Problem is with the click

Discussion in 'Clock Construction' started by ernienoa, Jun 8, 2017.

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  1. ernienoa

    ernienoa Registered User

    May 3, 2017
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    I have been building the American Clock based on the book from Steven G Conover. This is my first build. I have no experience in clock repair, but I have broken one clock and fixed three so far. It has been a learning experience and I am close to finished. It runs very good and is easy to adjust and is keeping very good time so far.
    My problem is with the click. It does wind if you are carful, but as it get to the end of the wind the click spring comes off with the resulting unwinding. I did not use brass wire for the spring as in the book, but used steel spring wire. The photo shows how it is made. So any thoughts about what is wrong.

    307115.jpg 307116.jpg

    307117.jpg
     
  2. Tinker Dwight

    Tinker Dwight Registered User

    Oct 11, 2010
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    The end of the click spring may have a sharp edge and is catching.
    It should have a curl so that it is a smooth surface against the click.
    Tinker Dwight
     
  3. Allan Wolff

    Allan Wolff Moderator
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    Mar 17, 2005
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    As you describe it, the click holds until the spring is near fully wound at which time it lets go, that is, the click comes out of the ratchet slot. Is that what you mean by the spring comes off? If that is the case, then an adjustment may be needed to the ratchet teeth profile or the face of the click, or both. The ratchet teeth need to lean forward so that the click is driven down into the ratchet rather than allowed to slide out of the slot. In you photo, it appears the tip of the ratchet teeth are in contact with the click, when what you want is the tip of the click to be in contact with the bottom of the slot. Perhaps a picture will explain better.
    I have attached one of your photos with a red line showing how the ratchet teeth should lean. The blue line shows how the front of the click should also lean. The slopes of the red and blue lines are exaggerated to make them easier to see. Ideally, the slope of the red and blue line are the same so the force is distributed across the face of the click. My lines may not be as parallel as they should be. This profile helps to put a downward force on the click to hold the click in the slot as spring pressure increases.
    307177.jpg
     

    Attached Files:

  4. John MacArthur

    John MacArthur Registered User
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    Feb 13, 2007
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    I'd go with Tinker on this one, without being able to see exactly what the spring end looks like. It should be smooth, maybe burnished, and ride freely in the slot on top of the click. And, as Tinker says, should have a slight reverse curl at the end. Also, double check to see that the click itself rotates freely on its rivet. The angle on the engaging end looks to me to be sufficient to hold, if the spring is working correctly. Nice job on the movement.

    Good luck,
    Johnny
     
  5. ernienoa

    ernienoa Registered User

    May 3, 2017
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    Thanks all for the suggestions. I have put a little up curve on the end of the spring and I did a little fitting of the click for what I hope is a better fit. I also changed the spring steel to hard piano wire curved to fit. There are a few more things I have to do before it can go back together so it will be a day or two before I can finish. But if it works I'll let post the results.
     
  6. tok-tokkie

    tok-tokkie Registered User

    Nov 25, 2010
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    I agree with Allan. The line normal to the face of the ratchet must pass between the click arbor & the arbor of the ratchet wheel. Then the force will tend to push the click deeper into the ratchet. As you have it it is tending to force it out of the ratchet - which is what is happening. The face of the click must match the face of the ratchet or be even steeper so that the tip is in contact - Allan's red line, the blue line should match that or only make contact at the bottom of the red line.
     
  7. Randy Beckett

    Randy Beckett Registered User
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    May 23, 2012
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    It looks to me like one problem might be with the way the spring is bent. From your picture it looks like the spring might be resting on the tip of one of the ratchet wheel teeth about 2 teeth before the click, maybe not allowing the spring to hold the click in it's fully seated position. This wouldn't likely matter if the angle of the click face was steeper into the slot of the ratchet wheel, but could allow just enough slack to start raising the tooth when enough pressure is applied, allowing it to jump up.
     
  8. THTanner

    THTanner Registered User
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    #8 THTanner, Jun 10, 2017
    Last edited by a moderator: Dec 15, 2017
    It looks like the original spring lies very close to the top of the teeth and that some teeth are a bit longer than others. Is a long tooth lifting the spring out of the slot on the click and pushing it away?

     
  9. ernienoa

    ernienoa Registered User

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    As noted in my June 9 post, it is working great now. All of the items listed here were corrected. I think the most important item was the stronger spring. Now it we can see how well it will run. So far it is easy to adjust and seems to keep good time. Then a case will have to be made.

    Thanks all.
    Ernie
     
  10. John MacArthur

    John MacArthur Registered User
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    Tidbit of horological arcana:

    I've been wracking my brains (and library) trying to find a diagram and explanation of "draw" in a click situation that I know I've seen somewhere in the last 50-odd years, and have finally found it, in Goodrich "The Modern Clock".

    I think what tokkie is saying is that a click needs "draw". This can be accomplished two ways. First, one can undercut the tooth shape slightly, as is commonly done, and impart a "natural" draw. Also, one can impart an "induced" draw, by making the length of the click shorter than the distance from its pivot to the tangent of the root circle of the ratchet. This makes a perceived undercut to the face of the tooth, even though it is still radial, but also makes the wheel actually pull the click into its root circle. These both are equally if not more important in maintaining power detents. They also both fit tokkie's description of the line normal to the ratchet face laying between the click pivot and the barrel arbor.


    307593.jpg . 307592.jpg
     
  11. tok-tokkie

    tok-tokkie Registered User

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    #11 tok-tokkie, Jun 15, 2017
    Last edited by a moderator: Dec 31, 2017
    The line normal to the face of the ratchet wheel is the line of the force coming from the ratchet to the click. That is elementary force analysis. The force is directed at 90° to the face.

    If that normal force is directed 'inside' the arbor of the click then it is trying to rotate the click towards the 'inside'. Originally the normal force was directed slightly to the 'outside' of the click arbor so it was trying to rotate the click towards the 'outside'.

    There is also a friction force on the face. The friction force is directed across the face of the ratchet - it is at 90° to the normal force. With the original ratchet wheel under light winding load that friction force was sufficient to hold the click in place. Before the clock was fully wound the normal force became great enough to overcome the friction force and the click was driven out of the ratchet wheel.

    Changing the angle of the ratchet so the force line is to the 'inside' makes the click want to slide deeper into the ratchet when it becomes greater than the friction force. The friction force is then in the opposite direction.
     
  12. Tinker Dwight

    Tinker Dwight Registered User

    Oct 11, 2010
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    Using excessive force on the click, more than what is needed to
    hold the spring and to keep it from slipping out will accelerate
    the chance of fracturing the click or loosening the rivet.
    Being just a degree or so less then the 90 degree is all that is
    needed. More than that just increases the chance of sudden
    failure from excess force.
    Tinker Dwight
     
  13. ernienoa

    ernienoa Registered User

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    Wow, I'll keep this in mind for the next clock. Thanks for the detail analysis! I am working on a case and should have a photo in the next week or so. en
     
  14. ernienoa

    ernienoa Registered User

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    Here is the clock finished in it's case. 308174.jpg 308175.jpg
     

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