Automatic mainspring normal slippage?

[mbwatch]

Hi all - As I have acquired more automatics, I've started to wonder what normal behavior should be for a mainspring that is wound until it begins to slip. My first auto was a Vostok 2416 and if hand wound up to say, 18-20 turns, the mainspring slips audibly with that soft "twang" of unwinding the same as when placing a spring from a winder expanding into a barrel. It will then accept another 8-10 turns before it slips again, 8-10 turns, slip, etc. It runs for about 34-36hrs if wound to just before it the slip.

Knowing that automatic mainsprings had to slip in the barrel to prevent overwinding, I had just assumed it was normal to slip and unwind halfway. Other autos I've since acquired including another Vostok 2416 do not behave the same way (so it's probably not another oddball Vostok behavior). I never hear or feel a slip from an NH35, or from the other 2416. And a Chinese auto when hand wound will reach a point where the wind feels rougher, as though the bridle has started to rotate around the barrel wall without unwinding.

Does it sound like my original 2416 is not behaving as expected? Possible that insufficient or no braking grease was applied to its barrel? It's coming up on my list to attempt a service and I guess I'm trying to gauge whether I should start sourcing a new mainspring if you think it's likely something is broken in there. I have not disassembled it yet.

[Paul80]

Hi

I have not worked on a huge amount probably under 40, and mainly Seiko and Citizen and a TAG and have never felt or heard the mainspring slip on any of them.

I got the impression when I asked about it that the slip is so gradual that it should not be detectable.

Given that I have not don't that many and am quite new at this dont take what I say as correct, await a more knowledgeable reply

[jdm]

4 hours ago, mbwatch said:

I never hear or feel a slip from an NH35

On Seikos the transition is very smooth because the entire system is designed for maximum efficiency. There is no sound, but you can feel the reduction in torque by holding the driver with the very tip of two fingers, and turning it slowly, exercising just the minimum force needed.

 

4 hours ago, mbwatch said:

Does it sound like my original 2416 is not behaving as expected? 

Testing on bench is just indicative. If the auto winding behaves on the wrist, as in skipping a day of wearing without the watch stopping or slowing down, then all is good in that department.

[Kalanag]

4 hours ago, mbwatch said:

…My first auto was a Vostok 2416 and if hand wound up to say, 18-20 turns, the mainspring slips audibly with that soft "twang" of unwinding the same as when placing a spring from a winder expanding into a barrel. It will then accept another 8-10 turns before it slips again, 8-10 turns, slip, etc….

This behavior is not normal! It indicates a worn spring or bent bridle. The mainspring bridle should just slip to the next notch in the barrel wall which is 1/6 turn only.

[HectorLooi]

4 hours ago, mbwatch said:

Hi all - As I have acquired more automatics, I've started to wonder what normal behavior should be for a mainspring that is wound until it begins to slip. My first auto was a Vostok 2416 and if hand wound up to say, 18-20 turns, the mainspring slips audibly with that soft "twang" of unwinding the same as when placing a spring from a winder expanding into a barrel. It will then accept another 8-10 turns before it slips again, 8-10 turns, slip, etc. It runs for about 34-36hrs if wound to just before it the slip.

Knowing that automatic mainsprings had to slip in the barrel to prevent overwinding, I had just assumed it was normal to slip and unwind halfway. Other autos I've since acquired including another Vostok 2416 do not behave the same way (so it's probably not another oddball Vostok behavior). I never hear or feel a slip from an NH35, or from the other 2416. And a Chinese auto when hand wound will reach a point where the wind feels rougher, as though the bridle has started to rotate around the barrel wall without unwinding.

Does it sound like my original 2416 is not behaving as expected? Possible that insufficient or no braking grease was applied to its barrel? It's coming up on my list to attempt a service and I guess I'm trying to gauge whether I should start sourcing a new mainspring if you think it's likely something is broken in there. I have not disassembled it yet.

I have this problem with my Vostok Amfibia. Originally before I  used braking grease in the barrel, it didn't have this problem. I haven't tried cleaning out the barrel and using normal grease. I should really do that and post my findings.

[Nucejoe]

No diag be conclusive without full inspection of the barrel, arbour ...etc. 

Regs

[Kalanag]

I had this issue with a Citizen and assume that the bridle got slightly deformed when pushed into the winder barrel. The grease has no major influence imho.

[mbwatch]

17 hours ago, Kalanag said:

This behavior is not normal! It indicates a worn spring or bent bridle. The mainspring bridle should just slip to the next notch in the barrel wall which is 1/6 turn only.

Interesting, thanks. It has had this behavior since it was brand new so I wonder if it's a bad spring install. I do plan to strip it probably next month and see what happens after relubricating it.

17 hours ago, HectorLooi said:

I have this problem with my Vostok Amfibia. Originally before I  used braking grease in the barrel, it didn't have this problem. I haven't tried cleaning out the barrel and using normal grease. I should really do that and post my findings.

Yes, I'd be interested to hear the results.