The top ring section is made in pretty much the same way as the centre section. I get a bar of brass and bend it into a ring and solder the joints. This technique is worth developing here because it can be extended to precious metals even though, with brass, the relatively inexpensive cost of the metal means the ring section could be machined from a solid piece of metal.
In the picture, above, I'm flattening out the ends to make a good join.
Now the joint is nicely flattened I bend the metal back so the join is good:
see here I haven't bothered to make the ring too circular yet; the flat section around the joint makes it a bit easier to get the end joints properly flat and square-on to each other.
Now the metal needs to be cleaned thoroughly so there is no grease on the joint. The ring is fluxed and hard silver solder used to solder the joint. This leaves me with this:
that can now be hammered on a stake to make it more circular.
I made the ring and checked the size against the, already made, middle section and found it was too large! I've done it again. Well, it's all good practice, I'm not too worried at this stage, so I removed a section of the ring
The removed section is around the solder joint, so I remove the last joint
and hammer the ring closed, checking the join is square-on to give a good intersection
Here's a close up of the join
I'm certainly getting better at doing this. Mind you, I'm giving myself plenty of practice with my getting the sizes wrong! I'll just double check the size is right before I solder this one:
I realized that, for the top section, I needed material on either side of the middle section ring, i.e. a thicker ring. This was why I ended up doing it again just now. I didn't have enough metal to continue the profile of the watch but also to provide a shelf for the watch glass to go into. When I'm sure of the final design I can get the sizes a bit tighter, but for now I need plenty of extra material.
I soldered the ring again,
then hammered it on a stake to a near circle.
Next I put the ring on a lathe chuck, and used some copper shims to lift the ring off the front of the chuck to give a bit of space for the cutter to get at all of the outside of the ring. I take the shims out before the piece is turned, otherwise they could shoot across the room!
Here I am turning the outside of the ring,
I cut the front of the ring too
I then take the ring off the chuck and reposition it to cut the inside of the ring and, also, the other face. The ring now matches the outside diameter of the middle section with plenty of material for cutting the watch glass shelf