Degrees, Gears & Ratios, Part 1

Sep 12, 2022,18:10 PM

Degree is a very complex word in English, with many meanings:
  • a unit of measuring temperatures, as in  40° C
  • a unit of measuring rotation, such as "a right angle is 90°"
  • a measure of technical difficulty of skill in an athletic competition, such as gymnastics or high diving
  • a certificate given for completion of a course of study
  • distance between people who know one another, as in "there is one degree of separation between myself and the new King, because I know Richard and Richard knows the recently-crowned King Charles.

Today I propose to take a look at the degrees required on a watch dial. I'm using my perpetual because it has multiple subdials and complicated divisions.

Here you can see I have divided the dial into 12 segments (hours) with green lines.

Each line is 30° of rotation from the previous line (30x12=360 or a full circle) and each line represents 5/60th of an hour.

I overlaid some more lines and it became too complex to explain, so in the right-hand example below I subtracted the dial itself so we can just concentrate on the lines and circles.

SMALLEST purple circle is divided into 12 months (360/12=30°) and 24 half-hours (360/24=15°). This circle is smaller than the distance between the green (12th) lines.

LEFT light blue circle is subdivided into 7 days (360/7=51.42° of rotation) and 60 seconds (360/60=6° of rotation). This circle just touches the green lines.

RIGHT light blue circle is divided into 31 days (360/31=11.61° of rotation). This circle also just touches the green lines.

LARGEST red circle at 12 o'clock traces the opening cut into the dial, to display the revolving, twice-a-month moonphase subdial (2 x 29.5=59 so 360/59=6.1° of rotation) and a 30-minute counter for the Chronograph (360/30=12° of rotation). This circle is larger than the distance between the green lines.

The centers of these sub-dial circles are equidistant from the center point of the dial, so they fall on the circumference of the orange circle below.

Notice that I haven't defined the LARGEST dark blue circle. It needs a drawing of its own! The items outside the pink dotted line were left off or buried under something else on the dial. And I got bored with creating the diagram and didn't put in the outermost display -- would you say those are seconds markers?


Now I have to ask: which part of the watch manufacturing process has the greatest "degree of difficulty" (in your humble opinion)?
  1. Designing the overall dial concept / design
  2. Executing the detailed degrees/rotation/size design of each of the markers on dial and sub-dials
  3. Making the dial base, then printing, positioning & lume coating the dial markers, windows, etc.
  4. Making the movement underneath operate correctly and have its arbors sticking up in the right places to rotate the hands
  5. Making sure the movement frequency (let's say 28,000 vph or 4 per second) is evenly divisible so the chrono hands line up with the marks on the seconds scale
  6. Can you give an example of any watch you own where the manufacturer FAILED to properly execute these 5 factors?
Do you think IWC was primarily a DESIGN-oriented company or an ENGINEERING-oriented company when this line of watches was created?

Thanks for reading, and please come back for Part 2 of Degrees, Gears and Ratios.


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Comments: view entire thread


Am at odds with....

 By: enjoythemusic : September 12th, 2022-18:20
Mathematical perfection versus 'the soul of flow'. Many musicians can play The Notes, yet far fewer can play The Music. I feel these relate to dials and visual art, though a pure tool MIL timepiece might have one desired visual 'perfection' for the task a... 

That’s a splendid analogy with the notes vs the music

 By: mrds : September 12th, 2022-20:08
Dial design and proportions must be the single most difficult task when designing a watch. Especially for a simple 2 or 3 hander.


 By: InHavenPro : September 12th, 2022-22:58
it totally depends on the intended context and application. As it relates to musicians, I always admired the fact that Phil Collins - my favorite singer/songwriter never learned to read sheet music (notes) . During my 6 years at a hyper traditional music ... 

Impressive InHavenPro 🎶🎵🎶

 By: enjoythemusic : September 13th, 2022-03:29

I guess one of the more common flaws is the division markers between seconds

 By: mrds : September 12th, 2022-20:15
One example is the VC Cornes de Vache, which runs on 3Hz but has 1/5th of a second markers, I guess for esthetic reasons. I think they changed this on the (later) steel model, but the Pt version shows this inconsistency.