Basically what Eddie said. My Taper bar is set to be over size at both ends.
Over 13mm or .526, if I remember and over at the joint end. Altho, I prefer my joint ends approx .842, one has to leave them over in case someone else needs a shaft with a larger diameter.
When it comes to the final hand sanding, I follow what most will do. Use a full sheet of paper. That way, holding the paper correctly, obviously more contact between the paper and shaft wood. Sometimes, depending on what you are doing, a half sheet will suffice.
Obviously much less chance of putting a roll in the shaft.
Most of the time, I have pulled a taper back a bit for a person, leaving the original tip diameter the same.
Changing the diameter of the tip for a person is also a fairly straight forward job.
Keep in mind that either job is not, or shouldn't be performed all at once. Just like cutting a dowel from the beginning, you can't take off too much at one time.
Depending on how much is coming off, it should be done over a period of time as to not warp the shaft.
Joey probably knows how to take a roll out, or attempt it. I have a basic idea but not 100% on it so wouldn't tell a customer that I can.
I made a simple Warp taker Outter used with surgical tubing. I have had varying amounts of success with it.
The way I tell it to a customer. I don't charge for it as it is pretty much zero time involved on my behalf, other than setting it up in the first place.
I let them know that I will give it a whirl. The outcome unknown and even if there is some amount or 100% success, there is no guarantee that it will stay that way for any length of time.
So, it pretty much gets me a free beer, the next time I see the person.
There is only one thing better than a paid for beer, and that is a free one. My time is worth at least that much.