Greetings all, I am a student of the British Horological Institute DLC and new to this club. I have a question about Pivot defects and how they occur. From what I understand there are 4 types of defects: Undercut shoulder, Rounded Shoulder,Rounded Pivot Root,Undercut(or Necked)Pivot.

I understand ware and friction. However since the pivots are hardened and the bearing surface the pivot rides in is softer metal how is it possible for each of these defects occur? One would think the softer metal metal would ware away before the hardened metal.

Regards

Denny

Dirt and debris in the area becomes impregnated in the softer material giving it the abrasive property of sandpaper.

I asked this at a young age when my father and I were looking at an antique thrashing machine, it had steel shafts riding in oak bearings, the bearings were fine but the shafts heavily worn. Dad always had the answers

Paul. Never could understand why they didn't make the bearing out of hard, good quality material and then put a replaceable sleeve over the pinion. If there was just some way to take the load off the parts it would also help.