UN Marine Chronometer escape wheel

[nevenbekriev]

Today I had to make new table for the badly damaged escape wheel. Here are some photos

 

 

[RichardHarris123]

I would expect nothing less, Nev.

[JohnR725]

26 minutes ago, nevenbekriev said:

some photos

the photos are nice but you missed a few steps and maybe a few words describing things would be nice.

I assume you made your own cutter? I would be curious about how exactly worked out the profile etc. plus did you flawlessly faces after your cutting or was the cutting good enough for the finished

then the crossing out of the wheel here it's rough and in the final product is perfect but we didn't get to see the pictures of how that was done

then unless you posted it someplace else which I did not look for what did the rest of the clock look like? Because usually when this happens the balance staff pivots get broken jewels get broken and I'm amazed escape wheel still has its pivots.

This is where those not familiar the detent escapement is really a thing of beauty until it has a problem then it's a thing of extreme destruction.

 

 

[nevenbekriev]

Jes John, You are right.

Both balance pivots are broken, the EW pivot of the side where the wheel is was broken, the down side hole jewel of EW is broken, the detent spring stone is broken, a part of the detent spring is broken and needs attention. Still some work to do...

The cutter is simple flying cutter, and some hand filing to form the spokes. The teeth surface is good enough I think, but soon will check how it works in real and will show here.

[watchweasol]

Well Neven. You are the man  a true pro. Some excellent work . Los of respect.

[nickelsilver]

14 hours ago, nevenbekriev said:

 

Both balance pivots are broken, the EW pivot of the side where the wheel is was broken, the down side hole jewel of EW is broken, the detent spring stone is broken, a part of the detent spring is broken and needs attention. Still some work to do...

 

Man, when these guys fail it's usually dramatically!

25 years ago one could still find (some) spare parts for the UN chronometers, but not anymore. There's a fellow in the U.S. who had some locking stones made for Hamilton chronometers and sells them for a fair price. I bet they would work on a UN. Hope the detent survives; can't remember if the spring on these is a separate part?

 

Great looking escape wheel there!

[Michael60]

Wonderful and inspiring work, as usual.

Can I ask for a reference or guide on the relationship between wheel material and cutting speed? I've tried it several times with 0.5 mm brass and the results were very poor.

All appreciation. Sorry in advance for the language, it's Google Translate.

[nevenbekriev]

Today I had only time to repivot the balance staff (piece of cake), the detent spring left for tomorrow (i hope)

Here is a picture of the detent spring. The stone is missing, that's how I received it. The part that supports the little golden spring is sheared and missing

I have to decide if to make the missing locking stone out of glass or of tungsten carbide. Glass - will look more authentic, but carbide I guess will be firmer... Ideas?

 

8 hours ago, Michael60 said:

...Can I ask for a reference or guide on the relationship between wheel material and cutting speed? I've tried it several times with 0.5 mm brass and the results were very poor.

Well, with brass the things are easy to do, but there are different types of brass. The hard brass is easier to work with. Anyway, the higher revolutions are - the better. The most important thing is the cutter to be sharp and to have proper chamfer (to be backed off - hope to use correct terminology as looking at the dictionary), then the cutting will be clean and easy

[RichardHarris123]

The stone is acting against brass, both glass and tungsten are significantly harder.  I would use glass. 

[Michael60]

10 hours ago, nevenbekriev said:

Today I had only time to repivot the balance staff (piece of cake), the detent spring left for tomorrow (i hope)

Here is a picture of the detent spring. The stone is missing, that's how I received it. The part that supports the little golden spring is sheared and missing

I have to decide if to make the missing locking stone out of glass or of tungsten carbide. Glass - will look more authentic, but carbide I guess will be firmer... Ideas?

 

Well, with brass the things are easy to do, but there are different types of brass. The hard brass is easier to work with. Anyway, the higher revolutions are - the better. The most important thing is the cutter to be sharp and to have proper chamfer (to be backed off - hope to use correct terminology as looking at the dictionary), then the cutting will be clean and easy

Thank you for your interest and response,

dear. Of course, I'm here to gain some experience from professionals like the pioneers in this field. I apologize for the jargon, but I usually resort to Google Translate.

[nickelsilver]

20 hours ago, nevenbekriev said:

I have to decide if to make the missing locking stone out of glass or of tungsten carbide. Glass - will look more authentic, but carbide I guess will be firmer... Ideas?

If you have the means to finish carbide to the level necessary for the locking stone then you can make it from ruby/sapphire. Boules and other ruby blanks can be found (Ebay Ali etc.), but if color isn't a concern a good source is a sapphire watch crystal. This works well for hole jewels too, which are impossible to find in sizes to suit marine chronometers. A really quick search on Ali turned up these ruby rods, I'm sure there are other sizes available but for 8 bucks you can't go wrong. 

 

Ali is also a great source for diamond paste and powders for shaping jewels. I was struggling along making a jewel a few years ago and a friend handed me an assortment of cheap Ali diamond paste and it worked great. I think it was mainly just having more options of grit, I had fancy Swiss sourced powder and paste that was just a bit too fine for the roughing operations.

Edited March 20 by nickelsilver

[Neverenoughwatches]

On 3/18/2025 at 11:04 PM, nevenbekriev said:

Today I had to make new table for the badly damaged escape wheel. Here are some photos

 

 

Fascinating process Nev, i love to watch you figure things out.

[nevenbekriev]

7 hours ago, nickelsilver said:

If you have the means to finish carbide to the level necessary for the locking stone then you can make it from ruby/sapphire. Boules and other ruby blanks can be found (Ebay Ali etc.), but if color isn't a concern a good source is a sapphire watch crystal. This works well for hole jewels too, which are impossible to find in sizes to suit marine chronometers. A really quick search on Ali turned up these ruby rods, I'm sure there are other sizes available but for 8 bucks you can't go wrong. 

 

Ali is also a great source for diamond paste and powders for shaping jewels. I was struggling along making a jewel a few years ago and a friend handed me an assortment of cheap Ali diamond paste and it worked great. I think it was mainly just having more options of grit, I had fancy Swiss sourced powder and paste that was just a bit to fine for the roughing.

This is great idea about the sapphire glass. Thanks a lot, I have never tried to shape sapphire, but this is what I will try to do. The other stones (on the balance rollers) are white color too.

Today i made several unsuccessful attempts to make glass 'stone', but the glass is too brittle for the way I try to make it. Interesting, I have made many impulse jewels of glass, but here the part that enters the hole in the spring is round and the glass breaks right on the border between the round and flat part when I try to lapp. But anyway, the glass seems to be not firm enough for this place.

The way I repaired the broken part of the spring is rather ugly, but think it is reliable and I try to avoid making new spring.

 

[nickelsilver]

Just some info which you quite likely already know

 

 

The locking stone is held in by a brass wedge, which can be undersized on diameter as the locking stone can be too. "Too precise" can be counterproductive here, there's a lot of margin.

 

Ruby/sapphire does well in compression, the wedge serves well and only needs a small amount of force- a little shellac and all is well.

Edited March 21 by nickelsilver

[nevenbekriev]

OK, today I visited a friend who is watchmaker and asked him if he has useless old sapphire crystal. He took out one from an old Seiko Kinetic for parts and gave it to me.

I came home and started work. The first I did was to break the crystal with the hope some small piece will have suitable shape to work on. For my surprise, appears there is thin (0.35mm) sapphire layer on top of a thick glass piece.  I first was disappointed, as the stone I need is with diam 0.65mm (and then ground to half to obtain D cross-section) but then figured that it may be actually better for me. Realized that I can use one of the flat and polished faces as locking face of the jewel and thus there is still enough meat in thickness of the sapphire. So, I ground small rectangle piece and glued it with shellac on the side of a 0.6mm steel plate, then filed it round and lapped  it to form the 'back' of the stone.

I think the stone is good enough and will do the job it is meant for.

I cleaned all the parts of the movement as there was gummed oil everywhere. The spring is very strong and it was challenge to get it wound while holding the barrel and collect it in the winder barrel to extract it.

It left for tomorrow to test everything

 

 

[nickelsilver]

Fantastic work Neven!

[nevenbekriev]