Crystal removal from a watch casing.

[Seth]

Hi there,I hope you are all keeping safe during this global pandemic and I wonder if anyone can help me with a problem I have.I have purchased a Military watch that was not running.On removing the movement the mainspring was found to have broken so I purchased a replacement from Cousins and the watch now runs fine but my problem is that the crystal is cracked right across.On inspecting the case there is a pipe which the winding stem passes through to the movement but how do I remove this to get the crystal out?? Inside the case the pipe passes into a large nickel ring which is threaded into the watch casing but I don't know if this pipe is threaded into the case/nickel ring or is it just pressed into the casing??It also looks like there is a large nylon spacer ring between the case and the nickel ring as the case is stamped waterproof.If anyone can help me on how to get this disassembled I would be most grateful.I enclose photos of the case and pipe.Regards to all,Seth.

[Marc]

Crystals usually come out the front.

The way that yours has cracked makes it likely that you won't be able to remove it without breaking it. This wouldn't be a disaster but it helps if you can measure the diameter of the old crystal to inform what size new crystal to order.

To get the old one out you could simply push it out from the back with your thumbs, although a more elegant solution would be to use a crystal lift or better still, a press. You will need one or the other to install the new crystal anyway, and if it is a tension ring crystal it will need to be a press.

[Seth]

Hi there Marc, many thanks for your reply I have both a crystal lift and press but looking at this crystal it appears to be held between the bezel of the case and this screwed in nickel ring which I presume is something to do with the waterproofing??It looks like I have to remove this ring to fit the new 31.8mm crystal.I am not bothered about breaking the old one but I am at a loss on how to remove this ring as the pipe that the winding stem passes through is fastened into this ring and case somehow and I don't know if it's just pressed into both or screwed in that's what I am try to find out.Regards, Seth.

[Marc]

If it can only come out the back then you're right, the pendant tube will have to be removed so that the nickel insert can be extracted, clearing the way for the crystal.

I've not come across this arrangement before so I'm guessing here, but if the crystal has to be installed before the pendant tube then it's unlikely to have been soldered in as the heat would damage the crystal, so it is either pressed in or threaded, as you already suspect.

I would try unscrewing it first. I would probably use a snug fitting plug inside the pendant tube to prevent crushing it, and either a pin vice or a lathe collet (or more likely a collet and spindle from my Boley screw head polishing tool) to grip the pendant tube and see if it unscrews. A little localised heat may help if thread lock has been used.

If it turns out that it is a press fit tube then check out this thread for tool options for removing press fit pendant tubes.

[rodabod]

I can’t see a threaded retaining ring on this one. If it’s a press-fit and won’t move by pushing with your thumb or a crystal press, then insert a small block of wood or plastic and tap gently with a small hammer. 

[HSL]

I looked at your pictures but can't see that is a three piece casing.
What you see from the inside by the crown tube is just the tension ring in the crystal.
So I think you can go ahead as Marc suggested or take a clear shot of the side of the movement.

Edited April 18, 2020 by HSL
swinglish

[Seth]

5 minutes ago, Marc said:

If it can only come out the back then you're right, the pendant tube will have to be removed so that the nickel insert can be extracted, clearing the way for the crystal.

I've not come across this arrangement before so I'm guessing here, but if the crystal has to be installed before the pendant tube then it's unlikely to have been soldered in as the heat would damage the crystal, so it is either pressed in or threaded, as you already suspect.

I would try unscrewing it first. I would probably use a snug fitting plug inside the pendant tube to prevent crushing it, and either a pin vice or a lathe collet (or more likely a collet and spindle from my Boley screw head polishing tool) to grip the pendant tube and see if it unscrews. A little localised heat may help if thread lock has been used.

If it turns out that it is a press fit tube then check out this thread for tool options for removing press fit pendant tubes.

Hi there Marc,I have tried gently turning the tube with a pin vice but it won't move so it possibly is a press fit tube.Looking down the bore with my microscope the dia narrows down just enough to allow the winding stem to pass through then before it reaches the inside case it widens back out to the same dia as the outside.I am going to try holding the tube in a collet on my Lorch lathe and gently twisting it to see if it will come loose or unscrew.Regards,Seth.

[Marc]

41 minutes ago, Seth said:

I am going to try holding the tube in a collet on my Lorch lathe and gently twisting it to see if it will come loose or unscrew.Regards,Seth.

Best of luck.

If you can pack the inside of the tube with a plug to prevent crushing it might enable a better grip.