Do I have the right part to replace the lower chaton in my Hamilton 649?

[jrdn92]

Well, it finally happened and I lost a chaton. I still have the spring and cap jewel but after 2 hours of combing with a UV light the carpet has claimed victory. I believe I've identified the correct replacement on eBay but want to double check with people more knowledgeable than me. 

It seems the 649 is just a rebranded ETA 2750, so I presume the chaton will be compatible?

Thank you!

 

Edited January 12 by jrdn92
Error in title

[mikepilk]

Jules Borel lists the base movement as ETA 2750, so unless they changed the shock settings, I would say you have the correct part.

[AndyGSi]

Depending where in the world you are and how much you plan on
working with this type of movement you could look at Cousins.

[jrdn92]

Perfect, thank you very much.

[mikepilk]

I like to keep a stock of cap jewels, as they are prone to disappearing. The most common (have a look in your list) are 121.11 and 122.11 (as used in your movement).  

[jrdn92]

That's smart - I'll add those to my next Cousin's shipment.

[jrdn92]

Well, unfortunately either the ebay listing I purchased was incorrectly labeled or the 649 movement does not use the same shock system as the ETA 2750. This is the original top shock spring, chaton, and cap jewel:

 

And this is the bottom shock system, with the original spring, cap jewel, and the new chaton:

You can already see the issue. The chaton is definitely too big I believe, since there is so much empty space around the cap jewel when its set:

I tried to install the chaton before I noticed and I could barely get the spring set over it, and the movement wouldn't run due to the friction.

Now I'm totally at a loss for what to do. My digital calipers aren't precise enough to accurately measure these things, and I'm not even sure I know how to measure the hole diameter. The 649 has no tech sheet that I can find online either.
Not gonna lie, feeling pretty defeated at the moment.

[mikepilk]

Unfortunate. Which is why I said in my post " so unless they changed the shock settings," and you didn't show a pic of the jewels.

I cannot identify that shock spring. I had a look in BestFit, and my usual references, but can't see it. 

Anyone?

[jrdn92]

8 hours ago, mikepilk said:

Unfortunate. Which is why I said in my post " so unless they changed the shock settings," and you didn't show a pic of the jewels.

I cannot identify that shock spring. I had a look in BestFit, and my usual references, but can't see it. 

Anyone?

Lesson learned, I'll make sure I lead with more pics in the future. I'm sure at some point I'll find a use for this chaton... I also had a look online and can't find anything matching this either. Even other images of Hamilton 649s show standard Incabloc springs instead of these weird things.

[mikepilk]

I did see one image which did seem to show a similar spring, but I can find no references

It's a KIF spring 5 -  for the ETA 2750 

 

 

[jrdn92]

30 minutes ago, mikepilk said:

I did see one image which did seem to show a similar spring, but I can find no references

It's a KIF spring 5 -  for the ETA 2750 

 

 

Wow, that's a fantastic find, thank you! I see what I should have been looking for now on EmmyWatch - this will be super handy in the future.

Edited January 17 by jrdn92

[mikepilk]

 

Edited January 17 by mikepilk

[AndyGSi]

Here's all the KIF on Cousins.

https://www.cousinsuk.com/category/kif-blocs-jewels-springs

[jrdn92]

Unfortunately this story does not end here. I have received the chaton replacement, but the sizing is still not correct. I believe the jewel is the right size, but the setting is too small.

Any recommendations on what to try next? 

Top is new, bottom is original

[Jon]

1 hour ago, jrdn92 said:

Any recommendations on what to try next? 

By a donor ETA 2570 movement. No brainer really

[AndyGSi]

1 hour ago, jrdn92 said:

Any recommendations on what to try next? 

So what Part No did you buy?

[JohnR725]

On 1/17/2025 at 1:18 AM, mikepilk said:

I cannot identify that shock spring. I had a look in BestFit, and my usual references, but can't see it. 

disturbing and that it's not listed as there is a lot of springs to look at their?

 

On 1/12/2025 at 2:08 PM, jrdn92 said:

It seems the 649 is just a rebranded ETA 2750, so I presume the chaton will be compatible?

currently I'm looking at a different source which is best fit online. Does not list the Hamilton number at all I was hoping for a confirmation of yes they really are exactly the same. Then the editor part number comes up very clearly as a 170.03. Which your spring in your picture very definitely is not that spring.

 

On 1/17/2025 at 10:13 AM, mikepilk said:

It's a KIF spring 5 -  for the ETA 2750

this brings up the problem of assuming that a watch has only been rebranded when typically they are not 100%. So basically the base caliber is ETA but Hamilton has modified it. Which is why the balance jewels are not right because they're not ETA balance jewel assembly or the spring for that matter

[jrdn92]

2 hours ago, AndyGSi said:

So what Part No did you buy?

This one: Kif 303Ø10

2 hours ago, Jon said:

By a donor ETA 2570 movement. No brainer really

Yes, but since Hamilton modified the movement with a different shock system I'd have to replace the entire base plate, correct? I'll do it if I have to but I'd prefer to keep the original parts as much as possible.

[AndyGSi]

I'm confused.

I thought you were getting a chaton not a jewel?

Edit

Sorry misread the parts.

Double edit

So what size are the old and new?

Edited January 31 by AndyGSi

[jrdn92]

2 hours ago, AndyGSi said:

I'm confused.

I thought you were getting a chaton not a jewel?

Edit

Sorry misread the parts.

Double edit

So what size are the old and new?

New is 303Ø10, I thought that old was the same based on the chart Mikepik posted above but its clearly something else.

[AndyGSi]

8 hours ago, jrdn92 said:

New is 303Ø10, I thought that old was the same based on the chart Mikepik posted above but its clearly something else.

So what size are the old and new, can you measure them?

[jrdn92]

On 2/1/2025 at 1:06 AM, AndyGSi said:

So what size are the old and new, can you measure them?

I don't have anything accurate enough at the moment. I'll follow up on this after I get a micrometer and measure them.