Learning to equalize horizontal and vertical rates is one of the hardest skills required by new watchmakers to learn when new to horology. However, with a little practice this skill will become second nature. You can use this process for balance wheels with or without adjustment screws. However, you really need a timegrapher to measure your results. Although watchmakers were able to adjust watches before the invention of timing machines, not having one will just take a lot longer.
Before you begin this process of adjusting a watch, you will need to clean and rinse the movement thoroughly. There can be no residue on the watch parts as this will react with the oils you use to lubricate with. All watch jewels must be spotless with no cracks or chips. The Pivots must be straight, polished, and free of defects. You must properly oil the jewels and pivots with the appropriates lubricants. The mainspring must be able to supply at least 270 degrees of amplitude. The teeth of the train wheels as well as the pinion leaves must be clean and defect free. In other words, all the watch parts must be free of defects and in good order.
Before you Start Equalizing Horizontal and Vertical Rates
First Get the Horizontal Positions Equal
Before you can begin to adjust vertical positions, you must first equalize the horizontal position rates. The amplitude must also be the same. If your horizontal rates and amplitude differ, that is telling you there is a fault somewhere in the rotating parts of the watch. It is normal for rates and amplitude to be different between the horizontal and vertical positions because of the effects of friction and gravity. However, since friction and gravity are the same in the dial up and dial down positions, rates and amplitude should be the same as well. I have found the following to be the most common problems which can cause horizontal rates to differ, although there are many other causes.
- The pivots differ in their cleanliness or lubrication.
- The hairspring is rubbing against something in one position.
- One of the balance pivots has become bent, rough, or flattened.
Close the Regulator Pins
When the regulator pins are too wide, the effective length of the hairspring becomes greater in the vertical positions. This is one of the most common problems with regulator pins I see in my shop. When the hairspring is vertical, gravity causes it to sag. This is normal. If the regulator pins are too wide the hairspring will hang even lower than it should. This slow down in rate will be directly proportional to the change in the amplitude from dial to vertical positions. Therefore, the vertical positions will show a slower rate than the horizontal rates.
Check the Fit of the Impulse Jewel in the Fork Slot
If the impulse jewel is too small for the slot of the pallet fork, it affects the vertical positions more than the horizontal positions. This is due to the increased vibration of the fork and loss of amplitude when it receives its impulse from the impulse jewel. However, the loss of power is less in the horizontal position because there is less friction, and the amplitude is greater. Since the speed that the impulse jewel is passing through the pallet slot is greater, there is less chance for the vibration to cause a slow rate in the horizontal position. There should be 0.2 mm of clearance between the impulse pin and the fork slot. More than that will cause a loss in amplitude and a slower rate.
Check the Fit of the Pallet Arbor
In my article, The Basic 6 Step Escapement Inspection, I talk about checking the side shake in the pallet fork arbor. When trying to equalize horizontal and vertical position rates, any side shake will have the same effect as an impulse jewel being too small. The extra movement in the jewel hole causes a loss in power delivery, therefore causing a slower rate in the vertical positions.
Check the Amount of Total Lock on the Escapement
If the total lock between the pallet jewel and escape wheel tooth is a little bigger than it should be, it causes increased resistance during unlocking. The added force needed to unlock the pallet jewel causes an increased loss of amplitude which causes a slower rate. The increased lock between the pallet jewels and escape wheel will reduce the amplitude in all position but will be amplified in the vertical positions. The correct lock on an 18,000-beat watch is 1/3 of the width of the pallet stone. On higher beat watches its about 1/6 of the width of the pallet stone.
When there is a slight amount of magnetism in the movement, but not enough to cause the hairspring to stick together which causes a faster rate, there is a tendency for the vertical positions to show a slower rate than the horizontal positions.
- The watch needs to be clean, defect free and properly oiled.
- You need an amplitude minimum of 270 degrees.
- The dial up and dial down rate and amplitude need to be close before starting.
- Regulator pins too far apart cause slow rates.
- Impulse jewels that are too small cause slow rates in vertical positions.
- To much side shake in the pallet arbor causes slow rates in vertical positions.
- Too much lock in the pallet jewel causes amplitude to drop and rates to slow.
- Slight magnetism can cause slow rates in vertical positions.