Non-eccentric devices

A method of forming a extension rotor and a chamber rotor in a non-eccentric device, comprising:

• selecting a compression ratio for the non-eccentric device;
• calculating a curve of one side of an extension on the extension rotor comprising selecting a value for Theta—1 wherein Theta—1 corresponds to the selected compression ratio:
• repeatedly solving equations:
• X=[A+C] Cos(Theta−Theta—1)−[C] Cos(([A+C]/[C])Theta),
• and
• Y=[A+C] Sin(Theta−Theta—1)−[C] Sin(([A+C]/[C])Theta),
• where A=chamber rotor radius, C=extension rotor radius and Theta has a starting value of zero radians, by positively incrementing Theta:
• and then calculating a curve of an other side of the extension on the extension rotor comprising repeatedly solving equations:
• X=[A+C] Cos(Theta+Theta—1)−[C] Cos(([A+C]/[C])Theta),
• and
• Y=[A+C] Sin(Theta+Theta—1)−[C] Sin(([A+C]/[C])Theta),
• where A=chamber rotor radius, C=extension rotor radius and Theta has a starting value of zero radians, by negatively incrementing Theta;
• calculating a curve of a chamber of the chamber rotor;
• shaping the chamber rotor from a chamber rotor blank by removing material from the chamber rotor blank from inside the calculated curve of the chamber to form one or more chambers;
• and
• shaping the extension rotor from an extension rotor blank by removing material from the extension rotor blank from outside the calculated curves of the sides of the an extension to form one or more extensions.