Bulle clock hints
The British Horological Institute has archived and edited the following from e-mails sent to the Clock/Clockers mailing lists on the Internet. The information here does not necessarily indicate a method approved by the BHI, we are only publishing this digest so that others can decide for themselves whether the methods listed below will suit them.
From:
John Locke, Bob Sheff, Art Bjornestad, David J. Smith
- The magnet in Bulle clocks is magnetised thus:
S---------N---------S. - Bulle clocks should never be oiled.
- You should consider the possibility that you Bulle is not swinging far enough to ALWAYS engage the ratchet gear. I have never had this problem on my Bulle, but this was the cause of failure on a BARR (hipp trigger) clock. My clock swings about 1.5"+, and will swing more with a new battery. You might also consider that the voltage is less than 1.5v or resistance in the Y switch or other wires can reduce voltage/current to the electro magnet. You might also consider that the magnet has a short (heaven forbid) causing less magnetic power.
- I have found that the primary reason that Bulle clocks stop is a lack of lubrication. Some have come to me so dry that they squeak when the pendulum is swung. The only place you shouldn't oil a Bulle is the contacts, all other pivots should be treated as pivots. This same advice goes for all other electric clocks as well, treat them as clocks but do not oil the contacts or near where the oil may migrate to the contacts.
- With reference to squeaking Bulle clocks, where does the squeak come from? The silver pin rubbing on the Y contact, unlikely; the Y arbor, probably. But then the contact between the arbor and its bearings is part of the electrical circuit, supplemented by the small spring running in a groove at one end of this arbor. The end contact strip touching the end of this arbor seems to be too stiff to provide electrical contact without seriously increasing the end thrust friction. Was it there just to limit end float?
Quoting from the instructions issued by Bulle:
" The BULLE Clock, Instructions
1. Free pendulum by removing wedge etc. placed to steady it.
2. Connect red wire to central terminal (red) of battery and black wire to the other terminal.
3. Place battery in position to be held by the clips.
4. See that the pendulum swings freely and does not rub against the black bar. The adjusting foot under and at the back of the clock case, screwed up or down, levels the clock to this effect. Wall clocks have two adjusting screws at the back of the case, one at each side.
The BULLE Clock should not be oiled
Never transport the clock with the battery connected.
Regulation of the BULLE Clock is easy by means of the brass nut at the bottom of the pendulum. If slow, screw nut up; when fast screw down. One complete turn corrects a variation of approximately two minutes in 24 hours. To ensure satisfactory working of the BULLE Clock, no other parts must be interfered with."
- The Magnet
I have come across magnets which have the North poles at the end but I suspect that they have been remagnetised incorrectly, not that it matters too much as reversing the battery polarity will make the clock run. Check the colour of the battery connections against the battery polarity to see if a change has been made. What the effect of arc erosion at the wiping contacts on the pendulum is with reversed polarity, I am not sure.
- The contact between the arbor and its bearings is only incidentally if at all an electrical contact. The little spring running in the groove seems to be intended as the primary (perhaps only) contact since it is made of silver and when properly adjusted its large loop end rolls back and forth in the groove without slipping, making a good and frictionless contact. There must surely be no oil in this groove.
I assumed the instructions about not oiling the clock apply to the owner of the new clock and are given on the assumption that the clock is ready to set up and run, having been lubricated already in all necessary places at the factory or workshop.
- Generally speaking the voltage which is needed to power this clock is 1 1/2 volts. I'm working on a nice early one at the moment which is merrily gaining about 3 hours per day by dint of the fact that what the French call the "Roue d'echappement" is having more than one tooth gathered at each swing of the pendulum. The problem is that the amplitude check spring (correcteur automatique d'isochronisme- clock parts sound far more interesting in French) is too weak and allows the amplitude to become too large so the driving pawl starts to gather more than one tooth.
The early claims made for the battery life in a Bulle are rather interesting. Based on the fact that the battery supplied had a capacity of about 25 ampere hours with a current consumption of 1 milliampere and an impulse that lasts for only 0.3 seconds it was suggested that the battery would last for a period of ten years. In modern terms a standard 1 1/2 volt torch battery should give a running time of about two years.
The easiest way of correcting the Bulle clock when it gathers two teeth is to raise the silver contact pin on the pendulum to give less movement to the 'y' contact. The pin has a clamping bolt on the opposite side of the pendulum rod to the pin.
