ETA 2410
Description
The ETA 2410 was the first of a series of tiny and flat windup movements, made by ETA, which already use the modern construction without center minute wheel. Its tiny size was ideal for the especially flat and elegant ladies’ watches of the time being.
version with Glucydur screw balance
Depending on customer requirements, it was available in a variety of versions, from a simple nickel screw balance to the top-of-the-line version with a gold-colored Glucydur screw balance.
version with 21 jewels
The number of jewels could also vary; if more were required, a number of cap jewels were used, which increased the number up to 21 jewels.
gear train
The gear train construction was revolutionary at the time, around 1960, as it dispensed with a central minute wheel and was therefore able to offer a larger mainspring barrel and balance wheel.
The mainspring barrel drove the large third wheel, followed by the third wheel, seconds wheel, and escapement wheel.
On the dial side, the hand train was driven by the pinion of the third wheel, which acted on the minute wheel equipped with a slip clutch.
side view of the gear train
The balance was already shock-resistant at that time, usually with an Incabloc shock protection bearing, but it still operated with slow 18,000 A/h which, depending on the execution, were adjusted directly using the hairspring key or with the help of a long regulator hand.
The beat error was not easy to adjust at that time, as the ETA 2410 did not yet have a movable hairspring stud carrier.
yet empty dial side
On the yet empty dial side, you can see the yoke winding mechanism and, at 8:30 near the center, the pinion of the third wheel. The minute wheel engages with this, as shown in the next image.
dial side with minute whee
The cannon pinion, which carries the minute hand, is mounted on this minute wheel, fitted with a slipping clutch.
ETA 2410: Dial side
The ETA 2410 was also available in various colors upon customer request, mostly in steel, but rose gold was also possible, which gave the movement a particularly refined appearance.
dial side of the 21j version
One trick to further minimize the height of the movement is to bevel the edge of the dial side.
Since the third wheel runs beneath the mainspring barrel, the height would be too low for it, so the movement has a recess where the third wheel would be, allowing the wheel to be seen.
In the lab
Timegrapher result
The timegrapher rates are impressive for such a tiny windup movement!| horizontal positions | |||
|---|---|---|---|
| dial up | +2 s/d | 246° | 0.6ms |
| dial down | +1 s/d | 290° | 0.7ms |
| vertical positions | |||
| crown right (12 up) | +5 s/d | 215° | 0.4ms |
| crown up (3 up) | +-0 s/d | 206° | 1.0ms |
| crown left (6 up) | -14 s/d | 201° | 1.4ms |
| crown down (9 up) | +-0 s/d | 212° | 0.7ms |
Technical data
| Manufacturer: | ETA |
| Caliber: | 2410 |
| Caliber base: | ETA 2410 |
| Size: | 6 3/4''' (measured: 15,2mm) |
| Height: | 3,40mm |
| A/h: | 18000 |
| lift angle: | 51° |
| Number of jewels: | 17/21 |
| Escapement: | Pallet lever |
| Balance types: | Glucydur screw balance (two legs) monometallic screw balance (two legs) |
| Shock protection(s): | Incabloc |
| Balance bearing / direction hairspring: | Clockwise |
| Moveable stud: | no |
| Adjust mechanism: | Long regulator arm / hairspring key |
| Construction: |
|
| Winding mechanism: | yoke winding system |
| Setting lever spring: | 2 holes |
| Attachment of setting lever: | screwed |
| References: | Feilner: Bl. 62 6201 Flume: 1962 2 |
| Mentioning in literature (years): | 1963 - 1964 |
| Inventory number: | 24016 |
Usage gallery
BWC ladies' watch
Blumus De Luxe ladies' watch (case missing)
Exquisit ladies' watch (case missing)
Cito ladies' watch (case missing)