chronograph subdials

[Jumpingjackflash]

Hello

Why do some chronograph watches have two subdials and others have three subdials?

For example some Omega Speedmasters have two and three.

[AmosMoses]

Depends on the movement/ what complications they have added to the watch.

For instance the traditional man on the moon speedy:



Left dial is the second hand for non chrono operation.

Bottom dial is hours the chrono has been running for.

Right dial is 30 minute timer for the chrono.

Big second hand is for seconds when the chrono runs.

If you look at a 2 dial speedy:



Left dial is the second hand for non chrono operation.

Right dial is hours the chrono has been running for.

Big second hand is for seconds when the chrono runs.

[glazbagun]

As above. Three subdial watches usually have an hour counter for the chronograph, two subdial watches don't. One of the subdials is the normal seconds of the watch.

[andy_s]

None - EZM1 with the minute/second totalizers on the center spindle [my fave...]



One - Lemania with minute/second totalizers on the center spindle plus a running second subdial


And Tutima ZUZ, this time with an hour totaliser:


And Tissot Navigator with running second:



Two - Heuer Bund with the more common configuration of a second totalizer on the center spindle and a running second and minute totalizer subdials



Or the more unusual Sinn 156 [1st gen] with running second and hour subdials with the second/minute totalizers on the center spindle:


Three - another common config. with the standard h/m/running second totalizer subdials, here on the A386, the [jointish] first automatic chrono:



Three - but this time with the minute/second totalizers on the center, running second, hour totalizer plus the additional 24hr subs.



Same for the Omega -



There's loads of variety in chronos!

[gregs656]

I’d love an EZM1.

Probably the only watch now that I really want to get an example of. One or two have sold very cheap this year but I was in the process of sorting a PO GMT.

[Gren]

Supplementary question...

Love my Moonwatch but always wondered why the minute chrono dial is 30 minutes and not 60.

[andy_s]

Gren said:

Supplementary question...

Love my Moonwatch but always wondered why the minute chrono dial is 30 minutes and not 60.

Basically legibility, difficult to discern individual minutes on a 60 scale as they'd be very small, however it is more 'intuitive' in 60' scale and saves you having to refer to the position of the hour totalizer to see whether it's 2'32 or 2'02 for example.

45' scales were sometimes used in earlier watches and a few use a 15' scale [Breguet X].

This is why I like the center spindle min/sec layout, you get the whole watch face as the 'subdial' and it's intuitive as it's the same 60 scale as normal time reading. [Mainly Lemania for older watches but Damasko and Sinn both have movements that do this]. In addition, if lumed, it means you can use the chrono in the dark.

[wag2]

I used to use a Breitling chronograph to time yacht race starts. I found the elapsed minutes subdial too difficult to read and thought for a while about an IWC Portugieser. As time goes by, I should not be able to read that at a glance either. I now use a £60 digital yacht timer.

[Spydaman]

Just two here. Hours and minutes on the sub-dials with seconds on the main dial. 30 minutes per rotation of the minutes sub-dial and it clicks from one minute to the next.

[Fullook]

andy_s said:

Gren said:

Supplementary question...

Love my Moonwatch but always wondered why the minute chrono dial is 30 minutes and not 60.

Basically legibility, difficult to discern individual minutes on a 60 scale as they'd be very small, however it is more 'intuitive' in 60' scale and saves you having to refer to the position of the hour totalizer to see whether it's 2'32 or 2'02 for example.

45' scales were sometimes used in earlier watches and a few use a 15' scale [Breguet X].

This is why I like the center spindle min/sec layout, you get the whole watch face as the 'subdial' and it's intuitive as it's the same 60 scale as normal time reading. [Mainly Lemania for older watches but Damasko and Sinn both have movements that do this]. In addition, if lumed, it means you can use the chrono in the dark.

Yes but, no but...

I think there is also a technical engineering reason as well as the legibility one.

it bugs me massively that the Valjoux 2 or 3 sub-dial chrono movements used in the vast majority of mechanical chronos only show 30 minutes before re-zeroing, it makes the chrono function hugely less useful for me and as soon as it becomes less useful it just feels like a silly and purely decorative use of dial space.

So I had a little look into why Valjoux do this and found this explanation:

person on reddit said:

One is readability, the other is a technical viewpoint. The minutes get pushed by a finger(well, a spring) that is on the seconds hand. If the wheel has 60 teeth instead of 30, you are effectively halfing the stroke length of that finger, and with the tolerances staying the same, you are actually quartering it (if not more). So since showing 60 minutes is a pain in the ass, technically, the readability argument is an easy one to swallow for the engineers. I havent done the math to verify the quartering, i suspect it might be more. Since the seconds finger needs to be in contact with the minute wheel(via its intermediary) for a much shorter time, the penetration depth needs to be very precise, with axial shakes, axle concentricity, wheel sub-assembly tolerances etc, 20-30mu differences are to be expected. In a normal chrono, i have a vague memory of the 7750 penetration depth being something like 50-70mu(any know the number?). which means that with a 60 minute counter, you are basically left with microns. Yes, sometimes a simple thing multiplies the complexity hugely.

I've no idea if it is 100% correct, but it chimes with something I read when I first started letting the 30 minute thing irritate me.

it's the reason I went for this when I wanted a functional chrono - I also optioned a 12 hour bezel which means it's very easy and intuitive to read as a seconds / minutes / hours chrono.




Interestingly (well, for me anyway) Damasko used a modified version of the Valjoux movement to achieve the central second & minutes chrono hands - so the technical complexities described above are obviously not insurmountable.

[gregs656]

I wasn't aware of that Damasko. Lovely.

[SturdyHSV]

Odd question but seems the time to ask it...

Have there been any chrono implementations that have the normal running seconds on the centre, and exclusively use the subdials for the chronograph?

For me it would make some logical sense that the big 3 hands show the time, and then the little 3 dials cover the secondary chronograph behaviour, just wondered if it had been done?

[andy_s]

Fullook said:

I've no idea if it is 100% correct, but it chimes with something I read when I first started letting the 30 minute thing irritate me.

I'd never thought about that to be honest, my initial thought would be that as we have 28800bpm to play with everything else was just gearing and slaving, and if you can do it quite easily from the center there wasn't ay real difference to doing it from the subdial. There's an ETA quartz [nothing fancy] that I can't remember the name of that displays 10th of a second on a subdial, I assumed you could use the same principles - impulse -> gears.

No idea!

[ETA - ETA 251.262]
-

Yeah - it's nice the Damasko, the Tutima modern config of it is a bit outlandish [imo] and the Sinns are 'recreations' of older watches - nothing wrong with that, but I like the various options on the Damaskos and they have kept a purposeful look while still being smart. If Habring2 had a better aesthetic [to my eye] I'd be all over them as well.

Edited by andy_s on Tuesday 24th November 15:32

[glazbagun]

Re: 30 mins vs 60, I don't think it's manufacturing difficulty. The teeth on a chrono wheel are stupidly fine and concentric, ditto the heart cams for resetting the chrono.

The depthing between teeth is already absolutely essential and minute counters are positively sloppy compared to the rest of the watch.

I think it's more likely a legibility thing and a function of what was being measured- lap time? Full race? Pulse? Distance?

If you really need to know hours, then you have the Hour Counter which on a 7750 or Lemania 861 (speedmaster) is geared from the rotation of the barrel and moves at a glacial pace, but (with only 12 hours to choose from, lets you see at a glance if a full hour or only half an hour has passed.