# Parts of a watch, and how a watchmaker looks one over

> The parts on the outside of a watch, from crystal and crown to lugs, spring bars and clasp, and the order a watchmaker looks a watch over in. Free lesson guide.

Source page: https://thewatchschool.com/lessons/parts-of-a-watch

Name 12 external parts, inspect in a defensible order, record observations not guesses, spot stop signs. This guide is the readable version of Lesson 1 in The Watch School, where Mr F or Mr P talks you through it on a real vintage watch you can turn in 3D.

## First rules at the bench

- Watchmakers inspect first. Record what is already there before anything changes.
- Work outside in: identity, completeness, case, crystal, dial, hands, crown, then the back.
- Write what you see, not what you guess. 'Fog under the glass at 9' is an observation. 'Water damage' is a conclusion.
- Fog under the glass or a pin sticking out is a stop sign: record it and stop.
- Opening a case lets dust in and can mark it. Not in this lesson.

## The order to inspect a watch in

Identity first, then outside in, recording what is already there before anything changes. The case stays closed.

1. **Identity:** Turn it over. Read the back: what is it?
2. **Completeness:** Is everything there and secure to handle?
3. **Case:** Case, lugs and spring bars.
4. **Crystal:** Glass surface and edge.
5. **Dial:** Dial, date window and bezel.
6. **Hands:** Hands straight and clear of each other.
7. **Crown:** Crown: what type is it?
8. **Case back:** Back: notches and markings. It stays closed.

## The parts you name in Lesson 1

Shown on the lesson's practice watch, a Seiko 2906-0020 automatic, c.1977.

- **Case (middle case):** Steel body. Look for dents, deep scratches and edges rounded by polishing.
- **Bezel:** On this watch a fixed, polished steel ring round the crystal. It does not turn. In the 1945 manual 'bezel' meant exactly this, the ring that holds the crystal; on divers' watches the turning ring is called a bezel too.
- **Crystal:** Acrylic on this watch. Look for chips at the edge, scratches, and fog under it. Fog under the crystal is a stop sign: record it and stop operating the watch.
- **Dial:** Legibility and marks. Never scrape or 'test' luminous paint; old luminous dials can be hazardous.
- **Hands:** Hour, minute and seconds hands: straight, clear of each other, the dial and the crystal.
- **Day and date window:** Is the date centred in its window?
- **Crown:** At 3 o'clock, a plain push-in crown, not screw-down. Pulled out one step it sets the day and date, two steps the time. Not operated in this lesson.
- **Lugs:** The horns that hold the bracelet. Look for wear, cracks or bending.
- **Spring bars:** The sprung pins between the lugs. Both ends must sit in their holes. A protruding or rusted pin is a stop sign: the bracelet could come loose.
- **Bracelet and clasp:** Steel jubilee-style bracelet: three pieces across each link, and a signed fold-over clasp with adjustment holes. Check the pins and that the clasp shuts.
- **Case back:** A solid, screw-down steel back with six notches for an opening tool. Engraved 2906-0020 (calibre 2906, case 0020) and serial 788724. It stays closed in this lesson.
- **Rotor (hidden behind the solid back):** This back has no window, so the winding rotor cannot be seen. AUTOMATIC on the dial and calibre 2906 on the back are clues that it winds itself, not proof on their own.

## The practice watch

Lesson 1 uses a real watch from London Watch Market stock (stock number 1304-SEI-L), modelled in 3D from its photographs and measurements. The 3D model is a practice model, not a scan, and only the outside is modelled.

Seiko calibre 2906: automatic with hand winding, 17 jewels, 28,800 beats an hour (Hi-Beat), day and date.

- **Reference:** Seiko 2906-0020, circa 1977
- **Movement:** Automatic, calibre 2906, 17 jewels, Hi-Beat, day and date
- **Case:** Polished stainless steel, 25 mm
- **Dial:** White, applied baton indices, day and date at 3 o'clock
- **Crystal:** Acrylic
- **Bracelet:** Steel jubilee-style bracelet, signed folding clasp, 188 mm wrist
- **Condition:** Good: light surface scratches on the bezel and lugs, use marks on the clasp and links

Try it: [Play Lesson 1](https://thewatchschool.com/school?area=course)

## Sources

- US War Department, TM 9-1575, Ordnance Maintenance: Wrist Watches, Pocket Watches, Stop Watches, and Clocks, 6 April 1945. Pages cited as printed page (PDF page = printed + 5 in chapter 1).
- Seiko Watch Corporation, Instruction manual 4R35 / 4R36 / 4R37 / 4R38 / 4R39 / 4R71 / 4R72 (document JSY4RCC2-A2403), booklet pages EN n.
- London Watch Market listing photographs and condition notes for the practice watch

A learning game, not a qualification. Nothing here makes anyone ready to open or repair a real watch.