Introduction to the Anniversary or 400-Day Clock

This three-day workshop will focus on the anniversary or 400-day mechanical clock. Day 1 will focus on School of Horology clocks that will be set up and functional upon arrival. During the day, the clock movement will have the power let down safely and the movement will be completely disassembled. The movement will be closely examined for signs of wear and common repairs that typically need to be made. Additionally, participants will be using a clock cleaning station as well as using a mainspring winder to remove/insert a barreled mainspring. The clock should be reassembled and set up to run overnight.

On Day 2, participants will examine their own clocks that they bring. Although it is not possible to guarantee that participants’ clocks will be fully functional by the end of the workshop, every attempt by the instructors will be made to diagnose potential problems or fault areas in each clock. There will be a quantity of torsion springs and mainsprings that can be used by participants at a nominal cost. With cleaning and mainspring servicing and any other issues that may need attending, each participant’s clock should be set to run overnight.

On Day 3, participants will continue servicing either the School of Horology clocks or their own clocks.

Note: It is strongly recommended that participants read Charles Terwilliger’s Horolovar 400-Day Clock Repair Guide, 10th edition, edited by H. W. Ellison (1991) before the workshop begins. Several of these books will be available during the workshop, but those who wish to make the most of their experience should begin reading this book before attending. Additional handouts will also be provided at the workshop.

Equipment: All tools and materials will be provided. Please bring your own safety glasses and any magnification devices (visors) you may need. Participants may bring a few of their own 400-day clocks to work on.

Enrollment: Limited to 8 Participants

Instructors: Bill Forney, Instructor, and Sam Gradel, School of Horology Coordinator

Price for Members: $850.00
Price for Nonmembers: $975.00

When: April 10-12, 2026
Time: 9:00 a.m. – 5:00 p.m.
Where: NAWCC School of Horology, 454 Poplar Street, Columbia, PA 17512

Please contact education@nawcc.org or call 717 684-8261, ext. 237 with questions.