This mainspring barrel arbor belongs to a Langendorf 1 ladies watch. The diameter of the drill was .50mm. You can see that the center was not perfect, and the drill wobbled a bit. This is bad form, worthy of critique, but the drill was small enough that I did not cut into the threads at all, so it worked out.

Thanks for watching



The video referenced about making a drill bit.
   • Making a .12mm carbide drill bit for ...