Creating a dial chart or circular calculator

[unkaduck]

We've all seen them....dial charts, circle calculators.....also known as volvelles....mortgage calculators are the simplest, more difficult ones deal with steel and pipe sizes, gear ratios/vehicle speed/tire size. Used for centuries in astronomy, crop planning etc. How are these designed? How is the information converted so it reads correctly on a calculating wheel or slide chart. Is there software available or is it a mathmatical process tailored to specific needs of the dial chart goal? I am interested in a design that uses two pieces of information to calculate a third such as gas mileage (gallons, miles driven, miles per gallon). Can anyone steer me in the right direction for software or help. Thanks-

 

[wjm11]

.dial charts, circle calculators... ...(gallons, miles driven, miles per gallon)

If what you want is a circular slide rule, you might check out the Wikipedia entry:

http://en.wikipedia.org/wiki/Slide_rule

Multiplication and division (mi/gal = mpg) are accomplished by sliding two log scales along side each other.

Hope that helps.