The Tissot caliber 27B is a manual-winding mechanical movement produced during the mid-20th century, particularly around the 1940s and 1950s. It is part of Tissot’s 27-series of in-house calibers, which played a key role in the brand’s development during the post-war years. The 27B was designed for slim, time-only wristwatches, with a strong emphasis on reliability, mechanical simplicity, and ease of service.

Overview of the Caliber 27B

The Tissot 27B is a basic hand-wound movement that typically features:

• Central hour and minute hands

• A small seconds subdial at the 6 o’clock position

It was installed in classic men’s dress watches, which were usually housed in stainless steel or gold-plated cases, often measuring between 32 mm and 35 mm in diameter. These watches were known for their understated elegance, functional layout, and mechanical dependability.

This caliber is closely related to the original Tissot 27 movement, with slight modifications in layout or technical finish, which are reflected in the “B” designation.

Technical Specifications

• Type: Manual winding

• Functions: Hours, minutes, small seconds

• Jewels: 15

• Frequency: 18,000 vibrations per hour (2.5 Hz)

• Power Reserve: Approximately 40 hours

• Diameter: ~27 mm (approx. 12 lignes)

• Height: ~4 mm

• Shock Protection: Not included in early versions; later models may feature basic protection

• Finish: Functional, with matte or brushed plates, blued screws, and simple bridge design

The movement uses a traditional Swiss lever escapement and was designed to be robust, straightforward, and easy to regulate.

Maintenance Recommendations

As with any vintage mechanical movement, the Tissot 27B requires regular servicing to ensure accurate timekeeping and prevent wear. A complete overhaul is recommended every 4 to 6 years.

Standard service includes:

1. Disassembly of the entire movement

2. Ultrasonic cleaning of each part

3. Inspection for wear, especially in the mainspring, gear train, and pivots

4. Replacement of worn or damaged components, where possible

5. Lubrication with modern synthetic oils

6. Reassembly and regulation in multiple positions

7. Optional case cleaning and gasket replacement if applicable

It is crucial to entrust servicing to a watchmaker experienced with vintage Swiss movements, as some parts may only be available from donor watches.

Common Wear Points

• Mainspring fatigue, leading to poor amplitude or shortened power reserve

• Balance pivots and cap jewels suffering from wear if the watch ran dry

• Keyless works (winding and setting components) becoming worn or loose

• Corrosion on the stem or crown tube, especially if the watch was exposed to moisture

Since many watches housing this caliber lacked full water resistance, humidity and age-related corrosion are common risks.

Handling Tips

• Wind daily, ideally at the same time, and stop when resistance is felt

• Avoid exposure to water or high humidity, especially with older gaskets

• Keep away from magnets, which can disrupt the balance spring

• Store in a dry, stable environment, ideally dial-up when not in use

Collectibility and Value

While not a rare or high-complication movement, the Tissot 27B has earned respect for its:

• Solid engineering

• Ease of service

• Smooth manual winding action

• Role in post-war Swiss watchmaking history

Watches containing the 27B are a great option for collectors seeking a dependable, historically significant vintage mechanical watch at an affordable entry point.

Conclusion

The Tissot caliber 27B stands as a fine example of mid-century Swiss mechanical design. Its reliability, ease of use, and classic proportions make it a strong choice for those who appreciate vintage horology. With regular maintenance and thoughtful care, this movement can continue to deliver precise performance for many years, preserving a proud chapter in Tissot’s watchmaking heritage.