Week 2, Days 3 & 4

Week 2 (Days 3 & 4)

I am starting to sense a pattern with classes. Monday was working on watches. Tuesday was a lecture. Wednesday was working on watches, and Thursday was a lecture. I’ll throw up some pictures of some of the watches that I worked on at the end of the post, but there are only so many ways that I can say the same thing about the tear-down and reassembly of a basic three-hand watch without getting repetitive.

The lesson we went over on Thursday was about the different crystal, crowns and gaskets that are in watches. With the crystals, we went over the different materials that crystals are typically made of (plastic, mineral glass, sapphire crystal) and what the pros and cons are to each of them.

  • Plastic/Acrylic crystals are the cheapest to make. They can be made easily in all shapes, sizes, colors, and with different specifications (facets to look like how gemstones look after being cut, magnifying “Cyclops,” etc) If they get scratches, they can be buffed out easily by pretty much anyone. The downside to them is they look and feel cheap in higher-end watch. The only “luxury” watch that I’m aware of that uses an acrylic crystal is the Omega Speedmaster Professional (the only mechanical watch flight-certified by NASA, and the Apollo 13 crew used it to time their reentry when their systems started failing).
  • Mineral Glass is slightly more expensive to make compared to plastics. It looks nicer but is a bit prone to scratches and breaking. It can be manufactured to a number of different specifications and colors as well.
  • Sapphire Crystal is considered to be the “best” when talking about luxury watches. It is the most expensive of the three options, has dedicated skilled workers who create them, and is highly scratch resistant. You can do different sizes and shapes with Sapphire crystal, but the more domed the crystal is, obviously the more prone it is to breaking. There are some watch companies that have put tints of color in sapphire (Rolex has a green tinted crystal in some of their Milgauss watches, and Hublot has done a red-tint in some a King Power limited edition watch), but it is apparently pretty difficult and costly to get the right color/transparency, so don’t expect to see a lot of companies going that route. One company (Richard Mille) has made a watch case out of sapphire crystal and sold it for $1 million+.

With Crowns, there are two main classifications dress (also called dust resistant) and water-resistant. They come in a multitude of sizes, shapes and colors. Most of the time, if a crown on a watch needs to be replaced, as a watchmaker, I will try to get a replacement crown that goes with the exact model of watch that I am working on. If I can’t get one, then I’ll have to do my best to find one that matches the case design and work from there. Crowns are attached to what is called a “winding stem.” The winding stem has a threaded end onto which the crown is screwed tight (the other end of the stem goes through the case of the watch as well as the winding pinion and clutch). The winding stem can be cut down to match the original. I think later in my studies, I’ll be making winding stems.


Gaskets are pretty simple. Gaskets are usually an O-Ring made of silicon. The main purpose of a gasket in a watch is to help with water and dust resistance. The case backs, crown tubes and crystals can have gaskets in them to help seal the watch. A lot of “sport” themed watches (Casio, Timex, Suunto, dive watches like the Orange Monster, Spidolight, and Submariner, etc) use gaskets. Many dress watches do as well, but they offer minimal (light hand washing) water resistance. If you use your watch for an active purpose (swimming, snorkeling/diving, working out), you will want to get your gaskets replaced more often to ensure they are in working condition.

After the lesson, I finished putting together a Seiko that I had been working on, and Mr. Poye had me do an exercise dealing with watch crystals and learning how to use a crystal lift. A crystal lift is a tool that is used for plastic crystals.


When a watch uses a plastic crystal, the crystal is usually .1 mm larger than the diameter of the internal bezel of the watch. The crystal lift squeezes the crystal tight, causing it to flex enough that the bottom of the crystal gets a little smaller so you can press it into the case.



Once the pressure is released, the crystal expands as much as it can and causes the crystal to be tight in the case. The exercise that I did consisted of me removing the crystals from twelve watches.


Once I got them removed he mixed up the cases and crystals and handed me a set of digital calipers and told me figure out which crystal went with which watch.


It was pretty slow going at first due to figuring out how much pressure to apply to the calipers to get an accurate reading, but after that, it was pretty smooth sailing. I just made a list of the case sizes, the crystal sizes and was able to get most of the crystal right on the first try. There were a few that were a bit loose, but Mr. Poye said that they had seen a lot of use/abuse over a long while.

Once I was finished with that, I went back to watches. I am becoming pretty proficient with being able to identify the parts of a basic watch, and I am feeling the need to take less pictures for reference as to how things were so I can put them back. I have started using the Bestfit Encylopedia to start figuring out the movements that I am working on (moreso for fun and practice with the movement identification system). I am seeing a lot of Font 69 movements in class.

According to Mr. Poye, the Font 69 was one of the most popular women’s watch movements used-so if any of y’all have a Font 69 movement, take a look at some of these pictures, and you can see what it looks like.

I think next week we are going to get into crown fitting, so that should be interesting.

Thanks for stopping by!


One response to “Week 2, Days 3 & 4

  1. Pingback: Week 3, Days 2 & 3-Gaskets & Intro to Hairsprings (image heavy-ish) | watchmaking journey·

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