I recently repaired an Ithaca grandfather clock. Ithaca is famous for its double dial perpetual calendar clocks, and they made grandfather clocks from ca. 1898 until 1917 (when Ithaca closed).
This clock has an 8 day time and strike movement made by Gilbert Clock Co. in Winsted, Connecticut. It is spring driven, and is a modified version of their shelf clock movement, changed to use a long pendulum. The escapement is a “strip” semi-deadbeat type. It is very nearly deadbeat, there is only a very slight recoil on the entrance pallet. The movie below shows the action of the escapement.
I made the following repairs to the movement (in addition to other small things not mentioned):
- Polished the pivots;
- Broached out previous bushing that were too tight;
- Replaced 4 worn bushings;
- Replaced the strike click and spring (it had a previous replacement that had solder globs and was a sloppy fit on its rivet. I used a steel click spring (instead of the brass one that came with the replacement click) and made a custom steel rivet to secure the click;
- The cannon pinion was split, which removed the hand set tension. First, I pressed the pinion onto a tapered piece of steel rod to open the crack slightly, and squeezed the end of the split tooth closed. Then I secured the pinion to the arbor with a machinist’s clamp (put the center arbor and the hour wheel between the movement plates and screw them together so that the correct end shake can be obtained), held the arbor in a vice, drilled a cross hole through the pinion and center arbor, then installed a steel pin to secure it.
- Center wheel: 26 teeth
- Third wheel: 39 teeth, 8 pins
- Fourth wheel: 44 teeth, 10 pins
- Escape wheel: 34 teeth, 10 pins
This works out to 3792.35 beats per hour; 63.21 beats per minute or 1.05 beats per second.