Reassembling a screw crown
Internal threaded crowns have an inherent flaw. People like to tighten these crowns too much and eventually they can fall apart. On standard screw crowns you need to have the crown tight as this is what causes the seal to seal the watch but on internal threaded crowns the seal is not compressed the same way. The crown should just be finger tight so it doesn’t move.
Generally you find these on expensive watches like omegas so forking out a lot of money is not desirable (especially for the customer). Luckily there is a way of repairing them which works most of the time.
This is a classic example of the problem.
These are the parts I have been given. Unfortunately there is a part missing. A metal disc that holds the seal in the correct place so no matter what we will do will the watch be waterproof (the seal is rather knackered anyway)
I would prefer to replace the crown but the customer is reluctant to fork out for a new one. The Customer is always right (and I get to show you how to fix this problem)
First of all we have to clean all the parts.
The way these crowns are held together is by friction.
The part second from the left is pushed into the crown top. Unfortunately once it has come off once it never wants to stay on. The solution is to open it out and make it bigger than the hole in the crown top
Find a hole in your staking block which doesn’t touch the thread
Use a punch to open the tube slightly. It is only a small amount you need but it does take quite a whack. Start of with small taps and build up until you have opened it up a few 100ths of a millimetre.
Place it back in the staking block but in a smaller hole that catches on the bottom of the tube.
Remember to insert the spring.
Place the crown top over it. Line it up by feel.
This is where it can all go wrong. Hammer them together. If you have opened the tube too much then the tube will crumple before it fits in the crown top. If it is not tight enough then it will come off again in the future
Hopefully you should have a crown like this and not a dead tube.
Now to assemble the rest of the crown. Put the the ring in first then the seal with a bit of silicone grease. This is where the missing disc would be needed. It should press in place holding the seal in place
There we go a working crown but definitely not something you want to guarantee as waterproof.