Watch Case for ETA 2650, 2651, 2670, 2671, Oval, Polished – Swiss NOS

NOS vintage Swiss ladies’ watch case – oval, polished

Case specifications

Engravings on the case back

INCABLOC · WATERPROOF · STAINLESS STEEL BACK · 3 ATU 30 M · SWISS MADE

Probably compatible movements

Movement Ø = maximum space required (does it fit in the case?) | Fit Ø = centering (does it sit firmly and centered?)

Technical compatibility analysis

1. Diameter & centering

The most important factor for how well a movement sits is the fit diameter.

• Movement: ETA fit Ø = 17.20 mm
• Case (seat, first 2.5 mm): inner Ø = 17.30 mm
• Result: Ideal tolerance of 0.10 mm – the movement can be inserted without force, yet sits precisely centered. The overall Ø (17.50 mm) fits safely in the movement cavity (17.60 mm).

2. Winding stem height (crown position)

For the crown to engage the movement exactly, the stem height in the case must match that of the movement.

• Movement (ETA family): stem height = 1.75 mm (from dial seat)
• Case: stem height = approx. 1.70 mm
• Result: Difference of only 0.05 mm – within normal manufacturing tolerances. Can often be compensated by choosing the dial thickness or by using a movement spacer ring.

3. Height – suitable for automatic & manual winding

• Tallest movement (ETA 2651/2671 automatic): requires 4.80 mm
• Total case height: 9.45 mm
• Result: Even after deducting the crystal and case back, there is enough room for the rotor of the automatic versions to turn freely without rubbing against the case back.

Summary: The case is designed precisely for movements of 7 ¾”’ (lignes). Since the ETA 2650 family uses exactly this standard size and the stem position is nearly identical, this case is considered a technically suitable housing for these calibers.

Note on ETA 2650: The winding stem height of the ETA 2650 (1.75 mm) is slightly greater than the stem height on the case side of approx. 1.70 mm.

All dimensions were measured manually and may have a tolerance of ±0.10 mm. Compatibility information is provided to the best of our knowledge. Please check before installation.