Introduction
Reconnecting the calendar movement in an Ithaca Calendar Clock requires precise alignment, flexible connections, and careful adjustment of the lift cam, pull wire, and advance rods. This guide walks through the full reinstallation process, including troubleshooting tips and final verification steps.
Step-by-Step Reconnection Process
Step 1: Mount the Calendar Movement
Screw the calendar movement back into the case and reinstall the calendar dial if removed. Ensure the pull wire from the upper movement hangs straight. Adjust and re-staple the pull wire retainer if needed.
Step 2: Set the Upper Lift Cam
Rotate the minute hand clockwise to set the lift cam to approximately 11:55 p.m. Older models may allow manual cam rotation due to a friction bushing, but testing must always be done using the minute hand.
Step 3: Adjust the Advance Rods and Pull Bar
Position the pull bar into the bottom loop of the pull wire. Use four brass nuts to approximate spacing: one above and one below the pull bar on the 31-day rod, and both nuts above the pull bar on the 14-day rod. Secure the pull bar with a washer and brass wire—ensure a loose, flexible fit.
Step 4: Finalize the 31-Day Rod Adjustment
Loosen the bottom nut and lower it. Lift the rod fully without pulling. Tighten the bottom nut up to the pull bar and the top nut down to it. Ensure at least 1/16" play between the lift arm and lift cam. Confirm the rod is not twisted at the flattened end.
Step 5: Finalize the 14-Day Rod Adjustment
Pull up the rod and turn both nuts down to about 1/16" above the pull bar. Tighten them together but allow slight movement.
Testing and Troubleshooting
Initial Test
Turn the minute hand forward to activate the lift cam. When the lift arm drops, the calendar hand should advance one day.
Common Issues
If the lift arm does not drop, check for twisted rods, rubbing against the advance link, missing weight, or excessive spring tension.
Full Cycle Test
Advance the hands through 24 hours and observe both advance rods lifting and falling. Confirm the calendar changes correctly. Repeat 5–6 times.
Pawl Engagement
The 31-day pawl (S-103) and 14-day pawl (B-206) should engage the next tooth, move slightly past it, and engage nearly simultaneously.
Final Checks
Maintain 1/16" play between lift arm and lift cam. Test a 30-day month and February rollover. Adjust spring 8-013 if the calendar overshoots or undershoots March 1st.
Common Mistakes to Avoid
• Using a washer that is too thick
• Over-tightening nuts against the pull bar
• Twisting the advance rods
• Ignoring the 1/16" play requirement
• Testing by turning the cam instead of the minute hand
FAQs
Why won’t the calendar hand advance?
Usually due to lack of play between the lift arm and cam or twisted rods.
How do I test the calendar change?
Advance the minute hand through a 24-hour cycle and observe the calendar hand.
What if the calendar skips March 1st?
Increase tension in spring 8-013.
What if the calendar doesn’t reach March 1st?
Weaken spring 8-013 slightly.
Why must the pull bar connection be loose?
A flexible connection prevents binding and ensures smooth operation.
1 comment
Regarding reconnecting the calendar in an Ithaca Calendar Clock – Your instructions are quite good, as far as I can tell. I have one of these clocks in front of me and I’m trying to re-set the calendar to the correct date (and then test). There is precious little info that I can find that addresses this process. You might want to take some photos . . . or even better yet, a YouTube video, showing this process step by step. Yeah, it won’t be a NYT best seller, but it sure would be helpful to some of us.