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Discussion Starter · #1 ·
This is a tricky question because most people won't ever encounter a movement that has never been wound since new or since service.

On even a "perfect" ETA 2824-2, there is a point in the power reserve dissipation where the energy supplied by the escape wheel to the pallet fork is insufficient to propel the balance wheel on yet another self sustaining cycle. At this point there is still some energy stored in the partially wound mainspring and if one were to remove the pallet fork, the rapid and sustained rotation of the escape wheel would evidence this. The further disassembly of the movement and removal of the barrel from the plate and its bridge releases most of the energy to be extracted from the "bounded" spring. And if you've ever seen a mainspring removed from a barrel you are well of aware of the residual energy released as it slips from its containment.

So back to manual winding. The crown turns the winding pinion, the winding pinion turns the crown wheel, the crown wheel turns the ratchet wheel and the ratchet wheel turns the barrel arbor - around which the center of the mainspring is hooked. The winding pinion has 12 teeth, the crown wheel has 26 (which only engage every other tooth on the ratchet wheel) and the ratchet wheel has 63 teeth. One revolutution of the ratchet wheel turns the barrel arbor one revolution. The nominal diameter of the barrel arbor is 3.36mm. The thickness of the mainspring is typically .125mm and the length is a little over 400mm. (The inside diameter of the barrel is @ 11mm.)

As the crown is turned for the first time in the winding mode, the end of the mainspring bridle lodges in one of 6 equidistant notches in the interior of the barrel wall thereby arresting its further slippage. Now the arbor needs to turn about 22 full revolutions and for the ratchet wheel to turn the arbor one revolution the crown must be turned 2.625 times.

p
 

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So is your answer 2.625 X 22 = 57.75 full revolutions of the crown to fully wind??
 

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However: don't wind up your 2824. Rather, it is designed to be autowound, with a manual wind as a backup, not as primary winding method.

Why? The teeth of the winding mechanism are not hardened, as they were designed to only be used as a backup, rather than as the primary winding method. If you make a habit of winding up the 2824 manually, you will slowly start to degrade the hand-wind mechanism and it will, after an indeterminate time, fail. If you want a hand-wind watch, get one with the 2804 instead, as the winding mechanism here is hardened properly (if I am not mistaken, the winding mechanism of the 2804 uses stainless steel gears to wind, while the 2824 uses simple stamped steel gears for the same purpose).

This has been discussed in the Laco thread for the WUS special edition of the A-dial. Laco did not have 2804 movements and converted 2824 movements for that watch, replacing as well the winding mechanism to ensure proper longevity of that movement.

If your watch with the 2824 has been lying dormant, simply shake it a few times to get the seconds hand moving. Set the watch normally and simply wear it. Normal activities should have the watch fully wound within 18 hours or so, depending on how active you may or may not be.

Seriously: I have had a 2824 watch fail on me (Fortis Pilot watch) because I was in the nervous habit of giving the movement a few winds whenever I felt like it. The winding mechanism really is not designed for long-term hand winding, and after wearing it for 3 years constantly a gear lost a tooth, which ended in the hairspring and damaged it enough for both the winding mechanism and the hairspring needing to be replaced. The watchmaker I used at the time said that there was no reason for it to have failed unless I was fiddling with it. ETA designs their movements very carefully to control costs and as the winding mechanism on the 2824 is a back-up, rather than a prime component, it was not designed to be used as a prime mechanism.

This does not apply to the 2893 or the 7750.
 

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Discussion Starter · #4 ·
However: don't wind up your 2824. Rather, it is designed to be autowound, with a manual wind as a backup, not as primary winding method. . . . . . . . .
The design/material of the barrel bridge in the area of crown wheel support is a limitation on the 2824 autowind caliber family with respect to cumulative manual winding cycles. Catastrophic ratchet wheel damage is often a product of the altered geometry of the crown wheel / ratchet wheel tooth engagement under loading due to this same barrel bridge wear.

p
 

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Great technical treatise gentlemen, thank you for sharing. I have 2 of the above mentioned mvmt's and there is no mention, or caution, regarding hand winding in the generic manuals supplied by the mfg. I'm glad I was " scared" while learning more and limited my winds to 7 or 8 when getting them ready. Now, I'll just gently awaken them after their sabbatical. THANKS AGAIN!
 

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However: don't wind up your 2824. Rather, it is designed to be autowound, with a manual wind as a backup, not as primary winding method.

Why? The teeth of the winding mechanism are not hardened, as they were designed to only be used as a backup, rather than as the primary winding method. If you make a habit of winding up the 2824 manually, you will slowly start to degrade the hand-wind mechanism and it will, after an indeterminate time, fail. If you want a hand-wind watch, get one with the 2804 instead, as the winding mechanism here is hardened properly (if I am not mistaken, the winding mechanism of the 2804 uses stainless steel gears to wind, while the 2824 uses simple stamped steel gears for the same purpose).

This has been discussed in the Laco thread for the WUS special edition of the A-dial. Laco did not have 2804 movements and converted 2824 movements for that watch, replacing as well the winding mechanism to ensure proper longevity of that movement.

If your watch with the 2824 has been lying dormant, simply shake it a few times to get the seconds hand moving. Set the watch normally and simply wear it. Normal activities should have the watch fully wound within 18 hours or so, depending on how active you may or may not be.

Seriously: I have had a 2824 watch fail on me (Fortis Pilot watch) because I was in the nervous habit of giving the movement a few winds whenever I felt like it. The winding mechanism really is not designed for long-term hand winding, and after wearing it for 3 years constantly a gear lost a tooth, which ended in the hairspring and damaged it enough for both the winding mechanism and the hairspring needing to be replaced. The watchmaker I used at the time said that there was no reason for it to have failed unless I was fiddling with it. ETA designs their movements very carefully to control costs and as the winding mechanism on the 2824 is a back-up, rather than a prime component, it was not designed to be used as a prime mechanism.

This does not apply to the 2893 or the 7750.
This is why my next days watch goes on the winder over night, it gives me enough reserve to keep my watch running for hours.
 

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No, I just wanted to make sure that I understood you correctly. Your knowledge far exceeds mine.

Can you also compute how many turns of the rotor are required for a full wind?

Thanks,
Avo
 

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Discussion Starter · #10 ·
. . . . . . Can you also compute how many turns of the rotor are required for a full wind? Thanks, Avo
I think that one has already been done. Maybe in one of the watch winder reviews? Anyway, I'll put it on my projects list. p
 

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Found an old thread with the answer:
According to the data sheets for a 2824-2, it takes at 1250 rotations to fully wind the watch via the auto-wind mechanism.
 

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Hello everyone -

I have a Longines Flagship cal l650.2 which is an auto chrono - I it has a ETA 2824-2 with a module for the chrono which makes it a 2894 - I thought I read that here. Since the this is all based on the 2824, does that mean I should not manually wind it when needed ? I should just shake it a little and set the time and put it on ?
When I purchased the watch, the AD had told me to wind it about 20 times then it is ready. In the book (that came with the watch Caliber 650) it also mentions winding the watch to kick start it as well. Is this incorrect information ?
 

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I was in a malaise after 2 wheels in my COSC certified Sellita SW200 have disintegrated. An online watchmaker replaced the wheels with some ETA parts (I think most of the ETA 2824 and Sellita SW200 parts are interchangeable).

I still find it difficult to set the watch going by just shaking it. It often does not work and the seconds hand will not start sweeping. Contrary to what I have been told by watchmakers I often fall back then to hand winding it again. Lets see how long it will take this time for the Sellita to fail; last time it took me 1.5 years.

I also received conflicting messages from watchmakers: some insist you should never hand wind a ETA 2824 but some told me not just as myth and lore that a ETA 2824 is built to be hand wound.
 

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I was in a malaise after 2 wheels in my COSC certified Sellita SW200 have disintegrated. An online watchmaker replaced the wheels with some ETA parts (I think most of the ETA 2824 and Sellita SW200 parts are interchangeable).

I still find it difficult to set the watch going by just shaking it. It often does not work and the seconds hand will not start sweeping. Contrary to what I have been told by watchmakers I often fall back then to hand winding it again. Lets see how long it will take this time for the Sellita to fail; last time it took me 1.5 years.

I also received conflicting messages from watchmakers: some insist you should never hand wind a ETA 2824 but some told me not just as myth and lore that a ETA 2824 is built to be hand wound.
I haven't met any that say it's okay to constantly wind your watch to give it juice. I still think a winder is the best way to go, it doesn't damage the watch and it's a relatively inexpensive investment that will save you money in the long run.
 

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Discussion Starter · #17 ·
. . . . . . . I also received conflicting messages from watchmakers: some insist you should never hand wind a ETA 2824 but some told me not just as myth and lore that a ETA 2824 is built to be hand wound.
2801 is built to be manually wound.

2824 is designed to be autowound.

2801 has part #422. 2824 doesn't. Horological myth debunked (again).

p
 

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However: don't wind up your 2824. Rather, it is designed to be autowound, with a manual wind as a backup, not as primary winding method.

Why? The teeth of the winding mechanism are not hardened, as they were designed to only be used as a backup, rather than as the primary winding method. If you make a habit of winding up the 2824 manually, you will slowly start to degrade the hand-wind mechanism and it will, after an indeterminate time, fail. If you want a hand-wind watch, get one with the 2804 instead, as the winding mechanism here is hardened properly (if I am not mistaken, the winding mechanism of the 2804 uses stainless steel gears to wind, while the 2824 uses simple stamped steel gears for the same purpose).

This has been discussed in the Laco thread for the WUS special edition of the A-dial. Laco did not have 2804 movements and converted 2824 movements for that watch, replacing as well the winding mechanism to ensure proper longevity of that movement.

If your watch with the 2824 has been lying dormant, simply shake it a few times to get the seconds hand moving. Set the watch normally and simply wear it. Normal activities should have the watch fully wound within 18 hours or so, depending on how active you may or may not be.

Seriously: I have had a 2824 watch fail on me (Fortis Pilot watch) because I was in the nervous habit of giving the movement a few winds whenever I felt like it. The winding mechanism really is not designed for long-term hand winding, and after wearing it for 3 years constantly a gear lost a tooth, which ended in the hairspring and damaged it enough for both the winding mechanism and the hairspring needing to be replaced. The watchmaker I used at the time said that there was no reason for it to have failed unless I was fiddling with it. ETA designs their movements very carefully to control costs and as the winding mechanism on the 2824 is a back-up, rather than a prime component, it was not designed to be used as a prime mechanism.

This does not apply to the 2893 or the 7750.
[/QUOTE
 
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