It was difficult to reduce the stem from 1.2 to 0,9 mm. I broke in the way one stem and a tool to make the thread. The ring was impress in a 3D printer by a friend. The case came from AliExpress. Movement serviced by me, including the change of the balance staff.
Tips to reduce the stem:
1. Cut the stem to an approximate measurement before distempering it. If you do this afterward, it will bend instead of splitting.
2. Distemper the stem by getting a dull red in the fire and remove slowly from the heat to reduce slowly the temperature. If you get a bright red the steel will become brittle
3. Use a tool Dremel or similar and a file to reduce the diameter of the stem from 1.2 to 0.88.
4. Use the tool for make the threads and cutting oil to rethread the stem. Go one turn forward and half backward.
