At the base of the spindle, my reels have a thrust washer. It is meant to take any axial forces generated during cranking.
If this washer is thicker on one side than on the other, the spindle will not sit square with the frame, possibly leading to a rub.
I make the washer from phosphor bronze rod. Working with sheet material would be quite a different process.
With the raw material chucked, the O.D. and the working face can be turned. This is the time to finely sand the working face.
I put the washer in a pot chuck to ream the bore.
If the washer were thick enough, this chucking would be a good time to turn the back side. But I need a washer that is only 0.031 inch thick. It would flex if turned, making the washer thicker in the middle than at the edges.