How you ever wondered what keeps antique mechanical clocks going? It’s a miracle they work at all when they are as worn as this one.
Most old clocks I come across have common issues, dirty, oily movements and worn pivot holes here and there. Generally, all they need is a bushing or two and a good cleaning to put right.
Last week I wrote about a Jerome & Co. time and strike mantel clock I bought in Springfield Mass. during the annual convention of the National Association of Watch and Clock Collectors in June 2019. However, no amount of encouragement would make it run reliably.
It did not run well and there was another issue, the strike side mainspring refused to hook correctly onto its arbour
As I was servicing the movement I ran into several problems. I mentioned a bent second wheel on the time side, newer time-side mainspring and a worn stop pin on the warning wheel in my last post but there was plenty of pivot wear to address, more than I planned.
I put the bent wheel in the 3-jaw chuck of my Taig mini lathe, gave it a few spins to determine how much I had to straighten it, selected a punch from my stake set. I gently inserted the pivot in the hole end of the punch and straightened the arbour. The steel is relatively soft and bends easily.
I initially installed 9 bushings; S2F, S3F, minute wheel front plate, T2F, T3F and T4F front plate, T3R and escape wheel (T5), front and rear-plate. I pegged the pivot holes and reassembled, oiled and tested the movement on my test stand. It did not run well and there was yet another issue, the strike side mainspring refused to hook correctly onto its arbour.
My aim was to ensure the time-side operated correctly and for the next step I left out the strike-side entirely. Again, things did not go as planned. It had a very erratic beat. It would drift in and out of beat then stop after a few minutes. I discovered 3 more suspect pivot holes; T2R, T3R & T4R. That comes to 12 bushings. I have not installed this many bushings since my Sessions Beveled #2 project 3 years ago.
As a side note I know many clockmakers, especially if they are running a business, will bush just about everything with the view that the customer hopefully will not return with a problem. I take the view that I will bush the worst pivot holes and keep an eye on others that are iffy since I will be opening up the clock and checking, as part of my routine, every 2-3 years or so. This clock was very worn and is the exception.
Back to the drawing board. The entire time train runs freely and there is sufficient wheel-end shake. Therefore, I could not see anything that would cause an issue in that train. Using a trial and error approach I re-positioned the verge by moving the anchor slightly closer to the escape wheel to improve the depthing of the entrance and exit drop of the pallets. The improvement can be seen in this video.
I also experimented with several pendulum bob weights and found the bob that came with the clock, which is 2.8 oz., causes the clock to stop after a minute or so. Other bobs tried are 1 oz, a 1.7 oz and a 2.3oz. The best performance so far is a 2.3 oz bob as it maintains a steady beat and has good amplitude. Is bob weight really an issue? Some say no but there is no harm in trying. With a little more tweaking with a slight bending of the crutch, it should run perfectly.
At last, success. The time side of the movement had been running well for several days.
Now for the strike side assembly. After some convincing with needle nose pliers, I managed to hook the strike side mainspring onto its arbour. It is a tight fit. Once all the wheels were in place it took two tries to position the stop wheel in the correct position to allow warning.
While I was at it I replaced the hammer assembly helper spring.
I decided not to address the worn stop pin. It might last several years and if it broke the worst that would happen is that the strike side would run down.
The movement is now on the test stand and it is running (and striking) as it should. It has gone through 3 eight day cycles and has not missed a beat. It is not often that I come across a movement as worn and dirty as this one yet this project was both satisfying and at the same time, frustrating.
This Jerome & Co. time and strike mantel clock now has a new lease on life and should run for years.