Cuckoo clock mystery

One here for you clock enthusiasts. I offered to get an old cuckoo clock going again for a relative. The movement was badly clogged with dirt so I have cleaned and oiled it. I set it up on a bench out of its case to give it a test. It ran for an hour or two then stopped for no obvious reason, I checked the gear teeth up to the escapement for damage and any remaining dirt but found nothing obvious. There is some slight wear in the gear pivots. However as I have frequently re-started it it runs for longer periods but it was still stopping for no apparent reason. The movement has to be dead level for it to run at all. The action of the pendulum seemed rather weak to me and I decided to add a little weight to it. To my surprise this seems to have greatly improved things. The pendulum only weighs 15 gms and I only added a 2 gm weight but the clock has now been running for several hours. Could it be that this has improved the action of the clock and if so can anyone explain why?

I am not a horologist but you've partly answered the question by your statement about level. A little thought will show the escapement's action could be affected by the hang of the pendulum, whose rest position should be perpendicular to the movement in both planes.

Also, are the escapement pallets badly worn, shown by a groove in each? That might not help.

I think too the oil can have a marked effect. It would take only a slight thickening by evaporation to gum up the works.

When you say cleaned and oiled it, did you mean stripping down the clock completely and checking the condition of the pivots and pinions etc. ?

Adding extra weight can keep the clock running but will cause any existing wear to accelerate.

What did you use to clean and lubricate the clock?

WD40 is fatal for any clock.....

Regards

Derek

Thanks for the replies. The relative did say that the clock was extremely fussy about being level even when new, and yes there are signs of wear on the tops of the escapement teeth but not so the pallets. I did not take the movement apart, deciding to take the path of least resistance first! I soaked the movement in petrol for a day, dried it thoroughly then removed any staining etc. with alcohol. I used a very light application of 32 oil. On the pivots etc. The clock is still going this morning so it’s been running over 12 hours now, I’m getting hopeful!

Are the pallets just a bit of bent steel strip like mine? It is amazing they run at all with little regard to correct geometry.

Not sure what 32 oil is but proper clock oil is formulated not only to be thin enough but to not evaporate for years,

Sometimes it is better rather than stetting to correct time to set to 12:00 each round and see if it stops at a similar time eg at 12 minutes to the hour.

It does sound like you are getting there. When cleaning it’s good to clear the pivot holes by twiddling a tooth pick or similar in the hole. It sounds like you still had a little friction on the scape wheel pivots or the pallet pivots probably caused by specks of dirt. Running tends to disperse or break up the grime and ease things off. Adding weight to the pendulum will probably have increased the stored energy allowing the pendulum to cope with the losses before getting another impulse. If you can remove the pallet arbour without disassembling the rest of the clock then have a clean of the pivot holes, reassemble and oil. If not just keep going and see if it sorts itself out.

regards Martin

Yes, the pallets are just bent steel strip as you describe. The 32 oil is used as a hydraulic oil I believe, I have since found some thinner, clearer looking oil which may be more suitable. Whilst I didn’t strip and clean the pivot holes I did thoroughly check the gear teeth for any obstruction. Thanks for the tip about cleaning the pallet pivots, but I would have to open the whole movement plates to remove them. It’s still going so I’ll keep an eye on it for a day or two before delving in. Thanks again all.