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REGULATION / ADJUSTMENT OPERATIONS

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1. Introduction

Regulation / Adjustment is one of the major steps in the manufacture, or more rarely, in the overhaul or restoration of a mechanical watch. It is also one of the most complex and delicate. Just like Escapement-making (finishing), following the correct order of these operations is essential. There are different ways to carry out regulation. The methodology and order of operations may vary depending on the method chosen. The one presented here is the one found in the Swiss watchmaking schools’ book “Le réglage”. For a better understanding, watch the video for this chapter.

2. Riveting the balance onto its staff

The first step in the assembly of the Regulating organ consists of riveting the Balance on its Axis. It is essential here that the Balance be firmly fixed so that it cannot rotate around its Axis under the effect of its Inertia. Furthermore, the Balance must be perfectly concentric with its Axis, and the plane of the Balance must be perfectly perpendicular to that of its Axis in order to ensure that the Balance rotates true and flat.

3. Driving in the double roller

Although it belongs to the Distribution mechanism, the double roller is fixed to the Balance staff, beneath it. It is driven in there, which is enough to keep it attached to the Balance staff during operation and to allow its position to be adjusted or for it to be removed without damaging the Balance staff. It is important, during this operation, to position the Impulse pin (roller jewel) perfectly in terms of angle, generally on the median between the two arms of the Balance.

4. Static poising

The accuracy of the watch depends on the regularity of the Period of the oscillations of the Regulating organ, the Balance. Being a flywheel, it must be perfectly balanced so that its center of gravity is at the center of its Axis of rotation. An imbalance causes irregularity in the Period of the oscillations under the effect of the earth’s gravity, as soon as the Balance staff’s Axis is no longer perpendicular to the ground. Static poising must be carried out before the Hairspring (balance spring) is fitted.

5. Temporary driving-in of the Collet

The steps that make it possible to define the position of the fixing points of the Hairspring (balance spring) to the Collet and to the Stud (hairspring stud), the shape of the terminal curve of the Hairspring (balance spring), the Length of the Hairspring (balance spring), and assembling these three components to the Balance staff are commonly referred to by watchmakers as the construction of the Regulation / Adjustment. The first step consists of provisionally driving in the Collet onto the Balance staff.

6. Provisional fitting of the Hairspring (balance spring)

This involves provisionally positioning the Hairspring (balance spring) around the Collet. This operation allows shortening the inner end of the raw Hairspring (balance spring) and positioning it on the Collet with a provisional clamping, ahead of the next operation: the first Counting.

7. First Counting

In the case of a watch equipped with a Regulator, as in our example, the active Length of the Hairspring (balance spring) is the Length between the attachment point of the Hairspring (balance spring) to the Collet and a theoretical point located between the attachment point of the Hairspring (balance spring) to the Stud (hairspring stud) and the Regulator pins, near them. It is on this active Length, combined with the torque of the Hairspring (balance spring) and the Inertia of the Balance, that the Frequency of the Regulating organ depends. The first Counting consists of determining, as precisely as possible, the active Length of the Hairspring (balance spring) for the Frequency at which it must oscillate.

8. Determining the attachment point (at the Collet)

Taking into account the previously measured active Length, this step defines the position of the attachment point of the Hairspring (balance spring) at the Collet, that is, the location where the Hairspring (balance spring) comes into contact with it. This step will then allow the hook to be formed, which will secure the Hairspring (balance spring) to the Collet at the correct spot. Once the attachment point has been determined, the inner end of the Hairspring (balance spring) is cut at 60° beyond this point. Then, the end of the Hairspring (balance spring) is bent at the attachment point in order to form the hook that will secure the spring to the Collet by engaging in its hole.

9. Colleting

In industrial production, the hairspring is sometimes glued to the collet. Traditionally, and according to our example, it is pinned with a pin made of brass. This fixing method allows the assembly to be disassembled later in order to correct, in particular, the centring of the hairspring on the collet.

10. Centring and flattening the hairspring on the collet

Once the hairspring is fixed to its collet, it is important to adjust its position and check that its coils develop concentrically around the balance axis. This is the adjustment and testing of the centring on the collet. It is also checked that the plane of the hairspring is perfectly perpendicular to the balance axis. This is the adjustment and testing of the flatness on the collet.

11. Second counting

Once the Hairspring (balance spring) is securely fixed to the Collet, a second Counting is carried out, which allows the active Length of the Hairspring (balance spring) to be determined and thus its Frequency, with greater precision than during the first Counting. This second Counting is essential in order to subsequently correctly form the terminal curve of the Hairspring (balance spring). Here again, the active Length of the Hairspring (balance spring) is adjusted by holding its last coil in the pincers of the hairspring counting machine. It is shortened or lengthened until the nominal Frequency is reached as precisely as possible.

12. Studding

Studding consists in fixing the Stud (hairspring stud) to the Hairspring (balance spring). As with the Collet, the Stud (hairspring stud) is often glued to the Hairspring (balance spring) during industrial production. The example shown in our video fixes it traditionally by means of a Brass pin.

13. Construction of the terminal curve

The terminal curve of a flat hairspring prevents the second-to-last coil of the hairspring from striking the stud during operation of the watch while the hairspring is in an expansion vibration. The proper centering of the hairspring in relation to the balance cock and the regulator pins depends on the gap between the second-to-last coil and the terminal curve, as well as the position of the two bends of the latter. To measure this 60° angle, the balance and hairspring assembly is placed on a stand with an angle protractor, which can easily be replaced by a hole tool (hole gauge) and an angularly graduated paper. 60° is measured from the point measured and marked during the second counting, toward the end of the hairspring, then the hairspring is cut. The two bends of the terminal curve can then be formed using the angle protractor, ensuring its concentricity.

14. Dynamic regulation

During the operation of the watch, the hairspring does not develop concentrically with respect to the axis of the regulating organ, which causes a slight shift of its center of gravity over the course of the oscillations. This step consists of rebalancing the assembly on the movement under operating conditions. Good dynamic regulation ensures the accuracy of the watch and limits the differences in rate between the various positions of the watch when worn. The rate values in the 6 positions make it possible to determine any imbalance defect during operation and to correct it by milling under the felloe of the balance, at the location of the imbalance.

15. Final testing

Once the dynamic regulation is complete, the final testing of the daily rate is carried out in the six positions. If necessary, the rate of the watch will be corrected (see “Correction of the daily rate“).