What Is a Hacking Movement? Hacking Seconds Explained
"Hacking" shows up in almost every watch spec sheet, and it has nothing to do with computers. It is a simple feature that stops the seconds hand while you set the time. Here is what it does, why it matters, and how to check whether your watch has it.
What hacking means
A hacking movement (also called "stop-seconds") stops the seconds hand when you pull the crown out to the time-setting position. Push the crown back in and the watch starts again. That lets you set the time to the exact second instead of just to the nearest minute.
On a non-hacking movement the seconds hand keeps sweeping while you move the hour and minute hands, so the best you can do is get within a few seconds.
How it works
When the crown is pulled to the last position, a small lever inside the movement (the hacking lever or stop lever) swings in and gently touches the rim of the balance wheel. The balance stops oscillating, so the whole gear train stops with it. When you push the crown in, the lever moves away and the balance starts swinging again.
Why it matters (and when it doesn't)
Hacking became standard on military watches during the Second World War. Units could synchronize every watch to a single time call, which mattered for coordinated operations. Today it is mostly a convenience:
- Precise setting: you can match your watch to an atomic-clock reference to the second.
- Accuracy tracking: if you want to know how many seconds a day your watch gains or loses, you need to start from an exact time. See our guide to an automatic watch running fast for how to measure it.
- Peace of mind: it simply feels more precise.
It doesn't make the watch more accurate while running, and it doesn't affect durability. A non-hacking watch is still a perfectly good watch; you just get the time to within a few seconds.
How to check if your watch hacks
- Unscrew the crown if it screws down.
- Pull it all the way out to the time-setting position.
- Watch the seconds hand for a few seconds. If it stops, your watch hacks.
If the seconds hand keeps moving, the movement is non-hacking. It's not a fault.
Common movements: hacking or not?
| Movement | Hacking | Hand-winding |
|---|---|---|
| Seiko NH35 / NH36 / 4R35 / 4R36 | Yes | Yes |
| Seiko 7S26 / 7S36 (older Seiko 5) | No | No |
| Orient F6922 (Kamasu, newer Mako) | Yes | Yes |
| Miyota 8215 | Traditionally no* | Yes |
| Miyota 9015 | Yes | Yes |
| ETA 2824-2 / Sellita SW200 | Yes | Yes |
| Tissot Powermatic 80 | Yes | Yes |
*The Miyota 8215 is usually listed as non-hacking, but some sources report hacking on recent production. The quick test above tells you for sure.
The NH35 and NH36 differ only in the day display; both hack. See our NH35 vs NH36 comparison for details.
Setting a watch to the exact second
- Open an accurate time reference, such as time.gov or your phone's network time.
- Pull the crown out when the seconds hand reaches 12. The watch stops.
- Set the minute hand one minute ahead of the real time, aligning it exactly on the minute marker.
- When the reference reaches :00 of that minute, push the crown in. The watch starts in sync.
If your watch has a date, set the date first at a safe time. Our date-setting guide explains the danger zone.
Common questions
Is it bad to leave the crown pulled out?
Not for the movement, but an open crown lets in dust and water. Don't leave it out longer than you need to.
Can a non-hacking watch be converted?
Not practically. It means changing parts of the movement, or the whole movement. If hacking matters to you, choose a watch with a hacking calibre.
Does hacking wear out the balance?
No. The lever touches the balance rim very lightly and only while the crown is out. It's designed for daily use.
My watch should hack but doesn't. What's wrong?
Make sure the crown is fully in the last position, not the date position. If it still doesn't stop, the hacking lever may be bent or misaligned; a watchmaker can adjust it during a service.
Comments
Post a Comment