School is back in session! As is my blog. I really do want to apologize for the lack of updates towards the end of the semester and over my break. I am going to work on trying to figure out content that I can do when I am in the same project for over a week (that way I don’t miss updates, nor repeat myself). That being said, let’s get on with the show!
The Fall Semester is in full swing and there was an explosion in the population on campus. Obviously over the summer term, there are going to be less people on campus and in class, but we have 9 new students plus 2 students who returned for their fourth semester. For those keeping count, we now have 19 students in two classrooms between their 1st and 4th semesters. The watch department wasn’t the only one that had a high number of enrollees, jewelry and welding did as well.
The first project that I am doing this semester is dealing with the escapement. It’s going to be broken down into different sections, and the first one is learning how to work with shellac.
Shellac is resin that is secreted by the Lac bug that happens to make a great “glue” for watchmaking. It is easy to use, clean off, or re-heat if you need to reposition something. Shellac comes in flakes like you see above. In this form, it can be applied to parts for securing them together, or it can be heated and turned into threads. In order to do that, a couple pairs of tweezers is required, as is an alcohol lamp.
Holding the tweezers (one pair in each hand), you grab the shellac and move it towards the flame of the lamp. It will start to curl away from the flame and bubble a little bit. At this point, you move the shellac away from the flame and use the free tweezers and grasp the dark bubbly part. It is just a matter of pulling the tweezers apart at whatever speed you need to to get the desired thickness of a shellac string (faster for thinner, slower for thicker).
It cools off very quickly, and a quick pinch with the tweezers will separate the shellac string from the flake. Depending on the size of the flake, you can get about 3 or 4 strings done. Store them in a phial and they should be good for a while (unintended rhyme that I am going to leave in).
After making a few threads of shellac, it was time to start working on my roller tables (6 total).
To refresh your memory, the roller table sits on the balance wheel and acts in conjunction with the pallet fork. The roller table above does not have a roller jewel and would be an ideal candidate for this exercise. The D-shaped hole that you see is the space that the jewel goes. There are different shapes that a roller jewel can have
- Triangle (has curved angles)
The last two are the most commonly used in modern watchmaking. Square jewels are hardly used (if they are, they are in cheap watches). Circle and ovals are used in older watches. The D-Shape and Triangle are ideal because the curved angles allow for easy entry into the pallet fork and the flat part provides maximum contact between the horns of the fork.
The process for replacing the jewel is very simple (though, if I learned anything last semester, something being simple doesn’t always translate into easy when you are learning it).
1. Place the roller table(RT) in a container with denatured alcohol for a few minutes. The alcohol will loosen the shellac and help it to start dissolving. Place the RT on some watch paper and use a piece of pegwood to remove any traces of shellac.
2. Place the RT upside down on a bench block. Brace it with a pair of tweezers opposite the roller jewel and use either a pin or another pair of tweezers to gently push the jewel out
3. Once the jewel is out, take the RT and place it in a Roller Table Holder. Take the replacement jewel, set it on the RT and gently press it into the hole.
4. Light the lamp and heat the “wing” of the tool that extends from the tool. After about 10-12 seconds, there should be enough heat transfer from the flame, along the length of the tool and into the roller table that you can apply the shellac. Working quickly, take a thread of shellac in a pair of tweezers and dip it down onto the roller jewel. You want just enough to cover the jewel and a bit around it. This works via capillary action (much the same way oiling works).
If the shellac extends to far towards the center hole of the RT, you run the risk of the RT not seating properly on the balance staff. In this scenario, one or two things will happen-the shellac will crack and pieces of shellac will eventually work their way through the watch and causing a headache, and the roller jewel will most likely come off.
After completing 6 roller tables, it was time to move on to pallet forks. The process is pretty much the same (soak, replace the jewels, heat the appropriate tool, shellac), but I have found (and was warned) that pallet forks are trickier because you have to make sure that they are clean. Very, very, very clean before you consider applying the shellac. You also have to make sure that the jewels are in the right spot and facing the correct way. I’m going to go into more detail about this process on Saturday since I am still working with the Pallet Forks, but here are a couple pictures (with captions!) of some of the process.