This is Part II of a three part series on restoring this beautiful German FMS Mauthe (Friedrich Mauthe Schwenningen) wall clock. Part I can be found here. Part III, in a week or so, will cover case repairs and refinishing.
This attractive antique Victorian style German FMS Mauthe wall clock was purchased locally from a family that once lived in the town of Parrsboro. Nova Scotia over 100 years ago.
Why would someone solder the minute hand to the arbour
In this post I will discuss servicing of the time and strike movement.
As I began taking off the dial I noticed that the minute hand had been soldered to the arbour. Not only that, it was in backwards. A taper pin should secure the minute hand, not solder. Using a butane torch I freed the hand. Once the hands are off, removing the dial requires pulling 4 pins from the support posts. Following that, the bottom rail, which is secured by two machine screws, is removed. Now to work on the movement.
Before we do that, let’s look at the numbers on the back plate. 105 is the number of beats per minute, 42 is the length of the pendulum rod in centimeters. The number 55006 is a patent number which was issued to Heinrich Kielmann (Ruhrort/Rhein) in 1890/1 and concerned the method of hanging the pendulum. The number 20934 refers to a production run but I have no idea what date is assigned to that number. The Adler gong has the FMS eagle on the block and from my research the eagle was placed on gongs going forward in 1898. Therefore, the clock is from about 1898 – 1905.
The movement has not been serviced in some time. Expecting to see a significant amount of wear, I was pleased to discover the movement in generally good condition.
The pallets had little or no wear and the escape wheel likewise looked good. The pivots had very little wear and polished up nicely. There were 4 pivot holes that needed some degree of attention. I decided that two on the strike side were not so bad that they could wait but two others were quite worn, the centre wheel, front and the motion works wheel just above it. This is expected as these wheels carry most of the load from the mainsprings.
After a 30 minute cleaning cycle the solution was quite dirty, in fact so dirty that I disposed of the solution
I take plenty of photos as an aid in helping me relocate the movement parts on reassembly. Sometimes the wheels on the strike and time side look similar. In the case of this movement there was no confusing which side the wheels should go.
I disassembled the movement and placed the parts in my ultrasonic cleaner. After a 30 minute cycle the solution was very dirty, in fact so dirty that I disposed of the solution (it is biodegradable). Reassembly was straightforward as most of the adjustments to the strike side occur outside the plates, unlike a typical American time and strike movement where there a myriad of levers and helper springs that seem to pop out when you you are trying your best to get everything set up between the plates.
As a side note, Mauthe did make time and strike movement with the count wheel located between the plates and with conventional wire levers.
The only critical adjustment is the stop wheel which has to be in the correct position otherwise the strike will not function correctly. Trial and error is needed to get this right but I set it correctly on the first attempt.
Unfortunately, I do not have a test stand tall enough for this movement and the case was used to test the movement. The movement slides in and out on a set of rails making it relatively easy to make the necessary adjustments.
One issue, a broken suspension spring. Could have been my handling of the movement or it was already broken. Nevertheless, my order from the supplier arrived and the spring has been replaced. Most clockmakers would agree that it is a good practice to replace the suspension spring as they weaken with age.
During testing the strike side was sluggish and would not engage from time to time. I attributed this to an enlarged pivot hole on the star wheel, back plate one of the two I noticed earlier. The new bushing was a very small #7 Bergeon at 0.80 mm (inside dimension) with very little margin for error. With the new bushing (a total of 3 for the movement) the strike side was still sluggish. After taking the movement apart again I found a slightly bent arbour on the second wheel of the strike side which I fdiscovered when I attached it to my lathe. Using a hollowed punch tool I straightened it out.
The reassembled movement was oiled and mounted in the clock case. The recoil escapement is adjustable and a slight tweaking of the verge corrected the beat. After a few frustrating adjustments exacerbated by a bent arbour, the movement is running well after servicing.
Next, I will cover case refinishing for this fine old clock.
NOTE: After completing this project I designed and built an extension for my movement test stand to allow me to work on movements with long pendulums such as this one.