I just repaired an Ingraham oak shelf clock, with a date of 6 14 (June 1914) on the movement.
A previous repairer had installed a time mainspring that was way too strong (.018 inch thick), which had caused about 50% tooth wear on the time mainwheel. After the overhaul, I installed a Merritt’s P1496 mainspring 3/4 inch wide, 0.0155 inch thick, and 96 inches long. This gives a moderate amount of overswing to the pendulum, only time will tell if the power is sufficient to reliably run the clock for a long period. If not, I will install a spring about 0.0165 inch thick.
The strike train has its original mainspring of 3/4 x 0.0172 inches.
My job 4469.
Follow up: On 2/28/08, the clock came back because it would sometimes stop at three minutes before the hour. I did two things to correct this:
- Smoothed the tip of the strike locking lever.
- Replaced the time mainspring with one of the new Merritt’s 3/4 x 0.0165 x 96 inch spring.
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