2. Shock Protected Jewels


When we think about the benefit of jewels in a watch movement there, is not a more important one in its construction than the balance jewels and of course the more advanced shock setting jewel used in more modern movements.

The balance assembly in a watch, which needs to be relatively heavy and with a fairly large diameter to provide enough rotational inertia, turns on very fine pivots with coned tips to minimize friction. However, this very thin pivot design makes the balance staff pivots more susceptible to breakage when the watch is subjected to the shocks or impacts in everyday use.

Before shock settings were used, this was by far the number one problem watch owners faced before shock jewels became standard and balance staff replacement was the most common repair for watchmakers. To address this issue, shock protection systems were introduced, with the widely-used Swiss Incabloc system being a key player and is the style that is most widely used.

When a watch has shock protected balance jewels and in both longitudinal and lateral type shocks,now the only force applied to the pivot is what is required to overcome the force from the retaining spring. In a shock system it’s crucial to strike a balance: the retaining spring must not be too stiff or strong, which would not allow the chaton to move sufficiently during a shock, yet it should be strong enough to quickly return the chaton to its regular position after a shock has occurred.

These components are meticulously designed to consistently meet this criteria, ensuring the effective functioning of the shock protection systems while allowing the balance to run as freely as possible. Although there were in the past and are today many different designs used, they all basically work the same. We are going to look at two of the most common manufactures.

When taking work in or when buying more obscure movements, always check to see what kind of shock system was used and if parts are still available. Many non runners are non runners because a broken shock system can’t be replaced without buying donor movements.

For the complete listing of vintage shock protected jewels from the Bestfit catalog, Click here

2. Incabloc Shock Protection System

The Incabloc system which was widely adopted in the mid-20th century, provides protection against shocks in all directions. This includes shocks end-on to the balance staff, sideways, or at various angles. Let’s look into how the Incabloc system achieves this.Incabloc Shock Absorption

2.1 Components

  • Block: The block is friction fitted into the cock or plate. The chaton sits in the block, and the retaining spring, anchored in the block inside a groove, presses down on the endstone, firmly securing the chaton into the block.
  • Double-Stepped Chaton : Both jewels are mounted in this chaton, which ensures proper spacing for the endstone to retain oil for the balance staff pivots. The spacing between the balance hole jewel and the endstone is approximately 0.02 mm.
  • Balance Jewel: With an olive shaped center hole the balance jewel maintains the balance pivot in position. The olive shaped hole reduces the friction when the watch is in the vertical positions.
  • Endstone: The endstone is where the balance pivot rotates on when the movement is in the horizontal position.
  • Retaining Spring: This critical component, which we’ll look at more closely later, is held in the block and applies pressure to hold the chaton securely.
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Functionality:

  • The chaton’s sloping outer surfaces interact with the sloping inner surfaces of the block, centering the chaton and setting its vertical position.

Installation:

  • The Incabloc setting in the balance cock is either a friction fit and pressed into position or secured by a U-shaped retaining clip.
  • The lower Incabloc setting is typically pressed into the bottom plate and has to be removed if the retaining spring is broken.

Understanding the Incabloc system provides insight into other shock protection systems, as they often operate on the same basic principles. Fortunately, these systems are fairly robust, and damage when the movement is running is rare, minimizing the need for repair or replacement. Incabloc settings, along with their counterparts in other systems, are available in various forms, such as complete units, press-in, or clip-in units, facilitating maintenance in the watchmaking field.

In a shock-resistant setting, the balance hole jewel is designed as a press fit in the chaton, and its removal and adjustment for end-shake was not intended in the design. With that said, very small adjustments to the blocks position can be made if necessary. Remember that the end shake of the balance wheel and pallet fork should be identical. This keeps the clearances between the impulse table and jewel correct with the pallet fork slot and guard pin. If there is too much end shake on the balance wheel, most likely the balance pivot has been flattened by wear which also creates a divot in the endstone. This will cause too much endshake. If there is not enough endshake, that is an indication that the pivot is too long or the block has been pressed in too far.

2.2 Retaining Spring in Incabloc Shock Protection

The Incabloc retaining spring is characterized by its unique lyre shape, as depicted in Figure 7. This spring has a pivoting “hinge” and two arms that apply pressure on the endstone while securely fitting into notches on the block. During servicing, the arms can be unclipped, and the spring pivots away, facilitating the removal of the chaton along with the jewels. This design ensures an efficient and accessible mechanism for maintenance, allowing watchmakers to easily disassemble and reassemble the components as needed for cleaning and oiling.

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Figure 7- the Incabloc parts

3 Kif Shock Protection System

Manufactured by Parechoc in Switzerland, Kif shock-absorbing jewel settings consist of a fixed block pressed into the plate, a movable chaton, and a retaining spring securing the movable chaton within the fixed block. Both upper and lower blocks share identical designs, with the fixed block friction-tight into the plate or cock which can easily be installed with a standard jewelling tool. The recessed fixed block accommodates the chaton in this reliable shock protection system. There are many different styles of Kif springs which are identified by name.

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Figure 8- Kif Springs


3.1 Kif Trior

The chaton in the Kif shock protection system features conical sloping sides, interrupted near the bottom to create a step, allowing it to fit into a recess in the fixed seating. The sloping sides work in tandem with a rounded shoulder in the fixed seating. The endstone fits freely into a sink in the chaton, supported by it, while the balance hole jewel is pressed into the movable chaton. This is basically how all shock systems are constructed.

Securing the chaton in place is the retaining spring, as depicted in Figure 8. This spring is equipped with three tongues that pass over the endstone, applying uniform pressure around its circumference.

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Each of the three tongues has a horn or finger on the end that fits into a cutout in the block. The spring is then rotated in either direction so that the three horns rotate into a groove in the block holding the spring in place.

Disassembling

Removing Trior springs is pretty straightforward. You can simply use two pair of tweezers to rotate the spring until the tabs are free in the cut out notches. Use one set of tweezers to turn the spring and one set, touching on the endstone to prevent the spring from getting away from you as shown in figure 9. Reinstalling the spring is a different matter though. To reinstall the spring, a tool, either one purchased or shop made is required.

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Figure 9- removing the spring

Assembling

Assembly is much easier with either a store bought tool or a shop made tool. Figure 10A shows a set of pushers designed to push down on all three tongues at same time so they can be rotated into the groove. Notice that the 3 sizes correspond to the different block sizes measured from the outside of the shoulder. Figure 10B shows a shop made tool made from pegwood. The recess in the tip allows the edges of the tongues to be pushed down white the hollow tip allows for clearance of the endstone jewel.

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Figure 10- KIF Trior assembly tools

To install the spring, fit the outside horn or finger of the spring into the notches in the block. Then with the tool held in a upright position- figure 11, twist the spring while exerting pressure until you can feel the corners of the tool turning the spring along. The spring is in position when the horns are at an equal distance from the notches.

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Figure 11- pushing down the the spring tongues

3.2 Kif Flector

The KIF Flector spring looks similar to the Trior but has one horn and one notch instead of the three horns and three notches found on the Trior system. The other difference is that this spring is hinged on a hinge retainer that is inserted into the block- figure 12. The folded over tab slides along the rod when opening or closing the spring. -figure 13.

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figure 12- Trior setting with hinged spring



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Figure 13- hinge retainer

Dismantling

Using a pair of fine tip tweezers place the tip of the tweezer in the slot of the spring. Rotate your tweezer about 45 degrees in either direction then lift up the spring. A second pair of tweezers can be used to help the folded over hinge move on the retaining rod- figure 14.

Reassembly

To assemble the spring, it is hinged over the pin, and the lip is guided into the groove by rotating it about 45°. This design prevents the spring from getting lost during chaton removal, as it remains hinged to the fixed seating.

Fit the jeweled setting end the end stone and into the block and lower the spring. Push down the horn then again with your tweezer tip rotate the spring in the opposite direction of the disassembly so that the horn is set into the same slot.

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Figure 14- opening the spring

3.3 Duofix

The Kif Duofix and Seiko’s Diafix are basically the same design. They are easy to remove and install as long as you don’t remove the key from the block- figure 15.

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4 Ordering KIF Parts

Springs and endstones are the 2 parts that usually need to be replaced in shock settings. Using KIF parts as an example, these charts will help when ordering replacement parts for almost all shock settings.

Figure 15-KIF Duofix

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Figure 16-KIF Parts Chart

The guide below can be used by measuring the spring . As an example, if you were measuring a KIF Trior spring that measured 1.53 mm, you would order a 1-3 KIF spring-see figure 17.

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Figure 17- Spring measuring chart

Then looking on Cousins UK, we can see the spring to be ordered indicated by the 1.3.- figure 18

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Figure 18- KIF Spring supply on Cousins UK

When ordering replacement balance hole jewels you can measure the width and thickness of the chaton to determine the size – figure 18.



When ordering end stones, measure both the width and thickness. As an example if the endstone measured 0.9 mm wide and .13 thick , the size would be a 508- see figure 19.

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Figure 19- KIF endstone chart

Looking at Cousins UK, you can see the jewel in their catalog-figure 20.

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Figure 20- Cousins UK KIF jewels

Most Balance hole jewels can be harder to source so as a general rule you would want to replace the block as the chances are high that the setting is damaged in other ways.

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