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Long Case Clock Date Wheel...

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Hello there,

I had a most enjoyable day yesterday in making up a date wheel for a 1770 Long Case Grandfather clock. It works! BUT.... it moves the date two full days, so obviously there are too many teeth on the wheel for correct display. How can I work out exactly the number of teeth there should be?? or is there any other get around ways to correct this problem?

The wheel I made is a bit of a bodge as it was made from a winding spring barrel, the diameter was correct 48.74mm x thickness 3.62mm x 65 teeth. Thickness a bit too much, would be better if half stated. Teeth a bit fine but interlock with other wheel okayish. Are these wheel ready made up and available? if so where can I purchase one??

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As I see, You made the wheel that is engaged with the hours wheel, and has a pin that turns days wheel…

If the hours wheel has 32 teeth, then Your wheel should have 2x32= 64…  65 is no good number, as it is odd, not even…

But, this is not the reason for which 2 days a switched ahead… The position of switching pin on Your wheel is wrong… You must move the pin a little away from the days wheel, and this will solve the switching problem.

 But still, the time of day changing will constantly move, because of the wrong teeth number…

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Very interesting comment and thank you for your reply! This gives me some food for thought, I do think the pin that I made is too thick and would be a bit hard to bend, even with it being copper, probably copper is not a good material to use but I do have some much thinner material that I found after the job was done. Will try what you suggest. Cheers!

PS. My face wheel has only 31 teeth would that make any change to your calculation?


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The diameter of the date wheel comes into calculation, as it needs to move 11.61 degrees for every 24 hour revolution

So the position of the pin you fitted into the wheel, and the distance from the centre point of the wheel needs to be worked out.

A shortcut to this is to mount the pin on a small "eccentric" plate so you can adjust depth and therefore forward movement

It may be necessary to remove the 31 toothed cog and fit a smaller in diameter 31 toothed cog

Never assume the gears in a longcase clock are original or the dial is original to the movement, its always a minefield repairing something that has usually had about ten previous repairs and dial swops in its lifetime! Best of luck!

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No need of thinking at all, an nothing to calculate...

There is nothing to be done before You  don`t have the right wheel. This is all You need, nothing more. No difference if the other parts or dial are original  to the movement or not. The date wheel is good and You don`t need another.

As it will be very hard or impossible to find suitable wheel, I can cut one for You and send it by post... But, please, show a picture of the front of the movement, without dial, so the gears are seen and the teeth can be counted, as we need to know the right number of teeth.

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