Richard Raffan's book 'Turning Bowls' has a small section at the back on selling one's bowls. In the section he describes a rule of thumb he uses to calculate how long it takes to make a bowl. His cost for his time + current value of raw materials + something for fixed costs = the price he sets.
His rule of thumb for turning time assumes you start with seasoned wood. The rule says to multipliy the diameter of the bowl by the height. That number is the number of minutes it takes to make a bowl and is used in calculating how much to charge.
I recently timed how long it took to turn several oak bowls and the time they took was two to three times the number I got multiplying diameter times height. I started with two rough bowls aged for about four months instead of a dry bowl blank cut from a dry slab of wood. Needless to say my skills are not at the expert level but I got curious how long it takes other people to make a bowl starting with a dry rough bowl or dry slab of wood.
Has anyone used Raffan's rule of thumb ?