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Ronda 1017-21
Manual · 10.5‴ · Switzerland · 1970
Dimensions
23.7 mm
Height
4.80mm
Jewels
17
Power reserve
38h
Timegrapher
Beat rate
21,600bph
Frequency
3Hz
Reference: healthy amplitude ≈ 270–315° fully wound (>200° at 24 h); beat error ideally < 0.5 ms.
Movement
| Movement type |
Manual
Purely mechanical movements wound by hand via the crown, which tensions the mainspring to store energy. As the spring unwinds, it drives the gear train at a controlled rate set by the escapement and balance. Typical power reserves range from 38 to 80 hours, requiring daily or near-daily winding to keep the watch running.
|
|---|---|
| Winding type |
Stem Winding (Crown)
Winding the mainspring by turning the crown attached to the stem, transmitting torque through the winding pinion. Patented by Adrien Philippe in 1842, it replaced key winding and remains the standard manual winding method for both pocket watches and wristwatches.
|
| Setting type |
Stem Set (Crown Pull)
The dominant modern system: pulling the crown out to a setting position engages the hand-setting mechanism. Introduced in the late 19th century and refined into multi-position crowns (date, time, GMT). Used in virtually all modern wristwatches and most 20th-century pocket watches.
|
| Escapement type |
Pin Lever
Also known as the Roskopf escapement, this is a simplified, low-cost variant of the Swiss Lever using steel pins instead of jewelled pallet stones. Less accurate but inexpensive to produce, it democratized mechanical watchmaking in the 20th century, populating affordable alarm clocks and entry-level watches worldwide.
|
| Control type |
Balance Wheel
The heart of mechanical timepieces, the balance wheel is an oscillating component that, together with the hairspring, forms a harmonic oscillator regulating the gear train's pace. Its steady back-and-forth motion ensures the even release of energy from the mainspring, governing the watch's accuracy.
|
| Regulator type |
Pinned Regulator (or Index Regulator)
The most traditional regulator, consisting of a movable index pointer fitted with two curb pins (or a pin and a boot) that embrace the hairspring. Sliding the index along its scale changes the spring's active length, adjusting the rate. Simple, reliable, and easy to service, it remains the workhorse standard across countless mechanical movements.
|
| Shock protection |
KIF
A family of Swiss shock protection systems (Trior, Flector, Elastor, Duofix, Protechoc) produced by Parechoc SA, the main competitor to Incabloc. Uses a multi-point elastic spring design (typically three points in the Trior version) that excels in thinner calibres. Long favoured by Rolex (Duofix), Patek Philippe, and Audemars Piguet before each developed proprietary systems.
|
Specifications
| Lignes | 10.5‴ |
|---|---|
| Shape |
Round
It is the most common form that we can find.
|
| Complications |
Sweep Second
Contrary to the ticking motion of quartz watches, the sweep second hand in mechanical watches moves smoothly around the dial, offering a visual representation of time flowing continuously. This has become synonymous with the precision and craft of mechanical horology.
,
Day
Beyond hours and minutes, the day complication anchors wearers to their weekly schedule, providing context to our cyclical routine.
,
Date
An essential for many, the date display reminds wearers of their daily commitments, connecting the abstract concept of time to tangible daily events.
,
Moon Phase
This artistic complication connects wearers to celestial rhythms. Depicting the lunar cycle, it's both a technical marvel and an aesthetic feature, bridging earthly timekeeping with cosmic patterns.
|
| Hand count | 3 |
| Hand sizes | 1.80 x 1.30 x 0.20mm |
| Further measures | Mounting Diameter (Dm): 23.3mm Dial Spacer: 0.1mm Stem height (T): 2.7mm Mounting Height (F): 1.8mm |
Origin & References
| Manufacturer | Ronda AG |
|---|---|
| Country | Switzerland |
| Launch year | 1970 |
| COSC certified | No |
| Signature | ca. 1970: RL, 1217-21, Jura Watch Co, Swiss, 1 Jewel; Kif-Protechoc
(Ronda 1217-21, 12" ) |
Notes
Remarks: pin-lever escapement
in late samples glued hairspring terminal (cf. Ronda 1233-21)
stem mechanism without setting-lever spring
strange: train and hand gear separately driven by the barrel (cf. Ronda 9011)
Other data: balance staff: U3254 stem: W3215 mainspring / battery: Zf1051, 1.40 x 9.5 x 0.105 x 300mm
Ranfft mentioned about this caliber: There are variants with this quantity of jewels 1, 17
in late samples glued hairspring terminal (cf. Ronda 1233-21)
stem mechanism without setting-lever spring
strange: train and hand gear separately driven by the barrel (cf. Ronda 9011)
Other data: balance staff: U3254 stem: W3215 mainspring / battery: Zf1051, 1.40 x 9.5 x 0.105 x 300mm
Ranfft mentioned about this caliber: There are variants with this quantity of jewels 1, 17
Family
Series 1x11 - suffix -21
pin lever / Swiss lever:
1x11/1x31: manual, no second
1x13/1x33: manual, sweep second
1x15/1x35: manual, sweep second, date
1x16/1x36: auto, sweep second
1x17/1x37: manual, sweep second, day, date
1x18/1x38: auto, sweep second, date
1x19/1x39: auto, sweep second, day, date
1x21/1x41: manual, sweep second, digital display
1x23/1x43: manual, sweep second, alarm
1x26/1x46: auto, sweep second, digital display
1x66/1x86: auto, digital display incl. second
x=0: 10.5"
x=1: 11.5"
x=2: 12"
x=3: 13.5"
suffix -21: 21600A/h
Swiss-lever movements normally have the singature RAX under the balance, but some also RL like the pin levers.
Not all variants were actually made. Only those are listed, which are actually known or contained in current registers.
1x11/1x31: manual, no second
1x13/1x33: manual, sweep second
1x15/1x35: manual, sweep second, date
1x16/1x36: auto, sweep second
1x17/1x37: manual, sweep second, day, date
1x18/1x38: auto, sweep second, date
1x19/1x39: auto, sweep second, day, date
1x21/1x41: manual, sweep second, digital display
1x23/1x43: manual, sweep second, alarm
1x26/1x46: auto, sweep second, digital display
1x66/1x86: auto, digital display incl. second
x=0: 10.5"
x=1: 11.5"
x=2: 12"
x=3: 13.5"
suffix -21: 21600A/h
Swiss-lever movements normally have the singature RAX under the balance, but some also RL like the pin levers.
Not all variants were actually made. Only those are listed, which are actually known or contained in current registers.
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