Kern Miniature 400-Day Clock Runs Very Slow

[wingman]

I cleaned a Kern Miniature 400 day clock that I purchased not working. After assembling with the suggested suspension spring assembly from the Horolvar book plate #1340e I found it runs very slow and occasionally the escapement flutters. I have tried repositioning the fork with no change other than it appears the flutter ceases but the clock still runs slow (compared to my other 400 day clocks). The second issue is that when I attach the minute hand the movement stops. When I cleaned the clock the main spring looked good so I suspect the suspension spring assembly to be the problem. Hopefully no one fooled with the escapement anchor palates, however I don’t see any obvious signs of that occurring. Any suggestions?

Steve

[oldtimers]

Steve,
I have had bad luck in the past using complete spring assemblies. The springs were often the wrong size. I replace the spring now and don’t use assemblies. It sounds like the suspension spring is either too weak or your cannon pinion is slipping. If the clock is stopping there is probably something inhibiting the train somewhere like a bent pivot etc. Does the escape wheel tooth snap to the next pallet when it drops off the previous one? I don’t think a sluggish clock will effect the time keeping (not sure). Does seem like it needs a stronger spring.
Just a guess,
John

[pkamargo]

Steve,
The Kern miniature will use 0.0020″ OR 0.0023″ suspension spring, depending the model you have. Note that this is valid only if the pendulum is original and didn’t have its weight modifyed.

All 400 day clocks are very sensible and require excellent cleaning for proper running. All pivots need to be very clean, perfectly straight and polished, and the bushing holes must be polished inside too. Many times when repairing these clocks I also polish the pinions and gears teeth to reduce any possible friction. Check all this before you think that the mainspring isn’t strong enough.

Pallets and escape wheel also need be very clean and polished. The pallets need to be adjusted to a good lock to prevent that fluttering effect.

You say that when attaching the minute hand the clock stops. This happens independently of the hand position or only when it is going up? (I mean when going from ‘6’ to ’12’)

[wingman]

Thanks all good suggestions. I’ll try doing those things. I found that the palates are just catching about 30% of the escapement wheel tooth. That could be a problem I’ll have to fix. I’ll try polishing the pivots.

Steve

[Author]

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