Peter recently sent his watch in for a service and a new crystal. I’m a big fan of Rolex Submariners and this nice example from 1977 also happens to be my birth year!
It was running when it came in so it was thought that just a routine service was needed so I proceeded to disassemble the movement.
Then it came to removing the left hand threaded nut which keeps the date wheel in place. When trying to loosen the nut it just kept rotating freely but not rising up and off the post which meant that the post had to be broke.
Which indeed it was.
This is potentially a big problem, these posts are not available to purchase, so the only options are to buy an entire movement plate or to make a new post. Making a new post is of course preferable but it’s not an easy task. The post is just under 0.59mm diameter and has on the top of it a 0.5mm thread which is left handed to make it even more tricky!
Here is the nut with the snapped post stuck inside of it.
The first step is to remove the small piece of snapped post which is stuck inside of the nut, it wouldn’t turn freely out and it is too small to get a screw extractor in so it had to be milled out. First a hole is milled into some Acrylic for the nut to sit in to support it, it was made a tight push fit to keep it steady and centred. Before milling the hole to it is essential to first drill a smaller hole straight through the Acrylic. This is so the part can be pushed back out of the plastic from the other side when you’re done.
Here the end mill is cutting out the post. As the sink is cut first the zero position is set for the milling out of the post, providing the workpiece is a nice tight fit in the Acrylic.
The post is cleanly removed without any damage to the nut.
In our opinion the ability to do this kind of operation alone justifies the very reasonable cost of having one of these machines in your workshop.
The next step is to turn a post in the lathe, it is turned and then burnished to 0.585mm in diameter. The CNC machine will then be used to cut the 0.5mm left handed thread. A sink is milled into the Acrylic so that the rod is held secure, the thread cutter is then positioned in place and the thread cutting programme is run.
There is now a CNC section on the website, under CNC stuff https://watchguy.co.uk/cgi-bin/cnc
Here you will find several G code generating tools for anyone to use. Just enter the details into the boxes and click on generate G code. Then cut the text and paste on your computer to save and use on your CNC machine.
Here is the post and thread still attached to the rod.
The post then has to be removed from the rod so it was put back in the lathe to hold it while it was cut off with a fine saw.
The post then needs to be stoned to the correct length and with a small bevel on the end to aid fitting into the movement plate.
Here are the new and old posts next to each other.
The post is then pushed into the plate using a staking set.
The wheel and nut are fitted to check the depth of the post in the plate and to check that the end shake is correct.
And all is well, phew! The rest of the movement can now be assembled which was straight forward.
Peter also wanted a new crystal fitted but without a cyclops. I prefer the symmetry of the no date Submariner myself, but if I needed to have a watch with a date on it then I would definitely consider fitting a cyclops free crystal myself. It can easily be changed back in the future if you change your mind or decide to sell the watch.