A few weeks back my neighbour saw me repairing one of my mantle clocks triggering the fateful comment "ah, could you have a look at my cuckoo clock". Now about 35 hours of work later (cleaning, busing, repairs and adjustment) and yes it is driving me cuckoo but I am now down to two problems.
Cuckoo Arm (and Strike Counting)
The final step before returning to the case was to add the cuckoo arm (for poking the cuckoo out the door). The strike was working fine before doing this but with the arm installed in such a way that the correct degree of swing was achieved the strike train intermittently stalls.
I think I know the cause of this. One of the repairs I had to do was replace the spring on the minute hand lifting lever (the loop on the front of the plate was broken and so the spring was not providing any tension. But I made the replacement spring from slightly thicker (0.66mm instead of about 0.45mm) wire. My theory is that with this thicker spring when the cuckoo arm is added the weight of the arm has the effect of slightly further increasing the tension and the unlocking lever therefore retains too much tension on the control cam preventing it from starting to run. To support this theory - when the train stalls if I apply very slight pressure to the lever tail (that actuates the cuckoo arm) the train unlocks and the strike complete correctly.
I don't know if all this makes sense or whether anyone disagrees with the logic so far...
So, from what I've said the simple answer would seem to be: make another new spring of the correct thickness. But what I have found from various tinkering I've done so far is that if the tension of that new spring is reduced slightly (for example, I changed the anchor point so the spring had less starting tension) then I have another problem. That is the strike train will unlock and strike but often fails to lock at the end of the count period. This is usually (but not always) failing to lock at the end of the hour strike and locking only after having struck the half hour as well.
So, I think using a lighter spring is going to unleash this problem and I cannot see any other form of adjustment I can make to ensure the train locks correctly.
Am I completely on the wrong track or missing something important?
Music on Half Hour
The clock came to me not working correctly and I am reliant on my neighbours to advise on how it used to function – but their memory seems a bit hazy and I have slightly different description from both of them!
First, the clock is (except for the issues described above) working fine - striking on the half hour and hour and playing music on the hour. But, I'm told it used to play music on the hour and half hour. I think they are correct on that because there is currently significantly less (about half) drop on the music weight than the time train weight. But I can't see how to resolve this.
The operation of the strike train and it's interaction (via those horrible wires between the plates) with the music train seems identical at both the hour and half hour.
But I have noticed one thing that may explain it.....
When the half hour strikes the lever to the music side unlocks the music train and the music fan starts to rotate. But the single strike then completes (and the music fan lock lever drops back) before the music fan has completed one revolution. So the music train locks when the music fan completes its first revolution.
This suggests one of two things to me. Either the strikes train is running too fast and shuts of the music train before it should (on this point I have checked the strike fly is not unduly loose on its arbour) or the music train is running too slow.
Or is there something else I am missing?
Music Tunes
I am not considering this an outstanding problem as I have discounted it – but mention it "just in case".
Although they are in disagreement between their selves my neighbour tells me the clock played a different (and possibly shorter) tune on the half hour.
First, I don't think a different tune is possible… The music box is driven directly from the music train via a pinion that engages with the music train chain wheel. The pin barrel on the music box does move laterally against a spring on its arbour so in theory the barrel could be moved to play a different sequence of pins but there's no "mechanism" that would facilitate that movement of the pin barrel.
On the second point I don't see how a different length of play is possible either. The control cam on the music train means once the train is unlocked it has to complete one full rotation of the control cam, which equals one rotation of the pin barrel.
But I remain open to correction on either point!
Sorry, this has turned out a long post but perhaps better to include everything observed rather than leave it open to reading between the lines!
Andy
Cuckoo Arm (and Strike Counting)
The final step before returning to the case was to add the cuckoo arm (for poking the cuckoo out the door). The strike was working fine before doing this but with the arm installed in such a way that the correct degree of swing was achieved the strike train intermittently stalls.
I think I know the cause of this. One of the repairs I had to do was replace the spring on the minute hand lifting lever (the loop on the front of the plate was broken and so the spring was not providing any tension. But I made the replacement spring from slightly thicker (0.66mm instead of about 0.45mm) wire. My theory is that with this thicker spring when the cuckoo arm is added the weight of the arm has the effect of slightly further increasing the tension and the unlocking lever therefore retains too much tension on the control cam preventing it from starting to run. To support this theory - when the train stalls if I apply very slight pressure to the lever tail (that actuates the cuckoo arm) the train unlocks and the strike complete correctly.
I don't know if all this makes sense or whether anyone disagrees with the logic so far...
So, from what I've said the simple answer would seem to be: make another new spring of the correct thickness. But what I have found from various tinkering I've done so far is that if the tension of that new spring is reduced slightly (for example, I changed the anchor point so the spring had less starting tension) then I have another problem. That is the strike train will unlock and strike but often fails to lock at the end of the count period. This is usually (but not always) failing to lock at the end of the hour strike and locking only after having struck the half hour as well.
So, I think using a lighter spring is going to unleash this problem and I cannot see any other form of adjustment I can make to ensure the train locks correctly.
Am I completely on the wrong track or missing something important?
Music on Half Hour
The clock came to me not working correctly and I am reliant on my neighbours to advise on how it used to function – but their memory seems a bit hazy and I have slightly different description from both of them!
First, the clock is (except for the issues described above) working fine - striking on the half hour and hour and playing music on the hour. But, I'm told it used to play music on the hour and half hour. I think they are correct on that because there is currently significantly less (about half) drop on the music weight than the time train weight. But I can't see how to resolve this.
The operation of the strike train and it's interaction (via those horrible wires between the plates) with the music train seems identical at both the hour and half hour.
But I have noticed one thing that may explain it.....
When the half hour strikes the lever to the music side unlocks the music train and the music fan starts to rotate. But the single strike then completes (and the music fan lock lever drops back) before the music fan has completed one revolution. So the music train locks when the music fan completes its first revolution.
This suggests one of two things to me. Either the strikes train is running too fast and shuts of the music train before it should (on this point I have checked the strike fly is not unduly loose on its arbour) or the music train is running too slow.
Or is there something else I am missing?
Music Tunes
I am not considering this an outstanding problem as I have discounted it – but mention it "just in case".
Although they are in disagreement between their selves my neighbour tells me the clock played a different (and possibly shorter) tune on the half hour.
First, I don't think a different tune is possible… The music box is driven directly from the music train via a pinion that engages with the music train chain wheel. The pin barrel on the music box does move laterally against a spring on its arbour so in theory the barrel could be moved to play a different sequence of pins but there's no "mechanism" that would facilitate that movement of the pin barrel.
On the second point I don't see how a different length of play is possible either. The control cam on the music train means once the train is unlocked it has to complete one full rotation of the control cam, which equals one rotation of the pin barrel.
But I remain open to correction on either point!
Sorry, this has turned out a long post but perhaps better to include everything observed rather than leave it open to reading between the lines!
Andy
