A = 360/6 = 60

                        sqrt (2 * (1 - cos(60))) = sqrt (2 * (1 - 0.5)) = sqrt (1)

                        so C = R * 1 = R

                        For 14 divisions,

                        sqrt (2 * (1 - cos(360/14))) = 0.44504...
                        Regards, Marv

                        Home Shop Freeware - Tools for People Who Build Things
                        http://www.myvirtualnetwork.com/mklotz

                        Comment


                        • #13
                          The good thing about a ratchet escapement (I think that’s right) is it does not require the precision on a meshing hear, so long as the pawl engages it doesn’t matter what shape it is (within reason!) I restarted a grandfather clock recently ( the weights had been left suspended with the clock not ticking and bowed the shaft, a common thing to happen)
                          The ratchet wheel had clearly been marked with dividers and the teeth filed out, the thing had been working for fairly close to 100 years.
                          I’m no clockmaker btw, but the new shaft worked just fine, just a bit of rod really.
                          Mark

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                          • #14
                            Marv,

                            I am not trying to put anyone down, but not everyone here is going to remember trigonometry with a warm feeling as you and I would. And, in all likelihood, they will not consider this to be a faster way.



                            Originally posted by mklotz View Post
                            You can speed this process a bit by using the law of cosines to calculate the length of the required chord and using that value as your first setting.

                            C = R * sqrt (2 * (1 - cos(A)))

                            where:

                            C = chord length
                            R = radius of circle
                            A = 360/N
                            N = number of divisions

                            As a check, we know that this should reduce to C = R for N = 6 divisions...

                            A = 360/6 = 60

                            sqrt (2 * (1 - cos(60))) = sqrt (2 * (1 - 0.5)) = sqrt (1)

                            so C = R * 1 = R

                            For 14 divisions,

                            sqrt (2 * (1 - cos(360/14))) = 0.44504...
                            Paul A.

                            Make it fit.
                            You can't win and there is a penalty for trying!

                            Comment

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