BULLE CLOCK

[jkfabulos]

I HAVE A WALL MODEL THAT I AM ATTEMPTING TO SORT OUT AND GET RUNNING.
I HAVE DONE ALL THE NORMAL ELECTRICAL CHECKS AND CLEAN UP INCLUDING THE HOROLOGIX
MAGNET AND COIL TEST USING 1.5 VOLTS WITH RESULTING GREAT PENDULUM SWING. CLEANED ALL CONTACTS AND CONNECTIONS.
RUNS ON 1.5 VOLTS BUT VERY POOR SWING. RUNS WELL ON 3 VOLTS.
BASED ON THE COIL AND MAGNET TEST SHOWING GOOD SWING ON 1.5 VOLTS IT LEADS ME TO BELIEVE SOMETHING IN THE MOVEMENT ITSELF IS CAUSING THE PROBLEM.
ANY IDEAS AS TO WHAT MAY BE CAUSING THIS?

 

[praezis]

Did you clean and burnish the silver pin on the pendulum and silver contact on the fork? Is the latter ok or worn to the base metal? Has the silver spring good contact?
Maybe the silver pin should be lowered to dive deeper into the slot of the fork (gives longer impulse time).

Frank

 

[jkfabulos]

Did you clean and burnish the silver pin on the pendulum and silver contact on the fork? Is the latter ok or worn to the base metal? Has the silver spring good contact?
Maybe the silver pin should be lowered to dive deeper into the slot of the fork (gives longer impulse time).

Frank

Yes I did all the things you suggested as the usual part of movement clean up. I found the problem to be the end play adjustment on the main shaft
was set incorrectly and causing preload drag. I set it with some clearance and that allowed the fork to move freely.

 

[praezis]

I found the problem to be the end play adjustment on the main shaft

Good hint!
In the Bulle that I described recently, I found just a contrary issue: the shaft had extremely much end play.

Frank

 

[jkfabulos]

As a follow up I discovered another problem.
The silver pin was loose in its holder. It appeared to tightened up but the threads were worn allowing it to wobble just a tiny amount which
drained away some of the fork action. Since this is an electrical contact be careful using any type of epoxy or thread locker that could cause an open circuit.
There is a tiny flange where it meets the holder and this will provide the contact area.