Good to see you here Jack,
1mm diameter is beginning to get down there in size. As you move into smaller clocks and larger watches you’ll find that holding close tolerances in your tooling becomes more important. At these smaller sizes applied drill jigs (flags) should be made of steel and all bearing surfaces, such as the champfer used for locating the end of an arbor, should be polished smooth. If using a high carbon steel then hardening and polishing these tools will serve you well. Spade rather than twist drills are also better to use when dealing with smaller arbors. To test the hardness you can draw a fine jewelers file across the end of the arbor to see if it “cuts” the metal. If not then you will need to anneal this section of the arbor before drilling. Also if pivoting smaller pieces is new to you then it’s probably a good idea to practice on a few scrap arbors or tiny pieces of steel before tackling that arbor to get a feeling for the tooling.
Good luck and please let us know how it goes Jack,