CLOCK REPAIR CLASS
The Clock Repair Course is conducted under the sponsorship of the George McNeil’s Potomac Guild. This guild is one of the three guilds located throughout the commonwealth of Virginia that make comprise the Horological Association of Virginia (HAV). HAV is in turn an affiliate chapter of the American Watchmaker and Clockmaker Institute (AWCI). One of the primary objectives of the Guild and HAV is to provide Horological training to individuals interested in the repair and restoration of a variety of timepieces new and old. If you are serious in learning more about horological matters, you are welcome and encouraged to join the Guild.
- Administrative Matters
- Horology – What is it?
- Purpose and composition of the course – The purpose of this course will be to provide students with the knowledge of clock functions, principles, and control of various types of escapements and striking mechanisms. The class will include instructions of disassembly, cleaning, oiling, reassembling components, replacing parts, making simple repairs and time regulating, This course is designed for hands-on participation by the students working on their own clocks. It will be oriented toward the typical American 8-day, spring or weight driven mantle/wall clock with or without strike.
- Continuing education
- Scope of Course
- Beginning or basic course in clock repair.
- Pendulum clocks only. (American preferred)
- Start with most basic (kitchen or mantle)
- No Westminster or three chime movements
- No three train clocks (if clock has three winding arbors – it has three trains)
- No floating balances or hairspring escapements (Beyond the scope of the beginner)
- No Cuckoo or 400 Day/Anniversary Clocks
- Minimum of theory – only an initial lecture lasting one or two evenings
- “Hands on” approach
- Limited lathe work. Extensive lathe work if required will have to be sent to a specialist
- Student should be able to finish at least one clock.
- Work at your own pace
- Tools, Text Books and Materials
- Tools – Students should furnish their own basic tools, most of which can usually be found around the house. (See tool handout)
- Screwdrivers – straight slot and Phillips head
- Small pliers assortment
- Small hammers (brass, steel, rawhide)
- Side cutters
- Plastic margarine tub and lid or similar container for clock parts
- To work at home you will need additional specialized tools
- Text Books – With the exception of the furnished handout “Clock Repairing” by Marvin Whitney, there is no required text for the course. However, students are encouraged to acquire books relative to clock repair to add to their library, Horological books may be purchased online. Amazon.com is an excellent source. The following books are recommended:
- “This Old Clock” by David S. Goodman (available only from the author directly)
- “The Clock Repair” Primer by Phillip E. Balcomb
- “Practical Clock Repair” by Donald de Carle
- “Clock Repair Basics” by Steven G. Conover
- “Striking Clock Repair Guide” by Steven G. Conover
- Materials – Cleaning materials and some common parts (bushings) will be provided as part of the class. Other required parts, unique to the student’s individual clock will have to be purchased from a Horological supply house. The following are a few of the most popular:
1860 Weavertown Road
Douglassville, PA 19518-0277
Scottsdale, AZ 85267
PO Box 60
Harveysburg, OH 45032
625 Poppy Way
Broomfield, CO 80028
- Principle Clock Components – Every mechanical clock has four principal components
- Power Source
- Spring or Weight
- Function – to provide power to keep the last wheel in the time train, the escape wheel, turning
- Escapement – Pallets and Escape Wheel
- Function of Pallets is to keep the escape wheel from turning
- Function of the Escape Wheel is to push the pallets one way then the other (impulse) causing them to oscillate
- Function of the escapement is to keep the pendulum swinging by way of the crutch which is a physical extension of the oscillating pallets.
- Controller – Pendulum
- Function of the pendulum is to control the rate at which the pallets can oscillate
- The rate is set by the length of the pendulum.
- Function is to provide information or action
- Usually consists of a dial and two hands, but not always.
- Could also consist of striking, chiming, astronomical indications, or turning the barrel of a devise to record earthquake activity.
- Basic Terminology
- Movements – the brass engine or timepiece inside the case that ticks and makes the hands go around
- Wheels – The parts of the clock that some might refer to as gears. If it has twenty or more teeth it is a wheel.
- Pinion – If a gear has twenty or fewer teeth it is called a pinion and the teeth are called leaves or trundles, not teeth.
- Lantern Pinions – have trundles and look like a lantern
- Cut Pinions – Have leaves and are cut from a solid piece of brass or steel
- Arbors – These are what the shafts that carry the wheels and pinions are called
- Pivots – The turned down ends of the arbors that protrude through the holes in the two plates of the movement. The pivots allow the arbors to turn.
- Pillars – Four posts that are threaded or pined to hold the plates together.
- Time Train – A series of wheels and pinions, usually located at the right side of the movements as you face the front of the movement. The large wheels mate with small pinions that turn successive arbors at progressively increasing rates of speed. At the bottom end of the train is the main wheel and arbor which carries the mainspring that provides the power to move the train. One end of the arbor has a square which is used to wind the mainspring with a key. Hence the name winding arbor. At the top end of the train is the escape wheel whose speed is controlled by the pendulum. As you go up the train the speed increases as the power decreases.
- Motion work – Another set of wheels and pinions necessary to provide a visual indication of the passage of time as measured by the time train. Its sole function is to turn the minute and hour hands. The arrangement of wheels and pinions allow the hour hand to make one revolution in twelve hours while the minute hand makes twelve revolutions.
- Strike Train – The strike train is similar to the time train in that it is also made up of wheels and pinions. Its primary purpose is to give an audible indication of the time through the strike of a gong or bell. In addition to the wheels and pinions there are levers, cams and pins involved in this process. It also has a main wheel and winding arbor to wind a mainspring. However it has a fly or fan at the top end of the train. The details of the strike train will be covered later.
- Compound pendulum – Suspension spring, pendulum rod, and bob.
- Length of pendulum – measured from the point from which the pendulum is suspended to approximately the center of the bob.
- The length of a seconds pendulum (60 vibrations per minute) is theoretically 39.14 inches.
- Changing the height of the pendulum bob will change the speed of vibrations hence causing the clock to gain or lose time.
- Mechanical Clock Types – Infinite Variety
- Type of case – Tall case, Wall hanging, Mantle, Shelf, Kitchen, Carriage, etc
- Motive Power
- Others (Temperature, Water, etc)
- Type of Regulator
- Helical or Floating Balance
- Many differences but similar in major aspects, Depending on the type they will all have a train or trains with a power source, series of wheels, and regulator.
- Repair Procedures
- Remove movement from the case
- Remove pendulum bob
- Remove minute and hour hands,
- Remove screws (usually four) that hold the movement to the case
- Remove complete movement from the case
- Study clock movement – play with it – cause it to strike if possible. Observe and try to understand the interaction of the different parts.
- Draw a sketch – Include the following
- The direction the mainsprings wind
- Mark the mainsprings T or S and the arbors (and the barrels if present).
- Which pivot holes carry the U-W and C-L
- The amount of run to the warning
- LET THE POWER OF THE MAINSPRINGS DOWN
- Use retaining rings
- Use a “LETDOWN KEY”. Never use a key with ears unless you have an adapter.
- Take the movement apart. (Start with removal of pillar pins or nuts that hold the plates together).
- If possible keep strike side and time side parts separated
- Mark parts if necessary
- Note differences in wheel trains, relationships, etc.
- Cleaning – Must disassemble!
- Composition of cleaner – Commercial cleaner, ammoniated or non-ammoniated.
- By hand
- Mainsprings are best soaked in a separate bucket of cleaner and then scrubbed by hand.
- Rinse – Two stages
- First stage
- Water from the tap as hot as possible
- Purpose is to remove cleaning fluids from the parts.
- Second stage
- Immerse parts in mineral spirits
- Purpose is to aid in removing water from the parts
- Pay special attention to insure mainsprings are rinsed well in water so as to lessen the dirt deposited in the mineral spirit rinse
- Dry all parts
- Thorough, quick drying is important to minimize the formation of rust on steel parts, particularly pivots and springs.
- Use a hairdryer set on high heat and maximum fan speed to dry the parts.
- Peg out pivot holes in plates. Use bamboo skewers. Rotate skewer in hole, remove resulting dirt and crude from skewer with pen knife and repeat until skewer runs clean.
- Carefully examine each movement part for the following
- Check mainsprings for rust and/or “set” condition
- Check mainsprings for cracks or tears
- Broken or bent teeth
- Broken, scored, worn, or bent pivots
- Check for bent arbors, especially if the clock has a broken click or broken mainspring.
- Check pivot holes for wear – accomplished by partially reassembling the movement with the trains only.
- Check pallets on the verge for wear and grooving.
- Check lantern pinions for worn or broken trundles.
- Check Fly (regulator) for proper tension. Never solder!
- Check the plates to insure they are flat and the pillar posts are tight.
- Check clicks and click springs
- Put all parts in place on the plate that still has the pillars
- Replace second plate starting with the bottom pillars and loosely install pillar nuts or pins to hold the top plate in place
- Place arbors, pivots, and levers into place by working from bottom to top
- Reattach strike lever spring wires and hammer spring wire
- Don’t be concerned about pin location relative to wheels and levers. These will be adjusted when the strike side is set up.
- Set up strike – There are 5 critical relationships to setting up the strike train
- The COUNT WHEEL HOOK must be in a deep slot of the count wheel
- The LOCKING CAM HOOK must be in a slot of the locking wheel.
- If there is a primary locking, the PRIMARY LOCKING ARM must be against the LOCKING PIN
- The WARNING PIN must be the correct distance from the warning detent. This is called run. Up to, but not more than half way around the warning wheel Because:
- Insufficient run may not allow the locking cam to clear the slot and the train may not unlock and run to the warning position.
- Too much run may put the hammer tail “on the rise or lift”, or may be so great that a strike will take place at warning.
- The HAMMER TAIL must be just clear of the last in that released it.
- Place in beat
- Clock is put in beat on test stand to ensure it is running correctly.
- Accomplished in most cases on American clocks by slightly bending latterly the brass crutch wire.
- Final beat adjustment cannot be accomplished until the movement is placed back in the case and leveled. Best done after placing clock where it will be located in the home.
- When the movement is in the case use the “Matchbook maneuver”. Place a matchbook or wedge-type device under one side or the other of the clock to tip it until the even and regular ticks and tocks tell you it is in beat. Now bend the crutch toward the matchbook to put it in beat.
- Use oil sparingly – Too little is better than too much
- Excessive oil collects dirt and dirt causes wear.