The term Servicing a clock movement is not universally defined in the clockmaking or clock repair industry. Many will perform portions of the procedure as I define it but in my opinion performing any sort of cleaning procedure without disassembly does not provide value for your money
Servicing a Clock Movement
I start by completely disassembling and cleaning the parts in an Ultrasonic cleaner, using wooden pegs or tooth picks to ensure no residue is stuck in the pivot holes in the clock plates that make up half of the bearing surfaces. The other half of the bearing surfaces are the pivots or arbor ends that turn in the pivot holes. The holes are spaced so the gears mesh correctly. In the world of horology (the art of measuring time), large gears are referred to as wheels and small gears are referred to as pinions. As the holes and the pivots wear, the wheels and pinions may bind reducing performance or preventing the movement from running.
While an arbor is mounted in a lathe, I examine the pivot through a stereo microscope and file or grind it flat to remove ridges. This procedure will leave microscopic peeks and valleys. The peaks are physically pushed into the valleys with a hardened steel tool, evening out the surface. The moving of the metal hardens it the same way a wire can be hardened to the point of breaking by bending it back and forth. This is referred to as Burnishing, which not only smoothes but makes the surface harder than the parent metal.
I partially reassemble the movement to determine the wear of the pivot holes and determine if the wear is great enough to require bushing. Some lateral movement is necessary, but when it is excessive, I select bushings and install them to compensate for the condition. Brass can be burnished as well as steel and I burnish the walls of the pivot holes.
Another main area of interest is the escapement. The escapement is the portion on the movement that throttles or controls how the power, by weight or spring, is allowed to expend its energy. The escapement pushes the pendulum or balance wheel that regulates this process. There are two main components of an escapement. One is the escape wheel (large gear). The other is referred to as the verge or anchor or lever, depending on the style of escapement, but all have impulse faces that interact with the escape wheel. The escape wheel teeth may be bent and need to be straightened. The impulse faces typically become worn and need to be smoothed. I do that on a micro milling machine set up as a surface grinder. I must then adjust the escapement components to interact properly.
I inspect many other components for damage or impending failure such as cracks in the mainsprings, worn or damaged clicks that aid in holding the power of a mainspring, and fraying of cords from which the weights hang in a weight driven movement. Correcting some of these conditions may be included in the Servicing fee, while some corrections may constitute an additional charge.
I completely assemble, lubricate, adjust and regulate the movement. Typically I will run the clock on a test stand and observe it for a period of time in an effort to ensure no failures. Then, if applicable, I will install it in its case and observe it before I contact you to pick it up. I do not regulate clocks to be any more precise than their design and history allow. They may require some minor adjustment by you in their home environment to meet your precision requirements.
I make every effort to address all issues that could lead to failure, but if something does go wrong, please contact me and allow me to correct the problem. These are old clocks!