What causes a second hand to sweep?

[mretzloff]

Why do some watches have a sweeping second hand and some not? Why do some Swiss watches have sweeping second hands and others not?

I'm sorry if this has been asked before, but I couldn't find anything.

[The GMT Master]

All auto watches have something resembling a sweep hand, although some may be more jerky than others - it simply comes down to the number of beats per second the balance wheel makes. A modern Rolex, for example, has a balance wheel that oscillates 8 times per second, or 28.8k times per hour, giving it a relatively smooth (but by no means perfect) sweep. Some have higher beat rates, some have lower, but no mechanical watch will have the jerky one per second tick of a quartz.

If we're being pedantic, the only watch with a perfect sweep in the world is a Seiko spring drive, which works differently from a standard mechanical watch.

Hope that helps

[mretzloff]

Thanks for the info.

What about watches that need to be manually wound?

[The GMT Master]

Originally Posted by mretzloff

Thanks for the info.

What about watches that need to be manually wound?

It'll work on exactly the same principle

[watchfreak2003]

….. But the coolest looking “sweep second hand” is IMO not from a Swiss manufacture but from Japan – Seiko Spring Drive

[snow_rocks]

Originally Posted by The GMT Master

If we're being pedantic, the only watch with a perfect sweep in the world is a Seiko spring drive, which works differently from a standard mechanical watch.

The Bulova Accutron, with tuning fork mechanism was the 1st true sweeper.

I believe the calibre was a 214, made in the early '60s.

If the Rolex moment beat was 33 bps (instead of 8 bps), then the eye would discern it as a continuous action. This is why movie film is shot at this speed.

[padi56]

Originally Posted by mretzloff

Why do some watches have a sweeping second hand and some not? Why do some Swiss watches have sweeping second hands and others not?

I'm sorry if this has been asked before, but I couldn't find anything.

All purely mechanical watches will have a sweeping second hand Swiss, European,Japanese and Chinese.Most movements today use 28800BPH some use36000BPH.The older movements used 18000BPH,and19800BPH the higher the beat the smoother the second sweep.Most quartz watches will have a tick sweep once a second or so, but some were made to mimic the sweep of a mechanical watch.

[Tools]

It is because of the escapement:



As the hairspring does this, it imparts energy to the tail of the pallet fork located underneath, the pallet jewels swing back and forth and.............. it locks and unlocks the escape wheel:

like this:

553px-Anker_01.jpg

And it does it at X number of times per second.... this locking and unlocking gives the second hand the same "beat". If it only locked and unlocked the escape wheel 1 time per second, then it would look like a quartz..

[allanofcalifornia]

Originally Posted by Tools

It is because of the escapement:



As the hairspring does this, it imparts energy to the tail of the pallet fork located underneath, the pallet jewels swing back and forth and.............. it locks and unlocks the escape wheel:

like this:

Attachment 76321

And it does it at X number of times per second.... this locking and unlocking gives the second hand the same "beat". If it only locked and unlocked the escape wheel 1 time per second, then it would look like a quartz..

Good information and great picture!


Allan

[The GMT Master]

Originally Posted by snow_rocks

The Bulova Accutron, with tuning fork mechanism was the 1st true sweeper.

I believe the calibre was a 214, made in the early '60s.

If the Rolex moment beat was 33 bps (instead of 8 bps), then the eye would discern it as a continuous action. This is why movie film is shot at this speed.

I didn't know that, thanks for the info

[mretzloff]

This makes me wonder, though...I passed by a large AD today that sold many brands of watches. I looked at the PP Aquanauts and none of them had a sweeping second hand. Is there something I'm missing?

[watchfreak2003]

Originally Posted by The GMT Master

If we're being pedantic, the only watch with a perfect sweep in the world is a Seiko spring drive, which works differently from a standard mechanical watch.

Sorry - overlooked your point about the Seiko Spring Drive

[Skutt50]

Try this page and you will see how it works: http://www.geocities.com/CapeCanaver...34/bwatch.html

The second hand used to be separated from the minute and hour hand, attached to a wheel next to the escapement.Today with center mount on top of the minute and hour hand it's a different story.

As explained earlier the sweep is generated by the escapement. The faster the movement the smoother the sweep. Compare an old mechanical watch with a new Rolex. You can see the difference quite clearly. A watch with 18000 beats per hour moves the second hand 5 times per second. A Rolex with 28.800 b/h turns the second hand 8 times per second....

[watchfreak2003]

Originally Posted by mretzloff

This makes me wonder, though...I passed by a large AD today that sold many brands of watches. I looked at the PP Aquanauts and none of them had a sweeping second hand. Is there something I'm missing?

Hmm - The self-winding caliber 324 S C movement in the Patek Philippe 5165A Aquanaut runs at a frequency of 28.800 BPH. Sweep enough for my taste

[dkpw]

The Rolex sweeping second hand is a majestic and beautiful thing to see.

[Perdu]

Originally Posted by snow_rocks

The Bulova Accutron, with tuning fork mechanism was the 1st true sweeper.

I believe the calibre was a 214, made in the early '60s.

If the Rolex moment beat was 33 bps (instead of 8 bps), then the eye would discern it as a continuous action. This is why movie film is shot at this speed.

You always learn something new on this forum.

[Dr.B]

Originally Posted by Tools

It is because of the escapement:



As the hairspring does this, it imparts energy to the tail of the pallet fork located underneath, the pallet jewels swing back and forth and.............. it locks and unlocks the escape wheel:

like this:

Attachment 76321

And it does it at X number of times per second.... this locking and unlocking gives the second hand the same "beat". If it only locked and unlocked the escape wheel 1 time per second, then it would look like a quartz..

Larry, you never let us down....keep on "ticking".....

[onkyo]

GREAT info .... thanks!!

[edster]

found this on another forum, helped clearup a few areas of confusion for me:

http://vimeo.com/channels/digifreak#5407101

[Watchdog]

Some watches have too much caffeine.

[Deputydog]

Great post very informative.

[jimbo1mcm]

Now you can see why lubrication at regular intervals is important.

[snow_rocks]

Originally Posted by kingkongkelley

Some watches have too much caffeine.

err, do you mean the wearer of the watch?

[Watchdog]

Originally Posted by snow_rocks

err, do you mean the wearer of the watch?

It was my feeble attempt at humor . . . Caffeine can make a person jittery, so I was personifying the watch's second hand, assigning the second hand a traditionally human attribute of nervousness with caffeine as the impetus, hence the varying appearance of smooth, sweeping second hands or tick.

[rmcarlton]

Great info. Thanks!

[sexner]

Originally Posted by dkpw

The Rolex sweeping second hand is a majestic and beautiful thing to see.

x2
I am in agreeance!!!!!!!!!!!!

[allanofcalifornia]

Originally Posted by dkpw

The Rolex sweeping second hand is a majestic and beautiful thing to see.

Especially when the sweeping second hand is on a Rolex on YOUR wrist!!


Allan