Etachron regulation system

[BobG]

I’ve been playing with a NH35 movement that which has the classic Etachron regulation system and a few balance assemblies as practice. What I’m trying to do is get comfortable with the effect both the stud and regulator pin positions have on rate and positional error.

When I install a new balance assembly I install it with the assembly in place  on the cock and cock is attached to base plate. I use the back of the tweezers to push the stud into place and feel the click.

However, I noticed that the angle of the stud can be adjusted and what I also noticed is that some movements have the stud carrier arm bent down a little and that changes the angle of the hairspring leaving the stud. This angle effects how the spring goes through the regulator pins and also the spacing of the coils opposite the stud. What I thought I was supposed to do is set the regulator block in the middle of the curve, open the pins, and use the stud angle to center the spring.  Then the stud is set. 

Now on all the new NH movements I have seen the angle of the regulator block is about 60 degrees counter clockwise from full open. I watched a video where the author used the regulator pin adjust to adjust rate and position error. When I close down the pins I do notice that the rate increases but also the amplitude drops, the coil spacing changes and hairspring appears slight straighter between the stud and the regulator block. If I open the pins the amplitude comes back, the spring breathes a bit more between the stud and the regulator block and the rate slows. 

So, a long post I know but I would really appreciate any advice on how to correctly adjust the etachron system for rate, amplitude and positional error. 

 

[Mercurial]

This video explains how to set up and adjust the etachron regulator :

 

I hope that helps,

Mark

[BobG]

I’ve watched every video I can find on YouTube. Some of the info is contradictory and none mention  the effect on amplitude or spring coil spacing which I observed. I was hoping someone here is a Seiko expert and knows these inside out. 

 

Edited yesterday at 02:35 AM by BobG

[Mercurial]

The video I linked above does mention the spacing of the hairspring coils, and the importance of the regulator being able to move through its full range without distorting the hairspring - the terminal curve of the hairspring must be concentric with the regulator pins throughout the regulator’s range. 

If you meticulously follow every step in this video, the regulator system should behave as intended, regardless of the brand of the movement. 

Best Regards,

Mark

[BobG]

Alex mentions the coils below the stud should remain the same as you move the regulator block along the terminal curve. 
Mine do that. What he doesn’t discuss and is used in the other video is how the regulator block is used to adjust rate and positional error.  He also doesn’t mention how opening and closing the pins could and in my case does, alter amplitude 
In Alex’s video once he sets the stud he never adjusts the regulator pins yet every new movement I get have the pins signing closed. 

Edited yesterday at 02:48 AM by BobG

[Klassiker]

Some photos of the angles you are talking about, and the changes you are seeing to coil spacing etc. would be really useful.

Part of your problem could be that you are closing the pins too far and pinching the hairspring. Adjusting the pin separation should not affect amplitude. Nor should it change the coil separation.

[Mercurial]

Did you watch the whole video?

Once Alex has set the stud, he first corrects the best error, then checks that the hairspring coils are breathing concentrically, then turns the stud to centre the hairspring between the open regulator pins. 

He then checks that the regulator can traverse the terminal curve without disturbing the hairspring. A correction is needed, which he performs. 

He then reinstalls the balance and re-centres the hairspring between the regulator pins, and verifies that the regulator traverses the terminal curve without disturbing the hairspring. 

Finally, he demonstrates how to close the gap between pins. 

He then recaps the whole process, fleshing out more detail.

If you follow this process, you have correctly set up the regulator pins, and are ready to set the rate of the watch. 

If you are interested in learning more about the effects of the regulator pin spacing on positional rates etc, you can read any literature regarding regulator pins.

The etachron system makes adjusting beat, centering the hairspring between the regulator pins and adjusting the gap between the pins very convenient, but the same rules that apply to old style regulator pins apply to the etachron system. 

This video explains the basics : 

 

I hope that helps,

Mark

[BobG]

I posted a link to another video where he takes it a step further and uses the pins to set and adjust rate as well as positional error. 
Alex doesn’t manipulate the stud angle after he pushes it in but I find it makes a difference in the spring concentricity and bend.  Amex also doesn’t use the pin manipulation to adjust positional discrepancies. 
 

[BobG]

I wanted to post an update as I have two movements running really well now, 230-250 amplitude , 0.5 and under beat error, and +/-8 seconds or so. I removed the hairspring assembly in order to start over and noticed that the terminal curve between the stud and regulator arm was distorted. The stud was lower than it should be. I massaged the curve to look pretty good and reinstalled it. I followed Alex's video advice, best I could with 10x magnification, and with the regulator arm set in the middle of the curve I adjusted the stud so the spring was centered. I then made sure I could move the regulator arm the entire terminal curve without upsetting the coils. I then put it back on the Timegrapher and began closing down the regulator pins until I saw a change in amplitude which means to me that the pins were now pinching the spring. I opened them slightly and it looks good except I have a 0 on dial down, +3 on dial up but -16 on crown down. 
I'm a bit stuck on how to adjust out the positional error. I also noticed a drop in amplitude, 180-200 on crown down. In the other video link I posted at about minute 26 if I remember he adjusts out positional error by manipulating  the regulator pin gap. With crown down the hairspring falls away from the pin and the rate slows so he closes the pins a bit to keep them tighter in crown down position. That means the spring is tighter on dial up as well but then he moved the regulator arm to slow the movement.  There must be some Seiko experts here that have some methods for dialing out positional errors. 

[JohnR725]

11 hours ago, BobG said:

I'm a bit stuck on how to adjust out the positional error. I also noticed a drop in amplitude, 180-200 on crown down. In the other video link I posted at about minute 26 if I remember he adjusts out positional error by manipulating  the regulator pin gap. With crown down the hairspring falls away from the pin and the rate slows so he closes the pins a bit to keep them tighter in crown down position. That means the spring is tighter on dial up as well but then he moved the regulator arm to slow the movement.  There must be some Seiko experts here that have some methods for dialing out positional errors. 

I'm not entirely sure you fully understand what he's doing in the video. For one thing he's giving examples of things like about 16 minutes he talks about opening up the regulator just a little bit. Opening up the regulator slows the watch down to compensate for that he moves the regulator fast and now it's keeping time again but the regulator pins are too far apart. I have an image down below on top of it shows the effect of regulator pins and amplitude. If the regulator pins are farther apart than the example down below then at a higher amplitude timekeeping will be much worse. Why the regulator pins are supposed to be adjusted as an average rule approximately twice the thickness of the mainspring itself. In other words if you look at the spacing it have one half of the hairspring thickness on either side of the hairspring itself. There is like he talks about the video a little bit of adjustment here and there. So in his example where he opened them up it will really dramatically screw up timekeeping based on amplitude. Then when you get to the 20 some minutes like you say he is adjusting the regulator pins closer together to get a more even timekeeping based on amplitude and amplitude changes are caused by going to various positions.

Then and the other example of the image down below regulator pins too far apart and they hairspring is not centered and look what that does the timekeeping. So hairspring is supposed to be centered regulator pins are supposed to properly spaced. Then you get reasonably even timekeeping like it shows in the upper image. It's not like we're regulating out positional errors like poising errors because that's something entirely different.

 

On 4/22/2025 at 4:13 PM, BobG said:

NH35

In the part number above and in the video both of you left off details. I which version of either of your watches I will just make you's

timing specifications for your watch down below may specify how you're supposed to do it other words you wind up the watch fully wound up you wait 10 to 60 minutes in the four positions it should be within 60 seconds. Yes it can be closer but you may not actually get zero.

 

 

Now let's compare with the 2892 and see where we might have a discrepancy. First off we have a problem of which one is a using did he use the chronometer grade 1 or the top grade or what?  None is basically just much tighter timing tolerances. So when he's using an example watch conceivably might be a chronometer grade watch then things are going to be much more  perfect than what you're going to see.

 

 

 

NH35_TG.pdf ETA 2892-A2 Manufacturing info.pdf

[BobG]

Good stuff, thanks!!! 
I'm going to save it and re-read your post and watch the video again. 
I have a few follow-up question:  My understanding is that the spring vibrates or breathes between the the two regulator pins. When the pins are fully open the effective spring length is from the stud and theoretically no rate adjustment can be made by moving the regulator arm. As the pins are closed the spring gets closer to one side of the regulator block but doesn't touch a pin. You can still move the regulator carrier the entire terminal curve without upsetting the coils.  The rate can now be adjusted using the regulator because the effective spring length can be modified. 

My question is: Does the hairspring bounce off and touch one of the pins as it breathes? Is that why the effective hairspring length is adjusted by moving the regulator? 

And follow-up: How is amplitude affected by the spring between the pins? Does fully open pins, dial up position = max amplitude?  When spring adjusted to 1/2 width still = max amplitude? When I have crown down gravity is pulling the spring against one of the pins and I would expect rate to go up and amplitude to go down. Is that correct?

[Klassiker]

The idea is that the spring is centred between the pins when at rest. Then when the watch is running it will oscillate equally between the pins i.e. bounce off one pin then the other, as the hairspring breathes. If the spring is only hitting one pin, then it isn't centred, and most likely the pins are too far apart. Yes, the regulator pins are there to adjust the effective length of the hairspring.

The spacing of the regulator pins should not affect the amplitude.  The vertical positions typically have lower amplitude than the horizontal ones. This has nothing to with the regulator - hairspring interaction. Increased friction in the verticals sucks energy from the system and reduces the amplitude.

If the amplitude is less, the breathing is less. More tim between the pins = more effective length. Depending on how well the hairspring is centred, and which direction it sags, some vertical positions might run faster than the horizontal ones, and others slower. For example, if the spring is off centre towards on pin, and pressed against it by gravity, it might never bounce off that pin => faster. At the position 180 deg. away, the spring will spend more time in between the pins => slower.

[BobG]

My understanding is that In the Etachron system the spring is only centered n order to set the stud angle when the the pins are wide open and the regulator block in at the midway point.  After that the pins are rotated in one direction only so that the width between the spring and one of the studs is 1/2 width of the spring. This results in the spring always being closer to one stud than other one. 

 

[JohnR725]

2 hours ago, BobG said:

My understanding is that the spring vibrates or breathes between the the two regulator pins. When the pins are fully open the effective spring length is from the stud and theoretically no rate adjustment can be made by moving the regulator arm. As the pins are closed the spring gets closer to one side of the regulator block but doesn't touch a pin

Your only partially correct here.

2 hours ago, BobG said:

My question is: Does the hairspring bounce off and touch one of the pins as it breathes? Is that why the effective hairspring length is adjusted by moving the regulator? 

Let's look at a magnified view of the image up above. Then for a flat hairspring to function correctly there has to be a little bit of breathing room unfortunately. If you would like Better timekeeping if you get a watch with the over coil hairspring then those regulator pins are supposed to be as tight as possible but still allow the hairspring the slide. With if the pins are opened up at all you'll see a dramatic timing change based on amplitude.

So in our example down below initially hairspring is basically free-floating not touching anything the effective length of the hairspring is at the stud. As the amplitude picks up at some point in time they hairspring will just tide should one pin on one swing and the other pin on the other swing. As soon as it does that it changes the effective length to being closer to the regulator pins. As the amplitude picks up more and more it's obviously touching the regulator pins more and more and the length of the hairspring shortens the watch speeds up.

This is where in your video at around 16 minutes he opens up the regulator pins and the watch slows down. This is because they hairspring is no longer bouncing off either pin as much. Then because the watches running slow he speeds it up just to show that yes you could regulate the watch but now you have a problem. Because the regulator pins are much farther apart amplitude is going to have a much greater effect. Like in the image down below they hairspring is properly spaced between the pins. But if those pins are farther apart the effect of amplitude will be much greater. So he speeds up the watch to cancel out the effect of the regulator pins at the particular amplitude which was dial down then when he moves the watch to a crown position which will always have an amplitude decrease because the amount of friction on the sides of the pins now the hairspring is not touching the regulator pins as much and the watch dramatically slows down.

 

Let's look at the other example image. In this particular example they hairspring is actually touching the regulator pin at restWhich means the effective length of the hairspring is at the regulator pin the watch runs fast. As the amplitude picks up hairspring will lift off the PN moving the effective length towards the stud which is why the watches slowing down. As you can see is the amplitude picks up They hairspring is not centered C not getting even timekeeping and the watch is slowing even more down. But at some point in time when the amplitude gets high enough this will depend upon the watch the spacing Excedrin whatever the amplitude is will be balancing actually between the pins in the watch will of course speed up and then at some point time you reach that sweet spot where it's bouncing between the two pins but as you can see it's at a much higher amplitude. So this is why hairspring has to be properly centered between the pins and the pins have to be at the right spacing otherwise you going to get strange timekeeping based on amplitude which no matter what you're going to get a little bit of that as you do have to have a little bit a spacing. At least on a flat hairspring.

 

[BobG]

Than you so much for taking the time to write such a detailed and informative post. It really helps.
So, another question: With the Etachron system the stud pushes into the carrier but the angle on the vertical plane of the stud is based on the carrier arm. I expected it to be flat but I have seen some movements where it is bent slight down meaning the stud is pointing slightly inward at the bottom and the spring leaving the stud is affected. Is this something that is done at the factory to flatten the spring? 
I played around with manipulating the spring vertical angle as it leaves the stud and it has a significant effect on how it goes through the pins and also the angle of the coils on the other side of the balance. I can flatten the spring by adjusting the angle it leaves the stud. Now I know the NH35 is a mass produced movement so not the best quality but is the stud vertical angle ever manipulated to flatten the spring? 

[Klassiker]

1 hour ago, BobG said:

After that the pins are rotated in one direction only so that the width between the spring and one of the studs is 1/2 width of the spring. This results in the spring always being closer to one stud than other one. 

 

This is wrong. We have been talking about the regulator pins because conventionally the regulator is two pins, or a pin and a boot. The Etachron regulator is one round pin with a wide slot down the middle for the hairspring to sit in. To regulate, the pin is rotated anticlockwise (viewed from above) which brings the rear inner and front outer corners of the slot equally closer to the spring.

You can download a document with detailed instructions here:

https://calibercorner.com/etachron/

21 minutes ago, BobG said:

I played around with manipulating the spring vertical angle as it leaves the stud and it has a significant effect on how it goes through the pins and also the angle of the coils on the other side of the balance. I can flatten the spring by adjusting the angle it leaves the stud. Now I know the NH35 is a mass produced movement so not the best quality but is the stud vertical angle ever manipulated to flatten the spring? 

Can you please post some photos to show what you mean by "flatten the spring"?

[BobG]

Yes, I understand that in te Etachron system the regulator block is turned anti-clockwise. If I look at the spring in relation to the pins as I turn the block the gap appear to be "closing" and the spring is now closer to one pin than the other.  Closing is not the correct term because the pin gap is always contant but in relation to the spring the gap appears to get smaller and smaller until  the spring is actually on the pin. 

[Klassiker]

Do you have regulating pins, or a slot as per a normal Etachron? Post some photos.

[BobG]

I have a slot in a block. I didn't think Etachron had slots with a keeper like some Swiss systems. 

[JohnR725]

This conversation is becoming a very confusing. The etachron system is a very nice system for manufacturing watches. As you know it consists of two components the stud and the regulator pins. Beautiful thing of this system is you can open up your regulator pins center the hairspring and as you close the pins they will close equally on both sides providing you centered it in the first place. It's not like you're going to become closer to one side or the other as the definition of the regulator pins is a bit confusing it's not exactly a slot sort of.

I'm thinking maybe a little eight reading will be helpful for you. Then the file name was changed by me at the US patent but the wording of Seiko may or may not actually be attached to it soared up? I just did that so I can find it in my files. Normally patents are in people's name if they work for a company the company name will be there you'll notice the person lives in Japan which is interesting as the name would imply that this is a Swiss product. Somewhere I think I have the patents for the stud and I believe that is Swiss like a lot of things their Japanese and Swiss and then the Japanese let the Swiss name stand as it seems you more popular

in case as you read up on the patents of the regulator pins or pin will see and it should explain exactly how and why it works also why it's important to always close at an open in specific directions because the pins actually have a shaped to them it's very hard to see the shape as it's very tiny.

 

2 hours ago, BobG said:

So, another question: With the Etachron system the stud pushes into the carrier but the angle on the vertical plane of the stud is based on the carrier arm. I expected it to be flat but I have seen some movements where it is bent slight down meaning the stud is pointing slightly inward at the bottom and the spring leaving the stud is affected. Is this something that is done at the factory to flatten the spring? 
I played around with manipulating the spring vertical angle as it leaves the stud and it has a significant effect on how it goes through the pins and also the angle of the coils on the other side of the balance. I can flatten the spring by adjusting the angle it leaves the stud. Now I know the NH35 is a mass produced movement so not the best quality but is the stud vertical angle ever manipulated to flatten the spring? 

As a reminder with this system it's mass-produced. I wouldn't be at all surprised if they use cameras and computers to do all of the adjustments.  The meaning of this is that the majority of watches will function as there supposed to and do what they're supposed to do the system will allow us for some minor in tolerance and has more than likely as I said no human hand is ever touched those watches that's the way they left the factory and they work fine.

US2007091729A1 seiko etachron.pdf