When I was building specialized glass tube forming machinery we used a 3/4 dia dowel with a 1 inch square "pad" of scotchbrite red hot melt glued on the end. My machinist programed a grid pattern in our prototrack cnc mill & let her do all of the work. Cheating at its best! Looks good after black anodizing.That's a tall question to answer Mark. In the beginning it is to my understanding that Engine Turning was the Craftsmens signature. It served to tell who did the work, especially in watchmaking. Now it is a little known art used for decoration. At one time the swirls were thought to help in lubrication. This is a myth because when done correctly the surface is only6 burnished. Today it is cheated with abrasives. This began when they started using lapping compound to speed the process. Look up "Rose Engines, you will be pleasantly surprised.
I'm just trying to learn what this filer is/does...I just had a random thought -- what if we added a removable overarm and plunger style blade holder?? Maybe I should stop thinking.