Jump to content

Recommended Posts

Posted

Hi there!

I have been servicing an old Technos Star Chief from the 70s, and so far so good, except for the crown and stem.

This is only my 4th or 5th watch service after a year of fiddling with cheap movements, and I'm having a hard time understanding this seting mechanism.

 

1. What is is called?

2. How do I assemble it?

3. Can we confirm all is there?

ps.: bonus pics demonstrating how it was bought and how it is going.

 

20250505_222456(1).jpg

25147488_3.jpg

20250505_222525.jpg

Posted

It's a so-called split stem. I'm guessing the spring is for the screw-down crown operation. I don't think I've ever seen both features together before, but it looks complete. If I'm right, the crown will have an inner thread and the tube a matching external thread. Replace the seals if you want it to be watertight.

If you can compress the spring far enough, slide the two parts of the stem together sideways. If that doesn't work, you should be able to push them back together end to end, the opposite of how you pulled them apart. 

  • Like 2
  • Thanks 2
Posted
17 hours ago, Klassiker said:

If that doesn't work, you should be able to push them back together end to end, the opposite of how you pulled them apart. 

I had a feeling the worst would happen, and it did. The smallest pressure applied to the crown broke one side of its little leg.

I think I'll replace it with a traditional system if possible.

This, I believe. I'm shocked at how expensive the parts for this model are.

Posted

Richard and Andy both make very important observations, so let's take a step back and see what we are dealing with.

Does the crown tube in the case have a thread on it?

How did you remove the stem? Do you have a photo of the movement in the case?

You might be able to remove the female part of the split stem and reuse the existing crown. Can you see a thread?

There are one-piece stems available for the 2472 for reasonable prices. The split stems I found on ebay for the 2472 are a little more expensive, but have the male and female parts the opposite way round.

  • Like 3
Posted (edited)

OK. Little panic, but I'm composed now. haha

I need some support on this one, and you guys immediately noticed that. Thank you!

To help us navigate the situation, I recorded a video of the case and crown:

https://youtu.be/tfTLZrLiaqg?si=hIW8Jbmp1DPb9fZC

The measuremen

3 hours ago, Klassiker said:

Does the crown tube in the case have a thread on it?

 

Yes, it does.

3 hours ago, Klassiker said:

How did you remove the stem?

There was water damage, and the two pieces (stem and crown) split up when I removed the crown. I didn't have a chance to see the assembled mechanism, but this eBay ad has the same assembly with adequate pictures.

3 hours ago, Klassiker said:

You might be able to remove the female part of the split stem and reuse the existing crown. Can you see a thread?

I'll try that. Quite afraid of breaking it, thought.

Edited by Michalzeszen
Posted (edited)

So the eBay crown won't work with your case.

It's looking like your options are going to be limited with this one.

Edit

Just found this so looks like you can remove the stem part from
the crown but what you replace it with is another question.

image.thumb.png.a738d2562ba362efd771357b94cb2d1b.png

Edited by AndyGSi
  • Like 1
Posted

You guys were correct, I can reuse the crown. Now it is a matter of finding the small split steam on eBay!

20250507_114527.jpg

20250507_114710.jpg

20250507_114755.jpg

3 minutes ago, AndyGSi said:

the crown but what you replace it with is another question.

 

Yep, just realized this as well. Now it is a matter of finding the new piece, which will most certainly be a pain

Posted (edited)
2 minutes ago, nevenbekriev said:

You best option is t convert it to regular crown with tube sealing. But, the case and the back are totally  toasted, ready for the dust bin.

Can you elaborate? I'm really new to this. What Case and back are you reffering to?

Edited by Michalzeszen
Posted (edited)
7 minutes ago, RichardHarris123 said:

I don't understand why it needs to be a split stem. 

From my perspective it doesn't need to be. In this scenario, I'd love some help identifying the correct parts for a conversion.

Oscillating weight, bracelet and crystal are not original, so there is margin for adaptations.

Edited by Michalzeszen
Posted

What I mean is to use standard tube and crown, like 2.5mm tube for example. You will need to remove the existing tube or in some way to turn or file the part with the thread, then to put in 2.5mm tube and fix it in place. I don't know if the hole will have to be enlarged or if it is possible to just reshape the existing tube by removing the part with the thread from it. The new tube can be press fit wit some locktite for water tightness, or led soldered for example.

I doubt it was a split stem, it has to be just screw-in crown, and the construction is similar to split stem. With standard tube, You will not need split stem, but regular stem that will be shortened to size.

What I meant for the case and back is that watch cases polishing is separate, different craft that is not easy one. In my country only few people are good in this and I am not one of them. The main idea is not to change the shape of the cases, or keep them as close to the original look as possible. This includes never to round the edges and corners for example. Don't take me wrong, if You like it and it brings You joy, this is OK. But, the world is full with examples of not correctly done (ruined) cases. By the way, plated cases are the hardest thing to restore.

Posted
16 minutes ago, nevenbekriev said:

What I meant for the case and back is that watch cases polishing is separate, different craft that is not easy one. In my country only few people are good in this and I am not one of them. The main idea is not to change the shape of the cases, or keep them as close to the original look as possible. This includes never to round the edges and corners for example. Don't take me wrong, if You like it and it brings You joy, this is OK. But, the world is full with examples of not correctly done (ruined) cases. By the way, plated cases are the hardest thing to restore.

Looking at what @Michalzeszen has already done with the case and back I don't see a problem with it.

1 hour ago, RichardHarris123 said:

I don't understand why it needs to be a split stem. 

The only reason it's a split stem (of sorts) is because of the screw down crown not having the spring built into it.

1 hour ago, Michalzeszen said:

From my perspective it doesn't need to be. In this scenario, I'd love some help identifying the correct parts for a conversion.

You need to see how the existing tube is fitted in the case.

A photo of the inside would help.

  • Thanks 1
Posted
1 minute ago, RichardHarris123 said:

So not strictly necessary?

If they want to use the original screw down crown then yes it's necessary, otherwise there's no play from the winding position to screw it down

  • Like 1
Posted
1 hour ago, nevenbekriev said:

What I meant for the case and back is that watch cases polishing is separate, different craft that is not easy one. In my country only few people are good in this and I am not one of them. The main idea is not to change the shape of the cases, or keep them as close to the original look as possible. This includes never to round the edges and corners for example. Don't take me wrong, if You like it and it brings You joy, this is OK. But, the world is full with examples of not correctly done (ruined) cases. By the way, plated cases are the hardest thing to restore.

I mean... I'm buying 15-30 USD watches and doing my best to bring them to life. I don't expect it to be perfect, but if you check the YouTube link I provided above, you'll realize I did an OK job bringing the case back to life. Will it be a precious collectible? Hardly. But for daily use, it is awesome.

 

1 hour ago, AndyGSi said:

A photo of the inside would help.

Attached.

 

20250507_153235.jpg

20250507_153505.jpg

20250507_153510.jpg

20250507_153515.jpg

20250507_153519.jpg

  • Like 1
Posted

So to me you'd do more harm trying to remove that existing tube.

Unfortunately nothings coming to mind at the moment as an east fix while keeping the screw down crown.

  • Sad 1
Posted
1 hour ago, AndyGSi said:

So to me you'd do more harm trying to remove that existing tube.

Unfortunately nothings coming to mind at the moment as an east fix while keeping the screw down crown.

Andy, why you betray me?

 

I may have good news. I'll share later!

I have contacted an old watchmaker from my town, and the guy has it all. He is offline, so no parts are available to purchase, but he offered to send one for less than 10 USD, which is great.

I'm now checking if he has an oscillating weight as well, to close up all that I need to put this movement to work.

 

Thank you all for the support. And if any good soul finds a video of the assembly process of this stem and crown, it would complete my day!

 

Imagem do WhatsApp de 2025-05-07 à(s) 17.18.14_48c67fad.jpg

Imagem do WhatsApp de 2025-05-07 à(s) 15.49.43_564f6793.jpg

Posted (edited)
13 minutes ago, AndyGSi said:

Does the watchmaker know it's for a screw down crown and not just a standard split stem as the ones in the photo look standard?

Yes, we're actively discussing it! I believe tomorrow I'll go there so he assembles it. Better safe than sorry.

Dude is old and experienced.

Now, what it the purpose of the spring?

Edited by Michalzeszen
Posted
1 hour ago, AndyGSi said:

The spring is so the crown pops out to the winding position when unscrewed.

I see. And is there a possibility to convert it to a springless system by replacing it with a standard split stem model?

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Restore formatting

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.



  • Recently Browsing

    • No registered users viewing this page.
  • Topics

  • Posts

    • I see. And is there a possibility to convert it to a springless system by replacing it with a standard split stem model?
    • Sharpening gauge.   I found the easiest side to do was the safety roller as the roller table laid flat on a block provided stability.  The other way requires a specific stump for the roller and pin to sit in, but may also grip better way.
    • Yes, the problem isn't so much with the 'background' radiation but inhaling or digesting loose flakes and dust that can become airborne.
    • The spring is so the crown pops out to the winding position when unscrewed.
    • Radium and the horrible story of the Radium Girls scares everyone - But there is also a lot of paranoia here.  I did a whole bunch of readings on a watch with Radium lume recently. My Geiger counter read 2µsv/h through the crystal with the sensor part of the Geiger counter right on top of the watch.  This measurement dropped off to the normal background rate of 0.18µsv/h as soon at the Geiger counter is just a few cms away. Measuring from the back of the watch and there is virtually no increase.  The rate went up to 5µsv/h from the dial and hands when the movement was removed from the case. To put this in perspective a Frankfurt to New York flight would give you about 50µsv of exposure and a chest x-ray about 100µsv.  Norwegian labour law states “The limit value for workers over the age of 18 years is set to 20 mSv per calendar year.” - that is the equivalent of 400 flights across the Atlantic! I will however point out at this point it is important that you don’t ingest the radium from the watch! One of the worst things you can do is scrape the radium off the dials and create radioactive dust that you could breath in! That being said… If for each radium lumed watch you work on you spend 15 minutes getting the movement out of the case and the dial and hands off and then another 15 minutes at the end putting the dial and hands back on your exposure would be less than 2.5µsv  Once you have the hands and dial off they can go in a box and put safely out of the way (probably good practice for any watch!). I believe the risks are negligible If you take precautions such as wearing a mask and gloves and wiping your work surfaces down with a damp paper towel and disposing of the towel, gloves and mask once you are finished  
×
×
  • Create New...