What are the grinding methods for mechanical watch movements?

Movement polishing not only makes the movement more beautiful and increases appreciation, but also has practicality, which can prevent oxidation and make parts run more smoothly.

Even with the same polishing method, different brands, different grades, regions, and different levels of technicians will produce very different polishing effects.

Hairline (straight line)

The watch technician wipes the surface of the part with sandpaper in a straight line to form a thin straight line on the surface of the part. It is mostly used for movement splints.

Concentric circle pattern

Install the sandpaper on the grinding wheel equipment, and perform circular grinding on the part. After grinding, the part will have a concentric circle-like texture. It is mostly used for movement gears, barrels, ring splints and other parts.

Wavy pattern

This kind of polished texture is a texture with the same radian, which is used for the beautification of splints or automatic discs.

Mirror polished (black light polished)

This is an advanced sanding method. The technician will use very fine sandpaper to repeatedly polish the surface of the part until the surface of the part is completely polished, showing a mirror effect, and showing a black effect at certain angles. One of the characteristics of advanced movements. It is mostly used for pallet fork, gooseneck fine adjustment, tourbillon frame, etc.

Sun pattern

This is a spiral-shaped circular decorative stripe, which is generally used on the surface of the barrel and the small steel wheel. The parts that seem to be stationary but are slowly moving seem to have life.

Technicians use special tools to carve patterns on the parts, and then repeatedly polish and modify each line until they show a mirror luster. When appreciating, it can show a three-dimensional sense of hierarchy.

Geneva pattern

It was once literally translated as Geneva Water Ripple. This is a kind of grinding method that watch lovers are very familiar with, and it is often used in positions such as movement splints and automatic discs of automatic movements. It is characterized by equidistant parallel lines with curved lines in between. Although this is a very common way of polishing, there is a big gap between brands, and watch friends can slowly understand it when they appreciate it.

The work of Philippe Dufour, the Geneva pattern under different light, extremely polished.

The similar polishing in the top German watches is called Glashütte pattern, and the stripes between the parallel lines on the plywood are slightly different from the Geneva pattern.

Glashütte pattern in Lange movement under different light

There is also a polishing method that is very close to the Geneva pattern. The difference is that the parallel lines are not arcs, but straight lines. If you don’t look carefully, it is easy to be regarded as a Geneva pattern.

Circular Geneva pattern

As the name suggests, it is circular Geneva pattern grinding, which is used for decoration on movement splints, automatic discs and other parts.

Works of brands such as IWC, Piaget, and Emmy can be seen from time to time.

Fish-scale pattern

Also known as cloud pattern, etc., the technician uses the front end of the rotating grinding equipment to lightly press on the metal surface to complete a single fish scale pattern. Commonly used for substrate processing of movements.

This kind of grinding method seems very simple, and it can often be seen in many stainless steel utensils and tableware.

It is not easy to achieve good results with a small movement.

Chamfer

Whether the movement is advanced or not, and whether the edge of the plywood is chamfered is one of the important reasons.

Chamfering is the sharp part of the edge of the part, which is cut into a bevel and polished smoothly.

Common locations are the teeth of the gear, the edge of the screw head, the edge of the splint, the gem pocket, etc.

The next level is mirror chamfering.

Technicians repeatedly polish the chamfered part to a mirror finish by hand.

In recent years, with the popularization of CNC machine tools, parts have been chamfered after they come off the machine, and manual modification is rarely performed. It is easy to tell whether it has been polished by hand under a magnifying glass.

Patek Philippe movement, you can appreciate the gem pockets, screw holes, hand-chamfered edges of the plywood.

In some top watches and top independent watchmakers' works, there will be external linear chamfers.

This is where the two outward edges of the part meet, sanded into a sharp line. Such an approach is not difficult to see in the era of pocket watches, but it is rare in the current era of watches.

Arguably the most difficult sanding technique is internal sharp corner chamfering.

This kind of grinding method cannot be completed by CNC machine tools or stamping processes at present, and can only be done by hand. The two inward directions of the parts meet to perform mirror chamfering.

Whether a movement is advanced and beautiful, the polishing of the movement is very important.

In addition, whether the circuit design is smooth and beautiful, and the transition is natural is also very important. This is another topic, which requires continuous deliberation and accumulation by the movement designer.